George Air Force Base, California

Installation Restoration Program

Prepared for Air Force Center for Environmental Excellence Brooks City-Base, Texas

4P+ Services Contract Contract F41624-03-D-8608 Task Order 0032

Final Second Five-Year Review Report

December 2005 "

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION IX 75 Hawthorne Street San Francisco, CA 94105

February 6,2006

William Harris, PhD Regional Environmental Coordinator AFRP A Western Region Execution Center 3411 Olson Street McClellan, CA 95652-1003

Re: George AFB Final Five- Year Review

Dear Dr. Harris:

The Environmental Protection Agency (EPA) has received the Air Force (AF) Final Second Five- Year Review (FYR) Report dated December 2005. While we appreciate that the AF has addressed most of our concerns, we do not concur with the OUl protectiveness statement. The remedy for OUl is currently protective in the short term, however for long term protectiveness to be achieved the OUl remedy must be constructed in accordance with remedial design plans and specifications agreed to by the regulatory agencies.

As reflected in our comments included in Appendix F of the document, we remain concerned about the following issues: ( 1) the groundwater characterization at site CG- 70 is inadequatebecause it does not include necessarydata regarding depth and mass ofTCE contamination that will impact cleanup time; and (2) the discussions of Institutional Controls (IC) are incomplete becausethe AF has not provided a mechanism to ensure the effectiveness of the ICs for off base monitoring wells.

To address these issues, EPA recommends the following follow-up actions: (I) the AF should revise the OUl Remedial Design by June 2006 to address the site characterization plans for CG- 70 and (2) the AF should provide EP A with a plan for ensuring the effectiv~Ress ofICs for the offbase wells. "I;,

EP A acknowledges the Second FYR was completed for the former George AFB, and we thank the AF and staff for their cooperation in conducting this review. If you have any questions, please contact James Chang of my staff at extension (415) 972-3193.

Sinc~ly, dhJ.. II. .J ~~ f~ fW-

~thleen Johnson Chief, Federal Facilities and Site Cleanup Branch cc: Distribll;tion List ...

Distribution List:

Mr. Jeheil Cass Lahontan Regional Water Quality Control Board 14440 Civic Drive, Suite 200 Victorville, CA 92392

Mr. Calvin Cox Attn: Air Force Real Property Agency C/o Southern California Logistics Airport 18374 Phantom Way Victorville, CA 92392

Mr. Gilbert Dimidjian MWH 1340 Treat Blvd Suite 300 Walnut Creek, CA 94597-7966

Dr. Susan Soloyanis Mitretek Systems 4610 Fox Road Cascade,CO 80809

~

File: 046-finaISyr 30 December 2005

Mr. Jerry Bingham Department of the Air Force HQ AFCEE/BCW 3300 Sidney Brooks Brooks City-Base, TX 78235-5112

Subject: Transmittal of Final Second Five-Year Review Report Former George Air Force Base, Victorville, California Contract Data Requirements List No. A001

Dear Mr. Bingham:

MWH is pleased to submit the Final version of the subject document, consisting of replacement pages to be inserted in the previously distributed Draft document. The replacement instructions can be found after this transmittal. In addition, a portable document format (PDF) of the entire document has been included. Attached is a completed content checklist that was provided in the EPA guidance document. This checklist should be used to help streamline review of this document (Attachment A of this transmittal). Responses to EPA and Booz Allen Hamilton comments are provided in Appendix F.

We appreciate the opportunity to have provided this service to the Air Force and look forward to continuing to assist the Air Force with remedial activities at the former George AFB. Should you have any questions or comments, please contact Kurt Condie at (805) 560-7214 or me at (925) 975-3568.

Sincerely,

MWH

Gilbert Dimidjian Project Manager

Enc.

Distribution (attached)

1340 Treat Blvd. Tel: 925 933 2250 / 925 975 3400 Delivering Innovative Projects and Solutions Worldwide Suite 300 Fax: 925 945 1760 / 925 975 3412 Walnut Creek, California 94597-7966 DISTRIBUTION LIST Final Second Five-Year Review Report

Jerry Bingham – 2 copies Dept. of the Air Force HQ AFCEE/BCW 3300 Sidney Brooks Brooks City-Base, TX 78235-5112 (210) 536-4002

Jay Cass – 1 copy California RWQCB, Lahontan Office 14440 Civic Drive, Suite 200 Victorville, CA 92392 (760) 241-2434

James Chang – 3 copies USEPA, Region 9 SF08-1 75 Hawthorne Street San Francisco, CA 94105 (415) 972-3193

Calvin Cox – 3 copies C/O Southern California Logistics Airport Attn: Air Force Real Property Agency 18374 Phantom West Street Victorville, CA 92392 (760) 246-5360

Phil Mook and Bill Harris – 3 copies AFRPA/Western REC 3411 Olson Street McClellan AFB, CA 95652 (916) 643-6420

Susan Soloyanis - 1 copy Mitretek Systems 4610 Fox Road Cascade, CO 80809 (719) 684-0924

Bill Mabey – 1 copy TechLaw, Inc. 90 New Montgomery Street, Suite 1010 San Francisco, CA 94105 (415) 281-8730 Attachment A Content Checklist for the Second Five-Year Review Report Former George Air Force Base

General Report Format Location in 5-Year Review Document by Section † Signed concurrence memorandum (as Pending appropriate) † Title page with signature and date Pending † Completed five-year review summary form Before Executive Summary † List of documents reviewed Appendix A † Site maps (as appropriate) Figures Section † List of tables and figures TOC † Interview report (as appropriate) Appendix B † Site inspection checklist Appendix C † Photos documenting site conditions (as Photographs have not been appropriate) included Introduction 1.0 † The purpose of the five-year review 1.0 † Authority for conducting the five-year review 1.0 † Who conducted the five-year review (lead 1.0 agency) and when † Organizations providing analyses in support 1.0 of the review (e.g., the contractor supporting the lead agency ) † Other review participants or support agencies 4.1.2 and 5.1-10.2 † Review number (e.g., first, second) 1.0 † Trigger action and date 1.0 † Number, description, and status of all operable Table ES-1, Sections 1.0 and units at the site 3.2 † If review covers only part of a site, explain 1.0 approach † Define which areas are covered in the five- 1.0 year review † Summarize the status of other areas of the 1.0 and 3.2 site that are not covered in the present five- year Site Chronology Section 2.0, Tables 2-1, 2-2 † List all important site events and relevant dates (e.g., date of initial discovery of problem, dates of pre-NPL responses, date of NPL listing, etc.) Section 4 – OU1 Background 1.0, 3.0 and 4.0 † General site description (e.g., size, topography, and 3.0 and 4.1 geology) † Former, current, and future land use(s) of the site 4.1

Page 1 of 36 Attachment A Content Checklist for the Second Five-Year Review Report Former George Air Force Base

and surrounding areas † History of contamination 4.1 † Initial response (e.g., removals) 4.1 † Basis for taking remedial action (e.g., 4.1 contaminants) Remedial Actions Regulatory actions (e.g., date and description of 4.0 and 4.1 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 4.1.1.1 † Remedy description 4.1.1.1 † Remedy implementation (e.g., status, history, 4.1.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 4.1.1.3 † Systems operations/O&M requirements 4.1.1.3 † Systems operations/O&M operational 4.1.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 4.1.1.3 and 4.1.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 4.1.1.4 † Protectiveness statements from last review 4.1.1.4 † Status of recommendations and follow-up 4.1.1.4 actions from last review † Results of implemented actions, including 4.1.1.4 whether they achieved the intended effect † Status of any other prior issues 4.1.1.4 Five-Year Review Process 4.1.2 † Administrative Components 4.1.2 † Notification of potentially interested parties of 4.1.2 initiation of review process † Identification of five-year review team members (as 4.1.2 appropriate) † Outline of components and schedule of your 4.1.2 five-year review † Community Involvement 4.1.2 † Community notification (prior and post 4.1.2 review) † Other community involvement activities 4.1.2 (e.g., notices, fact sheets, etc., as appropriate)

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† Document review 4.1.3 † Data review 4.1.3.4 † Site inspection 4.1.3.2 † Inspection date 4.1.3.2 † Inspection participants 4.1.3.2 † Site inspection scope and procedures 4.1.3.2 † Site inspection results, conclusions 4.1.3.2 † Inspection checklist Appendix C † Interviews 4.1.3.1 † Interview date(s) and location(s) 4.1.3.1 † Interview participants (name, title, etc.) 4.1.3.1 † Interview documentation Appendix B † Interview summary 4.1.3.1 Technical Assessment 4.1.4 † Answer Question A: Is the remedy functioning 4.1.4.1 A as intended by the decision documents? † remedial action performance (i.e., is the 4.1.4 remedy operating as designed?) † system operations/O&M 4.1.4 † cost of system operations/O&M 4.1.4 † opportunities for optimization 4.1.4 † early indicators of potential issues 4.1.4 † implementation of institutional controls and 4.1.4 other measures † Answer Question B: Are the exposure 4.1.4.1 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 4.1.4 standards, TBCs † expected progress towards meeting RAOs 4.1.4 † changes in exposure pathways 4.1.4 † changes in land use 4.1.4 † new contaminants and/or contaminant 4.1.4 sources † remedy byproducts 4.1.4 † changes in toxicity and other contaminant 4.1.4 characteristics † risk recalculation/assessment (as applicable) 4.1.4 † Answer Question C: Has any other information 4.1.4.1 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 4.1.4

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risks † natural disaster impacts 4.1.4 † any other information that could call into 4.1.4 question the protectiveness of the remedy † Technical Assessment Summary 4.1.4.1 Issues 4.1.5 † Issues identified during the technical assessment 4.1.5 and other five-year review activities † Determination of whether issues affect current or 4.1.5 future protectiveness † A discussion of unresolved issues raised by 4.1.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 4.1.6 † Required/suggested improvements to identified 4.1.6 issues or to current site operations † Note parties responsible for actions 4.1.6 † Note agency with oversight authority 4.1.6 † Schedule for completion of actions related to 4.1.6 resolution of issues Protectiveness Statements 4.1.7 † Protective statement(s) for each OU (If the 4.1.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 4.1.7 covering all of the remedies at the site (if applicable) Next Review 4.1.8 † Expected date of next review 4.1.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

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Section 5.0 – OU3 Section 5.1: Site DP-03 1.0, 3.0 and 5.1 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1, 5.1 geology) † Former, current, and future land use(s) of the site 5.1 and surrounding areas † History of contamination 5.1 † Initial response (e.g., removals) 5.1 † Basis for taking remedial action (e.g., 5.1 contaminants) Remedial Actions 5.1.1 Regulatory actions (e.g., date and description of 5.1.1.1 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.1.1.1 † Remedy description 5.1.1.1 † Remedy implementation (e.g., status, history, 5.1.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.1.1.3 † Systems operations/O&M requirements 5.1.1.3 † Systems operations/O&M operational 5.1.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.1.1.3 and 5.1.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.1.1.4 † Protectiveness statements from last review 5.1.1.4 † Status of recommendations and follow-up 5.1.1.4 actions from last review † Results of implemented actions, including 5.1.1.4 whether they achieved the intended effect † Status of any other prior issues 5.1.1.4 Five-Year Review Process 5.1.2 † Administrative Components 5.1.2 † Notification of potentially interested parties of 5.1.2 initiation of review process † Identification of five-year review team members (as 5.1.2 appropriate) † Outline of components and schedule of your 5.1.2

Page 5 of 36 Attachment A Content Checklist for the Second Five-Year Review Report Former George Air Force Base

five-year review † Community Involvement 5.1.2 † Community notification (prior and post 5.1.2 review) † Other community involvement activities 5.1.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.1.3 † Data review 5.1.3.4 † Site inspection 5.1.3.2 † Inspection date 5.1.3.2 † Inspection participants 5.1.3.2 † Site inspection scope and procedures 5.1.3.2 † Site inspection results, conclusions 5.1.3.2 † Inspection checklist Appendix C † Interviews 5.1.3.1 † Interview date(s) and location(s) 5.1.3.1 † Interview participants (name, title, etc.) 5.1.3.1 † Interview documentation Appendix B † Interview summary 5.1.3.1 Technical Assessment 5.1.4 † Answer Question A: Is the remedy functioning 5.1.4. A as intended by the decision documents? † remedial action performance (i.e., is the 5.1.4 remedy operating as designed?) † system operations/O&M 5.1.4 † cost of system operations/O&M 5.1.4 † opportunities for optimization 5.1.4 † early indicators of potential issues 5.1.4 † implementation of institutional controls and 5.1.4 other measures † Answer Question B: Are the exposure 5.1.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.1.4 standards, TBCs † expected progress towards meeting RAOs 5.1.4 † changes in exposure pathways 5.1.4 † changes in land use 5.1.4 † new contaminants and/or contaminant 5.1.4 sources † remedy byproducts 5.1.4 † changes in toxicity and other contaminant 5.1.4

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characteristics † risk recalculation/assessment (as applicable) 5.1.4 † Answer Question C: Has any other information 5.1.4. C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.1.4 risks † natural disaster impacts 5.1.4 † any other information that could call into 5.1.4 question the protectiveness of the remedy † Technical Assessment Summary 5.1.4.1 Issues 5.1.5 † Issues identified during the technical assessment 5.1.5 and other five-year review activities † Determination of whether issues affect current or 5.1.5 future protectiveness † A discussion of unresolved issues raised by 5.1.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.1.6 † Required/suggested improvements to identified 5.1.6 issues or to current site operations † Note parties responsible for actions 5.1.6 † Note agency with oversight authority 5.1.6 † Schedule for completion of actions related to 5.1.6 resolution of issues Protectiveness Statements 5.1.7 † Protective statement(s) for each OU (If the 5.1.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.1.7 covering all of the remedies at the site (if applicable) Next Review 5.1.8 † Expected date of next review 5.1.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the

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technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.0 – OU3 (continued) Section 5.2: Site DP-04 1.0, 3.0 and 5.2 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1, 5.2 geology) † Former, current, and future land use(s) of the site Section 5.2 and surrounding areas † History of contamination Section 5.2 † Initial response (e.g., removals) Section 5.2 † Basis for taking remedial action (e.g., Section 5.2 contaminants) Remedial Actions 5.2.1 Regulatory actions (e.g., date and description of 5.2.1.1 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.2.1.1 † Remedy description 5.2.1.1 † Remedy implementation (e.g., status, history, 5.2.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.2.1.3 † Systems operations/O&M requirements 5.2.1.3 † Systems operations/O&M operational 5.2.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.2.1.4 and 5.1.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.2.1.4 † Protectiveness statements from last review 5.2.1.4 † Status of recommendations and follow-up 5.2.1.4 actions from last review † Results of implemented actions, including 5.2.1.4 whether they achieved the intended effect † Status of any other prior issues 5.2.1.4

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Five-Year Review Process 5.2.2 † Administrative Components 5.2.2 † Notification of potentially interested parties of 5.2.2 initiation of review process † Identification of five-year review team members (as 5.2.2 appropriate) † Outline of components and schedule of your 5.2.2 five-year review † Community Involvement 5.2.2 † Community notification (prior and post 5.2.2 review) † Other community involvement activities 5.2.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.2.3 † Data review 5.2.3.4 † Site inspection 5.2.3.2 † Inspection date 5.2.3.2 † Inspection participants 5.2.3.2 † Site inspection scope and procedures 5.2.3.2 † Site inspection results, conclusions 5.2.3.2 † Inspection checklist Appendix C † Interviews 5.2.3.1 † Interview date(s) and location(s) 5.2.3.1 † Interview participants (name, title, etc.) 5.2.3.1 † Interview documentation Appendix B † Interview summary 5.2.3.1 Technical Assessment 5.2.4 † Answer Question A: Is the remedy functioning 5.2.4 A as intended by the decision documents? † remedial action performance (i.e., is the 5.2.4 remedy operating as designed?) † system operations/O&M 5.2.4 † cost of system operations/O&M 5.2.4 † opportunities for optimization 5.2.4 † early indicators of potential issues 5.2.4 † implementation of institutional controls and 5.2.4 other measures † Answer Question B: Are the exposure 5.2.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.2.4 standards, TBCs

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† expected progress towards meeting RAOs 5.2.4 † changes in exposure pathways 5.2.4 † changes in land use 5.2.4 † new contaminants and/or contaminant 5.2.4 sources † remedy byproducts 5.2.4 † changes in toxicity and other contaminant 5.2.4 characteristics † risk recalculation/assessment (as applicable) 5.2.4 † Answer Question C: Has any other information 5.2.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.2.4 risks † natural disaster impacts 5.2.4 † any other information that could call into 5.2.4 question the protectiveness of the remedy † Technical Assessment Summary 5.2.4.1 Issues 5.2.5 † Issues identified during the technical assessment 5.2.5 and other five-year review activities † Determination of whether issues affect current or 5.2.5 future protectiveness † A discussion of unresolved issues raised by 5.2.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.2.6 † Required/suggested improvements to identified 5.2.6 issues or to current site operations † Note parties responsible for actions 5.2.6 † Note agency with oversight authority 5.2.6 † Schedule for completion of actions related to 5.2.6 resolution of issues Protectiveness Statements 5.2.7 † Protective statement(s) for each OU (If the 5.2.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?)

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† Comprehensive protectiveness statement 5.2.7 covering all of the remedies at the site (if applicable) Next Review 5.2.8 † Expected date of next review 5.2.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.3: Site LF-12 1.0, 3.0 and 5.3 Background † General site description (e.g., size, topography, and Section 3.1.1, 3.2.1, 5.3 geology) † Former, current, and future land use(s) of the site Section 5.3 and surrounding areas † History of contamination Section 5.3 † Initial response (e.g., removals) Section 5.3 † Basis for taking remedial action (e.g., Section 5.3 contaminants) Remedial Actions 5.3.1 Regulatory actions (e.g., date and description of 5.3 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.3.1.1 † Remedy description 5.3.1.1 † Remedy implementation (e.g., status, history, 5.3.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.3.1.3 † Systems operations/O&M requirements 5.3.1.3 † Systems operations/O&M operational 5.3.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.3.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.3.1.4

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† Protectiveness statements from last review 5.3.1.4 † Status of recommendations and follow-up 5.3.1.4 actions from last review † Results of implemented actions, including 5.3.1.4 whether they achieved the intended effect † Status of any other prior issues 5.3.1.4 Five-Year Review Process 5.3.2 † Administrative Components 5.3.2 † Notification of potentially interested parties of 5.3.2 initiation of review process † Identification of five-year review team members (as 5.3.2 appropriate) † Outline of components and schedule of your 5.3.2 five-year review † Community Involvement 5.3.2 † Community notification (prior and post 5.3.2 review) † Other community involvement activities 5.3.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.3.3 † Data review 5.3.3.4 † Site inspection 5.3.3.2 † Inspection date 5.3.3.2 † Inspection participants 5.3.3.2 † Site inspection scope and procedures 5.3.3.2 † Site inspection results, conclusions 5.3.3.2 † Inspection checklist Appendix C † Interviews 5.3.3.1 † Interview date(s) and location(s) 5.3.3.1 † Interview participants (name, title, etc.) 5.3.3.1 † Interview documentation Appendix B † Interview summary 5.3.3.1 Technical Assessment 5.3.4 † Answer Question A: Is the remedy functioning 5.3.4 A as intended by the decision documents? † remedial action performance (i.e., is the 5.3.4 remedy operating as designed?) † system operations/O&M 5.3.4 † cost of system operations/O&M 5.3.4 † opportunities for optimization 5.3.4 † early indicators of potential issues 5.3.4 † implementation of institutional controls and 5.3.4 other measures

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† Answer Question B: Are the exposure 5.3.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.3.4 standards, TBCs † expected progress towards meeting RAOs 5.3.4 † changes in exposure pathways 5.3.4 † changes in land use 5.3.4 † new contaminants and/or contaminant 5.3.4 sources † remedy byproducts 5.3.4 † changes in toxicity and other contaminant 5.3.4 characteristics † risk recalculation/assessment (as applicable) 5.3.4 † Answer Question C: Has any other information 5.3.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.3.4 risks † natural disaster impacts 5.3.4 † any other information that could call into 5.3.4 question the protectiveness of the remedy † Technical Assessment Summary 5.3.4.1 Issues 5.3.5 † Issues identified during the technical assessment 5.3.5 and other five-year review activities † Determination of whether issues affect current or 5.3.5 future protectiveness † A discussion of unresolved issues raised by 5.3.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.3.6 † Required/suggested improvements to identified 5.3.6 issues or to current site operations † Note parties responsible for actions 5.3.6 † Note agency with oversight authority 5.3.6 † Schedule for completion of actions related to 5.3.6 resolution of issues Protectiveness Statements 5.3.7

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† Protective statement(s) for each OU (If the 5.3.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.3.7 covering all of the remedies at the site (if applicable) Next Review 5.3.8 † Expected date of next review 5.3.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.4: Site LF-14 1.0, 3.0 and 5.4 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1, 5.4 geology) † Former, current, and future land use(s) of the site 5.4 and surrounding areas † History of contamination 5.4 † Initial response (e.g., removals) 5.4 † Basis for taking remedial action (e.g., 5.4 contaminants) Remedial Actions 5.4.1 Regulatory actions (e.g., date and description of 5.4 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.4.1.1 † Remedy description 5.4.1.1 † Remedy implementation (e.g., status, history, 5.4.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.4.1.3 † Systems operations/O&M requirements 5.4.1.3 † Systems operations/O&M operational 5.4.1.3

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summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.4.1.3 and 5.4.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.4.1.4 † Protectiveness statements from last review 5.4.1.4 † Status of recommendations and follow-up 5.4.1.4 actions from last review † Results of implemented actions, including 5.4.1.4 whether they achieved the intended effect † Status of any other prior issues 5.4.1.4 Five-Year Review Process 5.4.2 † Administrative Components 5.4.2 † Notification of potentially interested parties of 5.4.2 initiation of review process † Identification of five-year review team members (as 5.4.2 appropriate) † Outline of components and schedule of your 5.4.2 five-year review † Community Involvement 5.4.2 † Community notification (prior and post 5.4.2 review) † Other community involvement activities 5.4.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.4.3 † Data review 5.4.3.4 † Site inspection 5.4.3.2 † Inspection date 5.4.3.2 † Inspection participants 5.4.3.2 † Site inspection scope and procedures 5.4.3.2 † Site inspection results, conclusions 5.4.3.2 † Inspection checklist Appendix C † Interviews 5.4.3.1 † Interview date(s) and location(s) 5.4.3.1 † Interview participants (name, title, etc.) 5.4.3.1 † Interview documentation Appendix B † Interview summary 5.4.3.1 Technical Assessment 5.4.4 † Answer Question A: Is the remedy functioning 5.4.4.1 A as intended by the decision documents? † remedial action performance (i.e., is the 5.4.4

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remedy operating as designed?) † system operations/O&M 5.4.4 † cost of system operations/O&M 5.4.4 † opportunities for optimization 5.4.4 † early indicators of potential issues 5.4.4 † implementation of institutional controls and 5.4.4 other measures † Answer Question B: Are the exposure 5.4.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.4.4 standards, TBCs † expected progress towards meeting RAOs 5.4.4 † changes in exposure pathways 5.4.4 † changes in land use 5.4.4 † new contaminants and/or contaminant 5.4.4 sources † remedy byproducts 5.4.4 † changes in toxicity and other contaminant 5.4.4 characteristics † risk recalculation/assessment (as applicable) 5.4.4 † Answer Question C: Has any other information 5.4.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.4.4 risks † natural disaster impacts 5.4.4 † any other information that could call into 5.4.4 question the protectiveness of the remedy † Technical Assessment Summary 5.4.4.1 Issues 5.4.5 † Issues identified during the technical assessment 5.4.5 and other five-year review activities † Determination of whether issues affect current or 5.4.5 future protectiveness † A discussion of unresolved issues raised by 5.4.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.4.6

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† Required/suggested improvements to identified 5.4.6 issues or to current site operations † Note parties responsible for actions 5.4.6 † Note agency with oversight authority 5.4.6 † Schedule for completion of actions related to 5.4.6 resolution of issues Protectiveness Statements 5.4.7 † Protective statement(s) for each OU (If the 5.4.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.4.7 covering all of the remedies at the site (if applicable) Next Review 5.4.8 † Expected date of next review 5.4.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.5: Site LF-44 1.0, 3.0 and 5.5 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1,5.5 geology) † Former, current, and future land use(s) of the site 5.5 and surrounding areas † History of contamination 5.5 † Initial response (e.g., removals) 5.5 † Basis for taking remedial action (e.g., 5.5 contaminants) Remedial Actions 5.5.1 Regulatory actions (e.g., date and description of 5.5.1 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum)

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† Remedial action objectives 5.5.1.1 † Remedy description 5.5.1.1 † Remedy implementation (e.g., status, history, 5.5.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.5.1.3 † Systems operations/O&M requirements 5.5.1.3 † Systems operations/O&M operational 5.5.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.5.1.3 and 5.5.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.5.1.4 † Protectiveness statements from last review 5.5.1.4 † Status of recommendations and follow-up 5.5.1.4 actions from last review † Results of implemented actions, including 5.5.1.4 whether they achieved the intended effect † Status of any other prior issues 5.5.1.4 Five-Year Review Process 5.5.2 † Administrative Components 5.5.2 † Notification of potentially interested parties of 5.5.2 initiation of review process † Identification of five-year review team members (as 5.5.2 appropriate) † Outline of components and schedule of your 5.5.2 five-year review † Community Involvement 5.5.2 † Community notification (prior and post 5.5.2 review) † Other community involvement activities 5.5.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.5.3 † Data review 5.5.3.4 † Site inspection 5.5.3.2 † Inspection date 5.5.3.2 † Inspection participants 5.5.3.2 † Site inspection scope and procedures 5.5.3.2 † Site inspection results, conclusions 5.5.3.2 † Inspection checklist Appendix C † Interviews 5.5.3.1 † Interview date(s) and location(s) 5.5.3.1

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† Interview participants (name, title, etc.) 5.5.3.1 † Interview documentation Appendix B † Interview summary 5.5.3.1 Technical Assessment 5.5.4 † Answer Question A: Is the remedy functioning 5.5.4 A as intended by the decision documents? † remedial action performance (i.e., is the 5.5.4 remedy operating as designed?) † system operations/O&M 5.5.4 † cost of system operations/O&M 5.5.4 † opportunities for optimization 5.5.4 † early indicators of potential issues 5.5.4 † implementation of institutional controls and 5.5.4 other measures † Answer Question B: Are the exposure 5.5.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.5.4 standards, TBCs † expected progress towards meeting RAOs 5.5.4 † changes in exposure pathways 5.5.4 † changes in land use 5.5.4 † new contaminants and/or contaminant 5.5.4 sources † remedy byproducts 5.5.4 † changes in toxicity and other contaminant 5.5.4 characteristics † risk recalculation/assessment (as applicable) 5.5.4 † Answer Question C: Has any other information 5.5.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.5.4 risks † natural disaster impacts 5.5.4 † any other information that could call into 5.5.4 question the protectiveness of the remedy † Technical Assessment Summary 5.5.4.1 Issues † Issues identified during the technical assessment 5.5.5 and other five-year review activities † Determination of whether issues affect current or 5.5.5 future protectiveness

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† A discussion of unresolved issues raised by 5.5.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.5.6 † Required/suggested improvements to identified 5.5.6 issues or to current site operations † Note parties responsible for actions 5.5.6 † Note agency with oversight authority 5.5.6 † Schedule for completion of actions related to 5.5.6 resolution of issues Protectiveness Statements 5.5.7 † Protective statement(s) for each OU (If the 5.5.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.5.7 covering all of the remedies at the site (if applicable) Next Review 5.5.8 † Expected date of next review 5.5.8 † If five-year reviews will no longer be done, provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.6: SEDA 1.0, 3.0 and 5.6 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1, 5.5 geology) † Former, current, and future land use(s) of the site 5.6 and surrounding areas † History of contamination 5.6 † Initial response (e.g., removals) 5.6 † Basis for taking remedial action (e.g., 5.6 contaminants)

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Remedial Actions 5.6.1 Regulatory actions (e.g., date and description of 5.6 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.6.1.1 † Remedy description 5.6.1.1 † Remedy implementation (e.g., status, history, 5.6.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.6.1.3 † Systems operations/O&M requirements 5.6.1.3 † Systems operations/O&M operational 5.6.1.3 and 5.6.4 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.6.1.3 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.6.1.4 † Protectiveness statements from last review 5.6.1.4 † Status of recommendations and follow-up 5.6.1.4 actions from last review † Results of implemented actions, including 5.6.1.4 whether they achieved the intended effect † Status of any other prior issues 5.6.1.4 Five-Year Review Process 5.6.2 † Administrative Components 5.6.2 † Notification of potentially interested parties of 5.6.2 initiation of review process † Identification of five-year review team members (as 5.6.2 appropriate) † Outline of components and schedule of your 5.6.2 five-year review † Community Involvement 5.6.2 † Community notification (prior and post 5.6.2 review) † Other community involvement activities 5.6.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.6.3 † Data review 5.6.3.4 † Site inspection 5.6.3.2 † Inspection date 5.6.3.2 † Inspection participants 5.6.3.2

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† Site inspection scope and procedures 5.6.3.2 † Site inspection results, conclusions 5.6.3.2 † Inspection checklist Appendix C † Interviews 5.6.3.1 † Interview date(s) and location(s) 5.6.3.1 † Interview participants (name, title, etc.) 5.6.3.1 † Interview documentation Appendix B † Interview summary 5.6.3.1 Technical Assessment 5.6.4 † Answer Question A: Is the remedy functioning 5.6.4 A as intended by the decision documents? † remedial action performance (i.e., is the 5.6.4 remedy operating as designed?) † system operations/O&M 5.6.4 † cost of system operations/O&M 5.6.4 † opportunities for optimization 5.6.4 † early indicators of potential issues 5.6.4 † implementation of institutional controls and 5.6.4 other measures † Answer Question B: Are the exposure 5.6.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.6.4 standards, TBCs † expected progress towards meeting RAOs 5.6.4 † changes in exposure pathways 5.6.4 † changes in land use 5.6.4 † new contaminants and/or contaminant 5.6.4 sources † remedy byproducts 5.6.4 † changes in toxicity and other contaminant 5.6.4 characteristics † risk recalculation/assessment (as applicable) 5.6.4 † Answer Question C: Has any other information 5.6.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.6.4 risks † natural disaster impacts 5.6.4 † any other information that could call into 5.6.4 question the protectiveness of the remedy † Technical Assessment Summary 5.6.4.1

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Issues 5.6.5 † Issues identified during the technical assessment 5.6.5 and other five-year review activities † Determination of whether issues affect current or 5.6.5 future protectiveness † A discussion of unresolved issues raised by 5.6.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.6.6 † Required/suggested improvements to identified 5.6.6 issues or to current site operations † Note parties responsible for actions 5.6.6 † Note agency with oversight authority 5.6.6 † Schedule for completion of actions related to 5.6.6 resolution of issues Protectiveness Statements 5.6.7 † Protective statement(s) for each OU (If the 5.6.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.6.7 covering all of the remedies at the site (if applicable) Next Review 5.6.8 † Expected date of next review 5.6.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.7: Site FT-19 1.0, 3.0 and 5.7 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1, 5.7

Page 23 of 36 Attachment A Content Checklist for the Second Five-Year Review Report Former George Air Force Base geology) † Former, current, and future land use(s) of the site 5.7 and surrounding areas † History of contamination 5.7 † Initial response (e.g., removals) 5.7 † Basis for taking remedial action (e.g., 5.7 contaminants) Remedial Actions 5.7.1 Regulatory actions (e.g., date and description of 5.7 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.7.1.1 † Remedy description 5.7.1.1 † Remedy implementation (e.g., status, history, 5.7.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.7.1.3 † Systems operations/O&M requirements 5.7.1.3 † Systems operations/O&M operational 5.7.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.7.1.3 and 5.7.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.7.1.4 † Protectiveness statements from last review 5.7.1.4 (1st paragraph) † Status of recommendations and follow-up 5.7.1.4 actions from last review † Results of implemented actions, including 5.7.1.4 whether they achieved the intended effect † Status of any other prior issues 5.7.1.4 Five-Year Review Process 5.7.2 † Administrative Components 5.7.2 † Notification of potentially interested parties of 5.7.2 initiation of review process † Identification of five-year review team members (as 5.7.2 appropriate) † Outline of components and schedule of your 5.7.2 five-year review † Community Involvement 5.7.2 † Community notification (prior and post 5.7.2 review)

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† Other community involvement activities 5.7.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.7.3 † Data review 5.7.3.4 † Site inspection 5.7.3.2 † Inspection date 5.7.3.2 † Inspection participants 5.7.3.2 † Site inspection scope and procedures 5.7.3.2 † Site inspection results, conclusions 5.7.3.2 † Inspection checklist Appendix C † Interviews 5.7.3.1 † Interview date(s) and location(s) 5.7.3.1 † Interview participants (name, title, etc.) 5.7.3.1 † Interview documentation Appendix B † Interview summary 5.7.3.1 Technical Assessment † Answer Question A: Is the remedy functioning 5.7.4 A as intended by the decision documents? † remedial action performance (i.e., is the 5.7.4 remedy operating as designed?) † system operations/O&M 5.7.4 † cost of system operations/O&M 5.7.4 † opportunities for optimization 5.7.4 † early indicators of potential issues 5.7.4 † implementation of institutional controls and 5.7.4 other measures † Answer Question B: Are the exposure 5.7.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.7.4 standards, TBCs † expected progress towards meeting RAOs 5.7.4 † changes in exposure pathways 5.7.4 † changes in land use 5.7.4 † new contaminants and/or contaminant 5.7.4 sources † remedy byproducts 5.7.4 † changes in toxicity and other contaminant 5.7.4 characteristics † risk recalculation/assessment (as applicable) 5.7.4 † Answer Question C: Has any other information 5.7.4 C come to light that could call into question the

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protectiveness of the remedy? † new or previously unidentified ecological 5.7.4 risks † natural disaster impacts 5.7.4 † any other information that could call into 5.7.4 question the protectiveness of the remedy † Technical Assessment Summary 5.7.4.1 Issues 5.7.5 † Issues identified during the technical assessment 5.7.5 and other five-year review activities † Determination of whether issues affect current or 5.7.5 future protectiveness † A discussion of unresolved issues raised by 5.7.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.7.6 † Required/suggested improvements to identified 5.7.6 issues or to current site operations † Note parties responsible for actions 5.7.6 † Note agency with oversight authority 5.7.6 † Schedule for completion of actions related to 5.7.6 resolution of issues Protectiveness Statements 5.7.7 † Protective statement(s) for each OU (If the 5.7.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.7.7 covering all of the remedies at the site (if applicable) Next Review 5.7.8 † Expected date of next review 5.7.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

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Section 5.8: Site OT-51 1.0, 3.0 and 5.8 Background † General site description (e.g., size, topography, and Section 3.1.1, 3.2.1, 5.8 geology) † Former, current, and future land use(s) of the site Section 5.8 and surrounding areas † History of contamination Section 5.8 † Initial response (e.g., removals) Section 5.8 † Basis for taking remedial action (e.g., Section 5.8 contaminants) Remedial Actions 5.8.1 Regulatory actions (e.g., date and description of 5.8 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.8.1.1 † Remedy description 5.8.1.1 † Remedy implementation (e.g., status, history, 5.8.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.8.1.3 † Systems operations/O&M requirements 5.8.1.3 † Systems operations/O&M operational 5.8.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.8.1.3 and 5.8.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.8.1.4 † Protectiveness statements from last review 5.8.1.4 † Status of recommendations and follow-up 5.8.1.4 actions from last review † Results of implemented actions, including 5.8.1.4 whether they achieved the intended effect † Status of any other prior issues 5.8.1.4 Five-Year Review Process 5.8.2 † Administrative Components 5.8.2 † Notification of potentially interested parties of 5.8.2 initiation of review process

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† Identification of five-year review team members (as 5.8.2 appropriate) † Outline of components and schedule of your 5.8.2 five-year review † Community Involvement 5.8.2 † Community notification (prior and post 5.8.2 review) † Other community involvement activities 5.8.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.8.3 † Data review 5.8.3.4 † Site inspection 5.8.3.2 † Inspection date 5.8.3.2 † Inspection participants 5.8.3.2 † Site inspection scope and procedures 5.8.3.2 † Site inspection results, conclusions 5.8.3.2 † Inspection checklist Appendix C † Interviews 5.8.3.1 † Interview date(s) and location(s) 5.8.3.1 † Interview participants (name, title, etc.) 5.8.3.1 † Interview documentation Appendix B † Interview summary 5.8.3.1 Technical Assessment 5.8.4 † Answer Question A: Is the remedy functioning 5.8.4 A as intended by the decision documents? † remedial action performance (i.e., is the 5.8.4 remedy operating as designed?) † system operations/O&M 5.8.4 † cost of system operations/O&M 5.8.4 † opportunities for optimization 5.8.4 † early indicators of potential issues 5.8.4 † implementation of institutional controls and 5.8.4 other measures † Answer Question B: Are the exposure 5.8.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.8.4 standards, TBCs † expected progress towards meeting RAOs 5.8.4 † changes in exposure pathways 5.8.4 † changes in land use 5.8.4 † new contaminants and/or contaminant 5.8.4

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sources † remedy byproducts 5.8.4 † changes in toxicity and other contaminant 5.8.4 characteristics † risk recalculation/assessment (as applicable) 5.8.4 † Answer Question C: Has any other information 5.8.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.8.4 risks † natural disaster impacts 5.8.4 † any other information that could call into 5.8.4 question the protectiveness of the remedy † Technical Assessment Summary 5.8.4.1 Issues † Issues identified during the technical assessment 5.8.5 and other five-year review activities † Determination of whether issues affect current or 5.8.5 future protectiveness † A discussion of unresolved issues raised by 5.8.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.8.6 † Required/suggested improvements to identified 5.8.6 issues or to current site operations † Note parties responsible for actions 5.8.6 † Note agency with oversight authority 5.8.6 † Schedule for completion of actions related to 5.8.6 resolution of issues Protectiveness Statements 5.8.7 † Protective statement(s) for each OU (If the 5.8.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.8.7 covering all of the remedies at the site (if applicable) Next Review 5.8.8

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† Expected date of next review 5.8.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.9: Site OT-69 1.0, 3.0 and 5.9 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1, 5.9 geology) † Former, current, and future land use(s) of the site 5.9 and surrounding areas † History of contamination 5.9 † Initial response (e.g., removals) 5.9 † Basis for taking remedial action (e.g., 5.9 contaminants) Remedial Actions 5.9.1 Regulatory actions (e.g., date and description of 5.9 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.9.1.1 † Remedy description 5.9.1.1 † Remedy implementation (e.g., status, history, 5.9.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.9.1.3 † Systems operations/O&M requirements 5.9.1.3 † Systems operations/O&M operational 5.9.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.9.1.3 and 5.9.4 operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.9.1.4 † Protectiveness statements from last review 5.9.1.4 (1st paragraph) † Status of recommendations and follow-up 5.9.1.4 actions from last review

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† Results of implemented actions, including 5.9.1.4 whether they achieved the intended effect † Status of any other prior issues 5.9.1.4 Five-Year Review Process 5.9.2 † Administrative Components 5.9.2 † Notification of potentially interested parties of 5.9.2 initiation of review process † Identification of five-year review team members (as 5.9.2 appropriate) † Outline of components and schedule of your 5.9.2 five-year review † Community Involvement 5.9.2 † Community notification (prior and post 5.9.2 review) † Other community involvement activities N/A (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.9.3 † Data review 5.9.3.4 † Site inspection 5.9.3.2 † Inspection date 5.9.3.2 † Inspection participants 5.9.3.2 † Site inspection scope and procedures 5.9.3.2 † Site inspection results, conclusions 5.9.3.2 † Inspection checklist Appendix C † Interviews 5.9.3.1 † Interview date(s) and location(s) 5.9.3.1 † Interview participants (name, title, etc.) 5.9.3.1 † Interview documentation Appendix B † Interview summary 5.9.3.1 Technical Assessment 5.9.4 † Answer Question A: Is the remedy functioning 5.9.4 as intended by the decision documents? † Remedial action performance (i.e., is the 5.9.4 remedy operating as designed?) † System operations/O&M 5.9.4 † cost of system operations/O&M 5.9.4 † opportunities for optimization 5.9.4 † early indicators of potential issues 5.9.4 † implementation of institutional controls and 5.9.4 other measures † Answer Question B: Are the exposure 5.9.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the

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time of the remedy selection still valid? † changes in standards, newly promulgated 5.9.4 standards, TBCs † expected progress towards meeting RAOs 5.9.4 † changes in exposure pathways 5.9.4 † changes in land use 5.9.4 † new contaminants and/or contaminant 5.9.4 sources † remedy byproducts 5.9.4 † changes in toxicity and other contaminant 5.9.4 characteristics † risk recalculation/assessment (as applicable) 5.9.4 † Answer Question C: Has any other information 5.9.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.9.4 risks † natural disaster impacts 5.9.4 † any other information that could call into 5.9.4 question the protectiveness of the remedy † Technical Assessment Summary 5.9.4.1 Issues 5.9.5 † Issues identified during the technical assessment 5.9.5 and other five-year review activities † Determination of whether issues affect current or 5.9.5 future protectiveness † A discussion of unresolved issues raised by 5.9.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.9.6 † Required/suggested improvements to identified 5.9.6 issues or to current site operations † Note parties responsible for actions 5.9.6 † Note agency with oversight authority 5.9.6 † Schedule for completion of actions related to 5.9.6 resolution of issues Protectiveness Statements 5.9.7 † Protective statement(s) for each OU (If the 5.9.7 remedy is not protective of human health and/or the environment, have you provided supporting

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discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.9.7 covering all of the remedies at the site (if applicable) Next Review 5.9.8 † Expected date of next review 5.9.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Section 5.10 Site WP-17 1.0, 3.0 and 5.10 Background † General site description (e.g., size, topography, and 3.1.1, 3.2.1, 5.10 geology) † Former, current, and future land use(s) of the site 5.10 and surrounding areas † History of contamination 5.10 † Initial response (e.g., removals) 5.10 † Basis for taking remedial action (e.g., 5.10 contaminants) Remedial Actions 5.10 Regulatory actions (e.g., date and description of 5.10 Records of Decision, Explanations of Significant Difference, Administrative Orders on Consent, Consent Decrees and Action Memorandum) † Remedial action objectives 5.10.1.1 † Remedy description 5.10.1.1 † Remedy implementation (e.g., status, history, 5.10.1.2 enforcement actions, performance) † Systems operations/Operations & Maintenance 5.10.1.3 † Systems operations/O&M requirements 5.10.1.3 † Systems operations/O&M operational 5.10.1.3 summary (e.g., history, modifications, problems, and successes) † Summary of costs of system 5.10.1.3 and 5.10.4

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operations/O&M effectiveness (i.e., are requirements being met and are activities effective in maintaining the remedy?) Progress Since Last Five-Year Review (if applicable) 5.10.1.4 † Protectiveness statements from last review 5.10.1.4 † Status of recommendations and follow-up 5.10.1.4 actions from last review † Results of implemented actions, including 5.10.1.4 whether they achieved the intended effect † Status of any other prior issues 5.10.1.4 Five-Year Review Process 5.10.2 † Administrative Components 5.10.2 † Notification of potentially interested parties of 5.10.2 initiation of review process † Identification of five-year review team members (as 5.10.2 appropriate) † Outline of components and schedule of your 5.10.2 five-year review † Community Involvement 5.10.2 † Community notification (prior and post 5.10.2 review) † Other community involvement activities 5.10.2 (e.g., notices, fact sheets, etc., as appropriate) † Document review 5.10.3 † Data review 5.10.3.4 † Site inspection 5.10.3.2 † Inspection date 5.10.3.2 † Inspection participants 5.10.3.2 † Site inspection scope and procedures 5.10.3.2 † Site inspection results, conclusions 5.10.3.2 † Inspection checklist Appendix C † Interviews 5.10.3.1 † Interview date(s) and location(s) 5.10.3.1 † Interview participants (name, title, etc.) 5.10.3.1 † Interview documentation Appendix B † Interview summary 5.10.3.1 Technical Assessment † Answer Question A: Is the remedy functioning 5.10.4 A as intended by the decision documents? † remedial action performance (i.e., is the 5.10.4 remedy operating as designed?) † system operations/O&M 5.10.4 † cost of system operations/O&M 5.10.4

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† opportunities for optimization 5.10.4 † early indicators of potential issues 5.10.4 † implementation of institutional controls and 5.10.4 other measures † Answer Question B: Are the exposure 5.10.4 B assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? † changes in standards, newly promulgated 5.10.4 standards, TBCs † expected progress towards meeting RAOs 5.10.4 † changes in exposure pathways 5.10.4 † changes in land use 5.10.4 † new contaminants and/or contaminant 5.10.4 sources † remedy byproducts 5.10.4 † changes in toxicity and other contaminant 5.10.4 characteristics † risk recalculation/assessment (as applicable) 5.10.4 † Answer Question C: Has any other information 5.10.4 C come to light that could call into question the protectiveness of the remedy? † new or previously unidentified ecological 5.10.4 risks † natural disaster impacts 5.10.4 † any other information that could call into 5.10.4 question the protectiveness of the remedy † Technical Assessment Summary 5.10.4.1 Issues 5.10.5 † Issues identified during the technical assessment 5.10.5 and other five-year review activities † Determination of whether issues affect current or 5.10.5 future protectiveness † A discussion of unresolved issues raised by 5.10.5 support agencies and the community (States, Tribes, other Federal agencies, local governments, citizens, PRPs, other interested parties), if applicable

Recommendations and Follow-up Actions 5.10.6 † Required/suggested improvements to identified 5.10.6 issues or to current site operations † Note parties responsible for actions 5.10.6

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† Note agency with oversight authority 5.10.6 † Schedule for completion of actions related to 5.10.6 resolution of issues Protectiveness Statements 5.10.7 † Protective statement(s) for each OU (If the 5.10.7 remedy is not protective of human health and/or the environment, have you provided supporting discussion and information in the report to make this determination, such as current threats or level of risk?) † Comprehensive protectiveness statement 5.10.7 covering all of the remedies at the site (if applicable) Next Review 5.10.8 † Expected date of next review 5.10.8 † If five-year reviews will no longer be done, N/A provide a summary of that portion of the technical analysis presented in the report that provides the rationale for discontinuation of five- year reviews

Page 36 of 36 FINAL

SECOND FIVE-YEAR REVIEW REPORT

FOR

FORMER GEORGE AIR FORCE BASE

CITY OF VICTORVILLE

SAN BERNARDINO COUNTY, CALIFORNIA

DECEMBER 2005

Prepared for:

Air Force Center for Environmental Excellence Base Conversion Directorate Brooks City-Base, Texas

Contract No. F41624-03-D-8608, Task Order 0032 Contract Data Requirements List No. A001

Prepared by:

MWH Americas, Inc. 1340 Treat Boulevard, Suite 300 Walnut Creek, California 94597

Approved by: Date:

______Five-Year Review Summary Form

SITE IDENTIFICATION Site name (from WasteLAN): Former George Air Force Base, California EPA ID (from WasteLAN): CA2570024453 Region: 9 State: CA City/County: Victorville, San Bernardino County SITE STATUS NPL status: X Final Deleted Other (specify) Remediation status (choose all that apply): X Under Construction Operating Complete Multiple OUs?* X YES NO Construction completion date: ___ / ___ / ______Has site been put into reuse? X YES NO REVIEW STATUS Lead agency: EPA State Tribe X Other Federal Agency Air Force Real Property Agency Author name: MWH Americas Author title: Consultant Author affiliation: Air Force Center for Environmental Excellence Review period:** _04__ / _01__ / __2005____ to __07_ / _26__ / __2005____ Date(s) of site inspection: ___ / ___ / ______Various Inspection Dates Type of review: X Post-SARA Pre-SARA NPL-Removal only Non-NPL Remedial Action Site NPL State/Tribe-lead Regional Discretion Review number: 1 (first) X 2 (second) 3 (third) Other (specify) ______Triggering action: Actual RA Onsite Construction at OU #____ Actual RA Start at OU#____ Construction Completion X Previous Five-Year Review Report Other (specify) Triggering action date (from WasteLAN): _ 01_ / _16__ / __2001____ Due date (five years after triggering action date): _01__ / _16__ / __2006____ * [“OU” refers to operable unit.] ** [Review period should correspond to the actual start and end dates of the Five-Year Review in WasteLAN.] Second Five-Year Review Report Former George Air Force Base

FINAL SECOND FIVE-YEAR REVIEW REPORT FORMER GEORGE AIR FORCE BASE

TABLE OF CONTENTS

Section Page

EXECUTIVE SUMMARY ...... ES-1

1.0 INTRODUCTION ...... 1-1

2.0 SITE CHRONOLOGY ...... 2-1

3.0 BACKGROUND ...... 3-1 3.1 GEORGE AIR FORCE BASE ...... 3-1 3.1.1 Location ...... 3-2 3.1.2 Population ...... 3-2 3.1.3 Land Use ...... 3-2 3.1.4 Climate...... 3-3 3.1.5 Geology and Hydrogeology...... 3-4 3.1.6 Surface Water Features...... 3-5 3.1.7 Water Use and Well Inventory ...... 3-5 3.1.8 Wildlife ...... 3-7 3.1.9 Site Locations and Activities ...... 3-8 3.2 OPERABLE UNITS ...... 3-8 3.2.1 Operable Unit 1 ...... 3-8 3.2.2 Operable Unit 2 ...... 3-10 3.2.3 Operable Unit 3 ...... 3-11 3.2.4 Operable Unit 4...... 3-12

4.0 OPERABLE UNIT 1 SITES ...... 4-1 4.1 INSTALLATION RESTORATION PROGRAM SITE CG-70, NORTHEAST DISPOSAL AREA...... 4-1 4.1.1 Site CG-70 Remedial Actions...... 4-2 4.1.2 Site CG-70 Five-Year Review Process...... 4-6 4.1.3 Site CG-70 Five-Year Review Findings...... 4-7 4.1.4 Site CG-70 Technical Assessment...... 4-14 4.1.5 Site CG-70 Issues...... 4-22 4.1.6 Site CG-70 Recommendations and Follow-Up Actions...... 4-23 4.1.7 Site CG-70 Protectiveness Statement ...... 4-23 4.1.8 Site CG-70 Next Review ...... 4-24

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TABLE OF CONTENTS (continued)

Section Page

5.0 OPERABLE UNIT 3 SITES (LANDFILLS AND FUELS/VOLATILE ORGANIC COMPOUNDS SITES) ...... 5-1 5.1 LANDFILL DP-03 ...... 5-1 5.1.1 DP-03 Remedial Actions ...... 5-1 5.1.2 DP-03 Five-Year Review Process ...... 5-3 5.1.3 DP-03 Five-Year Review Findings...... 5-4 5.1.4 DP-03 Technical Assessment ...... 5-7 5.1.5 DP-03 Issues ...... 5-11 5.1.6 DP-03 Recommendations and Follow-Up Actions...... 5-12 5.1.7 DP-03 Protectiveness Statement...... 5-12 5.1.8 DP-03 Next Review ...... 5-12 5.2 LANDFILL DP-04 ...... 5-12 5.2.1 DP-04 Remedial Actions ...... 5-13 5.2.2 DP-04 Five-Year Review Process ...... 5-15 5.2.3 DP-04 Five-Year Review Findings...... 5-16 5.2.4 DP-04 Technical Assessment ...... 5-18 5.2.5 DP-04 Issues ...... 5-23 5.2.6 DP-04 Recommendations and Follow-Up Actions...... 5-23 5.2.7 DP-04 Protectiveness Statement...... 5-23 5.2.8 DP-04 Next Review ...... 5-24 5.3 LANDFILL LF-12 ...... 5-24 5.3.1 LF-12 Remedial Actions...... 5-24 5.3.2 LF-12 Five-Year Review Process...... 5-26 5.3.3 LF-12 Five-Year Review Findings ...... 5-27 5.3.4 LF-12 Technical Assessment...... 5-30 5.3.5 LF-12 Issues...... 5-35 5.3.6 LF-12 Recommendations and Follow-Up Actions...... 5-35 5.3.7 LF-12 Protectiveness Statement ...... 5-35 5.3.8 LF-12 Next Review...... 5-36 5.4 LANDFILL LF-14...... 5-36 5.4.1 LF-14 Remedial Actions...... 5-36 5.4.2 LF-14 Five-Year Review Process...... 5-38 5.4.3 LF-14 Five-Year Review Findings ...... 5-39 5.4.4 LF-14 Technical Assessment...... 5-42 5.4.5 LF-14 Issues...... 5-47 5.4.6 LF-14 Recommendations and Follow-Up Actions...... 5-47 5.4.7 LF-14 Protectiveness Statement ...... 5-47 5.4.8 LF-14 Next Review...... 5-48

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TABLE OF CONTENTS (continued)

Section Page

5.5 LANDFILL LF-44...... 5-48 5.5.1 LF-44 Remedial Actions...... 5-48 5.5.2 LF-44 Five-Year Review Process...... 5-49 5.5.3 LF-44 Five-Year Review Findings ...... 5-50 5.5.4 LF-44 Technical Assessment...... 5-52 5.5.5 LF-44 Issues...... 5-56 5.5.6 LF-44 Recommendations and Follow-Up Actions...... 5-56 5.5.7 LF-44 Protectiveness Statement ...... 5-56 5.5.8 LF-44 Next Review...... 5-57 5.6 SOUTHEAST DISPOSAL AREA (SEDA) ...... 5-57 5.6.1 SEDA Remedial Actions ...... 5-58 5.6.2 SEDA Five-Year Review Process ...... 5-60 5.6.3 SEDA Five-Year Review Findings...... 5-61 5.6.4 SEDA Technical Assessment ...... 5-64 5.6.5 SEDA Issues ...... 5-68 5.6.6 SEDA Recommendations and Follow-Up Actions...... 5-68 5.6.7 SEDA Protectiveness Statement...... 5-68 5.6.8 SEDA Next Review ...... 5-68 5.7 SITE FT-19 ...... 5-69 5.7.1 FT-19 Remedial Actions...... 5-69 5.7.2 FT-19 Five-Year Review Process...... 5-72 5.7.3 FT-19 Five-Year Review Findings ...... 5-73 5.7.4 FT-19 Technical Assessment...... 5-77 5.7.5 FT-19 Issues...... 5-81 5.7.6 FT-19 Recommendations and Follow-Up Actions...... 5-82 5.7.7 FT-19 Protectiveness Statement ...... 5-82 5.7.8 FT-19 Next Review...... 5-82 5.8 SITE OT-51 ...... 5-82 5.8.1 OT-51 Remedial Actions ...... 5-83 5.8.2 OT-51 Five-Year Review Process ...... 5-85 5.8.3 OT-51 Five-Year Review Findings ...... 5-86 5.8.4 OT-51 Technical Assessment ...... 5-89 5.8.5 OT-51 Issues ...... 5-95 5.8.6 OT-51 Recommendations and Follow-Up Actions ...... 5-95 5.8.7 OT-51 Protectiveness Statement...... 5-95 5.8.8 OT-51 Next Review...... 5-95 5.9 SITE OT-69 ...... 5-96 5.9.1 OT-69 Remedial Actions ...... 5-96 5.9.2 OT-69 Five-Year Review Process ...... 5-98 5.9.3 OT-69 Five-Year Review Findings ...... 5-99

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TABLE OF CONTENTS (continued)

Section Page

5.9.4 OT-69 Technical Assessment ...... 5-102 5.9.5 OT-69 Issues ...... 5-108 5.9.6 OT-69 Recommendations and Follow-Up Actions ...... 5-108 5.9.7 OT-69 Protectiveness Statement...... 5-108 5.9.8 OT-69 Next Review...... 5-109 5.10 SITE WP-17 ...... 5-109 5.10.1 WP-17 Remedial Actions ...... 5-109 5.10.2 WP-17 Five-Year Review Process...... 5-111 5.10.3 WP-17 Five-Year Review Findings...... 5-112 5.10.4 WP-17 Technical Assessment...... 5-115 5.10.5 WP-17 Issues ...... 5-119 5.10.6 WP-17 Recommendations and Follow-Up Actions...... 5-119 5.10.7 WP-17 Protectiveness Statement ...... 5-119 5.10.8 WP-17 Next Review ...... 5-120

REFERENCES ...... R-1

APPENDICES

A – Document List B – Interviews C – Inspection Documents and Landfill Inspection and Monitoring Description D – ARAR Tables E – Historical Landfill Groundwater Monitoring Data Plots for Landfills F – Response to Comments

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LIST OF FIGURES

Figure No.

3-1 Vicinity Map 3-2 Hydrogeologic Cross Section A-A’ 3-3 Potentiometric Surface Map of the Upper Aquifer, October 2004 3-4 Potentiometric Surface Map of Lower Aquifer, October 2004 3-5 Water Supply Well Inventory 3-6 Operable Unit Location Map

4-1 OU-1 Site Plan 4-2 TCE Concentrations in Groundwater, Upper and Lower Aquifers 4-3 Intermodal Project Overlay

5-1 Site DP-03 5-2 Site DP-04 5-3 Site LF-12 5-4A Site LF-14 5-4B Site LF-14 5-5A Site SEDA 5-5B Site SEDA 5-6 Site FT-19a Site Plan 5-7 Site FT-19c Site Plan 5-8 Site OT-51 Site Plan 5-9 Site OT-69 – September 2003 5-10 Site WP-17 Site Plan

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LIST OF TABLES

Table No.

ES-1 Summary of Comprehensive Environmental Response, Compensation, and Liability Act Sites

2-1 OU 1 Chronology of Site Events 2-2 OU 3 Chronology of Site Events

4-1 Maximum Concentrations of Volatile Organic Compounds, 1994 4-2 Historical Performance Data, OU 1 Groundwater Extraction/Treatment System 4-3 Historical Results of Emergent Chemicals - 1,4-Dioxane and Perchlorate 4-4 Detected Volatile Organic Compounds, January 1999 through December 2004

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ACRONYMS AND ABBREVIATIONS

AFCEE Air Force Center for Environmental Excellence AFRPA Air Force Real Property Agency AOC Area of Concern ARAR Applicable or Relevant and Appropriate Requirements BCT BRAC Closure Team bgs below ground surface BRAC Base Realignment and Closure BTEX benzene, toluene, ethylbenzene, xylenes Cal-EPA California Environmental Protection Agency CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CFR Code of Federal Regulations CMP corrugated metal pipe COPC chemical of potential concern DP disposal pit DTSC Department of Toxic Substances Control EBS Environmental Baseline Survey ESD Explanation of Significant Difference FFA Federal Facilities Agreement FOST Finding of Suitability to Transfer FS feasibility study FT fire training areas GAFB former George Air Force Base GCSM geologic conceptual site model GETS groundwater extraction pump and treatment system gpm gallons per minute HCSM hydrogeologic conceptual site model IC Institutional Controls ICE internal combustion engine IRP Installation Restoration Program IT International Technology Corporation JMM James M. Montgomery Consulting Engineers, Inc. JP Jet Propulsion lb/day pound(s) per day LF landfill LLU Lower Lacustrine Unit LRA Land Reuse Agency µg/L micrograms per liter mg/kg/day milligrams per kilogram per day [mg/kg-d]-1 milligrams per kilograms per day to the negative exponential M&E Metcalf & Eddy MAQMD Mojave Air Quality Management District MCL maximum contaminant level MLU Middle Lacustrine Unit

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ACRONYMS AND ABBREVIATIONS (continued) msl mean sea level MWA Mojave Water Agency MWH MWH Americas, Inc. MWHC MWH Constructors, Inc. NCEA National Center for Environmental Assessment NCP National (Oil and Hazardous Substances Pollution) Contingency Plan NEDA Northeast Disposal Area NFA No Further Action NPL National Priority List O&M operations and maintenance OT Other OU Operable Unit PAH polycyclic aromatic hydrocarbons PCE tetrachloroethene PLZ permeable lacustrine zone POL petroleum, oil, and lubricants ppmv parts per million by volume RAO remedial action objective RI remedial investigation ROD Record of Decision RW radiological waste RWQCB Regional Water Quality Control Board SAIC Science Application International Corporation scfm standard cubic feet per minute SCLA Southern California Logistics Airport SEDA Southeast Disposal Area SS spill site STP Sewage Treatment Ponds SVE soil vapor extraction SWRCB State Water Resources Control Board TBC to be considered TCE trichloroethene TPH total petroleum hydrocarbon TVPH total volatile petroleum hydrocarbons USACE United States Army Corps of Engineers USAF United States Air Force USEPA United States Environmental Protection Agency UST Underground Storage Tank VOC volatile organic compound VVEDA Victor Valley Economic Development Agency VVWRA Victor Valley Water Reclamation Authority

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ACRONYMS AND ABBREVIATIONS (continued)

WP waste pits WQPS Water Quality Protection Standards

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EXECUTIVE SUMMARY

This report provides the second statutory Five-Year Review for sites where remedial decisions have left contamination above unrestrictive levels at the former George Air Force Base (GAFB) in San Bernardino County, California. The review was conducted in accordance with the Comprehensive Five-Year Review Guidance issued by the United States Environmental Protection Agency (540-R-01-007) (USEPA, 2001). An analysis of the protection of human health and the environment by the remedial actions implemented for Operable Units (OU) 1 and OU 3 are discussed in this document. Three OUs were originally defined for the base: OU 1, OU 2 and OU 3. Subsequently 12 additional area of concerns (AOCs) were identified and included as OU 4, which the Air Force is in the process of adding to the GAFB Federal Facilities Agreement. OU 2 is being removed from the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process. Therefore, OU 2 and OU 4 sites do not have decision documents. These two OUs are referenced in this document for completeness, but protectiveness analyses have not been conducted.

Operable Unit 1 OU 1 consists of three sites: Site SD-25, the Industrial Storm Drain; Site WP-26, the Sewage Treatment Ponds; and Site CG-70, the dissolved trichloroethene plume identified in the groundwater beneath the northeast portions of the base and adjacent off-base area, in the Northeast Disposal Area. Site SD-25 was determined to be a no further action site and Site WP-26 was determined to be a no action site in the OU 1 Record of Decision (ROD). Detailed analysis of each site is provided in this Five-Year Review document and is summarized in Table ES-1.

Results of the review of the site data for OU 1 Site CG-70 indicate that the OU 1 remedy is not operating as effectively as predicted, but it is protective of human health and the environment. Optimization efforts are ongoing to ensure continued remedy effectiveness in compliance with the remedial action objectives (RAOs). Additionally, current information indicates the risk and toxicity information used during development of the ROD are still valid, there are no complete

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB ES-1 2nd 5-Yr Review Rpt_Final\Text\ES.doc Second Five-Year Review Report Former George Air Force Base exposure pathways, institutional controls remain in place, and there are no current issues affecting the protectiveness of the remedy.

Operable Unit 2 The nine identified Installation Restoration Program (IRP) sites comprising OU 2 are Sites SS- 30, ST-54, ST-57, ST-67a, ST-67b, SS-58, Facility 749 Underground Storage Tank Site, Monitoring Well MW-32 Area, and the Railroad Fueling System AOC. One of the sites, ST- 67a, has no further action planned by the Air Force based on previous investigations or cleanup efforts. Site ST-67b is currently being investigated further because of a recent fuel spill. The remaining four sites, SS-30, ST-54, ST-57, and SS-58, currently have interim remedial actions in place. OU 2 has been removed from the CERCLA process. The proposal to remove OU 2 from the CERCLA process was communicated by the Air Force in a letter to the USEPA dated November 8, 2004. The rationale for this proposal was that OU 2 comprises primarily petroleum hydrocarbons, which are excluded from CERCLA cleanup requirements. A corrective action plan is in the process of being drafted and will be submitted to the Regional Water Quality Control Board. Table ES-1 summarizes the OU 2 sites and their current status.

Operable Unit 3 OU 3 consists of 60 IRP sites located at GAFB. The OU 3 sites consist of a variety of potential contaminant source areas, including landfills, other waste disposal and storage sites, fire training areas, spill sites, and leach fields. These sites are distributed throughout GAFB and range in size from a few 100 square feet to over 90 acres. These sites have been designated as disposal pits (DP), fire training areas (FT), landfills (LF), radiological waste sites, spill sites, waste pits (WP), or “other” (OT). The OU 3 sites that require a Five-Year Review are the following: landfills DP-03, DP-04, LF-12, LF-14, LF-44 and the Southeast Disposal Area; and total petroleum hydrocarbon/volatile organic compound (VOC) sites FT-19a, FT-19c, FT-20, OT-51, OT-69, ST-56, and WP-17. Detailed analysis of each site is provided in this document and is summarized in Table ES-1. FT-20 and ST-56 have no further action planned by the Air Force based on previous investigations or cleanup efforts.

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Results of the review of the site data for these six landfill sites and five petroleum hydrocarbon/VOC sites for OU 3 indicate the remedies are protective of human health and the environment, are functioning as designed, and are operated and maintained in an appropriate manner. Current information review also indicates the risk and toxicity information used during development of the ROD is still valid and institutional controls remain in place and are effective. However, review of the site information for Site OT-69 suggests the natural attenuation remedy is not reducing concentrations of chemicals of potential concern in groundwater at predicted rates. Results of a recent subsurface investigation delineated a vadose zone source in the vicinity of Building 646 which is a continuing source to groundwater and is limiting the effectiveness of the natural attenuation remedy. The Air Force is pursuing a new vadose zone remedy for this site to ensure remedy effectiveness in compliance with the RAOs. Institutional controls remain in place and continue to ensure protection of human health and the environment.

Operable Unit 4 OU 4 consists of 12 AOCs: Pesticide (Dieldrin) Contaminated Groundwater, Current Skeet Range, Second Skeet Range, Original Skeet Range, Facility 615 Indoor Shooting Range, Dozer Scar Site, Disturbed Area, Explosive Ordnance Disposal Training Area, and Building 513 Chlordane Mixing Area.

Removal actions have been completed at the Current Skeet Range, Second Skeet Range, Original Skeet Range, Facility 615 Indoor Shooting Range, Explosive Ordinance Disposal Training Area, and Building 513 Chlordane Mixing Area. The Dozer Scar Site and the Disturbed Area have no further action planned by the Air Force based on previous investigations or cleanup efforts.

It should be noted that the Air Force is in the process of adding OU 4 to the GAFB Federal Facility Agreement, there are no remedial determinations for theses OU 4 sites, and that this Five-Year Review report will not analyze remedy protectiveness for these AOCs. Table ES-1 summarizes the OU 4 sites and their current status.

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1.0 INTRODUCTION

The Air Force Real Property Agency (AFRPA) and the Air Force Center for Environmental Excellence (AFCEE) directed MWH Americas, Inc. (MWH) to perform a Five-Year Review of the remedial actions implemented at the former George Air Force Base (GAFB) in San Bernardino County, California. The purpose of a Five-Year Review is to determine whether the remedy for a site, as described in the Record of Decision (ROD), is protective of human health and the environment; and the methods, findings, and conclusions of the reviews are documented in the five-year report. In addition, the Five-Year Reviews identify deficiencies found, if any, during the review process, and propose recommendations to address the identified deficiencies.

Comments on the first Five-Year Review for GAFB (Montgomery Watson, 2000) were received by the United States Environmental Protection Agency (USEPA) on 16 January 2001. This date was utilized to establish the due date of 16 January 2006 for this second Five-Year Review. Information from the first Five-Year Review has been incorporated into this document as appropriate. The USEPA did not concur with the protectiveness statements presented in the first Five-Year Review document. Specifically, the following deficiencies were identified:

• Data gaps in OU 1 limit the understanding of the behavior of the TCE plume movement in the subsurface. • A more defined understanding of the hydrogeologic controls within OU 1 is essential to designing a more effective remediation system that will bring performance expectations to the level agreed to in the ROD.

This second Five-Year Review was conducted from March 2005 through June 2005. This report documents the results of the review for remedial actions at the former GAFB where contamination was left in place above levels that allow for unlimited use and unrestricted exposure. This review is required by statute and is consistent with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). CERCLA § 121 (c) as amended, states:

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If the President selects a remedial action that results in any hazardous substances, pollutants, or contaminants remaining at the site, the President shall review such remedial action no less often than each five years after the initiation of such remedial action to assure that human health and the environment are being protected by the remedial action being implemented.

The NCP part 300.430(f)(4)(ii) of the Code of Federal Regulations (CFR) states:

If a remedial action is selected that results in hazardous substances, pollutants, or contaminants remaining at the site above levels that allow for unlimited use and unrestricted exposure, the lead agency shall review such action no less often than every five years after the initiation of the selected remedial action.

Due to the fact that hazardous substances, pollutants, or contaminants remain at GAFB above levels that allow for unrestricted land use and unlimited exposure, a Five-Year Review is required for (Operable Unit) OU 1 and OU 3. OU 2 sites have been removed from CERCLA and the Federal Facilities Agreement (FFA) because they comprise primarily petroleum hydrocarbons, and do not require a Five-Year Review. Also, the corrective action decision for OU 2 has not been made. OU 4 areas of concern (AOCs) are within the CERCLA program and removal actions have been completed for the Skeet Ranges, Facility 615 Indoor Shooting Range, Explosive Ordinance Disposal Training Area, and Building 513 Chlordane Mixing Area; however, remedies have not been selected for other OU 4 AOCs. The OU 4 ROD will be accomplished in the near future. The current status of the OU 2 and OU 4 sites is included in Table ES-1 for reference.

Technical assessments performed during this Five-Year Review examined the following questions:

• Question A – Is the remedy functioning as intended by the decision documents? • Question B – Are the assumptions used at the time of the remedy still valid? • Question C – Has any other information come to light that could call into question the protectiveness of the remedy?

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To answer these questions, the Five-Year Review included the following:

• Community notification of the Five-Year Review activities. • Review of applicable site documents such as RODs, remedial design documents, and site operations and maintenance (O&M) records and reports. • Review of newly promulgated standards and applicable or relevant and appropriate requirements (ARARs) (The ARAR analysis and review consisted mainly of identifying changes in toxicity values and cleanup levels that would impact the effectiveness of the remedies). • Interviews with site managers, O&M staff, local regulatory authorities, and community members, as appropriate. • Site inspections, including general site inspections, of system operations and institutional or access controls. • Historical evaluation. • Review of emergent chemicals. An analysis was performed to determine if there is any reason to believe that an emergent chemical may be posing a risk to the environment. Historical databases were also reviewed to determine if any chemical analyses were performed for any of these compounds.

Upon completion of the document reviews, interviews, and site inspections, conclusions for the Five-Year Review were developed. These conclusions include identifying remedy deficiencies, recommending remedy modifications and follow-up actions, and determining whether or not the remedy is expected to be protective of human health and the environment.

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2.0 SITE CHRONOLOGY

Tables 2-1 and 2-2 provide the chronology of events at GAFB for OU 1 and OU 3, respectively.

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3.0 BACKGROUND

This section provides an overview of the base and OU background and history.

3.1 GEORGE AIR FORCE BASE

GAFB, located near Victorville, California, was initially activated on 1 October 1941 as Victorville Army Airfield. The first contingent of men arrived on 24 November 1941, and training began in February 1942. The first class of cadets graduated on 24 April 1942. By 1943, more than 1,000 pilots had completed training at the base.

On 12 October 1945, after World War II ended, all flying operations were discontinued as part of a nationwide demobilization. The base was placed on standby status and, on 1 November 1945, was assigned to the Air Tactical Services Command as a storage facility for B-29s, AT-7s, and AT-11s.

Following the outbreak of the Korean War, GAFB was reactivated under the jurisdiction of the Air Defense Command. On 1 July 1950, the first Fighter Interceptor Wing, flying F-86 Saberjets, was stationed at the newly reopened field now known as George Air Force Base, in honor of Brig. Gen. Harold H. George. In November 1951 the Tactical Air Command took control of the base, which then included the 131st and 146th Fighter Bomber wings (United States Air Force [USAF], 1989).

From 1950 to 1992, GAFB was a fighter training base for many aircraft, including the F-86, T-33, F100A, F100C, F-104C, F-104G Wild Weasel, F-4C Wild Weasel, and F-4G Advanced Wild Weasel. Beginning in 1962, North Atlantic Treaty Organization pilots (primarily West German) also trained at GAFB. Prior to announcement of base closure, GAFB housed three training squadrons and two combat-ready squadrons (USAF, 1989).

On 29 December 1988, the Defense Secretary’s Commission on Base Realignment and Closure (BRAC) recommended the realignment and closure of 145 military installations, including

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GAFB. The Commission’s list was approved by the Secretary of Defense and Congress in 1989. GAFB was closed in 1992.

3.1.1 Location

GAFB encompasses an area of approximately 5,347 acres and is located in the western Mojave Desert near the city of Victorville, California. Victorville is located on Interstate 15, approximately 35 miles north of San Bernardino and 31 miles south of Barstow, as shown in Figure 3-1.

3.1.2 Population

The total population in the vicinity of GAFB/Victorville, California, is approximately 64,029 (U.S. Census Bureau, 2000).

3.1.3 Land Use

The major land uses in the vicinity of George AFB and Victorville include residential development, government and commercial services, cement manufacturing, railroad and highway transportation, localized agricultural activities along the Mojave River, and industrial mining in the outlying areas. The California Aqueduct carries water across the high desert approximately five miles south of the base and may impact long-term land use planning. A major fuels distribution pipeline parallels Air Expressway Road for half the length of the base and a high-voltage transmission utility corridor crosses the southeast corner of the base.

GAFB was established during World War II and provided the foundation for a steady economy for the Victorville, Adelanto, and Apple Valley areas. Until 1992 GAFB was the largest employer in the Victorville area. Residential and commercial development and growth of community services were, in large part, due to the presence of the base. Despite base closure, the climate and recreational attractions within the region continue to contribute to the development of vacation and/or second homes and the expansion of retirement communities.

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Growth in the Victor Valley has also been impacted as increasing numbers of people move to the area seeking to avoid the congestion and high cost of living in the Los Angeles Basin.

The proposed reuse for GAFB is development of an international airport and railway hub, along with commercial, industrial, and business park development. The Victor Valley Economic Development Agency (VVEDA) has designated the airport as the Southern California Logistics Airport (SCLA). There are currently light industry and commercial companies using the facilities. There are no current plans for residential development on former base property.

3.1.4 Climate

The climate in the GAFB area is typical of the high desert region of California and Nevada. The summers are hot and dry, with maximum daily temperatures often exceeding 100 degrees Fahrenheit (°F) in July and August. Winters are cool and dry, with nighttime temperatures often below freezing in December and January (Science Application International Corporation [SAIC], 1987). The annual average temperature is 62 °F.

Groundwater recharge from precipitation in the Victor Valley is negligible due to low precipitation rates and high evapotranspiration rates characteristic of the Mojave Desert. Air Force records from 1942 to 1992 indicate that annual precipitation at the base ranged from 0.77 to 11.22 inches, with an average annual precipitation of 5.72 inches. The wettest months are typically January through March. Snowfall is infrequent, but may total a few inches per year and was recorded as high as 17 inches in 1974 (Montgomery Watson, 1996a). The average annual potential evapotranspiration rate is about 82 inches (SAIC, 1987), far exceeding average annual precipitation.

Prevailing winds in the area of GAFB are from the south; however, the strongest gusts are typically from the west. Westerly gusts of 50 miles per hour or more usually occur in the spring. In the summer, strong southerlies blow over the San Bernardino Mountains (Cajon Pass) in the evenings. Northerly winds occur more frequently in the fall and winter months (SAIC, 1987).

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3.1.5 Geology and Hydrogeology

GAFB lies within the Upper Mojave River Groundwater Basin atop the Mojave River Bluffs, on the west side of the Mojave River. Subsurface geology is characterized by unconsolidated alluvial, fluvial, and lacustrine sediments identified as four main stratigraphic units. In ascending order from oldest to youngest, the units are identified as the Lower Alluvial Unit, the Lower Lacustrine Unit (LLU), the Middle Lacustrine Unit (MLU), and the Upper Fluvial Unit. Figure 3-2 illustrates cross-section A-A’ in the south-north direction.

The LLU is a predominately clay unit, ranging in thickness from approximately 100 feet to 10 feet, deposited at progressively higher elevations (ranging from 2,100 feet to 2,650 feet above mean sea level [msl]) from south to north. The MLU is an approximately 40-feet thick predominately clay unit, encountered approximately between 2,650 and 2,690 feet above msl and meets the LLU in a roughly west-east trending zone in the northern area of the former base. The MLU thins and becomes interfingered with sands and silts to the north and east, roughly parallel to the bluffs.

The hydrogeology is characterized by a broad regional aquifer (Lower Aquifer) overlain by a perched Upper Aquifer. In the interior of the former base, water in the two aquifers is separated by the MLU and LLU, with a limited extent of perched water encountered in the northern portion of the former base in the LLU. On the eastern edge, the interfingered and thinning MLU allows water to migrate from the Upper Aquifer to the Lower Aquifer. The Upper Aquifer is not present to the east of the Mojave River Bluffs.

Groundwater in the Upper Aquifer occurs within the Upper Fluvial Unit at elevations typically ranging from 2,750 feet to 2,700 feet above msl. The natural gradient is to the north and east, but stresses from infiltration ponds associated with the OU 1 groundwater extraction and treatment system (GETS) have historically shifted and steepened the groundwater gradients in local areas. Groundwater velocities range from 0.2 feet/day to 1.0 feet/day. Figure 3-3 illustrates the potentiometric surface of the Upper Aquifer.

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Groundwater in the Lower Aquifer occurs within the Lower Alluvial Unit at elevations typically ranging from 2,590 feet to 2,580 feet above msl. The natural groundwater gradient in the Lower Aquifer is to the northeast. However, the Mojave River is a losing stream, creating a groundwater divide west of the river. Infiltration in the areas of the Victor Valley Water Reclamation Authority (VVWRA) ponds drives the flow and the natural divide further to the west and increases the gradient to the east. Figure 3-4 illustrates the potentiometric surface of the Lower Aquifer.

3.1.6 Surface Water Features

The main surface water feature is the Mojave River, located east of the base. Surface water runoff from the base is channeled to a main arroyo located in the northern portion of the base, draining to the east, and numerous other smaller drainage channels that traverse the bluffs. This arroyo also received treated discharge from the OU 1 GETS from 1991 through 1997.

Other historic surface water units have included the following:

• Former Sewage Treatment Ponds (STP), which received sanitary wastewater and discharge from the OU 1 GETS through 1997. • The New Percolation Ponds, which received treated groundwater from the OU 1 GETS from November 1996 through March 2003. • The golf course pond located on the Westwinds Golf Course. • VVWRA percolation ponds, which have received treated water from 1991 until present.

3.1.7 Water Use and Well Inventory

Water usage includes domestic, industrial, and agricultural. The consumptive use in 2001 was 96,300 acre-feet for the Mojave Basin Area (MWA, 2004). The per capita rate of water demand in 2000 was estimated to be 284 gallons per day (MWA, 2004). Because of arid conditions and lack of surface water bodies in the Upper Mojave River Valley Groundwater Basin, groundwater has been the principal source of water used in the Victor Valley desert communities. The

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Mojave Water Agency (MWA) oversees the adjudication of groundwater within the Mojave River Groundwater Basin.

Population increases in the study area caused domestic water demand to almost double during the period between 1973 and 1983 (SAIC, 1987), and double again between 1983 and 1994 (Montgomery Watson, 1996a). Between 1995 and 2000, water consumptive use decreased by 6 percent largely due to the decline of agricultural use (MWA, 2004).

The increase in demand has led to overdraft conditions (water removed from the basin but not replenished) within the Mojave River Groundwater Basin. Groundwater consumption in the George Groundwater Sub-basin has not been specifically tracked by the MWA; however, tracking by smaller use areas is being pursued as groundwater overdraft in the region continues to be a concern.

As of 1990, the MWA has been entitled to 75,800 acre-feet per year of water from the California Water Project. However, due to recent statewide drought conditions, the MWA has not yet received their full entitlement. Once allotted, the MWA plans to begin utilizing their water entitlement to directly recharge groundwater in the Mojave River Basin (Montgomery Watson, 1996a) (MWA, 2004).

Two supply wells owned by the VVWRA are located northeast of the base. These two wells are reported to be screened at depths of 65 to 75 feet below ground surface (bgs) with pumping capacities of 500 gallons per minute (gpm) each. Based on the location and approximate elevations of the wellheads, these wells are believed to be screened in the Mojave River Aquifer. The groundwater table was measured at 36 bgs. Groundwater from these VVWRA wells is used only for non-potable and industrial applications, while bottled drinking water is supplied for workers at the VVWRA plant (Montgomery Watson, 1996a). Figure 3-5 shows the location of wells in the immediate vicinity of George AFB.

According to the records maintained by the California Department of Water Resources, four production wells exist southeast of the base. The production capacities of these wells range from

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100 to 1,200 gpm. The wells are screened to depths ranging from 500 to 610 bgs and may be screened in a deeper and possibly different aquifer system than are the monitoring wells installed at GAFB in the Lower Aquifer.

Currently six production wells supply water to both GAFB and the adjacent city of Adelanto, one of which is a new well that was brought into production in 2003 (Mojave Basin Watermaster, 2005). These production wells are located near the Mojave River beyond the eastern base boundary, on the west side of the Mojave River, just north of the Lower Narrows.

Three additional wells, located northeast of the GAFB production wells along the eastern bank of the Mojave River, supply water to the town of Oro Grande. It is suspected that privately owned wells and smaller capacity domestic and irrigation wells in the vicinity draw from the Lower Aquifer.

3.1.8 Wildlife

Animal life in the vicinity of GAFB includes both desert and riparian species, such as black-tail jackrabbit, cottontail rabbit, and antelope ground squirrel (Montgomery Watson, 1996a). Seventy-five bird species have been identified in the area, including ravens, hawks, owls, quail, flycatchers, larks, warblers, sparrows, and blackbirds. Other wildlife includes lizards, snakes, pocket mice, raccoons, and coyotes. Generally, animal activity is highest in the northern and southern portions of the base where native plants are least disturbed. Animal activity typically has been lowest in the high traffic areas of the base, such as the housing and industrial complex, recreation areas, and runways (USAF, 1989); however, it is likely that some activity and re- inhabitation has occurred since base closure.

The desert tortoise is the only animal species found on the base that is listed by the United States Fish and Wildlife Service as a threatened or endangered species. Two Category-2 animal species that may be present on GAFB are the ferruginous hawk and Mojave ground squirrel (USAF, 1989).

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3.1.9 Site Locations and Activities

The objective of the Air Force Installation Restoration Program (IRP) is to assess past hazardous waste disposal and spill sites at USAF installations and to develop remedial actions consistent with the NCP for sites that pose a threat to human health and welfare or to the environment. The Air Force initiated phased remedial investigation (RI)/feasibility study (FS) activities at GAFB, in accordance with the CERCLA, in 1982. In 1990 the USEPA evaluated GAFB for priority of response action under CERCLA Sections 104 and 120. As a result of this evaluation, GAFB was placed on the National Priority List (NPL) in February 1990. In October 1990 the USAF signed an FFA with the USEPA Region 9, California Department of Health Services, and the California Regional Water Quality Control Board (RWQCB), Lahontan Region. The FFA established a framework for continuing environmental restoration activities at the base. Under the FFA, three original OUs were defined and individual IRP sites were placed in these OUs as agreed upon by the BRAC Cleanup Team (BCT) for GAFB. A fourth OU (OU 4) is currently being added to the FFA. OU 2 has been removed from the FFA, because the IRP sites that comprise OU 2 are petroleum release sites. Table ES-1 summarizes the IRP and non-IRP sites identified at GAFB previously/currently being investigated and their current status.

3.2 OPERABLE UNITS

The specifics of OU 1, OU 2, OU 3, and OU 4 AOCs are discussed in the following sections. Figure 3-6 shows the locations of the OUs.

3.2.1 Operable Unit 1

OU 1 consists of three sites: Site WP-26, the STP Percolation Ponds; Site SD-25, the Industrial Storm Drain and Site CG-70, the dissolved trichloroethene (TCE) plume identified in the groundwater beneath the northeast portions of the base and adjacent off-base area, in the Northeast Disposal Area (NEDA).

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Site WP-26 includes five wastewater treatment plant percolation ponds that were used from the early 1950s to 1980. There are three large, main ponds and two smaller ponds that may not have been used. The percolation ponds were used primarily for discharge of treated sanitary wastes but also may have received waste oils and solvents from industrial shops that discharged into the sanitary system. Contaminants of concern for the percolation ponds include heavy metals, solvents, and nitrate. The location of the STP Percolation Ponds is shown on Figure 3-6.

Investigations at the site indicate that concentrations of contaminants of concern are within background concentrations for desert soils, with the possible exception of nitrates (James M. Montgomery Consulting Engineers Inc. [JMM], 1992). Elevated nitrates concentrations were detected in the upper 46 feet of soil. The OU-1 selected remedy initially included discharge to the STP Percolation Ponds (Site WP-26) causing concern of potential mobilization of nitrates from WP-26 to groundwater. However, it was determined that the potential for migration to groundwater was low, because of denitrification in the vadose zone or dilution resulting from mixing with groundwater. Groundwater monitoring was implemented to address this potential issue, and historic results did not show elevated nitrate concentrations. As a result, this site was determined to be a no action site in the OU-1 ROD. Therefore, this site does not require a protectiveness evaluation and will not be discussed further in this report. Table ES-1 provides summary information on the status of this site for reference.

Site SD-25 is located within the central and northeastern portions of GAFB, as shown on Figure 3-6. The Industrial Storm Drain consists of the storm drain southeast of the operational apron (East Storm Drain), the storm drain between the operational apron and Crosswind Secondary Runway (West Storm Drain), and the outfall ditch downgradient from the storm drains. As shown in Figure 3-6, the East Storm Drain is parallel to and just east of the operational apron. The East Storm Drain was constructed of various piping materials, including reinforced concrete pipe and corrugated metal pipe (CMP), but is predominantly CMP. Pipe sizes range from 4 to 24 inches in diameter. The overall length of the East Storm Drain pipe, including all laterals, is 10,235 linear-feet. Of this length, over 3,800 linear-feet of the CMP section was perforated pipe.

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Investigations indicated that the sediments within the storm drain were potentially hazardous. Consequently, the West Storm Drain was cleaned in place, sections of the East Storm Drain were cleaned, and the perforated sections were replaced with non-perforated piping. Soils underlying the perforated piping were also excavated and appropriately disposed. Subsequent confirmation sampling of soils underneath the Industrial Storm Drain indicated that contaminant concentrations were at background levels. Therefore, Site SD-25 was determined to be a no further action site as documented in the OU 1 ROD and does not require a protectiveness evaluation. This site will not be discussed further in this report. Table ES-1 provides summary information on the status of this site for reference.

Site CG-70 is an active CERCLA site and is discussed in detail in Section 4.1. The site is a TCE groundwater plume beneath the NEDA and adjacent off-base areas. This plume exists in both the Upper and Lower Aquifers, although the majority of the mass is contained within the Upper Aquifer. Several historic source areas have been identified for Site CG-70 as follows:

• Site SD-25 the former industrial storm drain. A removal action was completed and Site SD-25 was determined to be a no further action site in the OU 1 ROD. • Site WP-26, the former STP percolation ponds. Soil and groundwater monitoring were conducted and this site was determined to be a no action site in the OU 1 ROD. • Potentially unidentified sites in the northeastern area of the base including burial sites, landfill disposal sites and spill or liquid disposal sites were stated as potential source areas in the OU 1 ROD. A vadose zone source area was recently identified at the end of Runway 3/21. The Air Force (AF) is currently evaluating remedial alternatives for this area and will propose a vadose zone remedy. No other source areas have been identified. • FT-19, a former fire training area (an OU 3 site – see section 5.0). A SVE system was implemented as the remedy for Site FT-19. The system has been shut down and the site is currently being evaluated for closure.

3.2.2 Operable Unit 2

OU 2 is defined as the liquid fuels distribution system, which consists of the area that includes fuel pits 1 through 7, waste fuels storage Facility 690, pump station 708, the storage tank farm,

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and the liquid fuels distribution lines. The fuel pits are concrete vaults that extend approximately 8 feet bgs and provide access to valves and other plumbing related to the fuel supply lines. A series of underground fuel lines from the fuel pits supplied jet fuel to jets parked on the operational apron. The area is covered with concrete or asphalt pavement, except for an unpaved area between the operational apron and the runways. Approximately 50 percent of the surface soil between the runways are covered with steel matting (International Technology Corporation [IT], 1999).

The nine identified IRP sites comprising OU 2 are: Sites SS-30, ST-54, ST-57, ST-67a, ST-67b, SS-58, Facility 749 Underground Storage Tank Site, Monitoring Well MW-32 Area, and the Railroad Fueling System AOC. Site ST-67a has no further action planned by the Air Force, based on previous investigations or cleanup efforts. Site ST-67b is currently being further investigated because of a recent fuel spill from non Air Force activities and potentially historic releases. The remaining four sites currently have initial actions in place. These sites are SS-30, ST-54, ST-57, and SS-58.

OU 2 is being removed from the FFA and CERCLA process. Cleanup of OU 2 will be conducted under the California Underground Storage Tank Program overseen by the RWQCB, Lahanton District, because it is a petroleum site. A corrective action plan is being prepared and is scheduled for delivery to the RWQCB. The USAF plans to continue voluntary cleanup activities under the existing informal enforcement arrangement with the RWQCB. Therefore, OU 2 does not require a protectiveness evaluation and will not be discussed further in this report. Table ES- 1 provides summary information on the status of each OU 2 site for reference.

3.2.3 Operable Unit 3

OU 3 consists of 60 IRP sites located at GAFB. Sites that were not included in OU 1 or OU 2 were placed into OU 3. The OU 3 sites consist of a variety of potential contaminant source areas, including landfills, other waste disposal and storage sites, fire training areas, spill sites, and leach fields. These sites are distributed throughout the GAFB, as shown on Figure 3-6, and range in size from a few hundred square-feet to over 90 acres. These sites have been designated

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The remaining OU 3 IRP sites were determined to be no action or no further action sites as documented in the OU 3 ROD. Therefore, these sites do not require a protectiveness evaluation and will not be discussed further in this report. Table ES-1 provides summary information on the status of each OU 3 site for reference.

3.2.4 Operable Unit 4

OU 4 consists of 12 AOCs: Pesticide (Dieldrin) Contaminated Groundwater, Current Skeet Range, Second Skeet Range, Original Skeet Range, Facility 615 Indoor Shooting Range, Dozer Scar Site, Disturbed Area, Explosive Ordnance Disposal (EOD) Training Area, Facility 749 Underground Storage Tank (UST) Site Investigation, Building 513 Chlordane Mixing Area, Monitoring Well MW-32 Area, and the Railroad Fueling System AOC. These AOCs were identified after the three original OUs were established in the GAFB FFA. The Air Force is in the process of adding OU 4 to the GAFB FFA.

Removal actions have been completed at the Facility 615 Indoor Shooting Range, Current Skeet Range, Second Skeet Range, and Original Skeet Range. The USAF is proposing no action at the Dozer Scar Site and the Disturbed Area because contamination was found at levels that allow for residential use. Continuing investigations or removal activities are planned or are in progress for the Pesticide (Dieldrin) Contaminated Groundwater, Building 513 Chlordane Mixing Area, and EOD Training Area. The OU 4 sites are not discussed further in this document because these sites do not yet have remedies. Table ES-1 provides a status for each of these sites.

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4.0 OPERABLE UNIT 1 SITES

This section presents the procedures and results of the Five-Year Review for Site CG-70 in OU 1. Sites SD-25 was determined to be a NFA site and WP-26 was determined to be a no action site in the OU 1 ROD (Montgomery Watson, 1994). The historic and current site data continues to support the No Further Action (NFA) determinations, therefore, these sites will not be discussed further in this Five-Year Review.

4.1 INSTALLATION RESTORATION PROGRAM SITE CG-70, NORTHEAST DISPOSAL AREA

Subsurface investigations in the NEDA detected VOCs in groundwater, with TCE being the primary constituent of concern. Table 4-1 summarizes the maximum concentrations of VOCs detected in groundwater at the time of the ROD. TCE has been detected in both the Upper and Lower Aquifers, although the majority of the mass is contained within the Upper Aquifer. Several historic source areas have been identified for Site CG-70 as follows:

• Site SD-25 the former industrial storm drain. A removal action was completed, and Site SD-25 was determined to be a NFA site in the OU 1 ROD. • Site WP-26, the former STP percolation ponds. Soil and groundwater monitoring were conducted and this site was determined to be a no action site in the OU 1 ROD. • Potentially unidentified sites in the northeastern area of the base including burial sites, landfill disposal sites and spill or liquid disposal sites were stated as potential source areas in the OU 1 ROD. A vadose zone source area was recently identified at the end of Runway 3/21. The Air Force is currently evaluating remedial alternatives for and will propose a vadose zone remedy. No other source areas have been identified. • FT-19, a former fire training area (an OU 3 site – see Section 5.0). A soil vapor extraction (SVE) system was implemented as the remedy for Site FT-19. The system has been shut down, and the site is currently being evaluated for closure.

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4.1.1 Site CG-70 Remedial Actions

This section describes the remedy selection, implementation, O&M activities, and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

4.1.1.1 Remedy Selection. The OU 1 ROD (Montgomery Watson, 1994) was finalized and signed in March 1994 and identified the following remedial action objectives (RAOs):

• Prevent exposure to contaminated groundwater that poses a risk of greater than 1x10-6. • Reduce the TCE contamination in the groundwater beneath the NEDA to below the Federal maximum contaminant level (MCL) of 5 micrograms per liter (µg/L). • Reduce TCE in treated groundwater effluent to meet the enforceable levels of 2.5 µg/L TCE on a median basis with a maximum discharge level of 5 µg/L TCE, as measured at the effluent sampling port of the treatment system. Furthermore, seek to treat the discharge to attain a level of 0.5 µg/L TCE as measured at the percolation ponds. Although such efforts do not constitute an enforceable discharge standard, the USAF may make minor modifications, as necessary, in an effort to reach this goal. • Eliminate or reduce the potential for further migration of the existing TCE plume in the groundwater. • Provide a conceptual design for a preferred alternative, which will be expandable to remediate an aquifer volume greater than that assumed for this study, if required, based on the results of future monitoring.

The selected remedy that best met these objectives consisted of a GETS with 18 extraction wells. Extracted groundwater is treated by two packed-tower air strippers that discharge the VOCs directly to the atmosphere. Treated groundwater was then re-injected into the Upper Aquifer via percolation. This remedy includes deed restrictions, as appropriate, prior to sale or transfer of land overlying contaminated groundwater, to prohibit use of the groundwater until groundwater cleanup levels have been achieved.

4.1.1.2 Remedy Implementation. The extraction system was implemented in two phases. Performance of the first nine extraction wells (EW-1 through EW-9), installed in 1991 as part of the first phase, was used to determine the location of the final nine extraction wells

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(EW-10 through EW-18), installed as part of the second phase (Figure 4-1). Construction of the second phase began in February 1995 and was completed in March 1996. The first phase included installing nine extraction wells, eight monitoring wells, transmission piping, an influent wet well, an air stripping system, an effluent clearwell, and a pipeline with a distribution system for treated groundwater to the STP Percolation Ponds. The second phase included installing nine more extraction wells, five monitoring wells, additional pipelines, access roadways, and power distribution to the new wells.

TCE and other VOCs are removed from the extracted groundwater by the packed air stripping process. The system is capable of treating 1,100 gpm, assuming a maximum influent of 150 µg/L TCE (Montgomery Watson, 1994). Water is pre-treated with sodium hypochlorite to control biofouling of the strippers. The two packed-tower air strippers remove VOCs from the water, and VOC-laden air from the stripper is discharged directly to the atmosphere. A portion of the treated water is recycled back into the influent wet well to maintain the minimum water level necessary for the pumps and to pace the treatment system flow rate to match the total flow rate from the extraction pumps. The treatment system can be operated in series, in parallel, or independently depending on influent flow rate and concentrations.

Because the treated water is recharged into the Upper Aquifer, stringent discharge requirements were developed. Discharge facilities currently available include four old percolation ponds that served the now decommissioned GAFB STP ponds, an unlined arroyo, and three new percolation ponds constructed as part of the OU 1 phase two effort. Historically, water was discharged to both the old percolation ponds and unlined arroyo. Discharge to the new percolation ponds began in May 1997, although a portion was still being discharged into the unlined arroyo. The new percolation ponds received the entire effluent stream from August 1997 until March 2003. The Air Force gave the VVEDA permission to demolish the four old percolation ponds.

From startup in December 1991 to March 2003, the GETS has extracted and treated an estimated 1.563 billion gallons of water and removed an estimated 232 pounds of TCE from the subsurface. The GETS was shutdown in March 2003 to allow for groundwater recovery data collection, aquifer testing, and groundwater modeling to optimize the OU 1 remedy.

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4.1.1.3 System Operations/Operations and Maintenance. O&M is being conducted in accordance with the approved O&M Plan (Montgomery Watson, 1999). System operation requirements include the following:

• Weekly system checks, and flow meter and hour meter readings • Quarterly influent/effluent sampling and analysis • Quarterly extraction /treatment system process monitoring reports • Discharge to new percolation ponds • Annual extraction well sampling • Semiannual basewide groundwater reports

On 15 June 1999, the BCT reached consensus on temporarily discontinuing pumping in Lower Aquifer extraction wells EW-6, EW-14, EW-15, EW-16, and EW-17. These designated wells were shutdown on 21 June 1999. This effort was designed to maximize the OU 1 remedy by ceasing extraction from Lower Aquifer wells with TCE concentrations significantly below the MCL. The BCT agreed to implement a revised monitoring program in the Lower Aquifer to monitor future plume migration and containment.

As of March 2003, the GETS was shutdown to allow for monitoring of groundwater recovery, aquifer testing, and groundwater modeling in an effort to optimize the OU 1 remedy. Restart of the groundwater system is pending conclusion of the groundwater modeling effort; preliminary results are anticipated by September 2005.

4.1.1.4 Progress Since the Last Five-Year Review. A significant amount of work has been performed to optimize the OU 1 remedy since the last five-year review. Regulatory comments on the last five-year review stated that the remedy as implemented was not protective of human health and the environment. The following issues were identified by USEPA:

• Data gaps in OU 1 limit the understanding of the behavior of TCE plume movement in the subsurface.

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• A more defined understanding of the hydrogeologic controls within OU 1 is essential to designing a more effective remediation system that will bring performance expectations to the level agreed to in the ROD.

In an effort to address these issues, the Air Force has conducted the following activities:

• Twenty-five (25) data gap monitoring wells were drilled and installed from 2000 to 2003. Results of the work were published in the Data Gaps Well Installation Report, Operable Unit 1 (MWH, 2005a). This information was also used in support of a revised geologic conceptual site model (GCSM) and hydrogeologic conceptual site model (HCSM) (MWH, 2005b). • Monitoring well NZ-55 was converted to a groundwater extraction well in December 2001 to facilitate additional TCE mass removal from the Upper Aquifer. From December 2001 through March 2003 approximately 17.5 pounds of TCE were removed from NZ-55. • The GCSM, published by MWH in 2002, re-defined the stratigraphic units, developed a more detailed understanding of the regional geology, and proposed alternatives to account for the elevation differences in several of the stratigraphic units. • In March 2003, the GETS was shutdown to allow for groundwater recovery monitoring. Recovery monitoring was conducted for approximately nine months, and the data was used in support of the HCSM. • Twenty-eight pumping tests, of individual monitoring and extraction wells, were conducted from December 2003 to March 2004 in support of the HCSM. • In June 2004, wells NZ-40, NZ-82, and NZ-83 were converted to groundwater extraction wells to facilitate TCE mass removal from the Upper Aquifer. These wells have not been activated because the GETS was shutdown for recovery monitoring. • The HCSM was developed using the GCSM. Additional data gap information, recovery data, pumping test data was collected, and additional research was performed on the regional geology. The Final HCSM was published 6 May 2005. • A new groundwater model is being developed using the HCSM as the basis. The purpose of the model is to run simulations of various extraction and discharge scenarios to optimize the OU 1 remedy. • An investigation of a vadose zone source at the end of Runway 3/21 was performed. The Air Force is currently evaluating remedial alternatives for Runway 3/21 and will propose a vadose zone remedy to the regulatory agencies

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4.1.2 Site CG-70 Five-Year Review Process

Mr. Phillip Mook, P.E., AFRPA, Regional BRAC Environmental Coordinator directed this former GAFB Five-Year Review. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and site inspections where warranted. Community involvement was conducted in accordance with the five-year review guidance, Office of Solid Waste and Emergency Response (OSWER) No. 9355.7-03B-P, June 2001, and included pre-notification, to the community and interested parties via media notification in the Victorville Daily Press that a five-year review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

The schedule for the five-year review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 September 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

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4.1.3 Site CG-70 Five-Year Review Findings

This section describes the findings of the Five-Year Review for Site CG-70. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports and the OU 1 ROD (Document List, Appendix A).

4.1.3.1 Interviews. The following individuals were contacted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He understands that there is no plan to extract water from the Upper Aquifer and that the contamination of the Lower Aquifer may affect the Mojave River Basin. He believes that there are no known effects on the community, but is concerned that the groundwater extraction and treatment system has been shutdown for over two years, indicating that there are no current efforts to cleanup and treat the contaminated groundwater.

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The following other personnel were contacted for interviews but were not responsive: Mayor of Victorville, City Manager of Victorville, Prison Warden, Foreign Trade Zone Director, and local Assembly representative.

4.1.3.2 Site Inspections. Site CG-70 is a groundwater plume with approximately 250 monitoring wells and 22 groundwater extraction wells. The associated GETS is located north of Perimeter Road on the very edge of the former GAFB boundary. Since shutdown of the GETS in March 2003, the GETS has been inspected and operated quarterly to process water from sampling events. The most recent sampling event occurred in April 2005. MWH and M&M Environmental operated the treatment plan and inspected the plant conditions. Inspection documents are included in Appendix C.

No operational problems have been noted during these events and the system is operating as designed. Additionally, monitoring wells are inspected during quarterly and semi-annual sampling events and any wellhead or casing problems noted by the sampling contractor. Occasionally a crash post is noted as damaged and well padlocks become rusted. These are replaced on an as-needed basis.

4.1.3.3 Risk Information Review. This section presents the site-specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 1 ROD (Montgomery Watson, 1994).

Dissolved TCE is present in both the Upper and Lower Aquifers above the MCL of 5 µg/L. Potential receptors include the Lower Aquifer and water supply wells screened in the Lower Aquifer.

The OU 1 ROD (Montgomery Watson, 1994) included a baseline carcinogenic risk assessment, hazard index calculations, and an environmental assessment of sensitive plants and species. The results are as follows:

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A baseline carcinogenic risk assessment associated with TCE was performed and the highest human carcinogenic risk to the future resident, using the groundwater beneath the NEDA, was estimated at 9 x 10-5 for the combination of water ingestion, dermal contact, and inhalation of volatiles from the groundwater. This risk level is within the 1 x 10-4 to 1 x 10-6 (1:10,000 to 1:1,000,000) range established by the NCP. The baseline risk assessment has not been recalculated, because remediation has been ongoing, there are no complete exposure pathways, and there are no plans for residential use.

Hazard index calculations for non-cancer risks indicate the benchmark of 1.0 was exceeded at the NEDA for the Future Child Reasonable Maximum Exposure (2.9) scenario. However, the probability that an adverse human health effect would occur is low, given the conservative exposure assumptions and the potential toxicity of VOCs to humans (Montgomery Watson, 1994). The non-cancer risks have not been recalculated, because remediation has been ongoing, there are no complete exposure pathways, and there are no plans for residential use.

An environmental assessment was conducted to assess the potential risks to plants and animals due to the presence of TCE in groundwater beneath the NEDA. Since groundwater does not reach the surface, surface water is not a current route of exposure to the environmental receptors. However, potential construction activities associated with the GETS could adversely affect plants and animals at the NEDA. The Mojave ground squirrel and the desert tortoise are considered to be the most sensitive species identified at former GAFB. The desert tortoise is on the Federal Endangered Species List and the Mojave ground squirrel is on the California Endangered Species. Site conditions have not changed; therefore, an updated environmental assessment is not warranted.

An analysis of chemical-action - and location-specific ARARs was presented in the OU 1 ROD (Montgomery Watson, 1994), and the following ARARs were identified.

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Chemical-Specific ARARs

• National Primary Drinking Water Regulations (40 CFR 141.61 MCLs for organic chemicals)

Location-Specific ARARs

• Endangered Species Act (40 CFR 6-302, 50 CFR Part 200 and 50 CFR Part 402)

Action-specific ARAR’s – Groundwater and Air Emissions

Groundwater

• Porter Cologne Water Quality Control Act, California Water Code, Section 13267. Provides the basis for development of reporting, notification, and monitoring programs. • State Water Resources Control Board (SWRCB) Resolution Number 68- 16, anti-degradation policy is an ARAR with respect to discharges of TCE at OU 1. On 22 April 1993, the USEPA administrator issued a decision finding that the anti-degradation policy was an ARAR for OU 1 and, based upon negotiations on 9 July 1993, a final dispute resolution decision set the median treatment system discharge effluent level at 2.5 µg/L and the maximum discharge level at 5 µg/L. The decision further stated that the USAF would seek to treat discharge to attain a level of 0.5 µg/L TCE as measured at the percolation ponds. • Water Quality Control Plan “Basin Plan” for the Lahontan Region. • Hazardous Waste Management Regulations, 22 CCR (Div. 4.5, Sec 66260 et seq). Potentially applicable to remedial alternatives involving the use of air strippers and other miscellaneous facilities that treat, store, or dispose of hazardous waste.

Air Emissions

• Health and Safety Code (Sections 39000-44563; CCR Title 17, Part III). The Mojave Air Quality Management District (MAQMD) has stated that they will not require emissions controls on the air strippers as long as TCE emissions are below 1 pound per day (lb/day).

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An evaluation of risk to indoor air quality was not performed as part of the OU 1 ROD, and thus this evaluation was not included in development of the remedy or the remediation goals at this site. Since the OU 3 ROD, evaluation of indoor air quality risk has become a standard part of the site investigation process within CERCLA, and this evaluation should be performed when a potential pathway exists. The Air Force is currently evaluating remedial alternatives for the vadose zone source and will propose a vadose zone remedy to the regulatory agencies. The indoor air risk will be evaluated as part of the selection of the new remedy.

The presence of emergent chemicals at Site CG-70 is an issue that was not evaluated in the OU 1 ROD because these chemicals were not of known public concern at that time. The historical databases were searched for any analyses of emergent chemical, and Table 4-3 lists the results. Of the few samples analyzed for perchlorate, none of the results has exceeded the USEPA action level of 4 to 18 µg/L. Samples have also been analyzed for 1,4-dioxane, and none of those results has exceeded the USEPA’s tap water preliminary remediation goal of 6.1 µg/L. The base does not have any historical analyses of hexavalent chromium, 1,2,3-trichloropropane, N- nitrosodimethylamine and polybrominated diphenyl ethers. It is Air Force policy that additional investigation for emergent chemicals will be performed where previous site activities suggest the possibility for the use, storage, or disposal of specific emergent chemicals.

4.1.3.4 Data Review. The site data review consisted of reviewing appropriate documents (See Appendix A). The operational data for the OU 1 GETS, hydrogeology, and distribution of the contaminant plumes were reviewed.

From startup in December 1991 to shutdown in March 2003, the GETS has extracted and treated an estimated 1.563 billion gallons of water and removed an estimated 232 pounds of TCE from the subsurface. The GETS was shutdown in March 2003 to allow for recovery data monitoring, aquifer pumping tests, and groundwater modeling to optimize the OU 1 remedy. Table 4-2 lists the historical performance data for the GETS.

The hydrogeology at Site CG-70 is complex and is affected by many groundwater stressors. Figures 3-3 and 3-4 show the potentiometric surface maps for the Upper and Lower Aquifers,

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respectively. Review of these maps indicates groundwater from the Upper Aquifer migrates to the Lower Aquifer through a permeable lacustrine zone (PLZ). The PLZ, a facies change, is discussed in detail in the HCSM (MWH, 2005b). The rate of movement from the Upper to the Lower Aquifer through the PLZ was calculated at a range of 50 gpm to 90 gpm, depending on groundwater stressors (e.g., groundwater extraction and infiltration to the new percolation ponds).

The natural groundwater gradient in the Lower Aquifer is to the northeast. The VVWRA ponds are east of the Mojave River Bluffs and infiltrate directly to the Lower Aquifer. The Upper Aquifer is not present east of the Mojave River Bluffs. This infiltration drives the flow in the Lower Aquifer to the west and increases the gradient to the east. This has implications for the existing Lower Aquifer monitoring well network and its ability to monitor the western edge of the TCE plume in the Lower Aquifer. Currently wells NZ-44, NZ-98, and NZ-105R are the controlling points to evaluate the plume in the westward direction.

Groundwater sampling has been conducted in the OU 1 plume since 1986. The monitoring well network has expanded since that time and groundwater extraction has occurred. Subsequently, the distribution and magnitude of the TCE plumes have changed accordingly. The maximum TCE concentration detected in the Upper Aquifer was at well NZ-55, at 1,280 µg/L, in April 2000. The maximum TCE concentration detected in the Lower Aquifer was at well NZ-37, at 210 µg/L, in November 1987. Table 4-4 provides the historical analytical results, for the last five years, for detected VOCs, basewide. For historical chemical concentrations please refer to the Annual Basewide Groundwater monitoring reports.

Figure 4-2 illustrates the distribution of TCE concentrations over time in the OU 1 Upper Aquifer and Lower Aquifer over time. Table 4-4 provides analytical results for TCE from 1999 through 2004. A review of historical data trends for the OU 1 groundwater plumes suggests the following:

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Upper Aquifer (see Figure 4-2)

• From September 1995 through October 2002, an increase in plume size is noted. This has been interpreted as an artifact of the expanding monitoring well network. • From October 2000 through October 2002, TCE concentrations have increased in a north-south elongated area near the eastern edge of the Upper Aquifer. This appears to be the result of groundwater extraction pulling contaminated groundwater towards the wells and infiltration from the percolation ponds pushing contaminated groundwater to the east. • From October 2002 through October 2004, TCE concentrations in the elongated north-south area ranged 100 µg/L to 400 µg/L, with concentrations above 1,000 µg/L detected near the end of runway 3/21 during the recent CG-70 source area investigation. • The magnitude and extent of the TCE plume in the Upper Aquifer are defined.

Lower Aquifer (see Figure 4-2)

• From September 1995 through October 2002, the increase in plume size is noted. This has been interpreted as an artifact of the expanding monitoring well network. • From October 2002 through October 2004 the plumes are elongating in a north- south direction and to the northeast. This is likely a result of infiltration of water from the VVWRA ponds. • From October 2000 through October 2004 the TCE concentrations have remained relatively consistent ranging from 5 µg/L to a high of 41 µg/L in well NZ-48 in May of 2004. In October 2004 concentrations in NZ-48 decreased to 15 µg/L. A small area defined by well MW-108 had a TCE concentration of 11 µg/L in October of 2004. Historically TCE concentrations have not been detected about the method detection limits in this well. • The magnitude and extent of the TCE plume in the Lower Aquifer are defined.

Estimates of the TCE mass in the Upper and Lower Aquifer are summarized below.

Upper Aquifer TCE Lower Aquifer TCE Mass (pounds) Mass (pounds) Pre-Design Study, 1995 830 170 October 2002 1348 105 May 2004 788 85 September 2004 1205 97

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The increase in TCE mass from May of 2004 to September of 2004 is likely the result of the Upper Aquifer rebounding after groundwater extraction ceased in March of 2003. This rebound of TCE concentrations may result from a combination of the continuing source of TCE to groundwater from the newly discovered CG-70 source area and TCE mass no longer being recovered through groundwater extraction.

4.1.4 Site CG-70 Technical Assessment

In accordance with the USEPA Five-Year Review Guidance document (USEPA, 2001), the technical assessment of the former GAFB has been structured in terms of three questions The following conclusions support the determination that the remedial actions performed at OU 1 are protective of human health and the environment.

Question A: Is the remedy functioning as intended by the decision documents? An evaluation of how the remedy is functioning in relation to the decision documents was done using the remedial action performance data, system operation and maintenance data, opportunities for optimization, early indicators of potential issues and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the OU 1 remedy has been evaluated against the RAOs stated in the OU 1 ROD.

RAO – Prevent exposure to contaminated groundwater that poses a risk of greater than 1 x 10-6.

• Compliance with this RAO has been achieved. • A comprehensive understanding of the transport and transformation of the TCE plumes has been developed through detailed studies of the geology (GCSM) and hydrogeology (HCSM) in and around GAFB. This understanding will be further supplemented with the completion of the groundwater modeling effort in September 2005. These detailed studies indicate that exposures are currently prevented.

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• The USAF is in communication with the VVWRA to ensure that its plant use wells are not impacted with TCE and that water from the wells is identified as non-potable. Analytical results did not detect TCE concentrations in the plant use groundwater wells. • The USAF has monitored and will continue to monitor the TCE groundwater plumes for changes in chemical concentrations and plume migration.

RAO - Reduce TCE concentrations in the groundwater beneath the NEDA to below the federal MCL of 5 µg/L.

• Compliance with this RAO has been partially achieved. TCE concentrations in the groundwater in the Upper Aquifer near the new percolation ponds were reduced to less than 5 mg/L during system operation. Actions are being continued to achieve full compliance with this RAO. • Groundwater extraction and treatment has recovered 232 pounds of dissolved TCE. • O&M costs are less than predicted in the OU-1 ROD and within the acceptable range of minus 30 percent to plus 50 percent. • Ongoing optimization of the remedy will further assist in meeting this objective.

RAO – Reduce the TCE in treated groundwater effluent to meet enforceable levels of 2.5 µg/L TCE on a median basis with a maximum discharge level of 5 µg/L TCE as measured at the effluent sampling port of the treatment system. Furthermore, seek to treat the discharge to attain a level of 0.5 µg/L TCE as measured at the percolation ponds. Although such efforts do not constitute an enforceable discharge standard, the USAF may make minor modifications, as necessary, in an effort to meet this goal.

• Compliance with this RAO has been achieved. • The GETS has effectively treated groundwater effluent to below 2.5 µg/L at the treatment system effluent and to 0.5 µg/L at the percolation ponds. • O&M costs are less than predicted in the OU-1 ROD and within the acceptable range of minus 30 percent to plus 50 percent.

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RAO – Eliminate or reduce the potential for further migration of the existing TCE plume in the groundwater.

• Compliance with this RAO has been partially achieved. As data continues to be collected and evaluated, actions have been taken as described in text to achieve full compliance with this RAO. • The extent and magnitude of the TCE plumes in both the Upper and Lower Aquifers have been defined. • The configuration and magnitude of the TCE plumes in the Upper and Lower Aquifers have changed over time as a result of expanding monitoring well networks and groundwater stressors. • Discharge to the new percolation ponds has been stopped as a precautionary measure. • The identification of Runway 3/21 as a source area and the understanding gained from the OU-1 HCSM study have clarified the mechanisms limiting the effectiveness of the OU 1 remedy. The groundwater modeling is expected to provide the information necessary to effectively optimize the OU 1 remedy. • The USAF conducts quarterly groundwater monitoring. The sampling program, and the fact that there are no drinking water receptors, demonstrates that the USAF has been, currently is and will be in the near future, protective of human health. The remedy was not operating as effective as predicted, so it is being optimized to ensure remedy effectiveness in compliance with the RAOs.

RAO – Provide a conceptual design for a preferred alternative, which will be expandable to remediate an aquifer volume greater than that assumed in the OU 1 ROD, if required, based on the results of future monitoring.

• Compliance with this RAO has been achieved. • Selected Remedy. The original GETS was built in two phases and includes 18 extraction wells. Extracted groundwater is pumped via pipeline to a treatment compound and treated by two packed-tower air strippers that discharge the VOCs directly to the atmosphere. Treated groundwater is then re-injected into the Upper Aquifer via percolation. This system was designed to be expandable based on results of monitoring. As such, 4 monitoring wells were converted to extraction wells continuous to address hot spot areas, for a total of 22 extraction wells.

System /O&M: Prior to shutdown, the GETS operated as designed. Operating procedures such as addition of extraction wells were implemented as needed to improve the effectiveness of the

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remedial action. Operation of the OU 1 treatment system is performed consistent with the procedures identified in the OU 1 O&M Manual.

Opportunities for Optimization: It was determined at the time of the October 2000 Five-Year Review that the remedy was not operating as effectively as predicted. Since that time, as discussed in section 4.1.1, a number of tasks have been completed in an effort to optimize the OU 1 remedy. The final steps of the optimization process (groundwater modeling, revision of the conceptual site model and design, and implementation of an optimized remedy) are anticipated to be completed in 2006.

Early Indicators of Potential Issues: Early indicators of potential issues were noted in the first Five-Year Review. The understanding of the transport and transformation of the TCE plumes and hydrogeologic conditions were determined to be insufficient to appropriately evaluate remedy effectiveness. Therefore studies in support of optimization efforts have been ongoing to ensure remedy effectiveness in compliance with the RAOs.

Implementation of Institutional Controls and Other Measures: The OU 1 ROD did not list Institutional Controls (ICs) as part of the remedy. The OU 1 ROD stated that deed restrictions would be included to prohibit use of groundwater until cleanup levels have been achieved and that land use restrictions as ICs would be recorded prior to sale or transfer of the property overlying the NEDA. The on-base portions of OU 1 are retained by the Air Force, are on lease to the Land Reuse Agency (LRA), and will not be transferred by deed until the Air Force receives regulatory concurrence that the remedial actions, including ICs, are in place and operating properly and successfully. Until that time the Air Force retains full authority in restricting use and has implemented the following land use and engineering controls.

Current – On Base: The Air Force has prohibited use of groundwater from the Upper Aquifer and ensures compliance with repeated communication to the lessee and by maintaining a daily presence at the former base so that issues are identified and resolved on a real-time basis. Several specific terms and conditions from the lease are as follows:

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1. Lessee and any sublessee shall comply with all Federal, State and local laws, regulations and standards. 2. Government retains the right to inspect. 3. Lessee expressly acknowledges that it fully understands that response actions undertaken with respect to the FFA or IRP program may impact "quiet use and enjoyment" of leased property. 4. Lessee agrees to comply with provisions of any health and safety plan in effect under the IRP, hazardous substance remediation or response agreement. 5. Lessee acknowledges receipt of the Environmental Baseline Survey (EBS). 6. Lessee acknowledges receipt of the information that GAFB has been identified as a NPL Site and why (see EBS above). 7. Lessee acknowledges receipt of FFA, and that the FFA terms take precedence over the lease. 8. The Government, USEPA, and State retain the right to enter lease premises for purposes of executing the FFA and IRP program (access, inspection, investigation, response/remedial actions, etc). 9. Lessee shall not construct or make, or permit its sublessees to construct or make, any alterations (construction, demolition, excavation, restoration, additions, or other changes in, to or upon the property) which may impede or impair any activities under the IRP or FFA without prior written consent of the Air Force. 10. The failure to comply with any provision of the lease shall constitute a default and may result in the termination of the lease.

Current – Off Base: The Air Force has implemented the following to ensure that the remedy is protective:

• The Air Force has completed extensive studies to develop a comprehensive understanding of the transport and transformation of the TCE through detailed studies of geology (the GCSM) and hydrogeology (the HCSM). This understanding will be further supplemented with the completion of the groundwater modeling efforts expected to be published September 2005. These detailed studies indicate that exposures are currently prevented and will assist in ensuring continued protectiveness. • The Air Force is in communication with the VVWRA to ensure that its plant use wells are not impacted by TCE and that water from the wells is identified as non- potable. TCE was not detected in the plant use wells. • The Air Force is monitoring and will continue to monitor the TCE groundwater plumes for changes in chemical concentrations and plume migration. The Air Force is monitoring 10 Lower Aquifer perimeter wells on a quarterly basis as part

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of the Focused Monitoring Program. As part of the evaluation to optimize the OU 1 plume, sentinel wells may be included in the future.

Future: Deed covenants will be identified in the Finding of Suitability to Transfer (FOST), CERCLA 120(h)3 and state land use covenant to ensure that ICs are identified. The next five- year review process will be used to verify that the ICs are functioning as intended.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objectives for the remedy that support the positive conclusion.

Changes in Standards and To Be Considered (TBC): ARARs and SWRCB policy standards are the standards used for the RAOs. No TBCs were identified. No changes in standards have been identified that affect the protectiveness of the RAOs.

Changes in Cleanup Levels: The following cleanup levels, as presented in the OU 1 ROD (Montgomery Watson, 1994), were reviewed and were determined to be applicable.

• SWRCB Anti-Degradation Policy 68-18 • The Federal MCL of 5 µg/L for TCE in groundwater • A maximum of 2.5 µg/L for TCE in the treatment system effluent • MAQMD air emission level of 1 pound/day

Possible future changes include the following:

1) Four monitoring wells (NZ-55, NZ-40, NZ-82, and NZ-83) were converted to groundwater extraction wells in 2001 and 2004. The system has not been operational since wells NZ-40, NZ-82, and NZ-83 were converted in 2004. The influent concentration with the addition of these wells is estimated at 45 µg/L. The treatment system will be able to treat the additional mass to levels below the discharge limit of 2.5 µg/L. The additional volume of water generated from these

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wells is 19 gpm and is easily accommodated by the 1,100-gpm capacity of the treatment system. 2) Similarly, air emissions with the four new extraction wells have been calculated at 0.09 lb/day. This is well below the discharge limit of 1 lb/day for TCE. 3) As previously discussed, extensive work is being conducted to optimize the OU 1 remedy. Groundwater modeling is underway and the results may require redesign of the groundwater extraction well network and treatment system, altering influent concentrations and volume treated.

Changes in Exposure Pathways: Land use in the area remains light industrial and commercial. There are no plans for residential development on the former GAFB property. The only exposure pathway for TCE in groundwater, identified in the OU 1 ROD (Montgomery Watson, 1994), was to the construction worker during installation of the GETS. This exposure pathway still applies and will be considered during implementation of any optimization tasks and as a result of construction or well relocation activities associated with the intermodal rail project proposed along the eastern boundary of former GAFB. The baseline risk assessment has not been recalculated, because remediation has been ongoing, there are no complete exposure pathways, and there are no plans for residential use.

The flow direction of the Lower Aquifer has been altered by water infiltration at the VVWRA ponds, reversing flow to the west. Wells NZ-44, NZ-105R, and NZ-98 monitor the western edge of the plume. Potential receptors in this direction are the City of Adelanto production wells. These wells are approximately 5 miles to the west of the current western edge of the plume; therefore, the pathway is considered incomplete at this time.

New Contaminants or Contaminant Sources: A new source area has been identified at the end of Runway 3/21, just south of converted monitoring well NZ-55. The area is within the footprint of the existing OU 1 plume, so no changes in exposure pathways result from this newly identified source area. It is under active investigation, and a remedy is being developed. If a remedy is needed, it will be designed to remove the source, shorten the groundwater remedy, and take into account indoor air. Soil gas samples were collected according to guidance (DTSC, 2004) for the evaluation of indoor air.

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Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy. No chemical byproducts have been created from the remedy.

Currently, the Cal-EPA cancer slope factor is recommended for use at GAFB. The California Environmental Protection Agency (Cal-EPA) has developed inhalation (0.007 milligrams per kilograms per day to the negative exponential [mg/kg-d]-1) and oral (0.013 [mg/kg-d]-1) TCE cancer slope factors for use in California.

Changes in Risk Assessment Methodologies: There have been no changes in risk assessment methodologies since the OU 1 ROD was signed that call into question the protectiveness of the remedy.

Expected Progress Towards Meeting the RAOs: Optimization efforts are expected to enhance the remedy effectiveness in compliance with the RAOs.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

The intermodal project proposed along the eastern property boundary may affect the protectiveness of the remedy. SCLA is planning the development of a 2,900-acre facility for product transportation. This rail complex will provide the capacity to process more than 800 million pounds of international and domestic trade annually. In conjunction with the rail complex, a 700-acre multimodal logistics and distribution complex is planned, providing a consolidated center for automobiles, container storage, repair and maintenance facility, and various other services. The footprint of the rail complex and multimodal distribution complex is shown on Figure 4-3. Construction of these projects will require destruction and replacement of many of the OU 1 remedy monitoring and extraction wells. Pending results of the groundwater modeling, an optimized monitoring and extraction well network will be designed and constructed, as appropriate, with these changes considered. USAF and the regulators have

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communicated concerns about this development; SCLA and the developer understand that the development of this property must be protective of human health and the environment.

No natural disasters have occurred in the area that have altered the effectiveness of the remedy.

Endangered species are not impacted by OU 1 groundwater, because groundwater does not reach the surface. However, protective measures continue to be taken during site construction activities.

4.1.4.1 Technical Assessment Summary: The site data was reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy was not operating as effectively as predicted but is protective of human health and the environment. Optimization efforts are on-going to ensure remedy effectiveness in compliance with the RAOs.

B) Are the exposure assumptions, toxicity data, cleanup levels and remedial action objectives used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD, based on risk and toxicity information, are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy. The future intermodal rail project should not affect protectiveness of the remedy, as long as required system modifications are managed appropriately.

4.1.5 Site CG-70 Issues

No deficiencies were noted during this five-year review. However, the OU-1 remedy has not operated as effectively as predicted, so optimization efforts (developing a more defined

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB 2nd 5-Yr Review Rpt_Final\Text\Section 4.doc 4-22 Second Five-Year Review Report Former George Air Force Base understanding of the behavior of the TCE plumes and hydrogeologic controls) have been ongoing to ensure remedy effectiveness in compliance with the RAOs.

4.1.6 Site CG-70 Recommendations

The following summarizes the recommendations to ensure remedy effectiveness in compliance with the RAOs.

1) Continue and complete optimization of the OU 1 remedy by 2006; responsible party USAF. 2) Design and implement a remedy for soil at the new source area identified at CG-70 (near Runway 3/21), by 2006; responsible party USAF. 3) Expand, if appropriate, Lower Aquifer monitoring and extraction well network as determined from groundwater modeling. Complete in 2006-2007; responsible party USAF. 4) Coordinate destruction and replacement of monitoring and extraction wells with the City of Victorville, based on results of groundwater modeling effort and intermodal project footprint. Complete in 2006-2007; responsible party, City of Victorville and USAF. 5) Monitor planning for the SCLA Rail Center and Multimodal Complex project to determine impact on indoor air exposure pathways (ongoing); responsible party, USAF.

4.1.7 Site CG-70 Protectiveness Statement

The remedy at OU 1 currently protects human health and the environment because:

• Upper Aquifer water is prohibited from use via lease restrictions. • Upper Aquifer water does not reach surface water; therefore there are no exposure pathways. • Lower Aquifer water use is restricted on and off-base. (See land use controls discussion). • The Lower Aquifer plume migration is limited to the north and east due to losing stream conditions of the Mojave River. Definition of the extent of the plume to the north and east is under investigation. Based on historic concentrations it is not anticipated to have reached the northern VVWRA boundary.

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However, in order for the remedy to be protective in the long-term, the following actions have and/or are being taken:

• Conducting data gap investigations. • Developing a comprehensive geologic conceptual site model. • Converting 4 monitoring wells to extraction wells, • Conducting extensive aquifer tests for development of a comprehensive hydrogeologic conceptual site model. • Conducting additional source area investigations and planning for implementation of a vadose zone remedy to eliminate TCE mass loading to the Upper Aquifer. • Groundwater modeling based on detailed data documented in the Geologic and Hydrogeologic CSMs is in progress. The groundwater modeling results will be used to optimize the OU 1 remedy to meet the RAOs ensuring long term protectiveness of human health and the environment. Specific remedy modification tasks such as; reconfiguration and/or expansion of the extraction and groundwater monitoring well networks, alteration of treated water discharge location and/or modification of the remedy, to achieve compliance will be determined after completion and acceptance of the results of the simulation scenarios.

4.1.8 Site CG-70 Next Review

The next Five-Year Review will be conducted in 2010.

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5.0 OPERABLE UNIT 3 SITES (LANDFILLS AND FUELS/VOLATILE ORGANIC COMPOUNDS SITES)

This section presents the procedures and results of the Five-Year Review for landfill Sites DP-03, DP-04, LF-12, LF-14, LF-44, and the SEDA; and the TPH/VOC sites FT-19a, FT-19c, OT-51, OT-69, and WP-17.

5.1 LANDFILL DP-03

Landfill DP-03 is a suspected acid and oil burial site. It is located approximately 400 feet north of the northeast end of Runway 3/21 (the crosswind/secondary runway), as shown in Figure 3-6. Figure 5-1 provides a site plan for DP-03. The location of landfill DP-03 is coincident with the location of a disposal site for construction demolition debris (hardpack), known as LF-45, and is located in an unpaved, relatively undeveloped area. Hydrochloric acid, sulfuric acid, oil, fuel, and unidentified drums were reportedly disposed of at the site. Both the period of use and volumes of wastes disposed at the site are unknown.

5.1.1 DP-03 Remedial Actions

This section describes the remedy selection, implementation, O&M, and progress since the previous Five-Year Review for GAFB (Montgomery Watson, 2000).

5.1.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for landfill DP-03 and the other OU 3 landfills (Montgomery Watson, 1998):

• Prevent direct contact with landfill contents. • Minimize infiltration that may result in waste constituents leaching to groundwater. • Control surface water runoff and run-on and erosion. • Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

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The selected remedy includes access and land use restrictions, surface controls, surface restoration, groundwater monitoring, and the five-year site review.

5.1.1.2 Remedy Implementation. A removal action has been implemented at landfill DP-03. In an effort to accelerate the remedial progress, minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at landfill DP-03 before finalization of the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB, and the Air Force.

The removal action at landfill DP-03 included grading of the existing soil cover to promote surface run-off and to decrease infiltration of surface water into the landfill, installing a 2-foot- thick soil cover to reduce the potential for exposure to contaminants, installing site perimeter fencing to control site access, installing perimeter drainage ditches to prevent surface water from running onto the landfills and to control surface water run-off, restricting land use to prohibit subsurface development, and re-establishing native plant species on the graded surface. The removal action was completed between June 1996 and April 1997. The actions minimize or mitigate human health and ecological risks by providing a physical barrier to potential contamination.

5.1.1.3 System O&M. O&M at landfill DP-03 includes groundwater monitoring; an annual engineering inspection of soil cover erosion, cap stability, access roads, warning signs, drainage channels, perimeter fencing, and vegetation, and an annual burrows management inspection. A more detailed description of the engineering and burrows management inspections is contained in Appendix C and in the Semiannual O&M Report for OU 3 Sites (MWH, 2004c).

Groundwater monitoring is used to assess whether contaminants have migrated into the groundwater. A more detailed description of the landfill groundwater monitoring and analysis program can be found in Appendix C, and is also presented in the Post-Closure Groundwater Monitoring Technical OU 3 (MWH, 2003a).

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5.1.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found the remedy at landfill DP-03 protective of human health and the environment.

Engineering and burrows management inspections at landfill DP-03 indicate the site remains in good condition. Repairs have not been performed at this site, except for minor maintenance such as filling in small burrows underneath the perimeter fencing. No repairs are recommended for the immediate future.

Groundwater monitoring data do not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater quality. Plots of historical groundwater monitoring results for landfill DP-03 were presented to the BCT during bimonthly meetings in 2004.

5.1.2 DP-03 Five-Year Review Process

The former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and site inspections where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance, OSWER No. 9355.7-03B-P (USEPA, 2001), and included pre-notification to the community and interested parties via media notification in

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the Victorville Daily Press stating that a five-year review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.1.3 DP-03 Five-Year Review Findings

This section describes the findings of the Five-Year Review for landfill DP-03. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports, the Semiannual O&M Reports for OU 3 Sites, and the OU 3 ROD (Document List, Appendix A).

5.1.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

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Mr. Bob Field, a Victor Valley Water District employee, stated he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He did not express concerns about any of the landfills.

5.1.3.2 Site Inspections. The most recent site inspection of landfill DP-03 was conducted in July 2004 and included the annual engineering and burrows management inspections. Since the findings of this site inspection are expected to be current through 2004, an additional site inspection was not conducted specifically for the Five-Year Review.

The July 2004 site inspection was conducted by Mr. Christopher Glenn (MWH), Ms. Elena Birch-Carl (MWH), and Mr. Steve Gardner (Southwest Desert Environmental). Findings of this site inspection were included in the October 2004 Semiannual O&M Report (MWH, 2004c). Inspection documents are included in Appendix C.

5.1.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

During the RI, a baseline risk assessment was performed for landfill DP-03; the exposure scenarios evaluated were based on the proposed reuse of the land parcel in which the site is located. Using the likely future land use of an airfield and related facilities, the baseline human health risk assessment estimated the highest excess lifetime cancer risk to be 1.9 x 10-5, primarily driven by polycyclic aromatic hydrocarbons (PAHs) under an industrial/commercial scenario. Because a landfill cap is in place, there are no complete exposure pathways, and there are no plans for residential use, the baseline risk assessment has not been recalculated.

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An environmental assessment was conducted to assess the potential risks to plants and animals due to the localized presence of PAHs. The qualitative ecological benchmark screening indicated that there are potential risks to ecological receptors due to the localized presence of PAHs. However, the results of subsequent quantitative food chain modeling, specifically for bioaccumulative compounds, show that bioaccumulative compounds of potential ecological concern pose no significant risks to vegetation and wildlife at the site. Human activities associated with the proposed land use for this parcel are expected to limit the selection of landfill DP-03 as a primary habitat by many ecological receptors. Site conditions have not changed; therefore, an updated qualitative ecological benchmark screening is not warranted.

A list of ARARs for landfill DP-03 is provided in Table 4 of the OU 3 ROD (Montgomery Watson, 1998), which is also included in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, Department of Toxic Substances Control (DTSC), USEPA, and the USAF. Based upon this discussion, the selected remedial action at landfill DP-03 is compliant with ARARs for landfill closure, such as grading, drainage, and slope protection through revegetation. The annual landfill monitoring at landfill DP-03 complies with ARARs for landfill closure monitoring, such as site security, notification signs, monitoring for settlement, soil cover maintenance, and groundwater detection monitoring. A review of the ARARs for this Five-Year Review process indicates that the OU 3 ROD ARARs remain up-to-date and relevant for landfill DP-03.

5.1.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). Landfill DP-03 was most recently inspected on 12 July 2004. The following summarizes the findings of this inspection, as reported in the Landfill Inspection Technical Memorandum (MWH, 2004c), and the document review.

The access roads, security fencing, entrance gate, soil cover, vegetative cover, and drainage channels at landfill DP-03 are in good condition. There is no evidence of erosion or settlement at this site. The biological inspection did not find any sensitive plant or animal species at DP-03. An animal had dug under the fence post in the western corner of the landfill to enter the site, and a small gap was noted at the fence post in the northeast corner of the landfill. These locations

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were repaired by filling the gap with rock and soil, and manually compacting. The tumbleweeds that had accumulated outside the landfill entrance gate were removed. Small burrows (less than 1-inch diameter) are located throughout the landfill cap and along the perimeter fence. Landfill DP-03 is in good condition and the soil cover remains intact.

Groundwater monitoring data at landfill DP-03 do not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater. Plots of historical groundwater monitoring results for landfill DP-03 are included in Appendix E.

5.1.4 DP-03 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at landfill DP-03 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues, and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the OU 3 landfill remedy has been evaluated against the RAOs stated in the OU 3 ROD.

RAO - Prevent direct contact with landfill contents.

• The landfill soil cover remains in place and is in good condition. Routine inspections note any issues and repairs are made, if necessary. ICs are in place and the land use remains the same as during the decision process. No direct contact has occurred.

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RAO - Minimize infiltration that may result in waste constituents leaching to groundwater.

• The drainage channels remain in good condition and allow for drainage of surface water from the landfill to reduce infiltration. Routine inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Control surface water runoff and run-on and erosion.

• Landfills were constructed to minimize surface water runoff and run-on and erosion. Engineering inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

• Groundwater monitoring is performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003). Groundwater monitoring data does not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater.

System O&M: Annual engineering and biological inspections, and landfill groundwater monitoring are performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003).

Cost of System O&M: O&M costs are less than predicted in the OU3 ROD and within the acceptable range of minus 30 percent to plus 50 percent.

Opportunities for Optimization: Landfill DP-03 has not required more than routine monitoring and very minor maintenance, thus there are no opportunities for optimization at present. Future optimization of the landfill groundwater monitoring program is prescribed in Post-Closure Landfill Groundwater Monitoring Technical Memorandum (MWH, 2003a), which recommends a reduction in the number of monitoring wells sampled and the sampling frequency if the initial results do not indicate impact of the landfills to the groundwater quality.

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Early Indicators of Potential Issues: The current monitoring results do not contain any indication that the institution controls and soil cover remedy is failing or may fail in the future.

Implementation of ICs and Other Measures: ICs are in place at landfill DP-03 and the land use remains the same as during the decision process. Annual engineering inspections are performed to verify the perimeter fencing; gates and warning signs remain in place and are effective. The perimeter of Landfill DP-03 is enclosed by fencing and the gate is kept locked at all times. This security effectively eliminates unauthorized access to the site, and hence its use is restricted. The land use restriction remains effective in prohibiting subsurface development and preventing excessive vehicle traffic at landfill DP-03, and are protective.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards To Be Considered (TBC): A review of the ARARs used to develop the remedy for landfill DP-03 (Section 5.1.3.3) indicates no change in standards from the previous Five-Year Review.

Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathway: No changes in the site condition or land use that would affect the exposure pathway were found during this five-year review. Land use may potentially be altered in the future by the SCLA rail and multimodal complex construction (described in Section 4.1.4). The current project footprint would allow landfill DP-03 to remain in place and unaffected.

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Changes in Land Use: There have been no changes in land use. Global Access, SCLA is planning the development of a 2,900-acre facility for production transportation that may impact the future land use at landfill DP-03. A rail complex and a multimodal logistics and distribution complex is planned. The footprint of the rail complex and multimodal distribution center are shown on Figure 4-3. The current footprint would not impact landfill DP-03 or associated monitoring wells, however planning of the project should be monitored for changes that may impact landfill DP-03.

New Contaminants or Contaminant Sources: No new contaminants or source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at landfill DP-03. No chemical byproducts have been created from the remedy.

Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the chemicals of potential concern (COPCs) present at landfill DP-03 since the previous Five-Year Review.

Expected Progress towards Meeting the RAOs: The RAOs are currently being met.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Maintenance and monitoring of landfill DP-03 indicates that the landfill cover remains intact and continues to serve as an effective remedy. The perimeter fencing, gates, and warning signs remain in place and appear to be effective in eliminating unauthorized access to the landfill. Landfill groundwater monitoring does not indicate any impact of the landfill to the groundwater quality beneath the site. None of the monitoring results include any information that might call into question the protectiveness of the remedy.

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New or Previously Unidentified Ecological Risk: There are no new or previously unidentified ecological risks.

Natural Disaster Impact: No natural disaster has occurred in the area that has altered the effectiveness of the remedy.

5.1.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy is operating as effectively as predicted and is protective of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD, based on risk and toxicity information are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy. The future intermodal rail project should not affect protectiveness of the remedy, as long as required system modifications are managed appropriately.

5.1.5 DP-03 Issues

There were no deficiencies identified for landfill DP-03 during the Five-Year Review. No changes to the routine monitoring program are necessary. An issue of concern at landfill DP-03 is the potential impact of the planned SCLA rail center and multimodal complex on the landfill or landfill monitoring wells.

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5.1.6 DP-03 Recommendations and Follow-Up Actions

The following is recommended to ensure remedy effectiveness in compliance with the RAOs for landfill Site DP-03:

1) Monitor planning for the SCLA rail center and multimodal complex project to determine impact on landfill DP-03 (ongoing); responsible party, USAF. 2) Continue engineering inspections, biological inspections, and landfill groundwater monitoring (ongoing); responsible party, USAF. 3) Monitor the SCLA Rail Center and Multimodal Complex to determine impact on landfill DP-03; responsible party, USAF.

5.1.7 DP-03 Protectiveness Statement

The remedy for the OU 3 landfill DP-03 is protective of human health and the environment in the short-term because the landfill cap and institutional controls effectively mitigate risk. The landfill cap and institutional controls will continue to be maintained to ensure long-term protectiveness.

5.1.8 DP-03 Next Review

The next Five-Year Review will be conducted in 2010.

5.2 LANDFILL DP-04

Landfill DP-04 is a reported pesticide and oil drum burial site located in an undeveloped area approximately 200-feet east of the northeast end of Runway 3/21, as shown on Figure 3-6. A site plan for landfill DP-04 is included as Figure 5-2. Investigations revealed that construction debris and miscellaneous debris were disposed at the site, but no evidence of buried drums or soil staining was found. Both the period of use and volume of waste at the site are unknown.

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5.2.1 DP-04 Remedial Actions

This section describes the remedy selection, implementation, O&M, and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.2.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for landfill DP-04 and the other OU 3 landfills (Montgomery Watson, 1998):

• Prevent direct contact with landfill contents. • Minimize infiltration that may result in waste constituents leaching to groundwater. • Control surface water runoff and run-on and erosion. • Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

The selected remedy includes access and land use restrictions, surface controls, surface restoration, groundwater monitoring, and the five-year site review.

5.2.1.2 Remedy Implementation. A removal action has been implemented at landfill DP-04. In an effort to accelerate the remedial progress, minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at landfill DP-04 before finalization of the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB and the Air Force.

The removal action at landfill DP-04 included grading of the existing soil cover to promote surface runoff and decrease infiltration of surface water into the landfill, installing of a 2-foot- thick soil cover to reduce the potential of exposure to contaminants, installing of site perimeter fencing to control site access, installing of perimeter drainage ditches to prevent surface water from running onto the landfills and to control surface water run-off, a land use restriction prohibiting subsurface development, and re-establishing native plant species on the graded surface. The removal action was completed between June 1996 and April 1997. The actions

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minimize or mitigate human health and ecological risks by providing a physical barrier to potential contamination. Prior to installing the soil cover at landfill DP-04, hot spot removal was performed by excavating approximately 10 cubic-yards of soil to reduce potential risk to burrowing animals.

5.2.1.3 System O&M. O&M at landfill DP-04 includes groundwater monitoring; an annual engineering inspection of soil cover erosion, cover stability, access roads, warning signs, drainage channels, perimeter fencing, and vegetation; and an annual burrows management inspection. A more detailed description of the engineering and burrows management inspections is included in Appendix C and is also contained in the Semiannual O&M Report for OU 3 Sites (MWH, 2004c).

Groundwater monitoring is used to assess whether contaminants have migrated into the groundwater. A more detailed description of the landfill groundwater monitoring and analysis program can be found in Appendix C and is also presented in the Technical Memorandum, Proposed Approach to Post-Closure Landfill Groundwater Monitoring at OU 3 Landfills (MWH, 2003a).

5.2.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found that the remedy at landfill DP-04 was protective of human health and the environment.

Engineering and burrows management inspections at landfill DP-04 indicate the site remains in good condition. Repairs have not been performed at this site, except for minor maintenance such as filling in small burrows underneath the perimeter fencing. No repairs are recommended for the immediate future.

Groundwater monitoring data from compliance wells do not contain abnormally high or erratic concentrations that would indicate impact from the landfill to the groundwater quality. Plots of historical groundwater monitoring results for landfill DP-04 have been presented to the BCT during bimonthly meetings in 2004.

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5.2.2 DP-04 Five-Year Review Process

The former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and a site inspection where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance, (USEPA, 2001), and included pre-notification to the community and interested parties via media notification in the Victorville Daily Press stating that a Five-Year Review was to be conducted, and notification that the Five-Year Review report was completed and available in the site repository.

The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document –22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

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5.2.3 DP-04 Five-Year Review Findings

This section describes the findings of the Five-Year-Review for landfill DP-04. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports, the Semiannual O&M Reports for OU 3 Sites, and the OU 3 ROD (Document List, Appendix A).

5.2.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He did not express concerns about any of the landfills.

5.2.3.2 Site Inspections. The most recent site inspection of landfill DP-04 was conducted in July 2004 and included the annual engineering and burrows management inspections. Since the findings of this site inspection are expected to be current through 2004, an additional site inspection was not conducted specifically for the Five-Year Review.

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The July 2004 site inspection was conducted by Mr. Christopher Glenn (MWH), Ms. Elena Birch-Carl (MWH), and Mr. Steve Gardner (Southwest Desert Environmental). Findings of this site inspection were included in the October 2004 Semiannual O&M Report (MWH, 2004c). Inspection documents are included in Appendix C.

5.2.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

During the RI, a baseline risk assessment was performed for landfill DP-04; exposure scenarios were evaluated based on the proposed reuse of the land parcel in which the site is located. The baseline human health risk assessment estimated the highest excess lifetime cancer risk to be 6.7 x 10-5, primarily because of Aroclor 1260, a polychlorinated biphenyl (PCB), under the industrial/commercial scenario. The baseline risk assessment has not been recalculated because a landfill cap is in place, there are no complete exposure pathways, and there are no plans for residential use.

An environmental assessment was conducted to assess the potential risks to plants and animals due to the localized presence of the PCB. The results of the ecological risk assessment indicated a potential risk to burrowing mammals and their predators (e.g., barn owl), primarily because of the presence of Aroclor 1260. A removal action of approximately 10 cubic yards of soil was performed at landfill DP-04 in response to this ecological risk. Site conditions have not changed; therefore, an updated qualitative ecological benchmark screening is not warranted.

A list of ARARs for landfill DP-04 is provided in Table 4 of the OU 3 ROD (Montgomery Watson, 1998), which is also included in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA, and the USAF. Based upon this discussion, the selected remedial action at landfill DP-04 is compliant with ARARs on landfill closure such as grading, drainage and slope protection through revegetation. The landfill monitoring performed annually at landfill DP-04 complies with ARARs for landfill closure monitoring, such as site security, notification signs, monitoring for

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settlement, soil cover maintenance, and groundwater detection monitoring. A review of the ARARs for this Five-Year Review process indicates that the OU 3 ROD ARARs remain up-to- date and relevant for landfill DP-04.

5.2.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). Landfill DP-04 was most recently inspected on 12 July 2004. The following is a summary of the findings of this inspection, as reported in the Landfill Inspection Technical Memorandum, published in the October 2004 Semiannual O&M Report (MWH, 2004c).

The access roads, security fencing, entrance gate, soil cover, vegetative cover, and drainage channels at landfill DP-04 are in good condition. Minor rill erosions exist (maximum 8-inches deep) on the steepest portions of the landfill, but have not increased in size or depth since the previous annual inspection. There is no evidence of settlement at this site. The biological inspection did not find any sensitive plant or animal species at DP-04. An animal had dug under the fence post in the easternmost corner of the landfill to enter the site. This location was repaired by filling the dug out area with rock and soil and manually compacting. Tumbleweeds that had accumulated within the fence on the eastern side of the landfill and near the entrance gate were removed. Small burrows (less than 1-inch diameter) are located throughout the landfill cap and along the perimeter fence. Landfill DP-04 is in good condition and the soil cover remains intact.

Groundwater monitoring data at landfill DP-04 do not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater. Plots of historical groundwater monitoring results for landfill DP-04 are included in Appendix E.

5.2.4 DP-04 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at landfill DP-04 has been structured in terms of three questions.

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Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues, and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the OU 3 landfill remedy has been evaluated against the RAOs stated in the OU 3 ROD.

RAO - Prevent direct contact with landfill contents.

• The landfill soil cover remains in place and is in good condition. Routine inspections note any issues and repairs are made, if necessary. ICs are in place, and the land use remains the same as during the decision process. No direct contact has occurred.

RAO - Minimize infiltration that may result in waste constituents leaching to groundwater.

• The drainage channels remain in good condition and allow for drainage of surface water from the landfill to reduce infiltration. Routine inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Control surface water runoff and run-on and erosion.

• Landfills were constructed to minimize surface water runoff and run-on and erosion. Engineering inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

• Groundwater monitoring is performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003). Groundwater

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monitoring data does not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater.

System O&M: Annual engineering and biological inspections, and landfill groundwater monitoring are performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003).

Cost of System O&M: O&M costs are less than predicted in the OU 3 ROD and within the acceptable range of minus 30 percent to plus 50 percent.

Opportunities for Optimization: Landfill DP-04 has not required more than routine monitoring and very minor maintenance, thus there are no opportunities for optimization at present. Future optimization in the landfill groundwater monitoring program is prescribed in the Proposed Approach to Post-Closure Landfill Groundwater Monitoring at OU 3 Landfills Technical Memorandum (MWH, 2003a), and recommends a reduction in the number of monitoring wells sampled and the sampling frequency if the initial results do not indicate impact of the landfills to the groundwater quality.

Early Indicators of Potential Issues: The current monitoring results do not contain any indication that the institution controls and soil cover remedy is failing or may fail in the future.

Implementation of ICs and Other Measures: ICs are in place at landfill DP-04 and the land use remains the same as during the decision process. Annual engineering inspections are performed to verify that the perimeter fencing, gates and warning signs remain in place and effective. The perimeter of Landfill DP-04 is enclosed by fencing and the gate is kept locked at all times. This security effectively eliminates unauthorized access to the site, and hence its use is restricted. The land use restriction remains effective in prohibiting subsurface development and preventing excessive vehicle traffic at landfill DP-04, and are protective.

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Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for landfill DP-04 (Section 5.2.3.3) indicates no change in standards from the previous Five-Year Review.

Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathways: No changes in the site condition or land use that would affect the exposure pathway were found during this five-year review.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use. Global Access, SCLA is planning the development of a 2,900-acre facility for production transportation that may impact the future land use at landfill DP-04. A rail complex and a multimodal logistics and distribution complex is planned. The footprint of the rail complex and multimodal distribution center are shown on Figure 4-3. The current footprint would not impact landfill DP-04 or associated monitoring well; however, planning of the project should be monitored for changes that may impact landfill DP-04.

New Contaminants or Contaminant Sources: No new source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: The toxicity values and carcinogenicity assessment for PCBs were revised in 1997, as part of the USEPA’s Integrated Risk Information System. The reassessment resulted in changes to the health-based screening levels for assessing potential health impacts of PCBs in soils. These toxicity changes do not affect the protectiveness of the remedy.

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Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at landfill DP-04 since the previous Five-Year Review.

Expected Progress towards Meeting the RAOs: The RAOs are currently being met.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Maintenance and monitoring of landfill DP-04 indicates that the landfill cap remains in tact and continues to serve as an effective remedy. The perimeter fencing, gates, and warning signs remain in place and appear to be effective in eliminating unauthorized access to the landfill. Landfill groundwater monitoring does not indicate any impact of the landfill to the groundwater quality beneath the site. None of the monitoring results include any information that might call into question the protectiveness of the remedy.

New or Previously Unidentified Ecological Risks: There are no new or previously unidentified ecological risks.

Natural Disaster Impact: No natural disaster has occurred in the area that has altered the effectiveness of the remedy.

5.2.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy is operating as effectively as predicted and is protective of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD, based on risk and toxicity information are still valid.

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C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy. The future intermodal rail project should not affect protectiveness of the remedy, as long as required system modifications are managed appropriately.

5.2.5 DP-04 Issues

There were no deficiencies identified for landfill DP-04 during the five-year review. No changes to the routine monitoring program are necessary. An issue of concern at landfill DP-04 is the potential impact of the planned SCLA rail center and multimodal complex on the landfill or landfill monitoring wells.

5.2.6 DP-04 Recommendations and Follow-Up Actions

The following summarizes the recommendations for landfill DP-04 to ensure remedy effectiveness in compliance with the RAOs for landfill Site DP-03:

1) Monitor planning for the SCLA rail center and multimodal complex project to determine impact on landfill DP-04 (ongoing); responsible party, USAF. 2) Continue engineering inspections, biological inspections, and landfill groundwater monitoring (ongoing); responsible party, USAF. 3) Monitor the SCLA Rail Center and Multimodal Complex to determine impact on landfill DP-04; responsible party, USAF.

5.2.7 DP-04 Protectiveness Statement

The remedy for the OU 3 landfill DP-04 is protective of human health and the environment in the short-term because the landfill cap and institutional controls effectively mitigate risk. The landfill cap and institutional controls will continue to be maintained to ensure long-term protectiveness.

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5.2.8 DP-04 Next Review

The next Five-Year Review will be conducted in 2010.

5.3 LANDFILL LF-12

Landfill LF-12 is an abandoned landfill located in an unpaved, relatively undeveloped area near the intersection of Phantom East Drive and Perimeter Road, as shown on Figure 3-6. A site plan for landfill LF-12 is included as Figure 5-3. The site was reportedly used for disposal of general base wastes from approximately 1953 until 1957. Wastes buried at the site may have included street sweeping debris, lube oil, paint, lacquer, naphthalene, TCE, PD-680, cleaning compounds, hydraulic fluid, fire fighting foams, batteries, oil spill adsorbent, and general refuse. The wastes may have been burned using waste oils in the mid-1950s. Trash and rubble may have been buried at the site during the 1960s and early 1970s. The site was reportedly used for street- sweeping disposal in the early 1980s.

5.3.1 LF-12 Remedial Actions

This section describes the remedy selection, implementation, O&M, and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.3.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for landfill LF-12 and the other OU 3 landfills (Montgomery Watson, 1998):

• Prevent direct contact with landfill contents. • Minimize infiltration that may result in waste constituents leaching to groundwater. • Control surface water runoff and run-on and erosion. • Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

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The selected remedy includes access and land use restrictions, surface controls, surface restoration, groundwater monitoring, and the five-year site review.

5.3.1.2 Remedy Implementation. A removal action has been implemented at landfill LF-12. In an effort to accelerate the remedial progress, minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at landfill LF-12 before finalization of the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB, and the Air Force.

The removal action at landfill LF-12 included removing surface debris; rehabilitating the existing soil cover to an estimated thickness of 12- to 18-inches; grading the surface to promote surface runoff and decrease infiltration of surface water into the landfill; installing perimeter drainage ditches to prevent surface water from running onto the landfill sites and to control surface water run-off from the landfills; installing site perimeter fencing to control site access; restricting land use to prohibit subsurface development; and re-establishing native plant species on the graded surface. The removal action was completed between June 1996 and April 1997. The actions minimize or mitigate human health and ecological risks by providing a physical barrier to potential contamination.

5.3.1.3 System O&M. O&M at landfill LF-12 includes groundwater monitoring; an annual engineering inspection of soil cover erosion, cap stability, terraces, access roads, warning signs, drainage channels, perimeter fencing, and vegetation; and an annual burrows management inspection. A more detailed description of the engineering and burrows management inspections is contained in Appendix E and in the Semiannual O&M Report for OU 3 Sites (MWH, 2004c).

Groundwater monitoring is used to assess whether contaminants have migrated into the groundwater. A more detailed description of the landfill groundwater monitoring and analysis program can be found in Appendix E and is also presented in the Post-Closure Groundwater Monitoring Technical Memorandum (MWH, 2003a).

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5.3.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found the remedy at landfill LF-12 was protective of human health and the environment.

Repairs have not been performed at landfill LF-12 prior to December 2004. However, the engineering inspection in 2004 indicated one area of significant rill erosion to the landfill soil cover at this site. This location is scheduled for repair in 2005. No other repairs are recommended for the immediate future. Groundwater monitoring data do not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater. Water Quality Protection Standards (WQPSs) will be established for landfill LF-12 in 2005 and will be presented in the OU 3 Semiannual Report.

5.3.2 LF-12 Five-Year Review Process

The former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and a site inspection where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance, (USEPA, 2001), and included pre-notification to the community and interested parties via media notification in the Victorville Daily Press that a five-year review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

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The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.3.3 LF-12 Five-Year Review Findings

This section presents the findings for the Five-Year Review for LF-12. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports, the Semiannual O&M Reports for OU 3 Sites, and the OU 3 ROD (Document List, Appendix A).

5.3.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB 2nd 5-Yr Review Rpt_Final\Text\Section 5.doc 5-27 Second Five-Year Review Report Former George Air Force Base not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He did not express concerns about any of the landfills.

5.3.3.2 Site Inspections. The most recent site inspection of landfill LF-12 was conducted in July 2004 and included the annual engineering and burrows management inspections. Since the findings of this site inspection are expected to be current through 2004, an additional site inspection was not conducted specifically for the Five-Year Review. The July 2004 site inspection was conducted by Mr. Christopher Glenn (MWH), Ms. Elena Birch-Carl (MWH), and Mr. Steve Gardner (Southwest Desert Environmental). Findings of this site inspection were included in the October 2004 Semiannual O&M Report (MWH, 2004c). Inspection documents are included in Appendix C.

5.3.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

During the RI, a baseline risk assessment was performed for landfill LF-12; exposure scenarios were evaluated based on the proposed reuse of the land parcel in which the site is located. The baseline human health risk assessment estimated the highest excess lifetime cancer risk to be 7.7x10-7, primarily because of dioxins under the future resident scenario. The calculated risk is less than the benchmark value. The results of the ecological risk assessment indicated a potential risk to burrowing mammals and their predators (e.g., barn owl), primarily due to the presence of dioxins, lead, zinc, and barium. The baseline risk assessment has not been recalculated because a landfill cap is in place, there are no complete exposure pathways, and there are no plans for residential use.

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An environmental assessment was conducted to assess the potential risks to plants and animals due to the presence of dioxins, lead, zinc, and barium. However, the results of subsequent quantitative food chain modeling, specifically for bioaccumulative compounds, show that bioaccumulative compounds of potential ecological concern pose no significant risks to vegetation and wildlife at the site. Human activities associated with the proposed land use for this parcel are expected to limit the selection of landfill LF-12 as a primary habitat by many ecological receptors. Site conditions have not changed; therefore, an updated qualitative ecological benchmark screening is not warranted.

A list of ARARs for landfill LF-12 is provided in Table 4 of the OU 3 ROD (Montgomery Watson, 1998), which is also included in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA, and the USAF. Based upon this discussion, the selected remedy at landfill LF-12 is compliant with ARARs on landfill closure such as grading, drainage and slope protection through revegetation. Annual landfill monitoring at landfill LF-12 complies with ARARs for landfill closure monitoring, such as site security, notification signs, monitoring for settlement, soil cover maintenance and groundwater detection monitoring. A review of the ARARs for this Five-Year Review process indicates that the OU 3 ROD ARARs remain up-to-date and relevant for landfill LF-12.

5.3.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). Landfill LF-12 was most recently inspected on 12 July 2004. The following is a summary of the findings of this inspection, as reported in the Landfill Inspection Technical Memorandum (MWH, 2004c) and the document review.

The access roads, security fencing, entrance gate, vegetative cover, and drainage channels at landfill LF-12 are in good condition. Rill erosion (up to 2-feet-deep) is forming on a steep slope on the north side of the landfill. Repair of this rill erosion is recommended and scheduled for 2005. A portion of the landfill cap near the northeastern corner of the landfill appears to be settling, indicated by cracks in the cap surface forming a circle approximately 14 feet in diameter and by a sunken area (approximately 4 inches lower than the surrounding area).

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The biological inspection did not find any sensitive plant or animal species at LF-12. There is a small gap under the fence at the northwest end of the landfill. This location was repaired by filling in the eroded area with rock and soil and manually compacting. Tumbleweeds that had accumulated outside the perimeter fence, along the southern side, and inside the perimeter fence, at the northeastern corner, were removed.

Small burrows (less than 1-inch diameter) are located throughout the landfill cap and along the perimeter fence. Except for the rill erosion that is scheduled for repair, landfill LF-12 is in good condition, and the soil cover remains intact.

Groundwater monitoring data at landfill LF-12 do not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater. Plots of historical groundwater monitoring results for landfill LF-12 are included in Appendix E.

5.3.4 LF-12 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at landfill LF-12 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues, and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the OU 3 landfill remedy has been evaluated against the RAOs stated in the OU 3 ROD.

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RAO - Prevent direct contact with landfill contents.

• The landfill soil cover remains in place and is in good condition. Routine inspections note any issues and repairs are made, if necessary. ICs are in place and the land use remains the same as during the decision process. No direct contact has occurred.

RAO - Minimize infiltration that may result in waste constituents leaching to groundwater.

• The drainage channels remain in good condition and allow for drainage of surface water from the landfill to reduce infiltration. Routine inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Control surface water runoff and run-on and erosion.

• Landfills were constructed to minimize surface water runoff and run-on and erosion. Engineering inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

• Groundwater monitoring is performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003). Groundwater monitoring data does not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater.

System O&M: Annual engineering and biological inspections, and landfill groundwater monitoring are performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003).

Cost of System O&M: O&M costs are less than predicted in the OU3 ROD and within the acceptable range of minus 30 percent to plus 50 percent.

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Opportunities for Optimization: The landfill erosion repair performed in 2005 is the first maintenance action beyond routine monitoring and maintenance at landfill LF-12. There are no opportunities for optimization at present. Future optimization of the landfill groundwater monitoring program is prescribed in the Post-Closure Landfill Groundwater Monitoring Technical Memorandum (MWH, 2003a), and recommends a reduction in the number of monitoring wells sampled and the sampling frequency, if the initial results do not indicate impact of the landfills to the groundwater quality.

Early Indicators of Potential Issues: The current monitoring results do not indicate the ICs and soil cover remedy are failing or may fail in the future. However, soil erosion and settling are early indicators of potential remedy failure. These issues are being addressed by the planned repairs, continued inspections, and sustained O&M activities.

Implementation of ICs and Other Measures: ICs are in place at landfill LF-12 and the land use remains the same as during the decision process. Annual engineering inspections are performed to verify that the perimeter fencing, gates and warning signs remain in place and effective. The perimeter of Landfill LF-12 is enclosed by fencing and the gate is kept locked at all times. This security effectively eliminates unauthorized access to the site, and hence its use is restricted Land use restriction remains effective in prohibiting subsurface development and preventing excessive vehicle traffic at landfill LF-12, and are protective.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for landfill LF-12 (Section 5.3.3.3) indicates no change in standards from the previous Five-Year Review.

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Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathways: No changes in the site condition or land use that would affect the exposure pathway were found during this five-year review.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use. Global Access, SCLA is planning the development of a 2,900-acre facility for production transportation that may impact the future land use at landfill LF-12. A rail complex and a multimodal logistics and distribution complex is planned. The footprint of the rail complex and multimodal distribution center are shown on Figure 4-3. The current footprint will tentatively impact landfill LF-12 and associated monitoring wells. While the complex itself will not impact landfill LF-12, the road servicing it may do so. The road is tentatively placed towards the center of this landfill. Planning of the project will continue to be monitored for changes that may concern landfill LF-12.

New Contaminants or Contaminant Sources: No new source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at landfill LF-12. No chemical byproducts have been created from the remedy.

Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at landfill LF-12 since the previous Five-Year Review.

Expected Progress towards Meeting the RAOs: The RAOs are currently being met.

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Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Although the landfill soil cover requires periodic maintenance, the repairs scheduled in 2005 are the first non-routine maintenance required since the remedy was installed. Maintenance and monitoring of landfill LF-12 indicates that the rehabilitated soil cover continues to serve as an effective remedy. The perimeter fencing, gates, and warning signs remain in place and appear to be effective in eliminating unauthorized access to the landfill. Landfill groundwater monitoring does not indicate any impact from the landfill to the groundwater quality beneath the site. None of the monitoring results include any information that might call into question the protectiveness of the remedy.

New or Previously Unidentified Ecological Risks: There are no new or previously unidentified ecological risks.

Natural Disaster Impact: No natural disaster has occurred in the area that has altered the effectiveness of the remedy.

5.3.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy is operating as effectively as predicted and is protective of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD based on risk and toxicity information are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of

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the remedy. The future intermodal rail project should not affect protectiveness of the remedy, as long as required system modifications are managed appropriately.

5.3.5 LF-12 Issues

There were no deficiencies identified for landfill LF-12 during the five-year review. No changes to the routine monitoring program are necessary. Issues of concern at landfill LF-12 are the erosion and settling of the soil. These issues are being addressed by the planned repairs, continued inspections, and sustained O&M activities. An additional issue for LF-12 is the potential impact of the planned SCLA rail center and multimodal complex on the landfill or landfill monitoring wells.

5.3.6 LF-12 Recommendations and Follow-Up Actions

The following summarizes the recommendations to ensure remedy effectiveness in compliance with the RAOs for landfill LF-12.

1) Monitor planning for the SCLA rail center and multimodal complex project to determine impact on landfill LF-12 (ongoing); responsible party, USAF. 2) Perform landfill rill erosion repair at one location within LF-12 (to be completed in 2005), responsible party USAF. 3) Continue engineering inspections, biological inspections, and landfill groundwater monitoring (ongoing); responsible party, USAF.

5.3.7 LF-12 Protectiveness Statement

The remedy for the OU 3 landfill LF-12 is protective of human health and the environment in the short-term because the landfill cap and institutional controls effectively mitigate risk. The landfill cap and institutional controls will continue to be maintained to ensure long-term protectiveness.

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5.3.8 LF-12 Next Review

The next Five-Year Review will be conducted in 2010.

5.4 LANDFILL LF-14

Landfill LF-14 is an abandoned landfill located in an unpaved, undeveloped area east of Runway 3/21 and near Federal Aviation Administration (FAA) Gate 1 into the active flightline, as shown on Figure 3-6. A site plan for landfill LF-14 is included as Figures 5-4A and 5-4B. Between 1970 and 1976, landfill LF-14 was reportedly used for disposal of municipal and industrial wastes. Industrial wastes may have included lube oil, paint, lacquer, naphthalene, TCE, PD-680, cleaning compounds, hydraulic fluids, fire fighting foams, batteries, oil spill absorbent, and general refuse. No burning of wastes was reported, and a soil cover was placed over the wastes at the end of each day. Some materials may have been disposed at this site during the mid- 1960s. The volume of material disposed at the site is unknown.

5.4.1 LF-14 Remedial Actions

This section describes the remedy selection, implementation, O&M, and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.4.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for landfill LF-14 and the other OU 3 landfills (Montgomery Watson, 1998):

• Prevent direct contact with landfill contents. • Minimize infiltration that may result in waste constituents leaching to groundwater. • Control surface water runoff and run-on and erosion. • Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

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The selected remedy includes access and land use restrictions, surface controls, surface restoration, groundwater monitoring, and the five-year site review.

5.4.1.2 Remedy Implementation. A removal action has been implemented at landfill LF-14. In an effort to accelerate the remedial progress, minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at landfill LF-14 before finalizing the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB and the Air Force.

The removal action at landfill LF-14 included the removal of surface debris; rehabilitating the existing soil cover to an estimated thickness of 12- to 18-inches; grading the surface to promote surface runoff and decrease infiltration of surface water into the landfill; installing perimeter drainage ditches to prevent surface water from running onto the landfill sites and to control surface water run-off from the landfills; installing site perimeter fencing to control site access, restricting land use to prohibit subsurface development; and re-establishing native plant species on the graded surface. The removal action was completed between June 1996 and April 1997. The actions minimize or mitigate human health and ecological risks by providing a physical barrier to potential contamination.

5.4.1.3 System O&M. O&M at landfill LF-14 includes groundwater monitoring; an annual engineering inspection of rehabilitated soil cover erosion, soil cover stability, rip-rap- lined channels, access roads, warning signs, drainage channels, perimeter fencing, and vegetation; and an annual burrows management inspection. A more detailed description of the engineering and burrows management inspections can be found in Appendix C, and is also contained in the Semiannual O&M Report for OU 3 Sites (MWH, 2004c).

Groundwater monitoring is used to assess whether contaminants have migrated into the groundwater. A more detailed description of the landfill groundwater monitoring and analysis program is presented in Appendix C and also in the Post-Closure Groundwater Monitoring Technical Memorandum (MWH, 2003a).

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5.4.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found the remedy at landfill LF-14 protective of human health and the environment.

Repair actions were performed at landfill LF-14 in the summer of 2000, including installation of a grouted rip-rap channel, surface regrading, and re-vegetation. This action was in response to the formation of erosional channels over a portion of the landfill soil cover. Additional repair actions were conducted in May 2004, and included installing tortoise fencing along the eastern fence of landfill LF-14 to prevent access to the landfill by desert tortoise. Engineering and burrow management inspections in 2004 indicated five additional areas of significant rill erosion to the landfill soil cover. These five locations are recommended and scheduled for repair in 2005. No other repair actions are recommended for the immediate future.

Groundwater monitoring data from compliance wells do not contain abnormally high or erratic concentrations that would indicate impact from the landfill to the groundwater. WQPSs will be established for landfill LF-14 in 2005 and be presented in the OU 3 Semiannual Report.

5.4.2 LF-14 Five-Year Review Process

The former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations

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contractors, and a site inspection where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance (USEPA, 2001), and included pre-notification to the community and interested parties via media notification in the Victorville Daily Press that a Five-Year Review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.4.3 LF-14 Five-Year Review Findings

This section presents the findings of the Five-Year Review for LF-14. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports, the Semiannual O&M Reports for OU 3 Sites, and the OU 3 ROD (Document List, Appendix A).

5.4.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

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Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He did not express concerns about any of the landfills.

5.4.3.2 Site Inspections. The most recent site inspection of landfill LF-14 was conducted in July 2004 and included the annual engineering and burrows management inspections. Since the findings of this site inspection are expected to be current through 2004, an additional site inspection was not conducted specifically for the Five-Year Review. The July 2004 site inspection was conducted by Mr. Christopher Glenn (MWH), Ms. Elena Birch-Carl (MWH), and Mr. Steve Gardner (Southwest Desert Environmental). Findings of this site inspection were included in the October 2004 Semiannual O&M Report (MWH, 2004c). Inspection documents are included in Appendix C.

5.4.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

During the RI, a baseline risk assessment was performed for landfill LF-14; exposure scenarios evaluated were based on the proposed reuse of the land parcel in which the site is located. The baseline human health risk assessment estimated the highest excess lifetime cancer risk to be 1.0x10-5, primarily driven by cadmium under an industrial/commercial scenario. Although this

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is above the benchmark value for risk assessment, cadmium at the site is considered naturally occurring and within background ranges. The results of the ecological risk assessment indicated a potential risk to burrowing mammals and their predators (e.g., barn owl), due to the presence of cadmium, lead, and pesticides. The baseline risk assessment has not been recalculated because a landfill cap is in place, there are no complete exposure pathways, and there are no plans for residential use.

An environmental assessment was conducted to assess the potential risks to plants and animals due to the presence of cadmium, lead, and pesticides. However, the results of subsequent quantitative food chain modeling, specifically for bioaccumulative compounds, show that bioaccumulative compounds of potential ecological concern pose no significant risks to vegetation and wildlife at the site. Human activities associated with the proposed land use for this parcel are expected to limit the selection of landfill LF-14 as a primary habitat by many ecological receptors. Site conditions have not changed; therefore, an updated qualitative ecological benchmark screening is not warranted.

A list of ARARs for landfill LF-14 is included in Table 4 of the OU 3 ROD (Montgomery Watson, 1998), which is also included in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA, and the USAF. Based upon this discussion, the selected remedial action at landfill LF-14 is compliant with ARARs on landfill closure, such as grading, drainage, and slope protection through revegetation. The annual landfill monitoring performed at landfill LF-14 complies with ARARs for landfill closure monitoring, such as site security, notification signs, monitoring for settlement, soil cover maintenance, and groundwater detection monitoring. A review of the ARARs for this Five-Year Review process indicates that the OU 3 ROD ARARs remain up-to-date and relevant for landfill LF-14.

5.4.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix C). Landfill LF-14 was most recently inspected on 12 and 13 July 2004. The following is a summary of the findings of this inspection, as reported in the Landfill Inspection Technical Memorandum (MWH, 2004c), and the document review.

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The access roads, security fencing, entrance gate, vegetative cover, and groundwater wells at landfill LF-14 are in good condition. Significant rill erosion (greater than 2-feet-deep) is present at five locations within the landfill. These rill erosion are recommended and scheduled for repair in 2005. The biological inspection did not find any sensitive plant or animal species at LF-12.

An animal had dug under the fence at three locations: in the southeast corner, on the north side near well NZ-13, and at the western access gate fence post. These locations were repaired by filling in the dug out area with rock and soil and manually compacting. Also repaired was one location where rill erosion had created a small gap under the perimeter fence. Fine-mesh fencing fabric has been installed along the entire eastern perimeter fence to secure areas where the existing fence did not reach the ground. Small burrows (less than 1-inch diameter) are located throughout the landfill cap and along the perimeter fence. Except for the rill erosion that is scheduled for repair, landfill LF-14 is in good condition and the soil cover remains intact.

Groundwater monitoring data at landfill LF-14 do not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater. Plots of historical groundwater monitoring results for landfill LF-14 are included in Appendix C.

5.4.4 LF-14 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at landfill LF-14 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues and implementation of institutional controls and other measures.

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Remedial Action Performance: The performance of the OU 3 landfill remedy has been evaluated against the RAOs stated in the OU 3 ROD.

RAO - Prevent direct contact with landfill contents.

• The landfill soil cover remains in place and is in good condition. Routine inspections note any issues and repairs are made, if necessary. ICs are in place, and the land use remains the same as during the decision process. No direct contact has occurred.

RAO - Minimize infiltration that may result in waste constituents leaching to groundwater.

• The drainage channels remain in good condition and allow for drainage of surface water from the landfill to reduce infiltration. Routine inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Control surface water runoff and run-on and erosion.

• Landfills were constructed to minimize surface water runoff and run-on and erosion. Engineering inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

• Groundwater monitoring is performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003). Groundwater monitoring data does not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater.

System O&M: Annual engineering and biological inspections, and landfill groundwater monitoring are performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003).

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Cost of System O&M: O&M costs are less than predicted in the OU3 ROD and within the acceptable range of minus 30 percent to plus 50 percent.

Opportunities for Optimization: Landfill LF-14 has required the most maintenance of the five OU 3 landfills. Actions have been performed on the drainage channels and the perimeter fencing, and landfill erosion repair was performed in 2005. This level of maintenance is to be expected due to the large size and steep terrain at this landfill. More extensive repairs, such as re-grading of the landfill, would reduce the level of maintenance required but are not justified based on the current level of maintenance.

Future optimization in the landfill groundwater monitoring program is prescribed in Post-Closure Landfill Groundwater Monitoring Technical Memorandum (MWH, 2003a), and includes a reduction in the number of monitoring wells sampled and the sampling frequency, if the initial results do not indicate impact of the landfills to the groundwater quality.

Early Indicators of Potential Issues: The current monitoring results do not indicate that the institution controls and soil cover remedy is failing or may fail in the future. However, soil erosion is an early indication of potential remedy failure, which is being addressed by the planned repairs, continued inspections, and sustained O&M activities.

Implementation of ICs and Other Measures: ICs are in place at landfill LF-14 and the land use remains the same as during the decision process. The fencing repair performed in 2004 effectively repaired gaps beneath the eastern boundary fence to this landfill. Annual engineering inspections are performed to verify that the perimeter fencing, gates, and warning signs remain in place and effective. The perimeter of Landfill LF-14 is enclosed by fencing and the gate is kept locked at all times This security effectively eliminates unauthorized access to the site, and hence its use is restricted The land use restriction remains effective in prohibiting subsurface development and preventing excessive vehicle traffic at landfill LF-14, and are protective.

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Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for landfill LF-14 (Section 5.4.3.3) indicates no change in standards from the previous Five-Year Review.

Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathways: No changes in the site condition or land use that would affect the exposure pathway were found during this five-year review.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use. Global Access, SCLA is planning the development of a 2,900-acre facility for production transportation that may impact the future land use at landfill LF-14. A rail complex and a multimodal logistics and distribution complex is planned. The footprint of the rail complex and multimodal distribution center are shown on Figure 4-3. The current footprint indicates a rail line will be constructed over the northeastern corner of landfill LF-14 and that construction will require the destruction of one of the landfill groundwater monitoring wells at landfill LF-14.

New Contaminants or Contaminant Sources: No new source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at landfill LF-14. No chemical byproducts have been created from the remedy.

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Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at landfill LF-14 since the previous Five-Year Review.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Although the landfill soil cover requires periodic maintenance, the repairs effectively maintain the soil cover, drainage channels and institution controls. Maintenance and monitoring of landfill LF-14 indicates that the rehabilitated soil cover continues to serve as an effective remedy. The perimeter fencing, gates, and warning signs remain in place and appear to be effective in eliminating unauthorized access to the landfill. Landfill groundwater monitoring does not indicate any impact of the landfill to the groundwater quality beneath the site. None of the monitoring results include any information that might call into question the protectiveness of the remedy.

New or Previously Unidentified Ecological Risks: There are no new or previously unidentified ecological risks.

Natural Disaster Impact: No natural disasters have occurred in the area that have altered the effectiveness of the remedy.

5.4.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy was is operating as effectively as predicted and is protective of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD based on risk and toxicity information are still valid.

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C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy. The future intermodal rail project should not affect protectiveness of the remedy, as long as required system modifications are managed appropriately.

5.4.5 LF-14 Issues

No deficiencies were identified for landfill LF-14 during the Five-Year Review. Repair of the rill erosion at this landfill is scheduled for 2005. No changes to the routine monitoring program are necessary. An issue of concern at landfill LF-14 is the potential impact of the SCLA rail center and multimodal complex on the landfill and landfill monitoring wells.

5.4.6 LF-14 Recommendations and Follow-Up Actions

The following summarizes the recommendations to ensure remedy effectiveness in compliance with the RAOs for landfill LF-14:

1) Monitor planning for the SCLA rail center and multimodal complex project to determine impact on landfill LF-14 (ongoing); responsible party, USAF. 2) Perform landfill rill erosion repair at five locations within LF-14 (to be completed in 2005); responsible party, USAF. 3) Continue engineering inspections, biological inspections, and landfill groundwater monitoring (ongoing); responsible party, USAF.

5.4.7 LF-14 Protectiveness Statement

The remedy for the OU 3 landfill LF-14 is protective of human health and the environment in the short-term because the landfill cap and institutional controls effectively mitigate risk. The landfill cap and institutional controls will continue to be maintained to ensure long-term protectiveness.

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5.4.8 LF-14 Next Review

The next Five-Year Review will be performed in 2010.

5.5 LANDFILL LF-44

Site LF-44 is an abandoned landfill site located about 1,000 feet south of Site LF-14, as shown on Figure 3-6. This landfill reportedly received miscellaneous trash and rubble. The period of use and volume of contents deposited at the site are unknown.

5.5.1 LF-44 Remedial Actions

This section describes the remedy selection, implementation, O&M, and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.5.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for landfill LF-44 (Montgomery Watson, 1998):

• Removal of surface debris at an off-site disposal facility. • Implementation of long-term groundwater monitoring in accordance with an approved basewide long-term groundwater monitoring plan. • Implementation of land use notifications identifying the area as a NFA site. • Five-Year site review to assess the effectiveness of the remedy.

5.5.1.2 Remedy Implementation. A removal action has been implemented at landfill LF-44. In an effort to accelerate the remedial progress, minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at landfill LF-44 before finalizing the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB and the Air Force.

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The removal action at landfill LF-44 included the removal of surface debris in September and October 1995.

5.5.1.3 Operation and Maintenance. O&M at landfill LF-44 is not required after the removal action was complete. The fence is in good condition.

5.5.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found the remedy at landfill LF-44 protective of human health and the environment.

5.5.2 LF-44 Five-Year Review Process

The former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and a site inspection where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance (USEPA, 2001), and included pre-notification to the community and interested parties via media notification in the Victorville Daily Press that a Five-Year Review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

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The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.5.3 LF-44 Five-Year Review Findings

This section presents the findings of the Five-Year Review for LF-44. A review of the relevant documents was conducted and included lease restrictions and the OU 3 ROD (Document List, Appendix A).

5.5.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

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Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He did not express concerns about any of the landfills.

5.5.3.2 Site Inspections. The most recent site inspection of landfill LF-44 was conducted in July 2005. The site is currently fenced and in good condition.

5.5.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

As part of the screening for the baseline human health risk assessment, no COPCs were identified; therefore, no human health risk assessment was completed.

The results of the ecological risk assessment suggest some potential ecological impacts at Site LF-44 from physical disturbances. Some stress on vegetation exists at the site as a result of physical disturbance related to former site activities. However, significant chemical risks to vegetation or wildlife were not indicated by the site characterization data. Nevertheless, because this site was an abandoned landfill with exposed debris, in order to restore the natural surface the site, closure actions were considered in the OU 3 FS. Site conditions have not changed; therefore, an updated qualitative ecological benchmark screening is not warranted.

A list of ARARs for landfill LF-44 is included in Table 4 of the OU 3 ROD (Montgomery Watson, 1998), which is also included in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA, and the USAF. Based upon this discussion, the selected remedial action at landfill LF-44 is compliant with ARARs on landfill closure, such as grading, drainage, and slope protection through revegetation. A review of the ARARs for this Five-Year Review process indicates that the OU 3 ROD ARARs remain up-to-date and relevant for landfill LF-44.

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5.5.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). Little data has been gathered because the RAO’s of the site have been fulfilled except for deed restriction implementation. The site inspection performed for this Five- Year Review indicated that the site has not been disturbed. The area is fenced and no-dig signs are intact.

5.5.4 LF-44 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at landfill LF-44 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues and implementation of institutional controls and other measures.

RAO - Removal of surface debris at an off-site disposal facility.

• The removal action met the RAO objectives.

RAO - Implementation of long-term groundwater monitoring in accordance with an approved basewide long-term groundwater monitoring plan.

• No groundwater monitoring was required based of vadose zone modeling performed, which indicated that even under the most conservative conditions, that there is no potential for contaminant leaching to groundwater. This is documented in the OU 3 ROD, LF-44 Site Characterization Section.

RAO - Implementation of land use notifications identifying the area as an NFA site.

• The land has not been transferred, therefore the deed restrictions to restrict use of the property for a residence, a long-term care hospital, a school and a day care center in accordance with the ROD has not been performed. Fencing and terms

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and conditions of a lease agreement are ensuring that the site is protective of human health.

RAO - Five-Year site review to assess the effectiveness of the remedy.

• This RAO is being met during the ROD Five-Year review process.

System O&M: O&M at landfill LF-44 is not required after the removal action was complete.

Cost of System O&M: O&M costs are less than predicted in the OU3 FS and outside the acceptable range of minus 30 percent to plus 50 percent. Less effort has been required than assumed in the ROD because groundwater monitoring was not required.

Opportunities for Optimization: Opportunities for further optimization is not applicable.

Early Indicators of Potential Issues: Data do not contain any indication that the ICs are failing or may fail in the future.

Implementation of ICs and Other Measures: ICs are in place at LF-44 and the land use remains the same as during the decision process. The portion of OU 3 near LF-44 is retained by the Air Force, and will not be transferred by deed until the Air Force receives regulatory concurrence that the remedial actions, including ICs are in place and operating properly and successfully. A deed restriction is in place that prohibits the use of the groundwater beneath LF-44. At present, there is no foreseeable change in land use at this site. Additionally the Air Force has prohibited use of groundwater from the Upper Aquifer and ensures compliance with repeated communication to the lessee and by maintaining a daily presence at the former base so that issues are identified and resolved on a real time basis. Several specific terms and conditions from the lease are:

1. The lessee and any sublessee shall comply with all Federal, State and local laws, regulations and standards. 2. Government retains the right to inspect.

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3. Lessee expressly acknowledges that it fully understands that response actions undertaken with respect to the FFA or IRP program my impact "quiet use and enjoyment" or leased property. 4. Lessee agrees to comply with provisions of any health and safety plan in effect under the IRP, hazardous substance remediation or response agreement. 5. Lessee acknowledges receipt of the Environmental Baseline Survey. 6. Lessee acknowledges receipt of the information that George AFB has been identified as a NPL Site and why (see EBS above). 7. Lessee acknowledges receipt of Federal Facility Agreement, and that the FFA terms take precedence over the lease. 8. The Government, EPA and State retain the right to enter lease premises for purposes of executing the FFA and IRP program (access, inspection, investigation, response/remedial actions, etc). 9. Lessee shall not construct or make, or permit its subleasees to construct or make, any Alterations (construction, demolition, excavation, restoration, additions, or other changes in, to or upon the property) which may impede or impair any activities under the IRP or FFA without prior written consent of the Air Force. 10. The failure to comply with any provision of the lease shall constitute a default and may result in the termination of the lease.

At the time of the deed, deed covenants will be identified in the FOST, CERCLA 120(h)3 and state land use covenant to ensure that ICs are identified. This will fulfill the ROD requirement of implementing land use restrictions.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for landfill LF-44 (Section 5.4.3.3) indicates no change in standards from the previous Five-Year Review.

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Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathways: No changes in the site condition or land use that would affect the exposure pathway were found during this five-year review.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use.

New Contaminants or Contaminant Sources: No new source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at landfill LF-44. No chemical byproducts have been created from the remedy.

Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at landfill LF-44 since the previous Five-Year Review.

Expected Progress towards Meeting the RAOs: The RAOs are currently being met.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

The removal action was effective at meeting the RAOs. Nothing has changed that effects the protectiveness of the remedy.

New or Previously Unidentified Ecological Risks: There are no new or previously unidentified ecological risks.

Natural Disaster Impact: No natural disaster has occurred in the area that has altered the effectiveness of the remedy.

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5.5.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy is operating as effectively as predicted and is protective of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD based on risk and toxicity information are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy.

5.5.5 LF-44 Issues

No deficiencies were identified for landfill LF-44 during the Five-Year Review.

5.5.6 LF-44 Recommendations and Follow-Up Actions

No recommendations were identified for landfill LF-44 during the Five-Year Review.

5.5.7 LF-44 Protectiveness Statement

The remedy at landfill LF-44 is protective of human health and the environment. The removal action and ICs are effective The ICs will continue to be maintained to ensure long-term protectiveness.

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5.5.8 LF-44 Next Review

The next Five-Year Review will be performed in 2010.

5.6 SOUTHEAST DISPOSAL AREA (SEDA)

The SEDA comprises nine sites, including four landfills (Sites DP-10, LF-07, LF-08, and RW- 09), one burial site (WP-40), one spill site (SS-52), and three munitions disposal areas (DP-15, DP-33, and DP-34). The SEDA is located in an unpaved and undeveloped area south of Air Base Expressway, just south of the Victorville Federal Prison, as shown on Figure 3-6. A site plan for the SEDA is included as Figures 5-5A and 5-5B. The background and specific wastes reported for each of the SEDA sites is discussed below:

• Site DP-10 was used for disposal of used jet engine starter cartridges, which prior to their use, contained standard munitions-type explosive mixtures. The site was active from approximately 1978 through 1981. The volume of waste disposed at this site is unknown. • LF-07 was the primary base landfill from approximately 1957 to 1970. Reported wastes included domestic waste, lube oil, paint, lacquer, naphthalene, TCE, PD-680, cleaning compounds, hydraulic fluid, fire fighting foams, batteries, oil spill absorbent, and other miscellaneous residues and materials. Waste oil and fuel were reportedly used for trash burning throughout the life of the landfill. • Site LF-08 is located within the boundaries of LF-07 and was used for the disposal of tetraethyl lead, Jet Propulsion-4 (JP) fuel, and leaded gasoline sludge from storage tank bottoms. The site reportedly operated from 1955 until 1966. The volume of wastes disposed is unknown. • RW-09 was reportedly used for the disposal of low-level radioactive wastes, as well as possible disposal of unidentified chemicals. This site was established in 1965 and closed by 1970. The volume of waste disposed of over this time period is unknown. Surface radioactivity measured in 1980 did not exceed normal background levels. • WP-40 was primarily used for the disposal of chemical toilet waste sludge. • SS-52 reportedly contains spills from a creosote operation prior to 1960. • DP-15 is a 225-foot long, 60-foot wide, 10-foot deep trench located north of LF- 08. The site was used for small arms munitions residue in the late 1950s and auto hobby shop waste oil disposal from 1972 to 1976. The volume of wastes disposed of at this site is unknown.

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• DP-33 is a disposal site where grenade debris, 20-millimeter cartridges, and a concrete-lined burn pit filled with paint cans were found. The site was reportedly closed in 1966 or 1967. • DP-34 is a 50- square-foot- area that was reportedly used for the burial of burned practice bombs and small arms cartridges. The exact operational dates and volumes of waste are unknown.

5.6.1 SEDA Remedial Actions

This section describes the remedy selection, implementation, O&M and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.6.1.1 Remedy Selection. The OU 3 ROD identified the RAOs for the SEDA and the other OU 3 landfills (Montgomery Watson, 1998):

• Prevent direct contact with landfill contents. • Minimize infiltration that may result in waste constituents leaching to groundwater. • Control surface water runoff and run-on and erosion. • Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

The selected remedy includes access and land use restrictions, surface controls, surface restoration, groundwater monitoring and the five-year site review.

5.6.1.2 Remedy Implementation. A removal action has been implemented at the SEDA. In an effort to accelerate the remedial progress, to minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at the SEDA before finalization of the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB and the Air Force.

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The removal action at the SEDA included removing surface debris, rehabilitating the existing soil cover to an estimated thickness of 12- to 18-inches, grading of the surface to promote surface runoff and decrease infiltration of surface water into the landfill, installing perimeter drainage ditches to prevent surface water from running onto the landfill sites and to control surface water run-off from the landfills, installing site perimeter fencing to control site access, restricting land use to prohibit subsurface development, and re-establishing native plant species on the graded surface. The removal action was completed between June 1996 and April 1997. The actions minimize or mitigate human health and ecological risks by providing a physical barrier to potential contamination.

5.6.1.3 Operation and Maintenance. O&M at the SEDA includes groundwater monitoring; an annual engineering inspection of soil cover erosion, cap stability, rip rap-lined channels, access roads, warning signs, drainage channels, perimeter fencing, and vegetation; and an annual burrows management inspections. A more detailed description of the engineering and burrows management inspections is contained in Appendix C and also in the Semiannual O&M Report for OU 3 Sites (MWH, 2004c).

Groundwater monitoring is used to assess whether contaminants have migrated into the groundwater. A more detailed description of the landfill groundwater monitoring and analysis program is presented in Appendix C and also in the Technical Memorandum, Proposed Approach to Post-Closure Landfill Groundwater Monitoring at OU 3 Landfills (MWH, 2003a).

5.6.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review determined that the remedy at the SEDA was protective of human health and the environment.

Engineering and burrows management inspections at the SEDA indicate the site remains in good condition. Repairs have not been performed at this site, except for minor maintenance such as filling in small burrows underneath the perimeter fencing. No repairs are recommended for the immediate future.

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Groundwater monitoring data do not contain abnormally high or erratic compliance well concentrations indicating impact from the landfill to groundwater quality. WQPS will be established for the SEDA in 2005 and be presented in the OU 3 Semiannual Report.

5.6.2 SEDA Five-Year Review Process

The former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and a site inspection where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance (USEPA, 2001) and included pre-notification to the community and interested parties via media notification in the Victorville Daily Press that a five year review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 30 June 2005

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4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.6.3 SEDA Five-Year Review Findings

This section presents the findings of the Five-Year Review for the SEDA. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports, the Semiannual O&M Reports for OU 3 Sites, and the OU 3 ROD (Document List, Appendix A).

5.6.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB 2nd 5-Yr Review Rpt_Final\Text\Section 5.doc 5-61 Second Five-Year Review Report Former George Air Force Base and TCE have leaked in to the lower and upper aquifer. He did not express concerns about any of the landfills.

5.6.3.2 Site Inspections. A site inspection of the SEDA was most recently conducted in July 2004 and included the annual engineering and burrows management inspections. Since the findings of this site inspection are expected to be current through 2004, an additional site inspection was not conducted specifically for the Five-Year Review. The July 2004 site inspection was conducted by Mr. Christopher Glenn (MWH), Ms. Elena Birch-Carl (MWH), and Mr. Steve Gardner (Southwest Desert Environmental). Findings of this site inspection were included in the October 2004 Semiannual O&M Report (MWH, 2004c). Inspection documents are included in Appendix C.

5.6.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

Vadose zone modeling results using SESOIL predict that, even under the most conservative conditions, the most mobile constituent at the SEDA would not migrate deeper than 20-feet below the bottom of the disturbed areas after 100 years. Therefore, the less mobile contaminants detected at this site are not expected to migrate enough to pose a threat to the groundwater.

Based on the results of the remedial investigations at the SEDA, particularly the surface geophysical survey, the site boundary was delineated. This boundary line was drawn tangent to the outermost boundaries of the disturbed and anomalous areas and the surface debris.

An environmental assessment was conducted to assess the potential risks to plants and animals due to the localized presence of several metals and dioxin/furan congeners. However, the results of subsequent quantitative food chain modeling, specifically for bioaccumulative compounds, show that bioaccumulative compounds of potential ecological concern pose no significant risks to vegetation and wildlife at the site. Human activities associated with the proposed land use for this parcel are expected to limit the selection of SEDA as a primary habitat by many ecological

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receptors. Site conditions have not changed; therefore, an updated qualitative ecological benchmark screening is not warranted.

A list of ARARs for the SEDA is included in Table 4 of the OU 3 ROD (Montgomery Watts, 1998), which can be also found in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA and the USAF. Based upon this discussion, the selected remedial action at the SEDA is compliant with ARARs on landfill closure such as grading, drainage and slope protection through revegetation. Annual landfill monitoring performed at the SEDA complies with ARARs for landfill closure monitoring, such as site security, notification signs, monitoring for settlement, soil cover maintenance, and groundwater detection monitoring. A review of the ARARs for this Five-Year Review process indicates that the OU 3 ROD ARARs remain up-to-date and relevant for the SEDA.

5.6.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). The SEDA was most recently inspected on 13 July 2004. The following is a summary of the findings of this inspection, as reported in the Landfill Inspection Technical Memorandum, published in the October 2004 Semiannual O&M Report (MWH, 2004c), and the document review.

The access roads, security fencing, entrance gates, vegetative cover, and drainage channels at the SEDA are in good condition. Minor rill erosion (up to 1-foot deep) is present at several locations. No evidence of settlement was found. The biological inspection did not find any sensitive plant or animal species at the SEDA. There is a small gap under the fence at the southeast and southwest ends of the landfill. These locations were repaired by filling in the eroded area with rock and soil and manually compacting. Small burrows (less than 1-inch diameter) are located throughout the landfill cap and along the perimeter fence. The SEDA is in good condition and the soil cover remains intact.

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Groundwater monitoring data from compliance wells at the SEDA do not contain abnormally high or erratic concentrations that would indicate impact from the landfill to the groundwater. Plots of historical groundwater monitoring results for the SEDA are included in Appendix E.

5.6.4 SEDA Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at SEDA has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the OU 3 landfill remedy has been evaluated against the RAOs stated in the OU 3 ROD.

RAO - Prevent direct contact with landfill contents.

• The landfill soil cover remains in place and is in good condition. Routine inspections note any issues and repairs are made, if necessary. ICs are in place, and the land use remains the same as during the decision process. No direct contact has occurred.

RAO - Minimize infiltration that may result in waste constituents leaching to groundwater.

• The drainage channels remain in good condition and allow for drainage of surface water from the landfill to reduce infiltration. Routine inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

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RAO - Control surface water runoff and run-on and erosion.

• Landfills were constructed to minimize surface water runoff and run-on and erosion. Engineering inspections are performed to verify that the landfill cap remains intact and effective. These inspections have proactively identified issues allowing necessary repairs to be made in compliance with the RAOs.

RAO - Monitor groundwater quality to determine if landfill contaminants are leaching to the groundwater.

• Groundwater monitoring is performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003). Groundwater monitoring data does not contain abnormally high or erratic compliance well concentrations that would indicate impact from the landfill to the groundwater.

System O&M: Annual engineering and biological inspections, and landfill groundwater monitoring are performed as prescribed by the Final Long-Term Maintenance and Monitoring Plan (Montgomery Watson, 2003).

Cost of System O&M: O&M costs are less than predicted in the OU3 ROD and within the acceptable range of minus 30 percent to plus 50 percent.

Opportunities for Optimization: The SEDA has not required more than routine monitoring and very minor maintenance, thus there are no opportunities for optimization at present. Future optimization in the landfill groundwater monitoring program is prescribed in the Proposed Approach to Post-Closure Landfill Groundwater Monitoring at OU 3 Landfills Technical Memorandum (MWH, 2003a), and includes a reduction in the number of monitoring wells sampled and the sampling frequency if the initial results do not indicate impact of the landfills to the groundwater.

Early Indicators of Potential Issues: The current monitoring results do not indicate that the institution controls and soil cover remedy are failing or may fail in the future.

Implementation of ICs and Other Measures: ICs are in place at the SEDA and the land use remains the same as during the decision process. Annual engineering inspections are performed

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB 2nd 5-Yr Review Rpt_Final\Text\Section 5.doc 5-65 Second Five-Year Review Report Former George Air Force Base to verify that the perimeter fencing, gates, and warning signs remain in place and effective. The perimeter of the SEDA is enclosed by fencing and the gate is kept locked at all times. This security effectively eliminates unauthorized access to the site, and hence its use is restricted. The land use restriction remains effective in prohibiting subsurface development and preventing excessive vehicle traffic at the SEDA, and are protective. There is no foreseeable change in the future land use at the SEDA.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for the SEDA (Section 5.5.3.3) indicates no change in standards from the previous Five- Year Review.

Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathways: No changes in the site condition or land use that would affect the exposure pathway were found during this five-year review.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use. Due to the location of the SEDA, the SCLA rail and multimodal complex project, which may impact future land use at the other OU 3 landfills, is not of concern.

New Contaminants or Contaminant Sources: No new source areas have been identified.

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Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at the SEDA. No chemical byproducts have been created from the remedy.

Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at the SEDA since the previous Five-Year Review.

Expected Progress towards Meeting the RAOs: The RAOs are currently being met.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Maintenance and monitoring of the SEDA indicates that the landfill cap remains in tact and continues to serve as an effective remedy. The perimeter fencing, gates, and warning signs remain in place and appear to be effective in eliminating unauthorized access to the landfill. Landfill groundwater monitoring does not indicate any impact of the landfill to the groundwater. None of the monitoring results include any information that might call into question the protectiveness of the remedy.

New or Previously Unidentified Ecological Risks: There are no new or previously unidentified ecological risks.

Natural Disaster Impact: No natural disasters have occurred in the area that have altered the effectiveness of the remedy.

5.6.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy is operating as effectively as predicted and is protective of human health and the environment.

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B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD, based on risk and toxicity information are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy.

5.6.5 SEDA Issues

No deficiencies were identified for the SEDA during the Five-Year Review. Therefore, no changes to the routine monitoring program are necessary.

5.6.6 SEDA Recommendations and Follow-Up Actions

The following is recommended to ensure remedy effectiveness in compliance with the RAOs for the SEDA.

1) Continue engineering inspections, biological inspections, and landfill groundwater monitoring (ongoing); responsible party, USAF.

5.6.7 SEDA Protectiveness Statement

The remedy for the SEDA is protective of human health and the environment in the short-term because the landfill cap and institutional controls effectively mitigate risk. The landfill cap and institutional controls will continue to be maintained to ensure long-term protectiveness.

5.6.8 SEDA Next Review

The next Five-Year Review will be conducted in 2010.

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5.7 SITE FT-19

Site FT-19 is a former fire training area located west of Runway 3/21 in the northeast portion of the base. This fire training area was reportedly used from 1969 to 1992.

Initial subsurface investigations at Site FT-19 were conducted by SAIC in 1986, JMM in 1987, Stevens Construction in 1987 and United States Army Corp of Engineers (USACE) in 1989. In 1994, Metcalf & Eddy (M&E) performed RIs that included a soil-gas survey, soil boring installation, biological testing, dioxin testing and removal actions. This site was divided into sub-sites FT-19a, FT-19b, and FT-19c, based on type of contaminant impact and the remedial approach.

Site FT-19a is a former fire training area that was bermed and concrete-lined. The M&E investigation identified concentrations of VOCs in shallow soil-gas samples and determined that concentrations of petroleum hydrocarbons exceeded initial evaluation criteria for TPH and benzene, toluene, ethylbenzene and xylenes (BTEX) in several locations at the site. Site FT-19b was a medical waste disposal area, located south of FT-19a and FT-19c. The medical wastes found at the site were removed and disposed of off the base. This site was evaluated in the OU 3 FS and NFA was recommended. Site FT-19c is located adjacent to and south of Site FT-19a. From approximately 1969 to the time of base closure, waste oils and fuels were pumped into a circular bermed area and then ignited for firefighter training. In addition to fuels and waste oil components, chlorinated solvents have been identified at Site FT-19c.

5.7.1 FT-19 Remedial Actions

This section describes the remedy selection, implementation, O&M, and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.7.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for Site FT-19a and FT-19c (Montgomery Watson, 1998).

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Protection of Human Health

• Prevent human exposure to soil resulting in 1×10-4 to 1×10-6 excess cancer risk from all carcinogens. • Prevent human exposure to soil contaminants with non-carcinogens at concentrations in excess of reference doses.

Protection of the Environment

• Reduce the toxicity, mobility, and volume of the contamination in unsaturated soil to reduce the potential for migration of contaminants to groundwater. • Remove, to the extent practical, the COPCs detected in unsaturated soils to meet or exceed the remediation goals defined in the OU 3 ROD.

Bioventing was the selected remedy for Site FT-19a. The no action alternative was selected for Site FT-19b. SVE was the selected remedy for Site FT-19c.

5.7.1.2 Remedy Implementation. A removal action has been implemented at Site FT-19. In an effort to accelerate the remedial progress, minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at Site FT-19 before finalization of the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB and the Air Force.

The removal action at Site FT-19a included installing a bioventing system. The principle behind bioventing is to inject atmospheric air into the subsurface to provide oxygen that stimulates indigenous soil microorganisms to aerobically metabolize petroleum hydrocarbons in the vadose zone. The bioventing system at Site FT-19a consists of three bioventing well clusters (BV-2, BV-3 and BV-4) and associated monitoring points, located as shown on Figure 5-6.

Site FT-19 is located near an active runway and is within the secured FAA gates of the SCLA. This security effectively eliminates unauthorized access to the site. The land use restriction

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remains in place and is effective in prohibiting disturbance of the soil at Site FT-19 and prohibiting the installation of wells other than for monitoring.

The removal action at Site FT-19b included removal and disposal of medical wastes found on the surface. This site was classified as an NFA site and downgradient groundwater monitoring was implemented to assess groundwater quality.

The removal action at Site FT-19c included installing a SVE system. The principle behind SVE is to induce the flow of large volumes of air through soil pores in the impacted region. The airflow promotes vaporization and diffusion of contaminants into soil vapor, which is then removed by the extraction wells and exhausted to the atmosphere. The SVE system at Site FT- 19c consists of four extraction well clusters (SVE-1, SVE-2, SVE-3, and SVE-4) and associated monitoring points, as shown on Figure 5-7.

5.7.1.3 Systems O&M. O&M at Sites FT-19a and FT-19c includes weekly monitoring of the remedial system and collection of laboratory samples. In-situ respiration testing is also performed at Site FT-19a to evaluate the rate of biodegradation.

Weekly monitoring includes checking that the blower is operating within its intended range of flow rate, pressure, and temperature. The air filter is cleaned or replaced as necessary. Weekly system monitoring logs are completed and reported in the OU 3 Semiannual Reports. Routine soil vapor sampling is performed using 6-liter Summa® canisters provided by the analytical laboratory. At Site FT-19a, soil vapor sampling is performed at three monitoring point clusters. At Site FT-19c, soil vapor sampling is performed at the influent and effluent of the SVE system. Respiration testing involves shutting off the bioventing system at Site FT-19a and monitoring the injection wells and monitoring points for oxygen, carbon dioxide, and total volatile petroleum hydrocarbons (TVPH). The objective of the respiration test is to determine the rate at which soil microorganisms are degrading the petroleum hydrocarbons.

5.7.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found that the remedy at Site FT-19 was protective of human health and the environment.

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The bioventing system at Site FT-19a has operated continuously since the last five-year review. TVPH concentrations in the vapor monitoring probes indicate a decrease in concentration from up to 11,000 parts per million by volume (ppmv), at system startup in 1996, to a range between 26 and 830 ppmv in April 2004. Respiration testing in 2004 indicated a biodegradation rate of 0 to 0.1 milligrams per kilogram per day (mg/kg/day) at Site FT-19a. At present, bioventing continues at Site FT-19a, and the Air Force is considering options for approaching site closure. The SVE system at Site FT-19c operated until July 2001, then was shut down for rebound testing. The TCE concentration in the system influent indicated a decrease in concentration from 11 ppmv (at system startup in 1996) to 0.5 ppmv (July 2001). The estimated mass removal of TCE is 658 pounds. In November 2004, the SVE system at Site FT-19c was converted into a bioventing system and the O&M program was altered to be appropriate for bioventing. At present, bioventing continues at Site FT-19c and the Air Force is considering options for approaching site closure.

5.7.2 FT-19 Five-Year Review Process

This former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and a site inspection where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance (USEPA, 2001), and included pre-notification

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to the community and interested parties via media notification in the Victorville Daily Press that a five-year review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment –2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.7.3 FT-19 Five-Year Review Findings

This section presents the findings of the Five Year Review for Site FT-19. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports, the Semiannual O&M Reports for OU 3 Sites, and the OU 3 ROD (Document List, Appendix A).

5.7.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

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Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He understands that there are no plans to extract water from the upper aquifer and that the contamination of the lower aquifer may affect the Mojave River Basin. He believes that there are no known effects on the community but is concerned that the groundwater extraction and treatment system has been shutdown for over 2 years, indicating that there are no current efforts to cleanup and treat the contaminated groundwater.

5.7.3.2 Site Inspections. Site visits for O&M of the bioventing systems at Site FT-19 are conducted weekly by Mr. Sam Grizzle of MWH Constructors, Inc. (MWHC). During site visits, the bioventing and SVE systems are inspected and maintained, monitoring parameters are collected, and the site is inspected for other needed repairs or maintenance.

5.7.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

The OU 3 ROD included a baseline risk assessment for each part of Site FT-19. The risk assessments indicated that Sites FT-19a, FT-19b and FT-19c have risks exceeding the California benchmark value of increased cancer risk, but the values are within the USEPA guidelines of 1x10-4 to 1x10-6. However, the elevated risks were primarily a result of metals that were considered naturally occurring. At Site FT-19a, the baseline human health risk assessment resulted in an estimated cancer risk of 2.2x10-5, primarily driven by soil ingestion under the construction worker scenario. At Site FT-19b, the baseline human health risk assessment resulted in an estimated cancer risk of 5.2x10-6, primarily driven by ingestion of beryllium and

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB 2nd 5-Yr Review Rpt_Final\Text\Section 5.doc 5-74 Second Five-Year Review Report Former George Air Force Base nickel in soils under the industrial/commercial scenario. At Site FT-19c, the baseline human health risk assessment resulted in an estimated cancer risk of 3.1x10-6, primarily driven by chromium under the industrial/commercial worker scenario.

The results of an ecological risk assessment at Site FT-19 indicated that the compounds of concern at this site are not of potential ecological concern. The baseline risk assessment has not been recalculated because a remediation system has been in place, there are no complete exposure pathways, and there are no plans for residential use.

Vadose zone modeling performed in support of the OU 3 ROD indicated that under the base case scenario (best estimate of site conditions for the calibrated model), the most mobile constituents of TVPH/BTEX at Site FT-19 would not adversely affect groundwater quality within 100 years. However, under the base case scenario, model results predicted that TCE from Site FT-19c would reach the Upper Aquifer within 75 years at concentrations greater than the MCL. Base case scenario defines the groundwater model results prior to performing sensitivity analysis.

A list of ARARs for Site FT19 is provided in Table 15 of the OU 3 ROD (Montgomery Watson, 1998), which is also included in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA and the USAF. Based upon this discussion, the selected remedial action at Site FT-19 is compliant with ARARs, including laboratory certification, well installation, groundwater protection, MCLs, air and stormwater discharge requirements, and hazardous waste disposals requirements.

A review of the ARARs for this Five-Year Review process indicates that the OU 3 ROD ARARs remain up-to-date and relevant for Site FT-19. The methodology for estimating baseline human health risks and for establishing soil cleanup levels based on MCLs and vadose zone modeling remains valid.

As evaluation of risk to indoor air quality was not performed at Site FT-19 as part of the OU 3 ROD, this evaluation was not included in development of the remedy or the remediation goals at this site. Since the OU 3 ROD, evaluation of indoor air quality risk has become a standard part

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of the site investigation process within CERCLA, so this evaluation should be performed when a potential pathway exists. However, there are no buildings at Site FT-19; it is located next to an active runway, and land use restrictions currently in-place prohibit future buildings. Therefore, an evaluation of indoor air quality risk is not necessary at this time. A change in future land use to include placement of buildings at Site FT-19 would make an evaluation of indoor air quality risk necessary.

The presence of emerging chemicals at Site FT-19 was not evaluated in the OU 3 ROD because these chemicals were not known at that time. Previous land uses at Site FT-19, including use as a fire training area and medical waste disposal area, are not uses that would lead to the presence of these emerging chemicals. It is Air Force policy that additional investigation for emerging chemicals will not be performed unless there were previous site activities suggesting the possibility for emerging chemicals. An evaluation of emerging chemicals at Site FT-19 is therefore, not required and emerging chemicals are not of concern at Site FT-19.

5.7.3.4 Data Review. Routine monitoring of the bioventing system at Site FT-19a indicates that TVPH concentrations in the vapor monitoring probes have decreased to between 26 and 830 ppmv as of April 2004. Respiration testing in 2004 indicated a biodegradation rate of 0 to 0.1 mg/kg/day at Site FT-19a. Plots of historical vapor monitoring data are presented in the Semiannual Report for O&M at OU 3 Sites (MWH, 2004c). A progress soil sampling event at Site FT-19a indicated some decrease in soil TPH and BTEX concentration in some locations. Results of the progress soil sampling event are presented in the Final OU 3 Site FT-19 Closure Work Plan (MWH, 2004a).

Routine monitoring of the SVE system at Site FT-19c, prior to conversion to bioventing, indicated the TCE concentrations in the system influent had dropped to 0.5 ppmv as of July 2001. The estimated mass removal of TCE is 658 pounds. A plot of the historical vapor monitoring data at the system influent is presented in the Semiannual Report for O&M at OU 3 Sites (MWH, 2004c).

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5.7.4 FT-19 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at Site FT-19 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the remedy for Site FT-19a and FT-19c has been evaluated against the RAO presented in the OU 3 ROD.

RAO - Prevent human exposure to soil resulting in 1×10-4 to 1×10-6 excess cancer risk from all carcinogens.

• ICs are in place at Site FT-19 and the land use remains the same as during the decision process.

RAO – Prevent human exposure to soil contaminants with non-carcinogens at concentrations in excess of reference doses.

• ICs are in place at Site FT-19 and the land use remains the same as during the decision process.

RAO - Reduce the toxicity, mobility, and volume of the contamination in unsaturated soil to reduce the potential for migration of contaminants to groundwater.

• At Site FT-19a, the selected remedy of bioventing has been in operation since 1996. Respiration testing indicates that biological degradation continues to occur in the subsurface, albeit at a slow rate.

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• At Site FT-19c the selected remedy of SVE operated from 1996 to 1998, removing an estimated 659 pounds of TCE from the subsurface and decreasing the TCE soil vapor concentration to approximately 0.5 ppmv.

RAO - Remove, to the extent practical, the COPCs detected in unsaturated soils to meet or exceed the remediation goals defined in the OU 3 ROD.

• At Site FT-19a, the selected remedy of bioventing has been in operation since 1996 and has reduced the concentration of TVPH in the soil vapor to asymptotic levels. The progress soil sampling event performed in 2000 showed that soil concentrations at Site FT-19 remained above the remedial goals established in the OU 3 ROD. Respiration testing indicates that biological degradation continues to occur in the subsurface, albeit at a slow rate. The Air Force is currently evaluating Site FT-19a for site closure. The results of this evaluation will shed further light on the effectiveness of the remedial action at this site. • At Site FT-19c the selected remedy of SVE operated from 1996 to 1998, removing an estimated 659 pounds of TCE from the subsurface and decreasing the TCE soil vapor concentration to approximately 0.5 ppmv. The Air Force is currently evaluating Site FT-19c for site closure. The results of this evaluation will shed further light on the effectiveness of the remedial action at this site. During the evaluation process, the Air Force elected in November 2004 to operate the Site FT-19c system in bioventing mode to further remediate the TVPH present at the site. The Air Force is currently evaluating Site FT-19c for site closure. The results of this evaluation will shed further light on the effectiveness of the remedial action at this site.

System O&M: System operation at Sites FT-19a and FT-19c are performed during weekly site visits. The O&M procedures follow those prescribed in the Bioventing and Soil Vapor Extraction O&M Manual (Montgomery Watson, 1996b).

Cost of System O&M: O&M costs are higher than predicted in the OU3 ROD and within the acceptable range of minus 30 percent to plus 50 percent.

Opportunities for Optimization: Optimization of the remedial systems has been performed at Site FT-19 and is reported in the Semiannual Report for O&M at OU 3 Sites (MWH, 2004c). These optimization efforts have included changing valve settings to target certain well screens, converting Site FT-19c to bioventing, streamlining the vapor sampling program, and adding

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moisture to the subsurface to improve the rate of biodegradation at Site FT-19a. The Air Force is evaluating Site FT-19 for site closure, so further optimization is not warranted at this time.

Early Indicators of Potential Remedy Failure: Progress soil sampling conducted in 2000 indicated that soil concentrations remained above remedial goals in several locations at Site FT-19. At the asymptotic concentrations and the lowered rate of TCE and TVPH removal at both Sites FT-19a and FT-19c, it is unclear whether the current remedies have or can effectively reduce soil concentration to below remediation goals. The evaluation of site closure being conducted by the Air Force will shed further light on this question.

Implementation of ICs and Other Measures: ICs are in place at Site FT-19 and the land use remains the same as during the decision process. Site FT-19 is located near an active runway and is within the secured FAA gates of the SCLA. This security effectively eliminates unauthorized access to the site. The land use restriction remains in place and is effective in prohibiting disturbance of the soil at Site FT-19 and prohibiting the installation of wells other than for monitoring. At present, there is no foreseeable change in land use at this site.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for Site FT-19 (Section 5.6.3.3) indicates no change in standards from the previous Five- Year Review.

Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

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Changes in Exposure Pathways: There have been no changes in the site condition or land use that would affect the exposure pathways since the previous Five-Year Review. However, the five-year review indicated that a future change in the land use at this site might open up an additional pathway via indoor air. While no pathway exists at present, and no pathway is expected in the future due to the land use restriction and the proximity to the active runway, an evaluation of indoor air quality risk would be appropriate should a building be placed on Site FT-19.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use.

New Contaminants or Contaminant Sources: No new source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at Site FT-19. Although an investigation for emerging chemicals has not been performed at Site FT-19, no investigation is required because activities that might lead to the presence of emerging chemicals at this site did not occur.

Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at Site FT-19 since the previous Five-Year Review.

Expected Progress towards Meeting the RAOs: The RAOs are currently being met.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Monitoring of the remedial systems at Site FT-19 indicate that TCE and TVPH have significantly declined as a result of the remedies. The Air Force is conducting an evaluation of Site FT-19 for site closure. Unauthorized access to the site continues to be restricted by the FAA security gates at the SCLA. The land use restriction that prohibits disturbance of the soil or

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installation of wells other than monitoring wells at Site FT-19 remains effective. Thus the remedy at Site FT-19 remains protective of human health and the environment.

New or Previously Unidentified Ecological Risks: No new or previously unidentified ecological risks have been identified.

Natural Disaster Impact: No natural disasters have occurred in the area that have altered the effectiveness of the remedy.

5.7.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy was is operating as effectively as predicted and is protective of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD, based on risk and toxicity information are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy.

5.7.5 FT-19 Issues

There were no deficiencies identified for Site FT-19 during the five-year review. No changes to the routine monitoring program are necessary. A further evaluation of the effectiveness of the remedy at this site will be conducted when the Air Force performs an evaluation of site closure at Site FT-19.

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5.7.6 FT-19 Recommendations and Follow-Up Actions

The following is recommended to ensure remedy effectiveness in compliance with the RAOs for the Site FT-19.

1) Perform evaluation for site closure at Site FT-19 for 2005; responsible party, USAF.

5.7.7 FT-19 Protectiveness Statement

The remedy at Site FT-19 is currently, and in the long term, protective of human health and the environment. The remedy has reduced the mobility and volume of the COPCs at this site, and has reduced the potential for migration of the COPCs to groundwater. Access restrictions and land use restrictions at Site FT-19 continue to protect human health.

5.7.8 FT-19 Next Review

The next Five-Year Review will be conducted in 2010.

5.8 SITE OT-51

Site OT-51 is located in the western portion of the base, southwest of the aircraft runways, as shown on Figure 3-6. A site plan for Site OT-51 is included as Figure 5-8. Jet fuel spills were reported at five engine test cells located near Site OT-51. The area designated as OT-51 is located near engine test cell 799 and 807. Test cell operation reportedly occurred during the early 1950s.

Initial subsurface investigations at Site OT-51 were conducted by CH2M Hill in 1982 and JMM in 1992. In 1994, M&E performed an RI, which included soil borings, installing one groundwater monitoring well and removing an underground storage tank/septic system. TPH and BTEX were detected in groundwater samples collected from the hot spot area.

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5.8.1 Site OT-51 Remedial Actions

This section describes the remedy selection, implementation, O&M and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.8.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for Site OT-51 (Montgomery Watson, 1998):

Protection of Human Health

• Prevent human exposure to soil resulting in 1×10-4 to 1×10-6 excess cancer risk from all carcinogens. • Prevent human exposure to soil contaminants with non-carcinogens at concentrations in excess of reference doses.

Protection of the Environment

• Reduce the toxicity, mobility, and volume of the contamination in unsaturated soil to reduce the potential for migration of contaminants to groundwater. • Remove, to the extent practical, the COPCs detected in unsaturated soils to meet or exceed the remediation goals defined in the OU 3 ROD.

Bioventing was the selected remedy for Site OT-51. Natural attenuation was the selected remedy for the groundwater at Site OT-51. As part of the natural attenuation, institutional controls and continued groundwater monitoring would be performed to assess potential future migration and degradation of COPCs in the groundwater.

5.8.1.2 Remedy Implementation. A removal action has been implemented at Site OT- 51. In an effort to accelerate the remedial progress, minimize present and future environmental risk and facilitate timely transfer of property to the community, an accelerated action was performed at Site OT-51 before finalizing the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB and the Air Force.

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The removal action at Site OT-51 included installing a bioventing system. The principle behind bioventing is to inject atmospheric air into the subsurface to provide oxygen that stimulates indigenous soil microorganisms to aerobically metabolize petroleum hydrocarbons in the vadose zone. The bioventing system at Site OT-51 consisted of one bioventing well cluster and associated monitoring points. In 2001, an Explanation of Significant Difference (ESD) was completed to alter the remedial action at Site OT-51 to SVE.

Natural attenuation was selected as the remedy for groundwater at this site. Long-term groundwater monitoring has been performed to track progress.

The remedy at Site OT-51 also includes an access restriction, to limit unauthorized access to the site, and a land use restriction, which prohibits disturbance of the soil at this site and the installation of wells except for the purpose of monitoring.

5.8.1.3 Operation and Maintenance. O&M at Site OT-51 includes weekly monitoring of the remedial system and collection of laboratory samples. Weekly monitoring includes checking that the blower is operating within its intended range of flow rate, pressure and temperature. The air filter is cleaned or replaced as necessary. Weekly system monitoring logs are completed and reported in the OU 3 Semiannual Reports. Routine soil vapor sampling is performed using 6-liter Summa® canisters provided by the analytical laboratory. Soil vapor sampling is performed at four monitoring point clusters at Site OT-51. Long-term groundwater monitoring is performed in accordance with the approved basewide long-term groundwater monitoring plan.

5.8.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found that the remedy at Site OT-51 protective of human health and the environment.

Following two years of bioventing operation at Site OT-51, from April 1996 to May 1998, a rebound test, sampling event, and SVE pilot study indicated that SVE was a more appropriate remedy for the site. With the concurrence of the BCT, the Air Force elected to construct an on- site SVE system consisting of two extraction wells and an internal combustion engine (ICE) and

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prepared an ESD to the OU 3 ROD. The SVE system was started in September 2000 and operated simultaneously with the bioventing system, creating an active injection/extraction system.

In January 2002, bioventing was discontinued because monitoring results indicated significant short-circuiting between the injection and extraction wells. In May 2003 two additional extraction wells were added to the SVE system, bringing the total number of extraction wells to four. At this time the ICE was replaced with a catalytic oxidation unit, which increased the flow rate from approximately 100 standard cubic feet per minute (scfm) to approximately 250 scfm.

The TVPH concentration in the system influent indicates a decrease in concentration from 4,700 ppmv (at SVE startup in 2000) to 790 ppmv (in December 2004). The estimated mass removal of TVPH is 130,000 pounds through December 2004. At present, SVE continues at Site OT-51 with a daily mass removal of TVPH in the range of 50 to 100 pounds per day.

5.8.2 Site OT-51 Five-Year Review Process

This former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and a site inspection where warranted. Community involvement was conducted in

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accordance with the Five-Year Review guidance (USEPA, 2001), and included pre-notification to the community and interested parties via media notification in the Victorville Daily Press that a five year review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.8.3 Site OT-51 Five-Year Review Findings

This section presents the findings of the Five Year Review for Site OT-51. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports, the Semiannual O&M Reports for OU 3 Sites, and the OU 3 ROD (Document List, Appendix A).

5.8.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

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Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He understands that there are no plans to extract water from the upper aquifer and that the contamination of the lower aquifer may affect the Mojave River Basin. He believes that there are no known effects on the community but is concerned that the groundwater extraction and treatment system has been shutdown for over 2 years, indicating that there are no current efforts to cleanup and treat the contaminated groundwater.

5.8.3.2 Site Inspections. Site visits for O&M of the SVE system at Site OT-51 are conducted weekly by Mr. Sam Grizzle (MWHC). During site visits, the SVE system is inspected and maintained, SVE parameters are collected and the site is inspected for other needed repairs or maintenance.

5.8.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

The OU 3 ROD included a baseline risk assessment for Site OT-51. The risk assessment estimated a cancer risk of 1.4x10-8, driven primarily by dermal exposure to soil under an industrial/commercial worker scenario. Although this risk value is lower than the California benchmark value of increased cancer risk of 1x10-6, and the USEPA guidelines of 1x10-4 to

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1x10-6, a remedial alternative was recommended for Site OT-51 because detected concentrations of TPH and BTEX exceeded the initial evaluation criteria. The baseline risk assessment has not been recalculated because a remediation system has been in place, there are no complete exposure pathways, and there are no plans for residential use.

A list of ARARs for Site OT-51 is included in Table 15 of the OU 3 ROD (Montgomery Watson, 1998), which is also in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA and the USAF. Based upon this discussion, the selected remedial action at Site OT-51 is compliant with ARARs, including laboratory certification, well installation, groundwater protection, MCLs, air discharge requirements, stormwater discharge and hazardous waste disposals requirements.

A review of the ARARs for this Five-Year Review process indicates the OU 3 ROD ARARs remain up-to-date and relevant for OT-51. The methodology for estimating baseline human health risks and for establishing soil cleanup levels remains valid.

An evaluation of risk to indoor air quality was not performed at Site OT-51 as part of the OU 3 ROD. As such this evaluation was not included in the development of the remedy or the remediation goals at this site. Since the OU 3 ROD, evaluation of indoor air quality risk has become a standard part of the site investigation process within CERCLA and this evaluation should be performed when a potential pathway exists. However, there are no habitable buildings at Site OT-51, and the land use restriction currently in place prohibits future buildings. Therefore, an evaluation of indoor air quality risk is not necessary at this time. Any changes in future land use to include placement of buildings would make an evaluation of indoor air quality risk necessary.

The presence of emerging chemicals at Site OT-51 is an issue that was not evaluated in the OU 3 ROD because these chemicals were not known at that time. Previous land use as a jet engine test facility does not indicate the types of activities that would lead to the presence of these emerging chemicals. It is Air Force policy that additional investigation for emerging chemicals will not be

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performed unless there were previous site activities suggesting the possibility for emerging chemicals. An evaluation of emerging chemicals at Site OT-51 is therefore, not required.

5.8.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). Routine monitoring of the SVE system at Site OT-51 indicates that the TVPH concentration in the system influent has decreased to 790 ppmv, as of December 2004. The estimated mass removal of TVPH is 130,000 pounds through December 2004. At present, SVE continues at Site OT-51 with a daily mass removal of TVPH in the range of 50 to 100 pounds per day. A plot of historical TVPH vapor results, estimated cumulative mass removal, and a table of TVPH and BTEX concentrations at extraction wells and monitoring points is presented in the Semiannual Report for O&M at OU 3 Sites (MWH, 2004c), and the document review.

Groundwater monitoring data indicates benzene has not been detected since 2001 in the four wells near OT-51. Xylenes, toluene, and ethylbenzene have also not been detected in recent years.

5.8.4 OT-51 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at Site OT-51 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the remedy for Site OT-51 has been evaluated against the RAO presented in the OU 3 ROD.

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RAO - Prevent human exposure to soil resulting in 1×10-4 to 1×10-6 excess cancer risk from all carcinogens.

• ICs are in place at Site OT-51 and the land use remains the same as during the decision process.

RAO – Prevent human exposure to soil contaminants with non-carcinogens at concentrations in excess of reference doses.

• ICs are in place at Site OT-51 and the land use remains the same as during the decision process.

RAO - Reduce the toxicity, mobility, and volume of the contamination in unsaturated soil to reduce the potential for migration of contaminants to groundwater.

• The selected remedy of SVE is operating at Site OT-51 since 2000 and was preceded by approximately four years of bioventing operations and reduced the concentration of TVPH in the soil vapor to asymptotic levels. SVE continues to reduce the concentrations of TVPH and BTEX in the soil vapor. It is estimated that 130,000 pounds of petroleum hydrocarbons have been removed since system startup. The system continues to remove an estimated 50 to 100 pounds of petroleum hydrocarbons from the subsurface per day. • Groundwater results do not indicate a continuing source of contaminants to the groundwater.

RAO - Remove, to the extent practical, the COPCs detected in unsaturated soils to meet or exceed the remediation goals defined in the OU 3 ROD.

• The selected remedy of SVE is operational and effective. The system continues to remove an estimated 50 to 100 pounds of petroleum hydrocarbons from the subsurface per day. The system will continue to run until remediation goals are met.

System O&M: System inspection at Site OT-51 is performed during weekly site visits. The O&M procedures follow those prescribed in the Semiannual Report for O&M at OU 3 Sites (MWH, 2004c).

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Cost of System O&M: O&M costs are higher than predicted in the OU3 ROD and outside the acceptable range of minus 30 percent to plus 50 percent. The costs are not within range because the ROD estimated O&M costs for a bioventing system. An ESD was completed in 2001, and an SVE is currently operating. SVE systems require more operational expenses than bioventing. An evaluation of the SVE O&M costs did not indicate any issues.

Opportunities for Optimization: Optimization of the SVE system at Site OT-51 is regularly performed, and these activities are reported in the Semiannual Report for O&M at OU 3 Sites. Optimization efforts have included installing a catalytic oxidation unit in place of an ICE, changing the valve settings to target certain well screens, installing additional soil vapor extraction wells, and streamlining the vapor sampling program. The opportunity for future optimization exists, including continuing to change valve settings to target extraction flow to those areas of Site OT-51 with the highest remaining soil vapor concentrations. Additional optimization may include continuing to streamline or reduce vapor sampling as the data needs at the site change.

Early Indicators of Potential Issues: Monitoring at Site OT-51 indicates a high rate of removal of petroleum hydrocarbons from the subsurface and there are no indications of potential issues.

Implementation of ICs and Other Measures: ICs are in place at Site OT-51 and the land use remains the same as during the decision process. Site OT-51 is located southwest of the active runways and is within the secured FAA gates of the SCLA. An additional security fence exists around the perimeter of Site OT-51. This security effectively eliminates unauthorized access to the site. The land use restriction remains in place and is effective in prohibiting disturbance of the soil at Site OT-51 and prohibiting the installation of wells other than for monitoring.

The portion of OU 3 near OT-51 is retained by the Air Force, are on lease to the Land Reuse Agency (LRA), and will not be transferred by deed until the Air Force receives regulatory concurrence that the remedial actions, including ICs, are in place and operating properly and successfully. A lease restriction is in place that prohibits the use of the impacted groundwater beneath Site OT-51. At present, there is no foreseeable change in land use at this site.

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Additionally the Air Force has prohibited use of groundwater from the Upper Aquifer and ensures compliance with repeated communication to the lessee and by maintaining a daily presence at the former base so that issues are identified and resolved on a real time basis. Several specific terms and conditions from the lease are as follows:

1. The lessee and any sublessee shall comply with all Federal, State and local laws, regulations and standards. 2. Government retains the right to inspect. 3. Lessee expressly acknowledges that it fully understands that response actions undertaken with respect to the FFA or IRP program my impact "quiet use and enjoyment" or leased property. 4. Lessee agrees to comply with provisions of any health and safety plan in effect under the IRP, hazardous substance remediation or response agreement. 5. Lessee acknowledges receipt of the Environmental Baseline Survey. 6. Lessee acknowledges receipt of the information that GAFB has been identified as a NPL Site and why (see EBS above). 7. Lessee acknowledges receipt of FFA, and that the FFA terms take precedence over the lease. 8. The Government, USEPA, and State retain the right to enter lease premises for purposes of executing the FFA and IRP program (access, inspection, investigation, response/remedial actions, etc). 9. Lessee shall not construct or make, or permit its subleasees to construct or make, any alterations (construction, demolition, excavation, restoration, additions, or other changes in, to or upon the property) which may impede or impair any activities under the IRP or FFA without prior written consent of the Air Force. 10. The failure to comply with any provision of the lease shall constitute a default and may result in the termination of the lease.

At the time of the deed, deed covenants will be identified in the FOST, CERCLA 120(h)3 and state land use covenant to ensure that ICs are identified. The five-year review process will be used to verify that the ICs are functioning as intended.

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Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for Site OT-51 (Section 5.7.3.3) did not indicate a change in standards from the previous Five-Year Review. Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathways: There have been no changes in the site condition or land use that would affect the exposure pathways since the previous Five-Year Review. However, the Five-Year Review identified that a future change in the land use at this site might open up an additional pathway via indoor air. While no pathway exists at present, and no pathway is expected in the future due to the land use restriction and the proximity to the active runway, an evaluation of indoor air quality risk would be appropriate should a building be placed on Site OT-51.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use.

New Contaminants or Contaminant Sources: No new source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at Site OT-51. Although an investigation for emerging chemicals has not been performed at Site OT-51, no investigation is required because activities that might lead to the presence of emerging chemicals at this site were not performed. No chemical byproducts have been created from the remedy.

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Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at Site OT-51 since the previous Five-Year Review.

Expected Progress towards Meeting the RAOs: The current TVPH and BTEX concentrations indicate the remedy has not yet achieved the objectives of the OU 3 ROD; however, the current recovery rates indicate the remedy will meet the RAOs given more time for operation.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Monitoring of the SVE system at Site OT-51 indicates a decline in TVPH and BTEX concentrations over the course of system operation. The system continues to remove a significant amount of TVPH and BTEX each day of operation. Unauthorized access to the site is restricted by the site security fence and the FAA security gates at the SCLA. The land use restriction, which prohibits disturbance of the soil or installation of wells other than monitoring wells at Site OT-51, remains effective. The Site OT-51 remedy remains protective of human health and the environment.

New or Previously Unidentified Ecological Risks: There are no new or previously unidentified ecological risks.

Natural Disaster Impact: No natural disasters have occurred in the area that has altered the effectiveness of the remedy.

5.8.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy is operating as effectively as predicted and is protective of human health and the environment.

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B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD, based on risk and toxicity information are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy.

5.8.5 OT-51 Issues

There were no deficiencies identified for Site OT-51 during the five-year review. No changes to the routine monitoring program are necessary.

5.8.6 OT-51 Recommendations and Follow-Up Actions

The following is recommended to ensure remedy effectiveness in compliance with the RAOs for Site OT-51.

1) Continued SVE optimization at Site OT-51 (ongoing); responsible party, USAF.

5.8.7 OT-51 Protectiveness Statement

The remedy at Site OT-51 is currently, and in the long term, protective of human health and the environment. The remedy has reduced the mobility and volume of the COPCs at this site and has reduced the potential for migration of the COPCs to groundwater. Access restrictions and land use restrictions at Site OT-51 continue to protect human health.

5.8.8 OT-51 Next Review

The next Five-Year Review will be conducted in 2010.

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5.9 SITE OT-69

Site OT-69 consists of the TCE and tetrachloroethene (PCE) groundwater contamination detected in the flightline and operations facilities area. The site is located along the flightline, as indicated on Figure 3-6. A site plan for Site OT-69 is included as Figure 5-9. The TCE/PCE contamination in this area was first identified during the 1992 investigation of JP-4 contamination within OU 2. At the request of the USEPA, Site OT-69 was subdivided into six sub-sections, OT-69a through OT-69f, as way of keeping the separate plumes easily identifiable. Subdivided areas "a-e" represent the five TCE plumes and "f" represents the PCE plume. This subdivision was originally documented in the Final Sampling Event Report, Operable Unit 3, Site OT-69 MW-49 Area (MWH, 2003).

5.9.1 OT-69 Remedial Actions

This section describes the remedy selection, implementation, O&M and progress since the previous five-year review at GAFB (Montgomery Watson, 2000).

5.9.1.1 Remedy Selection. The OU 3 ROD found no complete exposure pathway for petroleum hydrocarbons at Site OT-69 and identified the following RAO for the site (Montgomery Watson, 1998):

• Reduce the dissolved plume concentrations for identified COPCs in the groundwater at Site OT-69 so that the most stringent concentrations identified in the ARARs are not exceeded (MCLs, secondary MCLs, or quantifiable taste or odor criteria).

In order to meet this RAO, the OU 3 ROD selected the remedial approach of institutional controls and natural attenuation. ICs include land use restrictions prohibiting the installation of groundwater wells for domestic purposes and deed restrictions preventing use of the impacted groundwater. Natural attenuation is performed as part of the long-term groundwater monitoring program at GAFB.

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5.9.1.2 Remedy Implementation. The remedial approach of institutional controls and natural attenuation has been implemented at Site OT-69. Natural attenuation has been monitored by analyzing groundwater for specific parameters, including electron acceptors (oxygen, nitrate, sulfate, iron, etc.), metabolic by-products (nitrite, hydrogen sulfide, and methane), general biological parameters (alkalinity and redox potential), and the COPCs. Natural attenuation groundwater monitoring consists of semiannual collection of groundwater from wells in the Site OT-69 area and analysis for natural attenuation parameters and COPCs.

5.9.1.3 Operation and Maintenance. O&M at Site OT-69 includes semiannual sampling, for natural attenuation parameters, of the approximately 50 (actual number of wells varies and is contingent on prior event sampling results) groundwater wells located in the vicinity of Site OT-69. Based on these results, an analysis of natural attenuation is presented annually in the Basewide Groundwater Monitoring Report. Groundwater sampling is typically conducted in April and October of each year.

5.9.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found the remedy at Site OT-69 protective of human health and the environment.

Groundwater monitoring for natural attenuation has been conducted annually since the previous five-year review. The assessment indicates depressed concentrations of electron acceptors, elevated concentration of metabolic by-products, and a slightly low redox potential. In general, these parameters indicate moderately favorable conditions for natural attenuation.

However, natural attenuation was contingent upon TCE and PCE concentrations decreasing, as predicted by a groundwater model presented in the OU 3 ROD. Concentrations have not decreased as predicted, so in accordance with the ROD, more active remedies are being considered.

The Air Force has performed additional investigations of the site. Soil and groundwater grab samples were collected from five soil borings in April 2002. Results of this sampling effort helped to further define the extent of contamination, but did not identify a vadose-zone source

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB 2nd 5-Yr Review Rpt_Final\Text\Section 5.doc 5-97 Second Five-Year Review Report Former George Air Force Base area. An additional investigation to better delineate the extent of soil and groundwater impact at Site OT-69 was conducted from January to March 2005. Preliminary results have defined the extent of soil vapor concentrations and identified the probable source areas as the drain lines at the Maintenance Hangar. The Air Force is currently assembling the data and evaluating remedial alternatives for the vadose zone source area. The Air Force will propose a vadose zone remedy to the regulatory agencies subsequent to this evaluation.

5.9.2 OT-69 Five-Year Review Process

This former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH • Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

This Five-Year Review consisted of the following activities: a review of related documents, interviews with local government officials and representatives of the construction and operations contractors, and a site inspection where warranted. Community involvement was conducted in accordance with the Five-Year Review guidance (USEPA, 2001), and included pre-notification to the community and interested parties via media notification in the Victorville Daily Press that a five-year review was to be conducted and notification that the Five-Year Review report was completed and available in the site repository.

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The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.9.3 OT-69 Five-Year Review Findings

This section presents the findings of the Five-Year Review for Site OT-69. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports and the OU 3 ROD (Document List, Appendix A).

5.9.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

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Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He understands that there are no plans to extract water from the upper aquifer and that the contamination of the lower aquifer may affect the Mojave River Basin. He believes that there are no known effects on the community but is concerned that the groundwater extraction and treatment system has been shutdown for over 2 years, indicating that there are no current efforts to cleanup and treat the contaminated groundwater.

5.9.3.2 Site Inspections. Site OT-69 is located along the flightline and coincides with the OU 2 portion of the installation restoration program at George AFB. The OU 2 area is periodically visited due to the light, non-aqueous phase liquid skimming operation in this area. Additionally, Site OT-69 is monitored semiannually during routine groundwater sampling events. Any problems, such as casing damage, are reported by the sampling contractor. Results of the semiannual monitoring are presented annually in the Annual Basewide Groundwater Monitoring Report (MWH, 2004b).

5.9.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

An analysis of human health risk concluded that no likely exposure scenarios existed at Site OT- 69 because the area is not used as a source of domestic, industrial or agricultural water supply. The risk assessment evaluated several unlikely exposure pathways and estimated a total carcinogenic risk from dichlorethene, TCE, and PCE of 2 x 10-5 for a basewide residential development case and 3 x 10-8 for a limited residential development case. The baseline risk assessment has not been recalculated because there are no complete exposure pathways for the contaminated groundwater, and there are no plans for residential use. In addition, no ecological risk was determined to exist because groundwater does not reach the surface within the base boundaries; therefore, there is no exposure pathway. Site conditions have not changed, so an updated environmental assessment is not warranted.

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A list of ARARs for Site OT-69 is provided in Table 15 of the OU 3 ROD (Montgomery Watson, 1998). ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA and the USAF. Based upon this discussion, the selected remedial action at Site OT-69 is compliant with ARARs. Chemical-specific ARARs would be met by achieving the cleanup standards. Action-specific ARARs would be met by implementing the remedial action.

A review of the ARARs for this Five-Year Review process indicates the OU 3 ROD ARARs remain up-to-date and relevant for Site OT-69. The methodology for estimating baseline human health risks and the MCL-driven cleanup standards remain valid.

An evaluation of risk to indoor air quality was not performed at Site OT-69 as part of the OU 3 ROD, and thus this evaluation was not included in development of the remedy or the remediation goals at this site. Since the OU 3 ROD, evaluation of indoor air quality risk has become a standard part of the site investigation process within CERCLA and this evaluation should be performed when a potential pathway exists. The Air Force is currently evaluating remedial alternatives for the vadose zone source and will propose a vadose zone remedy to the regulatory agencies. The indoor air risk will be evaluated as part of the selection of the new remedy.

The presence of emerging chemicals at Site OT-69 is an issue that was not evaluated in the OU 3 ROD because these chemicals were not known at that time. Previous land use at Site OT-69 does not indicate the types of activities that would lead to the presence of these emerging chemicals. It is Air Force policy that additional investigation for emerging chemicals will not be performed unless there were previous site activities suggesting the possibility for emerging chemicals. An evaluation of emerging chemicals at Site OT-69 is therefore, not required.

5.9.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). Groundwater results collected at Site OT-69 and reported in the 2002 Annual Basewide Groundwater Monitoring Report (MWH, 2004b) indicate increasing concentrations in one portion of the site (sub-area OT-69e) and decreasing or stable trends over the rest of the site. This groundwater data also suggests that the extent of TCE and PCE in the groundwater is not

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB 2nd 5-Yr Review Rpt_Final\Text\Section 5.doc 5-101 Second Five-Year Review Report Former George Air Force Base yet fully defined in sub-area OT-69e and there may be a continuing source of contamination from the vadose zone. A natural attenuation assessment at Site OT-69 indicated generally favorable conditions for biological degradation, although natural attenuation of TCE or PCE could not be definitively proven. Detailed results, analysis, and conclusions are presented in the 2002 Annual Basewide Groundwater Monitoring Report (MWH, 2004b). The Air Force conducted a vadose zone and groundwater investigation from January to March 2005 to assess the possible vadose-zone source area. The Preliminary data indicates that the vast majority of the contamination is at depth and much lower concentrations exist from 0 to 30 feet bgs. The Air Force is currently evaluating remedial alternatives for the vadose zone source area and will propose a vadose zone remedy to the regulatory agencies.

5.9.4 OT-69 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at Site OT-69 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the remedy for Site OT-69 has been evaluated against the RAO presented in the OU 3 ROD.

RAO – Reduce the dissolved plume concentrations for identified COPCs in the groundwater at Site OT-69 so that the most stringent concentrations identified in the ARAR’s are not exceeded MCLs, secondary MCLs, or quantifiable taste or order criteria.

• The selected remedy of natural attenuation was implemented at Site OT-69 and monitoring results indicated moderately favorable conditions for natural

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attenuation. However, concentrations of the COPCs have not reduced at the rates predicted in the model. • Results of an additional site investigation conducted at OT-69(e) have defined a vadose zone source and further delineated the extent of the groundwater plume in the vicinity of building 676, an aircraft maintenance hangar. The vadose zone contamination is likely a continuing source of COPCs to groundwater, so it limits the rate at which the natural attenuation can attenuate the plume.

System O&M: Groundwater monitoring is performed at Site OT-69 during semiannual events. The groundwater sampling procedures follows the Basewide Sampling and Analysis Plan (HydroGeoLogic, 1998) and Final Sampling and Analysis Plan Addendum for Basewide Groundwater Monitoring Events (MWH, 2003b). The groundwater monitoring program has been sufficient to determine the effectiveness of the remedy.

Cost of System O&M: O&M costs are higher than predicted in the OU3 ROD and outside the acceptable range of minus 30 percent to plus 50 percent. The actual cost per sampling event is lower than predicted in the ROD, but additional effort is being required. The original cost assumptions assumed that 10 wells would be sampled 4 times per year (40 events per year). Currently, approximately 120 sampling events are occurring per year.

Opportunities for Optimization: The Air Force has performed an additional investigation and based on the results is pursuing an alternative remedy for Site OT-69 to ensure compliance with the RAO. Further opportunities for optimization will be addressed in the investigation and design of this alternative remedy.

Early Indicators of Potential Issues: Analysis of the groundwater sampling results from the semi-annual sampling program suggest that the remedy of natural attenuation is not reducing contaminant concentrations at rates predicted in the model. Additionally the results of the recent investigations have defined a continuing vadose zone source of COPCs to groundwater. Therefore, the Air Force is currently evaluating remedial alternatives for the vadose zone source area and will propose a vadose zone remedy to the regulatory agencies.

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Implementation of ICs and Other Measures: ICs are in place at Site OT-69 and the land use remains the same as during the decision process. The portion of OU 3 near OT-69 is retained by the Air Force, is on lease to the LRA, and will not be transferred by deed until the Air Force receives regulatory concurrence that the remedial actions, including ICs, are in place and operating properly and successfully. A lease restriction is in place that prohibits the use of the impacted groundwater beneath Site OT-69. At present, there is no foreseeable change in land use at this site. Additionally the Air Force has prohibited use of groundwater from the Upper Aquifer and ensures compliance with repeated communication to the lessee and by maintaining a daily presence at the former base so that issues are identified and resolved on a real time basis. Several specific terms and conditions from the lease are as follows:

1. The lessee and any sublessee shall comply with all Federal, State and local laws, regulations and standards. 2. Government retains the right to inspect. 3. Lessee expressly acknowledges that it fully understands that response actions undertaken with respect to the FFA or IRP program my impact "quiet use and enjoyment" or leased property. 4. Lessee agrees to comply with provisions of any health and safety plan in effect under the IRP, hazardous substance remediation or response agreement. 5. Lessee acknowledges receipt of the Environmental Baseline Survey. 6. Lessee acknowledges receipt of the information that GAFB has been identified as an NPL Site and why (see EBS above). 7. Lessee acknowledges receipt of FFA, and that the FFA terms take precedence over the lease. 8. The Government, USEPA, and State retain the right to enter lease premises for purposes of executing the FFA and IRP program (access, inspection, investigation, response/remedial actions, etc). 9. Lessee shall not construct or make, or permit its subleasees to construct or make, any alterations (construction, demolition, excavation, restoration, additions, or other changes in, to or upon the property) which may impede or impair any activities under the IRP or FFA without prior written consent of the Air Force. 10. The failure to comply with any provision of the lease shall constitute a default and may result in the termination of the lease.

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At the time of the deed, deed covenants will be identified in the FOST, CERCLA 120(h)3 and state land use covenant to ensure that ICs are identified. The 5 year review process will be used to verify that the ICs are functioning as intended.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

The Air Force has performed an additional investigation and will propose a vadose zone remedy to the regulatory agencies. The results of this investigation will also be used to provide an update to the toxicity data for the site. Cleanup levels and RAOs may be updated as well, because of possible vadose zone sources.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for Site OT-69 (Section 5.8.3.3) indicates no change in standards from the previous Five- Year Review.

• Changes in Cleanup Levels: The cleanup levels for groundwater, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable. The TCE and PCE cleanup levels will remain at 5 µg/L.

Possible future changes include:

• Determination of soil cleanup levels appropriate for vadose zone soil • Determination of appropriate Air emission levels for a soil vapor extraction system

Changes in Exposure Pathways: There have been no changes in the site condition or land use that would affect the exposure pathways since the previous Five-Year Review. However, the preliminary results of the recent vadose zone investigation at Site OT-69 and/or a future change

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in the land use may open up an additional pathway via indoor air in the vicinity of an active aircraft maintenance hangar. Indoor air quality risk will be evaluated in association with the evaluation of a new remedy at Site OT-69.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use.

New Contaminants or Contaminant Sources: The nature and extent of the impacted soil and groundwater has been further defined in the 2002 and 2005 subsurface investigations at OT-69. However, no new source areas have been identified.

Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics and no adverse chemical byproducts created from the current remedy. The subsurface investigation conducted in 2002 and 2005 continues to refine the nature and extent of impact at Site OT-69.

Currently, the Cal-EPA cancer slope factor is recommended for use at GAFB. The Cal-EPA has developed inhalation (0.007 [mg/kg-d]-1) and oral (0.013 [mg/kg-d]-1) TCE cancer slope factors for use in California.

Since the RI/FS was completed, the inhalation and oral TCE cancer slope factors for use in California have changed. The cancer slope factors used were 0.051 (mg/kg-d)-1 in the RI/FS. The current oral TCE cancer slope factor is 0.54 (mg/kg-d)-1 for both Cal-EPA and USEPA. The current inhalation cancer slope factor is 0.021 (mg/kg-d)-1 for both Cal-EPA and USEPA. The baseline cancer slope factors were not recalculated because remediation has been ongoing and there are no complete exposure pathways.

Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at Site OT-69 since the previous Five-Year Review.

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Expected Progress towards Meeting the RAOs: The Air Force is pursuing a new remedy for OT-69 that will ensure compliance with the RAO.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

As previously stated, results of the 2002 and 2005 investigations in the OT-69 area have further refined the understanding of the nature and extent of impact at OT-69. Although the natural attenuation remedy was not reducing the concentrations of COPCs at the predicted rates, the remedy is still protective, because there are no complete exposure pathways and institutional controls remain in place.

No natural disaster has occurred in the area that has altered the effectiveness of the remedy.

Endangered species are not impacted by OU 3 groundwater, because groundwater does not reach the surface. However, protective measures continue to be taken during site construction activities to continue to ensure protectiveness of the endangered species.

5.9.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy was not reducing concentrations of COPCs at the predicted rates. Results of recent investigations suggest that continued loading to the groundwater is occurring in the vicinity of Building 646, which is limiting the effectiveness of the remedy. ICs remain in place and continue to ensure protection of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAO developed at the time of the ROD, based on risk and toxicity information are still valid.

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C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy. However, based on the results additional investigations and the limited effectiveness of natural attenuation remedy in meeting the RAO, the Air Force is pursuing a vadose zone remedy for the site.

5.9.5 OT-69 Issues

The Air Force has conducted an additional investigation at Site OT-69 and will pursue a new remedy for this site. Development of this remedy will address the associated issue of the potential indoor air quality exposure pathway.

5.9.6 OT-69 Recommendations

The following summarizes the recommendations to ensure remedy effectiveness in compliance with the RAOs for the Site OT-69.

1) Complete evaluation of 2005 investigation results (by 2006), issue a work plan with the appropriate vadose zone remedy to the regulatory agencies (by 2006), and complete construction to address the vadose zone source (by 2007); responsible party USAF. 2) Address potential indoor air quality pathway during evaluation of new vadose zone remedy for Site OT-69 (by 2006); responsible party USAF.

5.9.7 The OT-69 Protectiveness Statement

The remedy of natural attenuation is currently, and in the long term, protective of human health and the environment because there are no complete exposure pathways and institutional controls remain in place. The Air Force has performed an additional investigation at Site OT-69 and will pursue a new remedy for this site to ensure remedy effectiveness in compliance with the RAO. Land use restrictions and deed restrictions remain protective of human health and the environment.

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5.9.8 OT-69 Next Review

The next Five-Year Review will be conducted in 2010.

5.10 SITE WP-17

Site WP-17 is located along Phantom West Drive, near Buildings 551 and 552 in the central portion of the base, as shown on Figure 3-6. A site plan for Site WP-17 is included as Figure 5-10. The site is a former leachfield used to dispose waste petroleum, oil, and lubricants (POLs) generated from vehicle maintenance activities and a fuels laboratory. It was estimated that the leachfield operated from 1965 to 1986. Investigations were undertaken at the site by SAIC in 1986, JMM in 1987, and the USACE in 1990. In 1994, M&E performed a RI, which included a historical records review, soil borings, and a soil-gas survey.

5.10.1 WP-17 Remedial Actions

This section describes the remedy selection, implementation, O&M, and progress since the previous Five-Year Review at GAFB (Montgomery Watson, 2000).

5.10.1.1 Remedy Selection. The OU 3 ROD identified the following RAOs for Site WP-17 (Montgomery Watson, 1998).

Protection of Human Health

• Prevent human exposure to soil resulting in 1×10-4 to 1×10-6 excess cancer risk from all carcinogens. • Prevent human exposure to soil contaminants with non-carcinogens at concentrations in excess of reference doses.

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Protection of the Environment

• Reduce the toxicity, mobility, and volume of the contamination in unsaturated soil to reduce the potential for migration of contaminants to groundwater. • Remove, to the extent practical, the COPCs detected in unsaturated soils to meet or exceed the remediation goals defined in the OU 3 ROD.

Bioventing was the selected remedy for WP-17.

5.10.1.2 Remedy Implementation. A removal action has been implemented at Site WP-17. In an effort to accelerate the remedial progress, minimize present and future environmental risk, and facilitate timely transfer of property to the community, an accelerated action was performed at Site WP-17 before finalization of the OU 3 ROD. This accelerated action was performed with the concurrence of the BCT, including the USEPA, RWQCB and the Air Force.

The removal action at Site WP-17 included installing a bioventing system. The principle behind bioventing is to inject atmospheric air into the subsurface to provide oxygen to stimulate indigenous soil microorganisms that aerobically metabolize petroleum hydrocarbons in the vadose zone. The bioventing system at Site WP-17 consists of one bioventing well cluster (BV- 1) and associated monitoring points as shown on Figure 5-10.

ICs are in place at Site WP-17 and the land use remains the same as during the decision process. Site WP-17 is located with a fenced area, which effectively eliminates unauthorized access to the site. The land use restriction remains in place and is effective in prohibiting disturbance of the soil at Site WP-17 and prohibiting the installation of wells other than for monitoring. At present, there is no foreseeable change in land use at this site.

5.10.1.3 Operation and Maintenance. During the time of operation of the biovent remedial system (February 1996 to December 2004), O&M at Site WP-17 included weekly monitoring of the remedial system and collection of laboratory samples. Weekly monitoring included checking that the blower was operating within its intended range of flow rate, and

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pressure and temperature readings. The air filter was cleaned or replaced as necessary. Weekly system monitoring logs are completed and reported in the OU 3 Semiannual Reports. Routine soil vapor sampling was performed using 6-liter Summa® canisters provided by the analytical laboratory.

5.10.1.4 Progress Since Last Five-Year Review. The previous Five-Year Review found the remedy at landfill WP-17 protective of human health and the environment.

Following two years of bioventing operation at Site WP-17, from February 1996 to May 1998, the system was briefly shutdown for rebound testing and confirmation soil sampling. Analytical results collected during operation showed a general decrease in TVPH concentrations to asymptotic levels. Respiration testing conducted during operation showed significant oxygen utilization in some areas; however, oxygen levels remained above 10 percent, which would indicate that the site is not oxygen-limited. With the concurrence of the BCT, operation of the bioventing system was suspended at Site WP-17 pending confirmation sampling results. The system was re-started in late 1998. Confirmation sampling was conducted in April 2000.

The system continued to operate until December 2004. Based on the results of the confirmation sampling and a qualitative risk analysis, the Air Force elected to pursue site closure for Site WP-17 and shut the system down in December 2004.

5.10.2 WP-17 Five-Year Review Process

This former GAFB Five-Year Review was directed by Mr. Phillip Mook, AFRPA, Regional BRAC Environmental Coordinator. The following team members performed the review:

• Mr. Kurt Condie, P.E., MWH • Mr. John Scott, P.G., MWH • Mr. Gilbert Dimidjian, MWH • Mr. Chris Glenn, P.E., MWH • Mr. Mark Bowland, R.E.A., MWH

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• Mr. Ken Kiefer, MWH • Ms. Sandra Ross, P.G., MWH

The schedule for the Five-Year Review process is as follows:

1) Implement Review Process and Prepare Report - March 2005 and April 2005 2) Submit Preliminary Draft for USAF Review – 10 May 2005 3) Receive USAF Comment – 2 June 2005 4) Incorporate Comment and submit Draft to USAF and Regulatory Agencies – 22 July 2005 5) Receive comments on Draft Document – 22 September 2005 6) Incorporate Draft Comments and Submit Final Document for Signature – 30 September 2005 7) Signatures – 30 October 2005 through 16 January 2006

5.10.3 WP-17 Five-Year Review Findings

This section presents the findings of the Five-year Review for Site WP-17. A review of the relevant documents was conducted and included the Annual Basewide Groundwater Monitoring Reports and the OU 3 ROD (Document List, Appendix A).

5.10.3.1 Interviews. The following individuals were contracted by MWH as part of the five-year review process. Interview records are included in Appendix B.

• Community members • Local Authorities

Ms. Loux, a former Apple Valley City Council Member, stated that she understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

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Mr. Bob Field, a Victor Valley Water District employee, stated that he is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

Mr. Robert Mall, a M&M Environmental employee who performs environmental remediation activities at the base, is aware that there is contamination at the George AFB, and that jet fuel and TCE have leaked in to the lower and upper aquifer. He did not express concerns about any of the landfills.

5.10.3.2 Site Inspections. Site visits for O&M of the bioventing system at Site WP-17 have been conducted regularly while the system was operating. During site visits, the bioventing system was inspected and maintained, and field measurement or sampling was conducted. Site visits have not been regularly conducted since 2004, when the bioventing system was shut down pending site closure at Site WP-17. The last site visit was conducted in December 2004.

5.10.3.3 Risk Information Review. This section presents an update of the site specific risk information and an ARAR analysis, and provides an analysis of any changes that could affect protectiveness as presented in the OU 3 ROD (Montgomery Watson, 1998).

The OU 3 ROD included a baseline human health risk assessment for Site WP-17. The baseline risk assessment resulted in an estimated cancer risk of 9.7x10-7, driven by naturally occurring chromium in soil. This risk value is less than both the California benchmark and the USEPA guidelines. Vadose zone modeling performed in support of the OU 3 ROD indicated that under even the most conservative conditions, the most mobile constituents would not migrate deeper than 20 feet within 100 years. Therefore, it was concluded that Site WP-17 does not pose a threat to groundwater. The baseline risk assessment has not been recalculated because a remediation system has been in place, there are no complete exposure pathways, and there are no plans for residential use.

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The results of an ecological risk assessment at Site WP-17 indicated that the compounds of concern at this site are not of potential ecological concern.

A list of ARARs for Site WP-17 is provided in Table 15 of the OU 3 ROD (Montgomery Watts, 1998), which is also included in Appendix D. ARARs were established during the OU 3 ROD process through discussions between the Lahontan RWQCB, DTSC, USEPA and the USAF. Based upon this discussion, the selected remedial action at Site WP-17 is compliant with ARARs, including laboratory certification, well installation, groundwater protection, MCLs, air discharge requirements, stormwater discharge and hazardous waste disposals requirements.

A review of the ARARs for this Five-Year Review process indicates the OU 3 ROD ARARs remain up-to-date and relevant for Site WP-17. The methodology for estimating baseline human health risks and for establishing soil cleanup levels based on MCLs and vadose zone modeling remains valid.

An evaluation of risk to indoor air quality was not performed at Site WP-17 as part of the OU 3 ROD, and thus this evaluation was not included in development of the remedy or the remediation goals at this site. Since the OU 3 ROD, evaluation of indoor air quality risk has become a standard part of the site investigation process within CERCLA and this evaluation should be performed when a potential pathway exists. A qualitative risk assessment performed at Site WP-17, based upon the results of the progress soil sampling in 2000, indicate that indoor air quality risk to existing buildings is with the acceptable range. A more detailed description of this qualitative risk assessment is included in the Draft Final Site WP-17 Closure Report (Malcolm Pirnie, 2005).

The presence of emerging chemicals at Site WP-17 is an issue that was not evaluated in the OU 3 ROD because these chemicals were not known at that time. Previous land use at Site WP-17 as a POL disposal site would not lead to the presence of these emerging chemicals. It is Air Force policy that additional investigation for emerging chemicals will not be performed unless there were previous site activities suggesting the possibility for emerging chemicals. An evaluation of emerging chemicals at Site WP-17 is therefore, not required.

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5.10.3.4 Data Review. The site data review consisted of reviewing appropriate documents (see Appendix A). Although the bioventing system at Site WP-17 has not been operated since the previous Five-Year Review, previous data collection indicates that TVPH concentrations have dropped to asymptotic levels. A confirmation sampling event was performed at Site WP-17 in April 2000 and results are presented in the Final Confirmation Sampling Event Report, Sites WP-17 and FT-19a (MWH, 2001). Based upon the results of the confirmation sampling and a qualitative risk analysis, the Air Force has elected to pursue site closure for Site WP-17. Closure was proposed in the Draft Final Site WP-17 Closure Report (Malcolm Pirnie, 2005)

5.10.4 WP-17 Technical Assessment

In accordance with the USEPA Five-Year Review guidance document (USEPA, 2001), the technical assessment at Site WP-17 has been structured in terms of three questions.

Question A: Is the remedy functioning as intended by the decision documents?

An evaluation of how the remedy is functioning in relation to the decision documents is discussed in the following paragraphs by evaluation of the remedial action performance, system operation and maintenance, opportunities for optimization, early indicators of potential issues, and implementation of institutional controls and other measures.

Remedial Action Performance: The performance of the remedy for Site WP-17 has been evaluated against the RAO presented in the OU 3 ROD.

RAO - Prevent human exposure to soil resulting in 1×10-4 to 1×10-6 excess cancer risk from all carcinogens.

• ICs are in place at Site WP-17 and the land use remains the same as during the decision process.

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RAO – Prevent human exposure to soil contaminants with non-carcinogens at concentrations in excess of reference doses.

• ICs are in place at Site WP-17 and the land use remains the same as during the decision process.

RAO - Reduce the toxicity, mobility, and volume of the contamination in unsaturated soil to reduce the potential for migration of contaminants to groundwater.

• The selected remedy of bioventing operated at Site WP-17 from 1996 to 1998, and reduced the concentration of TVPH in the soil vapor to asymptotic levels.

RAO - Remove, to the extent practical, the COPCs detected in unsaturated soils to meet or exceed the remediation goals defined in the OU 3 ROD.

• The selected remedy of bioventing operated at Site WP-17 from 1996 to 1998, and reduced the concentration of TVPH in the soil vapor to asymptotic levels. The progress soil sampling event performed in 2000 showed that TVPH soil concentrations had decreased. Respiration testing at Site WP-17 indicated biological degradation occurred during operation of the bioventing system. A qualitative risk analysis, performed based upon the results of the progress soil sampling in 2000, indicates that Site WP-17 is ready for closure. The Air Force is pursuing site closure at Site WP-17.

System Operations/O&M: Prior to shutdown, the biovent system was operating as designed. System O&M at Site WP-17 was performed during weekly site visits from 1996 to 2004. The O&M procedures follow those prescribed in the Bioventing and Soil Vapor Extraction O&M Manual (Montgomery Watson, 1996b).

Cost of System O&M: O&M costs are not applicable as the site is in the process of being closed.

Opportunities for Optimization: The bioventing system is currently not operating at Site WP-17 because the Air Force is pursuing site closure. Therefore, optimization efforts are not applicable.

Early Indicators of Potential Remedy Failure: The remedy appears to have been effective at Site WP-17, and the Air Force is currently pursuing site closure.

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Implementation of ICs and Other Measures: ICs are in place at Site WP-17, and the land use remains the same as during the decision process. Site WP-17 is located within a fenced area, which effectively eliminates unauthorized access to the site. The land use restriction remains in place and is effective in prohibiting disturbance of the soil at Site WP-17 and prohibiting the installation of wells other than for monitoring. At present, there is no foreseeable change in land use at this site.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and RAOs used at the time of remedy selection still valid?

The following sections summarize the review of exposure assumptions, toxicity data, cleanup levels, and remedial action objective for the remedy.

Changes in Standards and Standards TBC: A review of the ARARs used to develop the remedy for Site WP-17 (Section 5.9.3.3) do not indicate a change in standards from the previous Five-Year Review.

Changes in Cleanup Levels: The cleanup levels, as presented in the OU 3 ROD (Montgomery Watson, 1998), were reviewed and were determined to be applicable.

Changes in Exposure Pathways: There have been no changes in the site condition or land use that would affect the exposure pathways since the previous Five-Year Review. A qualitative risk assessment performed at Site WP-17, based upon the results of the progress soil sampling in 2000, indicate that indoor air quality risk to existing buildings is within the acceptable range.

Changes in Land Use: There have been no changes in land use, and there are no anticipated changes in land use.

New Contaminants or Contaminant Sources: No new source areas have been identified.

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Changes in Toxicity and Other Contaminant Characteristics: There have been no changes in toxicity or other contaminant characteristics that would affect the protectiveness of the remedy at Site WP-17. Although an investigation for emerging chemicals has not been performed at Site WP-17, no investigation is required because activities that might lead to the presence of emerging chemicals at this site were not performed. No chemical byproducts have been created from the remedy.

Changes in Risk Assessment Methodology: There have been no changes in the risk assessment methodology for the COPCs present at Site WP-17 since the previous Five-Year Review. A qualitative risk assessment was performed based upon the results of the progress soil sampling in 2000, which indicates that the site is ready for closure.

Expected Progress towards Meeting the RAOs: The RAOs are currently being met.

Question C: Has any other information come to light that would call into question the protectiveness of the remedy?

Monitoring of the remedial system at Site WP-17 and confirmation soil sampling indicate that soil and soil vapor concentrations of TVPH and BTEX have declined as a result of the remedy. The Air Force is pursuing site closure at Site WP-17. Unauthorized access to the site is restricted by the security fencing. The land use restriction that prohibits disturbance of the soil or installation of wells other than monitoring wells at Site WP-17 remains effective.

No natural disasters have occurred in the area that altered the effectiveness of the remedy.

New or Previously Unidentified Ecological Risks: No new or previously identified ecological risks have been identified.

5.10.4.1 Technical Assessment Summary. The site data were reviewed in the context of the three questions and is summarized as follows:

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A) Is the remedy functioning as intended by the decision documents? Review of the site information indicates that the remedy is operating as effectively as predicted and is protective of human health and the environment.

B) Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time of the remedy still valid? Review of current information indicates that the RAOs developed at the time of the ROD, based on risk and toxicity information are still valid.

C) Has any other information come to light that would call into question the protectiveness of the remedy? There are no current issues affecting the protectiveness of the remedy.

5.10.5 WP-17 Issues

No deficiencies were identified for Site WP-17 during the Five-Year Review. No changes to the routine monitoring program were necessary prior to the biovent system shut down in 2004.

5.10.6 WP-17 Recommendations and Follow-Up Actions

The following is recommended to ensure remedy effectiveness in compliance with the RAOs for Site WP-17.

1) Continue to pursue closure of Site WP-17 (anticipate closure in 2005), responsible party USAF.

5.10.7 WP-17 Protectiveness Statement

The remedy at Site WP-17 is currently, and in the long term, protective of human health and the environment. The remedy has reduced the mobility and volume of the COPCs at this site and has reduced the potential for migration of the COPCs to groundwater. Access restrictions and land use restrictions at Site WP-17 remain protective of human health.

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5.10.8 WP-17 Next Review

The next Five-Year Review will be conducted in 2010.

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REFERENCES

Department of Toxic Substances Control (DTSC), 2003. Memo from Patty W. Wong-Yim, Ph.D, Staff Toxicologist, Human and Ecological Risk Division: Trichloroethylene Toxicity Criteria for Use at California Military Sites. 19 February.

DTSC, 2004. Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air. California. December.

HydroGeoLogic, 1998. Final Basewide Sampling and Analysis Plan, George Air Force Base. August.

International Technology Corporation (IT), 1999. Draft Feasibility Study Report, Operable Unit 2, George Air Force Base. San Bernardino, California. January.

James M. Montgomery Consulting Engineers Inc. (JMM), 1992. Remedial Investigation, Operable Unit 1, George Air Force Base. Walnut Creek, California.

Malcolm Pirnie, 2005. Final Site WP-17 Closure Report, George Air Force Base, California. Emeryville, California. April.

Mojave Basin Watermaster, 2005. Eleventh Annual Report of the Mojave Basin Area Watermaster, Water Year 2003-04. 1 April.

Mojave Water Agency (MWA), 2004. 2004 Regional Water Management Plan. September.

Montgomery Watson, 1994. Operable Unit 1 Record of Decision, George Air Force Base. Walnut Creek, California. March.

Montgomery Watson, 1996a. Final Remedial Investigation Report, Operable Unit 3, George Air Force Base, California. Walnut Creek, California. April.

Montgomery Watson, 1996b. Bioventing and Soil Vapor Extraction Operations and Maintenance Manual, George Air Force Base, California. Walnut Creek, California. February.

Montgomery Watson, 1998. Final Operable Unit 3 Record of Decision, George Air Force Base, California. Walnut Creek, California. November.

Montgomery Watson, 1999. Operation and Maintenance Manual, OU 1 Groundwater Extraction/Treatment System, George Air Force Base, California. April.

Montgomery Watson, 2000. Draft Five-Year Review for Operable Units 1, 2, and 3 at George Air Force Base, California. October.

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REFERENCES (continued)

Montgomery Watson, 2003. Final Long-Term Maintenance and Monitoring Plan, George Air Force Base, California. Walnut Creek, California. January.

MWH 2001. Final Confirmation Sampling Event Report, Sites WP-17 and FT-19a, George Air Force Base, California. Walnut Creek, California. September.

MWH, 2003a. Proposed Approach to Post-Closure Landfill Groundwater Monitoring at OU-3 Landfills Technical Memorandum, George Air Force Base, California. March.

MWH, 2003b. Final Sampling and Analysis Plan Addendum for Basewide Groundwater Monitoring Events, George Air Force Base, California. Walnut Creek, California. May.

MWH, 2004a. Final Operable Unit 3 Site FT-19 Closure Work Plan, George Air Force Base, California. Walnut Creek, California. February.

MWH, 2004b. 2002 Annual Basewide Groundwater Monitoring Report, George Air Force Base, California. Walnut Creek, California. June.

MWH, 2004c. Semiannual Report for O&M at OU-3 Sites, George Air Force Base, California. Walnut Creek, California. October.

MWH, 2005a. Final Data Gaps Well Installation Report, Operable Unit 1, George Air Force Base. March.

MWH, 2005b. Final Hydrogeologic Conceptual Site Model, George Air Force Base, California. Sacramento, California. May.

Regional Water Quality Control Board (RWQCB), 2003. Memo from Stephen Hill, Toxics Cleanup Division: Status of Cancer Slope Factors for Trichloroethylene. San Francisco Region, 3 March.

Science Application International Corporation (SAIC), 1987. Installation Restoration Program Phase II – Confirmation/Quantification Stage 2, George Air Force Base California. January.

United States Air Force (USAF), 1989. Closure of George Air Force Base, San Bernardino County, California, Draft Environmental Impact Statement. December.

United States (U. S.) Census Bureau, 2000. http://quickfacts.census.gov.

United States Environmental Protection Agency (USEPA), 2001. Comprehensive Five-Year Review Guidance. June.

F:\Projects-Completed\AFCEE Files\GEORGE\2005_12-30_GAFB R-2 2nd 5-Yr Review Rpt_Final\Text\Ref.doc Barstow Kern Co. Kern San Bernardino Co.

395 r e iv R ve ja Mo 15

Los Angeles Co. Silver Lakes

San Bernardino Co. W O Helendale D A H SHADOWS

MOUNTAINSM 247 O STODDS T U O D N DAARD RIDGE T George R A D Air Force SILVERS I LV E R R I I N D G S Base MTNM T N E (Southern California Logistics Airport) SPARKHULES PA R K H U L E SIDEWINDERS I D El Mirage Lake MTNM T N E W QUARTZITEQ U A R T Z I T E I N BELL D MTNM T N E MTN R Oro Grande FAIRVIEWFA I RV I E W Adelanto Air Expressway MTNM T N

S N 395 T M Victorville Apple Valley Palmdale Rd. 18 E 18 T I N A C R al ifo GRANITEG MTNS rn ia A qu ed uct 18 Hesperia Lucerne Valley

138

15 SSANA N GABRIELG A B R I E L SSANA N MOUNTAINSM O U N TA I N S BERNARDINOB E R N A R D I N O MOUNTAINSM O U N TA I N S

Silverwood Lake LakeLake ArrowheadArrowhead

Sacramento Stockton San Francisco 0 2.5 5 San Jose Fresno SCALE IN MILES

215 Bakersfield 15 George AFB (Southern California Logistics Airport) Santa Barbara
San Bernardino GEORGE AIR FORCE BASE Los Angeles Long Beach SAN BERNARDINO COUNTY, CALIFORNIA San Diego VICINITY MAP FIGURE 3-1 Source: The Thomas Guide, 1992 04-05

TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 1 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References Groundwater Extraction and Treatment system installed in December 1991, CG-70 Trichlorothene (TCE) Groundwater Plume 1 Not Required Ongoing RA OU 1 ROD expanded in Fall 1996. Site is evaluated in this 5-Yr Review. Perforated piping along tarmac was replaced in Summer 1991. No further SD-25 Industrial/Storm Drain and Fallout Ditch 1 Completed Not Required NFA OU 1 ROD action recommended in OU 1 ROD. Site is not evalauted in this 5-Year Review. Various investigations conducted. No Base Sewage Treatment Plant (STP) Percolation further action recommended in OU 1 WP-26 1 Not Required Not Required NFA OU 1 ROD Ponds ROD. Site is not evalauted in this 5- Year Review. Created in Summer 1993 and SVE installed in Summer 2004. No ROD in AOC 32 Monitoring Well MW-32 Area 2 Ongoing Ongoing IRA NA place. Site is not evalauted in this 5- Year Review. USTs removed in May 2003. No ROD Facility 749 Underground Storage Tank Site Additional AOC 79 2 Ongoing Ongoing NA in place. Site is not evalauted in this 5- Investigation Investigation Year Review. Additional investigations and removal of Additional fuel lines currently in progress. No ROD AOC 81 Railroad Fueling System 2 Ongoing Not Required NA Investigation in place. Site is not evalauted in this 5- Year Review. Free-product recovery initiated in June 1992 and over 200,000 gallons SS-30 Jet Fuel (JP-4) Groundwater Plume 2 Not Required Ongoing IRA NA recovered. No ROD in place. Site is not evaluated in this 5-Yr Review. Started SVE in February 2002 and system shutdown in November 2003. SS-58 Facility 690 Tank Farm Leak 2 Ongoing Not Required IRA NA No ROD in place. Site is not evaluated in this 5-Yr Review. SVE in March 2002. No ROD in place. ST-54 Facility 708 JP-4 Tank Farm Leak 2 Ongoing Not Required IRA NA Site is not evaluated in this 5-Yr Review. TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 2 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References Started SVE in June 2002. No ROD in ST-57 JP-4 Fuel Leak at Fuel Pit #1 2 Ongoing Not Required IRA NA place. Site is not evaluated in this 5-Yr Review. System removed in Summer 1993. No ST-67a* JP-4 Liquid Fuels Distribution System (LFDS) 2 Completed Not Required NFA NA ROD in place. Site is not evaluated in this 5-Yr Review. Investigation conducted in summer 2004. ST-67b* JP-4 AST/Bulk Fuel Yard 2 Pending Pending SI NA No ROD in place. Site is not evaluated in this 5-Yr Review. No further action recommended in OU 3 DP-01 Paint Drum Burial 3 Not Required Not Required NFA OU 3 ROD ROD. Site is not evalauted in this 5- Year Review. 18-inch soil cover rehabilitation, surface controls and site is associated with Site DP-02 Pesticide and Paint Burial 3 Completed Not Required NFA OU 3 ROD LF-14. No further action recommended in OU 3 ROD. Site is not evaluated in this 5-Year Review. Two foot soil cover rehabilitation, surface controls and site is associated DP-03 Acid and Oil Burial 3 Completed Ongoing LTMM OU 3 ROD with Site LF-45. Site is evaluated in this 5-Yr Review. Two foot soil cover rehabilitation, OU 3 ROD surface controls and site is associated DP-04 Pesticide and Oil Burial 3 Completed Ongoing LTMM with Site LF-43. Site is discussed in this 5-Yr Review. 18-inch soil cover rehabilitation, surface OU 3 ROD DP-10 Landfill-Cartridges (SEDA) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA.

18-inch soil cover rehabilitation, surface OU 3 ROD DP-15 Munitions/Oil (SEDA) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA. Petroleum, Oils, and Lubricants (POL) Leach DP-16 3 Not Required Not Required NFA NA No futher action. Field TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 3 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References 18-inch soil cover rehabilitation, surface OU 3 ROD DP-33 Munitions Burial (SEDA) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA.

18-inch soil cover rehabilitation, surface OU 3 ROD DP-34 Munitions Burial (SEDA) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA. No further action recommended in OU 3 OU 3 ROD DP-46 F-111 Aircraft Burial 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. No further action recommended in OU 3 OU 3 ROD DP-47 Aircraft Parts Burial 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. No further action recommended in OU 3 OU 3 ROD DP-60 Sewage Sludge Disposal Area 3 Not Required Nor Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. OU 3 ROD Bioventing since April 1996. Site is FT-19a* Fire Training Area 3 Ongoing Not Required RA discussed in this 5-Yr Review. Medical wastes excavated in Summer FT-19b* Fire Training Area/Medical Waste Disposal 3 Completed Not Required NFA OU 3 ROD 1996. No further action recommended in OU 3 ROD Site is not evalauted in SVE from March 1996 to May 2001. OU 3 ROD FT-19c* Fire Training Area 3 Ongoing Ongoing RA Bioventing since November 2004. Site is discussed in this 5-Yr Review. Site located under High Desert Power OU 3 ROD Plant. No further action recommended in FT-20 Oil Fire Training Area 3 Not Required Not Required NFA OU 3 ROD. Site is not evalauted in this 5-Year Review. 18-inch soil cover rehabilitation, surface OU 3 ROD LF-07 Base Landfill (Southeast Disposal Area [SEDA]) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA 18-inch soil cover rehabilitation, surface OU 3 ROD LF-08 Tetraethyl Lead Disposal (SEDA) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA. TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 4 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References No further action recommended in OU 3 OU 3 ROD LF-11 Landfill-Paper Disposal 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. 18-inch soil cover rehabilitation and OU 3 ROD LF-12 Street Sweeping Disposal Site 3 Completed Ongoing LTMM surface controls. Site is discussed in this 5-Yr Review. No further action recommended in OU 3 OU 3 ROD LF-13 Original Base Landfill 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. 18-inch soil cover rehabilitation and OU 3 ROD LF-14 Base Landfill 3 Completed Ongoing LTMM surface controls. Site is discussed in this 5-Yr Review. Explanation Of Significant Difference was signed in October 2003 which OU 3 ROD abolished the Land Use LF-35 Wood/ Debris Disposal 3 Not Required Not Required NFA Covenant/Institutional Control (LUC/IC) that was in place. Site is not evalauted in this 5-Year Review. No further action recommended in OU 3 OU 3 ROD LF-36 Construction Debris/ Borrow Pit 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD LF-37 Landfill 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. No further action recommended in OU 3 OU 3 ROD LF-38 Trash Disposal 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. No further action recommended in OU 3 OU 3 ROD LF-39 Construction Debris/Trash 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. No further action recommended in OU 3 OU 3 ROD LF-43 Construction Rubble Disposal 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. OU 3 ROD LUC/IC Implemented. Site is evaluated LF-44 Miscellaneous Trash/Rubble Disposal 3 Completed Not Required NFA in this 5-Yr Review. TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 5 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References No further action recommended in OU 3 OU 3 ROD LF-45 Construction Demolition 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. Never Investigated Because Effluent Discharge Came From Site WP-26. No OU 3 ROD OT-22 Golf Courses 3 Not Required Not Required NFA further action recommended in OU 3 ROD. Site is not evalauted in this 5- Year Review. DRMO Salvage Yard, RCRA Closure in OU 3 ROD June 1994. No further action OT-48 Salvage Yard 3 Closed Not Required NFA recommended in OU 3 ROD. Site is not evalauted in this 5-Year Review. No further action recommended in OU 3 OU 3 ROD OT-49 Ten Aircraft Crash Burial Sites 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD OT-50 Firing-In Butt 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. SVE for soil and Natural Attenuation for OU 3 ROD OT-51 Facility 799 (Test Cell) Fuel Spill 3 Ongoing Ongoing RA groundwater. Site is evaluated in this 5- Yr Review. No further action recommended in OU 3 OU 3 ROD OT-61 Shop Waste Disposal Area 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD OT-62 Rinse Waste Disposal Area 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD OT-64 Leaking Transformer Sites 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD OT-65 Nine Outlying Revetments 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. No further action recommended in OU 3 Nonpoint Source Discharge from Base OU 3 ROD OT-66 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Residential Area Year Review. TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 6 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References TCE/PCE plumes commingling with OU- Three TCE and One PCE (Tetrachloroethene) Additional OT-69 3 Not Required Ongoing OU 3 ROD 2, SS-30. Site is evaluated in this 5-Yr Plumes Investigation Review. Site characterization/removal in 1994 OU 3 ROD and site known as SEDA. No further RW-09 Radioactive Disposal Site (SEDA) 3 Completed Not Required NFA action recommended in OU 3 ROD. Will be discussed as part of the SEDA. No further action recommended in OU 3 OU 3 ROD SD-18 Fuel and Oil Disposal 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 Abandoned Drain Pit/Dry Well for POL OU 3 ROD SD-27 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Disposal OU 3 RI Year Review. Site Location Undocumented. No OU 3 ROD further action recommended in OU 3 SD-28 Abandoned Drain Pit/Dry Well for Jet Fuel 3 Not Required Not Required NFA OU 3 RI ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD SD-41 Rip-Rap for Industrial Drain Discharge 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD SD-42 Rip-Rap for Off Base Water Supply Well Area 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD SS-21 Wing-Tip Fuel Tank Drainage Area 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. DRMO Hazardous Waste Storage Yard, OU 3 ROD RCRA Closure in June 1994. No further SS-23 Salvage Yard/ Hazardous Waste Storage Area 3 Closed Not Required NFA OU 3 RI action recommended in OU 3 ROD. Site is not evalauted in this 5-Year Review. No further action recommended in OU 3 OU 3 ROD SS-24 Facility 580 Unserviced Transformer Storage 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 7 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References 18-inch soil cover rehabilitation, surface OU 3 ROD SS-52 Creosote Spill Area (SEDA) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA. No further action recommended in OU 3 OU 3 ROD SS-53 Jet Fuel Spill 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD SS-55 Fuel Spill Collection Point 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. No further action recommended in OU 3 OU 3 ROD SS-59 Facility 819 (Test Cell) Fuel Spill 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 RI ST-56 Facility 549 Pipeline Leak 3 Not Required Not Required NFA RI/ROD. Site is not evalauted in this 5- OU 3 ROD Year Review. OU 3 ROD Bioventing from March 1996. Site is WP-17 Fuels Laboratory Leach Field 3 Completed Not Required RA discussed in this 5-Yr Review. Base (Old) Sewage Treatment Plant. No OU 3 ROD further action recommended in OU 3 WP-29 Sludge Drying Beds 3 Not Required Not required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 Leach Field For Sanitary and Aircraft OU 3 ROD WP-32 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Maintenance Waste OU 3 RI Year Review. 18-inch soil cover rehabilitation, surface OU 3 ROD WP-40 Chemical Toilet Sludge (SEDA) 3 Completed Ongoing LTMM controls and site known as SEDA. Will be discussed as part of the SEDA. No further action recommended in OU 3 OU 3 ROD WP-63 Sewage Sludge Disposal Areas 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- Year Review. No further action recommended in OU 3 OU 3 ROD WP-68 Facility 694 Paint Disposal Pit 3 Not Required Not Required NFA ROD. Site is not evalauted in this 5- OU 3 RI Year Review. TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 8 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References Located throughout housing. No ROD Pesticide (Dieldrin) Contaminated Soil and Additional AOC 71 4 Ongoing Ongoing NA in place. Site is not evalauted in this 5- Groundwater Areas Investigation Year Review. Removal action completed in April 2002. AOC 72 Current Skeet Range 4 Completed Not Required RAC NA No ROD in place. Site is not evalauted in this 5-Year Review. Removal action completed in September AOC 73 Second Skeet Range 4 Completed Not Required RAC NA 2003. No ROD in place. Site is not evalauted in this 5-Year Review.

Removal action completed in September AOC 74 Original Skeet Range 4 Completed Not Required RAC NA 2003. No ROD in place. Site is not evalauted in this 5-Year Review. Removal action completed in February AOC 75 Facility 615 Indoor Shooting Range 4 Completed Not Required RAC NA 1999. No ROD in place. Site is not evalauted in this 5-Year Review. Site investigated during OU 3 RI. No AOC 76 Dozer Scar Site 4 Not Required Not Required NFA NA ROD in place. Site is not evalauted in this 5-Year Review. Site investigated during OU 3 RI. No AOC 77 Disturbed Area 4 Not Required Not Required NFA NA ROD in place. Site is not evalauted in this 5-Year Review. Completion of Ordnance and Explosive (OE) Removal Work letter dated 13 April 1998 from United States Army Explosive Ordnance Disposal (EOD) Training Additional Corps of Engineers, Huntsville District AOC 78 4 Ongoing Not Required NA Area Investigation and soil sampling investigation completed in 2004/2005. No ROD in place. Site is not evalauted in this 5- Year Review. Investigation scheduled for 2005. No Additional AOC 80 Building 513 Chlordane Mixing Area 4 Ongoing Not Required NA ROD in place. Site is not evalauted in Investigation this 5-Year Review. UST Part of the UST program. Site is not ST-31 Underground Storage Tanks Ongoing Not Required NFA OU 3 RI Program evaluated in this 5-Year Review. TABLE ES-1

SUMMARY OF COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT SITES FORMER GEORGE AIR FORCE BASE, CALIFORNIA (Page 9 of 9) Operable Soil Cleanup Groundwater Current Supporting IRP Site Site Description Actions/Current Status Unit Status Cleanup Status Status References

NOTES: * - IRP sites FT-19a, FT-19b, FT-19c, ST-67a, and ST-67b are counted as individual IRP Sites

AOC - Area of Concern OE - Ordnance and Explosives DRMO - Defense Reutilization and Marketing Office PCE - Tetrachloroethene EOD - Explosive Ordnance Disposal POL - Petroleum, Oils, and Lubricants IRA - Interim Remedial Action RA - Remedial Action IRP - Installation Restoration Program RAC - Remedial Action Completed JP-4 - Jet Fuel Number 4 RI - Remedial Investigation LFDS - Liquid Fuels Distribution System SEDA - Southeast Disposal Area which contains nine IRP Sites LTMM - long-term monitoring and maintenance SI - Site Investigation LUC/LC - Land Use Covenant/Institutional Control STP - Sewage Treatment Plant NFA - No Further Action (Closed and Transferable) SVE - Soil Vapor Extraction NA - Not Applicable TCE - Trichloroethene

References: OU 1 ROD - Montgomery Watson, 1994. Operable Unit 1 Record of Decision, George Air Force Base. Walnut Creek, California. March. OU 3 RI - Montgomery Watson, 1996a. Final Remedial Investigation Report, Operable Unit 3, George Air Force Base, California. Walnut Creek, California. April 1996. OU 3 ROD - Montgomery Watson, 1998. Final Operable Unit 3 Record of Decision, George Air Force Base, California. Walnut Creek, California. November 1998. TABLE 2-1

OU 1 CHRONOLOGY OF SITE EVENTS FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 1 of 2)

Event Date

Initial Environmental Cleanup Program 1981 IRP received and first implemented 1982 IRP Phase I Records Search 1982 IRP Phase II Investigation 1985, 1987 RWQCB issued Cleanup and Abatement Order 1986 Supplemental Site Characterization 1987 Phase III and IV IRP Investigations 1988 - 1990 NPL listing 1990 Federal Facility Agreement Signature 1990 Phase I, Treatability Study 1991 Removal Activities, Industrial Storm Drain 1989 - 1991 George Air Force Base closed 1992 RI/FS complete 1993 ROD signature 1994 Pre-Design Study and Design-Basis 1995 Phase II, Construction 1995 - 1996 Begin pumping from new (Phase II) wells 1996 Construction completed 1996 Shutdown of Lower Aquifer Extraction Wells (EW-6, EW-14 through EW-17) 1999 Converted well NZ-55 to an extraction well 2001 Drilled 25 data gap wells 2000 - 2003 Published the Former GAFB Geologic Conceptual Site Model 2002 Shutdown of OU-1 Groundwater Extraction/Treatment System 2003 Converted monitoring wells NZ-40, NZ-82, and NZ-83 to groundwater June-04 extraction wells Published the Former GAFB Draft Hyrdrogeolgic Conceptual Site Model September-04 TABLE 2-1

OU 1 CHRONOLOGY OF SITE EVENTS FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 2 of 2)

Event Date

Conducted Site CG-70/NEDA Source Area Investigation 2004 - 2005 Published the Former GAFB Final Hyrdrogeolgic Conceptual Site Model May-05

Initiated groundwater modeling to optimize the OU-1 remedy 2005

Notes: CAO - Cleanup and abatement Order FS - feasibility study GAFB - George Air Force Base IRP - Installation Restoration Program NEDA - Northeast Disposal Area NPL - National Priorities List OU - Operable Unit RI - remedial investigation ROD - Record of Decision RWQCB - Regional Water Quality Control Board TABLE 2-2

OU 3 CHRONOLOGY OF SITE EVENTS FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 1 of 2)

Event Date

Initial Environmental Cleanup Program 1981

IRP received and first implemented 1982

IRP Phase I Records Search 1982

IRP Phase II Investigation 1985, 1987, & 1988

NPL listing 1990

Federal Facility Agreement Signed 1990

George Air Force Base closed 1992

Work Plan Addendum issued 1992

Phase I Remedial Investigation 1994

Engineering Evaluation/Cost Analysis (EE/CA) 1994

Phase II Remedial Investigation 1996

Accelerated remedial action implemented at Site FT-19 (Bioventing and SVE) 1996

Accelerated remedial action implemented at Site OT-51 (Bioventing) 1996

Accelerated remedial actions implemented at OU 3 Landfills (Soil Cover) 1996-1997

Accelerated remedial action implemented at Site OT-69 (Natural Attenuation) 1996

Accelerated remedial action implemented at Site WP-17 (Bioventing) 1996

Feasibility Study 1997

ROD signature 1998

Site WP-17 Bioventing Discontinued Pending Site Closure 1998

SVE System Installed at Site OT-51 2000

Final ESD Issued to Change Remedial Action at Site OT-51 to SVE 2002

Expansion of SVE System at Site OT-51 2002 TABLE 2-2

OU 3 CHRONOLOGY OF SITE EVENTS FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 2 of 2)

Event Date

Remedial Action at Site FT-19c Changed to Bioventing 2004

Air Force Elects to Perform Additional Investigation at Site OT-69 2004-2005 Notes: ESD - Explanation of significant difference IRP - Installation Restoration Program NPL - National Priorities List OU - Operable Unit ROD - Record of Decision SVE - soil vapor extraction TABLE 4-1

MAXIMUM CONCENTRATIONS OF VOLATILE ORGANIC COMPOUNDS, 1994 FORMER GEORGE AIR FORCE BASE, CALIFORNIA TABLE 4-2

HISTORICAL PERFORMANCE DATA OU-1 GROUNDWATER EXTRACTION/TREATMENT SYSTEM FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 1 of 3)

Approximate Cumulative Influent Effluent Incremental Cumulative Average Groundwater Volume of Water TCE TCE TCE TCE Flowrate Extracted Treated ConcentrationConcentration Removed Removed Date a (gpm) (gallons X 1,000) (gallons X 1,000)b (µg/L) (µg/L) (pounds) (pounds) Comments

12/3/1991 185 NA 266 21 <0.50 NA 0.05 System startup on December 2, 1991. 1/2/1992 191 8,409 8,675 31 <0.50 2.2 2 2/6/1992 185 8,121 16,796 25 <0.50 1.7 4 3/5/1992 186 8,151 24,947 35 <0.50 2.4 6 4/2/1992 151 6,626 31,573 33 <0.50 1.8 8 5/13/1992 115 5,040 36,613 30 <0.50 1.3 9 System shut down for replacement of air strippers. 1/5/1993 NA NA 71,101 33 19 4.0 13 System restart in July 1992. Limited data available 2/3/1993 113 4,981 76,082 17 <0.50 0.7 14 3/4/1993 77 3,393 79,475 19 <0.50 0.5 14 4/2/93c 167 7,317 86,792 18 <0.50 1.1 15 5/4/1993 171 7,504 94,296 16 <0.50 1.0 16 6/1/1993 141 6,175 100,471 19 <0.50 1.0 17 8/23/1993 NAd 5,601 106,072 3 <0.50 0.1 17 9/7/1993 28 1,226 107,298 2 <0.50 0.02 17 9/28/1993 67 2,924 110,222 14 <0.50 0.3 18 11/9/1993 91 3,997 114,219 15 <0.50 0.5 18 11/30/1993 108 4,725 118,944 12 <0.50 0.5 19 12/28/1993 138 6,046 124,990 14 <0.50 0.7 20 System shut down from 1/20 to 1/24 for effluent 1/6/1994 121 5,295 130,286 13 <0.50 0.6 20 pump repair. 2/24/1994 29 1,271 131,556 20 <0.50 0.2 20 3/4/1994 29 1,291 132,848 11 <0.50 0.1 20 Major repairs to pumps between 3/29 and 4/21. 4/21/1994 3 1,930 134,072 18 <0.50 0.3 21 5/5/1994 77 5,410 139,482 23 <0.50 1.0 22 6/2/1994 49 10,186 149,668 16 <0.50 1.4 23 7/14/1994 324 14,214e 163,883 20 <0.50 2.4 25 8/4/1994 155 6,818 170,700 39f <0.50 2.2 28 9/1/1994 199 8,741 179,441 13 <0.50 0.9 29 10/6/1994 119 5,242 184,683 27 <0.50 1.2 30 System shut down 9/8/94 to 9/29/94. 11/3/1994 211 9,268 193,951 24 <0.50 1.9 32 12/1/1994 228 9,994 203,945 28 <0.50 2.3 34 12/29/1994 198 8,688 212,633 28 <0.50 2.0 36 2/15/1995 182 12,560 225,193 33 <0.50 3.5 39 TABLE 4-2

HISTORICAL PERFORMANCE DATA OU-1 GROUNDWATER EXTRACTION/TREATMENT SYSTEM FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 2 of 3)

Approximate Cumulative Influent Effluent Incremental Cumulative Average Groundwater Volume of Water TCE TCE TCE TCE Flowrate Extracted Treated ConcentrationConcentration Removed Removed Date a (gpm) (gallons X 1,000) (gallons X 1,000)b (µg/L) (µg/L) (pounds) (pounds) Comments

3/15/1995 40 1,754 226,947 34 <0.50 0.5 40 3/29/95g 109 4,799 231,746 30 <0.50 1.2 41 4/26/1995 139 6,089 237,835 41 <0.50 2.1 43 5/31/1995 115 5,068 242,903 32 <0.50 1.4 45 6/21/1995 95 4,164 247,067 28 <0.50 1.0 46 7/19/1995 146 6,406 253,473 30 <0.50 1.6 47 8/9/1995 160 7,013 260,486 28 <0.50 1.6 49 9/27/95h 371 16,314 276,800 22 <0.50 3.0 52 10/11/1995 231 4,654 281,454 24 <0.50 0.9 53 10/25/1995 224 4,522 285,976 30 <0.50 1.1 54 12/27/95i 183 16,622 302,599 29 <0.50 4.0 58 1/10/1996 155 3,131 305,730 26 <0.50 0.7 59 3/26/1996 15 1,625 307,355 29 <0.50 0.4 59 6/26/96j 86 11,361 318,717 27 <0.50 2.6 62 9/25/96k 162 21,212 339,929 19 <0.50 3.4 65 10/18/96l 39 1,282 341,211 4.5 <0.50 0.05 65 Begin pumping from new, additional extraction we TCE removed revised 1st Quarter 1997 based on m 371 32,556 373,768 8.9 <0.50 2.4 67 12/18/96 revised flow data. 3/28/97n 223 32,140 405,908 12 <0.50 3.2 71 6/25/1997 420 60,497 466,405 10 <0.50 5.0 76 9/24/1997 620 81,191 547,596 14 <0.50 9.5 85 12/29/1997 630 81,782 629,378 17 <0.51 11.6 97 3/30/1998 316 41,391 670,769 16 <2.5 5.5 102 6/29/1998 398 52,197 722,966 13 <0.50 5.7 108 9/28/1998 505 66,157 789,123 10 <0.50 5.5 113 12/28/1998 537 70,411 859,534 6 <0.50 3.5 117 3/29/1999 580 76,186 935,720 8 <0.50 5.1 122 Lower Aquifer wells EW-6, EW-14, EW-15, EW-1 6/28/1999 722 94,660 1,030,380 8 <0.50 6.3 128 EW-17 shut down per RPM direction. 9/28/1999 240 31,826 1,062,206 14.5 <0.50 3.8 132 12/6/1999 282 34,103 1,096,309 14 <0.50 4.0 136 3/14/2000 289 40,735 1,137,044 10.1 <1.0 3.4 140 TABLE 4-2

HISTORICAL PERFORMANCE DATA OU-1 GROUNDWATER EXTRACTION/TREATMENT SYSTEM FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 3 of 3)

Approximate Cumulative Influent Effluent Incremental Cumulative Average Groundwater Volume of Water TCE TCE TCE TCE Flowrate Extracted Treated ConcentrationConcentration Removed Removed Date a (gpm) (gallons X 1,000) (gallons X 1,000)b (µg/L) (µg/L) (pounds) (pounds) Comments

5/16/2000 239 28,937 1,165,981 15.1 <1.1 3.6 143 8/16/2000 253 36,082 1,202,063 15.1 <1.0 4.5 148 12/22/2000 327 40,463 1,242,526 32.2 <1.0 10.9 159 3/14/2001 287 33,885 1,276,411 15.4 <1.0 4.4 163 6/29/2001 257 39,541 1,315,952 13.8 <0.5 4.5 168 9/27/2001 260 33,701 1,349,653 15.1 <0.5 4.2 172 12/28/2001 277 36,722 1,386,375 20.0 <0.5 6.1 178 Well NZ-55 online 12/27/01. 3/28/2002 285 36,975 1,423,350 35.2 <0.5 10.9 189 6/28/2002 284 37,612 1,460,962 49.5 <0.5 15.5 204 9/27/2002 245 32,155 1,493,117 41.8 <0.5 11.2 215 12/27/2002 292 38,313 1,531,430 32.2 <0.5 10.3 226 3/10/2003 307 32,222 1,563,652 22.5 <0.5 6.0 232

Notes: Example Calculation: a Date presented is the date of the last O&M visit of the quarter. Incremental TCE Removed (lb) = Influent TCE Concentration (mg/L) X Groundwater b Based on total metered flow minus the reading recorded at startup on 12/2/91. Extracted (gal) X 3.785 (L/gal) / 454 (g/lb) X 1,000,000 (mg/g) c Influent and effluent TCE concentrations from sampling event on 4/6/93. d System restart. g/lb - grams per pound e Includes data correction (+819,880 gallons). gal - gallons f Influent sampling port permanently installed upstream of influent wet well. gpm - gallons per minute g Estimated TCE concentrations based on analytical data from 3/15/95 sampling event. L/gal - liters per gallon h Estimated TCE concentrations based on analytical data from 9/13/95 sampling event. lb - pounds i Estimated TCE concentrations based on analytical data from 10/20/95 sampling event. mg/g - micrograms per gram j Estimated TCE concentrations based on analytical data from 5/14/96 sampling event. µg/L - micrograms per liter k Estimated TCE concentrations based on analytical data from 7/10/96 sampling event. mg/L - milligrams per liter l Estimated TCE concentrations based on analytical data from 10/18/96 sampling event. NA - not applicable or not available m Estimated TCE concentrations based on analytical data from 10/24/96 sampling event. O&M - operation and maintenance n Estimated TCE concentrations based on analytical data from 1/16/97 sampling event. OU - Operable Unit RPM - remedial project manager TCE - trichloroethene TABLE 4-3

HISTORICAL RESULTS OF EMERGENT CHEMICALS - 1,4-DIOXANE AND PERCHLORATE FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 1 of 3) Well ID Sample Date Compound Result Units Flag

FT-01 22-Oct-04 1,4-Dioxane <1 µg/L FT-01 22-Oct-04 Perchlorate <4 µg/L FT-02 22-Oct-04 1,4-Dioxane <1 µg/L FT-02 22-Oct-04 Perchlorate <4 µg/L FT-03 22-Oct-04 1,4-Dioxane <1 µg/L FT-04 22-Oct-04 1,4-Dioxane <1 µg/L FT-05 22-Oct-04 1,4-Dioxane <1 µg/L LW-1 15-Oct-04 1,4-Dioxane <1 µg/L LW-4 15-Oct-04 1,4-Dioxane <1 µg/L MW-48 22-Sep-03 1,4-Dioxane <1 µg/L MW-49 19-Sep-03 1,4-Dioxane <1 µg/L MW-59 19-Sep-03 1,4-Dioxane <1 µg/L MW-60 19-Sep-03 1,4-Dioxane <1 µg/L MW-90 03-Nov-04 Perchlorate <4 µg/L MW-102 26-Apr-04 1,4-Dioxane <1 µg/L MW-103 26-Apr-04 1,4-Dioxane <1 µg/L MW-104 26-Apr-04 1,4-Dioxane <1 µg/L MW-105 28-Oct-04 1,4-Dioxane <1 µg/L MW-106 29-Oct-04 1,4-Dioxane <1 µg/L MW-107 18-Oct-04 1,4-Dioxane <1 µg/L MW-108 18-Oct-04 1,4-Dioxane <1 µg/L NZ-03 23-Apr-04 1,4-Dioxane 2.2 µg/L NZ-06 28-Apr-04 1,4-Dioxane 0.83 µg/L F NZ-07 28-Apr-04 1,4-Dioxane 1.1 µg/L NZ-10 28-Apr-04 1,4-Dioxane 1 µg/L NZ-11 06-Oct-03 1,4-Dioxane 1.8 µg/L NZ-11 06-May-04 1,4-Dioxane 2 µg/L NZ-12 02-Oct-03 1,4-Dioxane 0.6 µg/L M NZ-12 05-May-04 1,4-Dioxane 0.94 µg/L F NZ-13 13-Oct-04 1,4-Dioxane <1 µg/L NZ-17 26-Apr-04 1,4-Dioxane <1 µg/L NZ-18 28-Apr-04 1,4-Dioxane 0.45 µg/L F NZ-20 02-Oct-03 1,4-Dioxane 1.4 µg/L M NZ-20 05-May-04 1,4-Dioxane 1.9 µg/L NZ-21 06-May-04 1,4-Dioxane 0.78 µg/L F NZ-22 06-May-04 1,4-Dioxane 0.77 µg/L F NZ-23 03-May-04 1,4-Dioxane 0.4 µg/L F NZ-24 11-Nov-04 1,4-Dioxane 0.76 µg/L F NZ-25 03-May-04 1,4-Dioxane 0.93 µg/L F NZ-27 07-Oct-03 1,4-Dioxane 2.1 µg/L NZ-27 10-May-04 1,4-Dioxane 2.8 µg/L NZ-28A 01-Oct-03 1,4-Dioxane 0.87 µg/L F NZ-28A 04-May-04 1,4-Dioxane 1.2 µg/L NZ-29 29-Sep-03 1,4-Dioxane <1 µg/L NZ-29 30-Apr-04 1,4-Dioxane <1 µg/L NZ-30 06-Oct-03 1,4-Dioxane 2.2 µg/L NZ-31 03-May-04 1,4-Dioxane 0.44 µg/L F TABLE 4-3

HISTORICAL RESULTS OF EMERGENT CHEMICALS - 1,4-DIOXANE AND PERCHLORATE FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 2 of 3) Well ID Sample Date Compound Result Units Flag

NZ-32 01-Oct-03 1,4-Dioxane 1.1 µg/L NZ-32 04-May-04 1,4-Dioxane 1.7 µg/L NZ-35 28-Apr-04 1,4-Dioxane 1.2 µg/L NZ-36 01-Oct-03 1,4-Dioxane 0.67 µg/L F NZ-36 04-May-04 1,4-Dioxane 0.95 µg/L F NZ-39 06-Oct-03 1,4-Dioxane 1.4 µg/L NZ-39 10-May-04 1,4-Dioxane 1.7 µg/L NZ-40 06-Oct-03 1,4-Dioxane 2 µg/L NZ-40 07-May-04 1,4-Dioxane 1.9 µg/L NZ-41 29-Sep-03 1,4-Dioxane <1 µg/L NZ-41 30-Apr-04 1,4-Dioxane <1 µg/L NZ-42 06-May-04 1,4-Dioxane 0.65 µg/L F NZ-44 26-Apr-04 1,4-Dioxane <1 µg/L NZ-46 03-May-04 1,4-Dioxane 1.1 µg/L NZ-48 05-May-04 1,4-Dioxane 1.4 µg/L NZ-49 22-Apr-04 1,4-Dioxane <1 µg/L NZ-50 21-Apr-04 1,4-Dioxane <1 µg/L NZ-51 27-Apr-04 1,4-Dioxane 3.8 µg/L NZ-52 27-Apr-04 1,4-Dioxane 4.5 µg/L NZ-54 27-Apr-04 1,4-Dioxane 0.33 µg/L F NZ-55 16-May-02 1,4-Dioxane <2000 µg/L NZ-56 07-Oct-03 1,4-Dioxane 0.81 µg/L F NZ-56 10-May-04 1,4-Dioxane 0.97 µg/L F NZ-57 12-Nov-98 Perchlorate <4 µg/L NZ-57 13-Oct-04 1,4-Dioxane 0.82 µg/L F NZ-58 20-Oct-98 Perchlorate <8 µg/L NZ-58 14-Oct-04 1,4-Dioxane 1.7 µg/L NZ-59 14-Oct-04 1,4-Dioxane <1 µg/L NZ-60 12-Oct-04 1,4-Dioxane <1 µg/L NZ-61 12-Oct-04 1,4-Dioxane <1 µg/L NZ-62 12-Oct-04 1,4-Dioxane <1 µg/L NZ-67 06-Oct-03 1,4-Dioxane 1.6 µg/L NZ-67 07-May-04 1,4-Dioxane 1.8 µg/L NZ-68 27-Apr-04 1,4-Dioxane 1.4 µg/L NZ-69 23-Apr-04 1,4-Dioxane <1 µg/L NZ-70 23-Apr-04 1,4-Dioxane <1 µg/L NZ-71 23-Apr-04 1,4-Dioxane <1 µg/L NZ-72 21-Apr-04 1,4-Dioxane <1 µg/L NZ-73 18-Oct-04 1,4-Dioxane 0.62 µg/L F NZ-74 21-Oct-98 Perchlorate <4 µg/L NZ-74 23-Apr-04 1,4-Dioxane <1 µg/L NZ-75 06-Oct-03 1,4-Dioxane 1.6 µg/L NZ-75 10-May-04 1,4-Dioxane 1.5 µg/L NZ-76 18-Oct-04 1,4-Dioxane <1 µg/L NZ-77 15-Oct-04 1,4-Dioxane <1 µg/L NZ-78 15-Oct-04 1,4-Dioxane <1 µg/L NZ-79 15-Oct-04 1,4-Dioxane <1 µg/L TABLE 4-3

HISTORICAL RESULTS OF EMERGENT CHEMICALS - 1,4-DIOXANE AND PERCHLORATE FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 3 of 3) Well ID Sample Date Compound Result Units Flag

NZ-80 22-Apr-04 1,4-Dioxane 3.5 µg/L NZ-81 02-Oct-03 1,4-Dioxane 1 µg/L M NZ-81 05-May-04 1,4-Dioxane 1.3 µg/L NZ-82 07-Oct-03 1,4-Dioxane 0.73 µg/L F NZ-82 10-May-04 1,4-Dioxane 1.3 µg/L NZ-83 07-Oct-03 1,4-Dioxane 0.74 µg/L F NZ-83 10-May-04 1,4-Dioxane 1.1 µg/L NZ-84 14-Oct-04 1,4-Dioxane 4.6 µg/L NZ-85 13-Oct-04 1,4-Dioxane <1 µg/L NZ-86 13-Oct-04 1,4-Dioxane <1 µg/L NZ-93 29-Sep-03 1,4-Dioxane <1 µg/L NZ-93 30-Apr-04 1,4-Dioxane 0.32 µg/L F NZ-94 02-Oct-03 1,4-Dioxane <1 µg/L M NZ-94 04-May-04 1,4-Dioxane <1 µg/L NZ-95 26-Apr-04 1,4-Dioxane <1 µg/L NZ-96 27-Apr-04 1,4-Dioxane 0.38 µg/L F NZ-97 21-Apr-04 1,4-Dioxane <1 µg/L NZ-98 26-Apr-04 1,4-Dioxane <1 µg/L NZ-99 29-Sep-03 1,4-Dioxane <1 µg/L NZ-99 30-Apr-04 1,4-Dioxane 0.33 µg/L F NZ-100 18-Oct-04 1,4-Dioxane 0.66 µg/L F NZ-101 01-Oct-03 1,4-Dioxane 1.1 µg/L NZ-101 07-May-04 1,4-Dioxane 1.5 µg/L NZ-102 02-Oct-03 1,4-Dioxane 1.6 µg/L M NZ-102 07-May-04 1,4-Dioxane 2.2 µg/L NZ-103 06-Oct-03 1,4-Dioxane 1 µg/L NZ-103 06-May-04 1,4-Dioxane 1.4 µg/L NZ-104 01-Oct-03 1,4-Dioxane 0.59 µg/L F NZ-104 04-May-04 1,4-Dioxane 0.49 µg/L F NZ-105R 06-May-04 1,4-Dioxane 0.53 µg/L F NZ-106 14-Oct-04 1,4-Dioxane 1.9 µg/L NZ-107 12-Oct-04 1,4-Dioxane 3.1 µg/L NZ-108 12-Oct-04 1,4-Dioxane <1 µg/L NZ-112 22-Apr-04 1,4-Dioxane <1 µg/L NZ-113 22-Apr-04 1,4-Dioxane 0.87 µg/L F NZ-114 19-Oct-04 1,4-Dioxane 0.74 µg/L F NZ-115 19-Oct-04 1,4-Dioxane 0.75 µg/L F NZ-116 27-Apr-04 1,4-Dioxane 0.43 µg/L F

Notes: µg/L - micrograms per liter mg/L - milligrams per liter B - The compound was found in an associated blank as well as in the sample. F - Detected concentration is method detection limit. J - Estimated concentration M - Results of associated quality control indicates possible matrix interference. ND - not detected TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 1 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

EW-1 5/15/2001 Trichloroethylene (TCE) 16.5 5/15/2001 Chloroform 0.56 J 5/15/2002 Trichloroethylene (TCE) 34.2 5/15/2002 Chloroform 0.6 B 2/27/2004 Trichloroethylene (TCE) 27.1 2/27/2004 Chloroform 0.41 8/26/2004 Trichloroethylene (TCE) 27 M EW-2 5/15/2001 Trichloroethylene (TCE) 112 5/15/2001 Chloroform 4.6 J 5/15/2002 Chloroform 3.9 B 5/15/2002 Trichloroethylene (TCE) 117 8/26/2004 Chloroform 0.89 8/26/2004 Trichloroethylene (TCE) 128 M EW-3 4/3/2000 Trichloroethylene (TCE) 31.8 4/3/2000 Chloroform 0.7 5/15/2001 Trichloroethylene (TCE) 22.5 5/15/2001 Chloroform 0.7 J 5/15/2002 Trichloroethylene (TCE) 34.2 5/15/2002 Chloroform 0.72 B EW-4 5/15/2001 Trichloroethylene (TCE) 29.6 5/15/2001 Chloroform 1.4 J 5/15/2002 Trichloroethylene (TCE) 54.4 5/15/2002 Chloroform 1.5 B 2/27/2004 Trichloroethylene (TCE) 39.8 2/27/2004 Chloroform 1.1 8/26/2004 Trichloroethylene (TCE) 29.5 M 8/26/2004 Chloroform 1 EW-5 5/15/2001 Chloroform 1 J 5/15/2001 Trichloroethylene (TCE) 59.1 5/15/2002 Chloroform 1.3 B 5/15/2002 Trichloroethylene (TCE) 75.5 3/5/2004 Trichloroethylene (TCE) 41.9 3/5/2004 Chloroform 0.67 8/26/2004 Styrene 0.49 8/26/2004 Trichloroethylene (TCE) 24.1 M EW-6 4/24/2000 Trichloroethylene (TCE) 2.8 5/15/2002 Trichloroethylene (TCE) 22.5 3/5/2004 Trichloroethylene (TCE) 21.3 8/26/2004 Trichloroethylene (TCE) 28.8 M EW-7 5/15/2001 Trichloroethylene (TCE) 11.5 5/15/2001 Chloroform 0.37 J 5/15/2002 Trichloroethylene (TCE) 27.9 5/15/2002 Chloroform 0.45 B EW-8 5/15/2001 Trichloroethylene (TCE) 6.5 5/15/2002 Trichloroethylene (TCE) 7.5 2/20/2004 Trichloroethylene (TCE) 4.4 8/27/2004 Trichloroethylene (TCE) 0.54 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 2 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

EW-9 7/11/2001 Trichloroethylene (TCE) 40.5 7/11/2001 Chloroform 0.53 B 5/15/2002 Trichloroethylene (TCE) 53.1 5/15/2002 Chloroform 0.66 B 2/20/2004 Dibromochloromethane 0.86 2/20/2004 Trichloroethylene (TCE) 16.8 8/25/2004 Trichloroethylene (TCE) 10.7 EW-10 5/15/2001 Trichloroethylene (TCE) 28.6 5/15/2001 Chloroform 1 J 5/15/2002 Trichloroethylene (TCE) 56.5 5/15/2002 Chloroform 1.4 B 2/20/2004 Dibromochloromethane 0.87 2/20/2004 Trichloroethylene (TCE) 36.4 2/20/2004 Chloroform 0.88 8/26/2004 Trichloroethylene (TCE) 10.4 M EW-11 5/15/2001 Chloroform 0.71 J 5/15/2001 Trichloroethylene (TCE) 99.8 5/15/2002 cis-1,2-Dichloroethylene 2.4 5/15/2002 Chloroform 1.1 B 5/15/2002 Trichloroethylene (TCE) 176 3/5/2004 Chloroform 0.58 3/5/2004 Trichloroethylene (TCE) 70.5 EW-12 5/6/1999 Trichloroethylene (TCE) 193 M 5/6/1999 Chloroform 1 B 5/15/2001 Chloroform 0.33 J 5/15/2001 Chlorobenzene 3.8 5/15/2001 Trichloroethylene (TCE) 62.8 5/15/2002 cis-1,2-Dichloroethylene 5.9 5/15/2002 Chloroform 1.1 B 5/15/2002 Trichloroethylene (TCE) 339 3/5/2004 Trichloroethylene (TCE) 213 8/25/2004 Trichloroethylene (TCE) 54 EW-13 5/15/2001 cis-1,2-Dichloroethylene 7.2 5/15/2001 Chloroform 0.76 J 5/15/2001 cis-1,2-Dichloroethylene 7.9 5/15/2001 Trichloroethylene (TCE) 238 5/15/2002 cis-1,2-Dichloroethylene 8.4 5/15/2002 Chloroform 1.1 B 5/15/2002 Trichloroethylene (TCE) 365 2/27/2004 cis-1,2-Dichloroethylene 2.7 2/27/2004 Chloroform 0.54 2/27/2004 Trichloroethylene (TCE) 146 8/25/2004 Ethylbenzene 1.9 8/25/2004 Styrene 0.49 8/25/2004 Trichloroethylene (TCE) 17.7 8/25/2004 Benzene 0.46 8/25/2004 Toluene 1.4 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 3 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

EW-14 2/27/2004 Trichloroethylene (TCE) 3.1 8/27/2004 Trichloroethylene (TCE) 3.1 EW-15 5/15/2001 Trichloroethylene (TCE) 0.75 5/15/2002 Trichloroethylene (TCE) 2.8 EW-17 1/10/2000 Trichloroethylene (TCE) 3.3 4/7/2000 Trichloroethylene (TCE) 1.9 7/18/2000 Trichloroethylene (TCE) 1.7 10/3/2000 Trichloroethylene (TCE) 1.8 12/5/2000 Trichloroethylene (TCE) 1.6 4/25/2001 Trichloroethylene (TCE) 1.9 5/15/2001 Trichloroethylene (TCE) 0.61 7/18/2001 Naphthalene 0.42 7/18/2001 Trichloroethylene (TCE) 2.3 10/31/2001 Trichloroethylene (TCE) 2.4 12/19/2001 Trichloroethylene (TCE) 2.6 4/10/2002 Trichloroethylene (TCE) 3.9 5/15/2002 Trichloroethylene (TCE) 1.9 7/17/2002 Trichloroethylene (TCE) 1.2 10/11/2002 Trichloroethylene (TCE) 1 12/17/2002 Trichloroethylene (TCE) 2.7 EW-18 5/15/2001 Trichloroethylene (TCE) 1.6 5/15/2002 Trichloroethylene (TCE) 2.6 8/27/2004 Toluene 2.4 8/27/2004 Ethylbenzene 0.69 8/27/2004 Styrene 3.8 EPA-VII 12/15/2004 Trichloroethylene (TCE) 3 FT-01 5/4/1999 Trichloroethylene (TCE) 3.5 M 5/4/1999 Chloroform 0.58 B 11/12/1999 Trichloroethylene (TCE) 5.6 R 4/28/2000 Trichloroethylene (TCE) 2.8 10/13/2000 Trichloroethylene (TCE) 3.5 4/27/2001 Trichloroethylene (TCE) 2.9 10/26/2001 Trichloroethylene (TCE) 3.1 4/26/2002 Trichloroethylene (TCE) 2.7 10/4/2002 Trichloroethylene (TCE) 2.5 9/24/2003 Trichloroethylene (TCE) 0.86 4/28/2004 Trichloroethylene (TCE) 0.99 10/22/2004 Trichloroethylene (TCE) 1.1 FT-02 5/4/1999 Trichloroethylene (TCE) 66.2 M 5/4/1999 Chloroform 3.1 B 5/4/2000 Trichloroethylene (TCE) 59.4 M 5/4/2000 Chloroform 2.7 9/25/2003 Trichloroethylene (TCE) 14.8 9/25/2003 Chloroform 0.65 4/28/2004 Trichloroethylene (TCE) 19.8 4/28/2004 Chloroform 0.45 10/22/2004 Trichloroethylene (TCE) 11.2 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 4 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

FT-03 5/4/1999 Trichloroethylene (TCE) 6.2 M 5/4/1999 Chloroform 1.3 B 11/19/1999 Trichloroethylene (TCE) 11 R 11/19/1999 Chloroform 0.56 4/28/2000 Trichloroethylene (TCE) 7.8 10/13/2000 Trichloroethylene (TCE) 7.4 4/27/2001 Trichloroethylene (TCE) 6.2 10/26/2001 Trichloroethylene (TCE) 9.6 4/26/2002 Trichloroethylene (TCE) 8.2 10/4/2002 Trichloroethylene (TCE) 7.5 9/25/2003 Trichloroethylene (TCE) 4.1 4/28/2004 Trichloroethylene (TCE) 4.8 10/22/2004 Trichloroethylene (TCE) 4.8 FT-04 11/19/1999 Trichloroethylene (TCE) 4.2 R 4/28/2000 Trichloroethylene (TCE) 2 10/13/2000 Trichloroethylene (TCE) 2.1 4/27/2001 Trichloroethylene (TCE) 1.9 10/26/2001 Trichloroethylene (TCE) 1.6 4/26/2002 Trichloroethylene (TCE) 2.4 10/4/2002 Trichloroethylene (TCE) 1.6 9/25/2003 Trichloroethylene (TCE) 0.6 4/28/2004 Trichloroethylene (TCE) 1.1 10/22/2004 Trichloroethylene (TCE) 0.96 FT-05 5/4/1999 Trichloroethylene (TCE) 112 M 5/4/1999 Chloroform 6.8 B 11/19/1999 Trichloroethylene (TCE) 52.8 R 11/19/1999 Chloroform 5.5 4/28/2000 Naphthalene 2.2 4/28/2000 Chloroform 7.8 4/28/2000 Trichloroethylene (TCE) 220 J 10/13/2000 Chloroform 9.1 10/13/2000 Trichloroethylene (TCE) 207 4/27/2001 Chloroform 6.2 4/27/2001 Trichloroethylene (TCE) 116 10/26/2001 Trichloroethylene (TCE) 69.5 10/26/2001 Chloroform 4.2 4/26/2002 Chloroform 4.3 4/26/2002 Trichloroethylene (TCE) 71.1 10/4/2002 Trichloroethylene (TCE) 48.9 10/4/2002 Chloroform 3.4 9/25/2003 Trichloroethylene (TCE) 24.1 9/25/2003 Chloroform 1.4 4/28/2004 Trichloroethylene (TCE) 26.6 4/28/2004 Chloroform 1.8 10/22/2004 Trichloroethylene (TCE) 32.3 10/22/2004 Chloroform 1.6 FT-06 5/4/1999 Trichloroethylene (TCE) 4.7 M TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 5 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

5/4/1999 Chloroform 1.1 B LW-1 4/23/1999 Trichloroethylene (TCE) 1.1 M 12/20/2001 Trichloroethylene (TCE) 0.6 B 4/19/2004 Trichloroethylene (TCE) 0.83 7/12/2004 Trichloroethylene (TCE) 0.85 7/12/2004 Chloroform 0.32 10/15/2004 Trichloroethylene (TCE) 0.89 12/13/2004 Trichloroethylene (TCE) 0.51 12/13/2004 Chloroform 0.69 LW-2 4/10/2000 Trichloroethylene (TCE) 1.4 10/11/2000 Trichloroethylene (TCE) 1 10/19/2001 Methylene chloride 4.8 M 10/19/2001 Trichloroethylene (TCE) 0.86 LW-4 12/20/2001 Trichloroethylene (TCE) 0.96 J 7/16/2002 1-chlorohexane 0.55 R 7/16/2002 m,p-Xylene 0.45 9/15/2003 Trichloroethylene (TCE) 2.2 12/8/2003 Trichloroethylene (TCE) 8.7 4/19/2004 Trichloroethylene (TCE) 8.5 7/12/2004 Trichloroethylene (TCE) 7.7 10/15/2004 Trichloroethylene (TCE) 4.3 12/13/2004 Trichloroethylene (TCE) 7 MW-1-OU3 5/1/2001 Benzene 82.5 M 5/1/2001 Toluene 6.3 M 5/1/2001 1,2-Dichloroethane 2.2 M 5/1/2001 1,3,5-trimethylbenzene 2.2 M 5/1/2001 m,p-Xylene 8.5 M 5/1/2001 o-Xylene 6.1 M 10/30/2001 Benzene 170 10/30/2001 Toluene 56.3 10/30/2001 1,2-Dichloroethane 5.3 10/30/2001 Ethylbenzene 2 10/30/2001 Isopropylbenzene (Cumene) 1.5 10/30/2001 N-propylbenzene 0.91 10/30/2001 Styrene 0.65 10/30/2001 1,1,2-Trichloroethane 10.8 10/30/2001 1,2,4-Trimethylbenzene 4.4 10/30/2001 1,3,5-trimethylbenzene 7.4 10/30/2001 m,p-Xylene 49.1 10/30/2001 o-Xylene 23.7 MW-102 11/12/1999 Trichloroethylene (TCE) 3.7 R 4/18/2000 Trichloroethylene (TCE) 5.2 B 10/18/2000 Tetrachloroethylene (PCE) 1.6 10/18/2000 Trichloroethylene (TCE) 4.9 10/18/2000 Chloroform 0.36 5/4/2001 Trichloroethylene (TCE) 3.4 5/4/2001 Chloroform 0.4 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 6 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

11/8/2001 Methylene chloride 3.7 B 11/8/2001 Trichloroethylene (TCE) 4.5 11/8/2001 Chloroform 0.31 5/8/2002 Tetrachloroethylene (PCE) 1.9 5/8/2002 Trichloroethylene (TCE) 5.4 10/16/2002 Trichloroethylene (TCE) 4.5 10/16/2002 Chloroform 0.32 9/24/2003 Trichloroethylene (TCE) 4.2 4/26/2004 Tetrachloroethylene (PCE) 1.5 4/26/2004 Trichloroethylene (TCE) 5 4/26/2004 Chloroform 0.37 10/25/2004 Tetrachloroethylene (PCE) 1.7 10/25/2004 Trichloroethylene (TCE) 5.5 10/25/2004 Chloroform 0.34 MW-103 4/30/1999 Trichloroethylene (TCE) 4 M 11/12/1999 Trichloroethylene (TCE) 2.3 R 10/18/2000 Trichloroethylene (TCE) 2 5/4/2001 Trichloroethylene (TCE) 0.72 5/7/2002 Trichloroethylene (TCE) 0.52 10/8/2002 Trichloroethylene (TCE) 0.58 9/24/2003 Trichloroethylene (TCE) 0.91 4/26/2004 Trichloroethylene (TCE) 4.2 10/25/2004 Trichloroethylene (TCE) 1.9 MW-104 5/6/2000 Trichloroethylene (TCE) 1.6 9/24/2003 Trichloroethylene (TCE) 1.4 4/26/2004 Trichloroethylene (TCE) 1.7 10/25/2004 Trichloroethylene (TCE) 2 MW-107 10/3/2000 Trichloroethylene (TCE) 1.1 12/6/2000 Trichloroethylene (TCE) 1.3 4/25/2001 Trichloroethylene (TCE) 1.5 7/18/2001 Trichloroethylene (TCE) 1.8 10/31/2001 Trichloroethylene (TCE) 2.1 12/19/2001 Trichloroethylene (TCE) 2.1 5/3/2002 Trichloroethylene (TCE) 2.8 7/17/2002 Trichloroethylene (TCE) 2.2 7/17/2002 m,p-Xylene 0.52 10/10/2002 Trichloroethylene (TCE) 1.6 12/17/2002 Trichloroethylene (TCE) 1.5 9/18/2003 Chloroform 0.42 12/10/2003 Chloroform 0.96 4/20/2004 Chloroform 1.1 7/15/2004 Chloroform 0.94 10/18/2004 Chloroform 0.54 12/15/2004 Chloroform 0.8 MW-108 1/14/2000 Methylene chloride 3.4 7/20/2000 Naphthalene 2.9 R 7/15/2002 m,p-Xylene 0.92 B TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 7 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/20/2004 Trichloroethylene (TCE) 4.5 7/13/2004 Trichloroethylene (TCE) 6.7 10/18/2004 Trichloroethylene (TCE) 11.9 12/14/2004 Trichloroethylene (TCE) 11 NZ-03 5/4/2001 Trichloroethylene (TCE) 0.75 11/2/2001 Trichloroethylene (TCE) 0.86 5/7/2002 Trichloroethylene (TCE) 0.73 9/22/2003 Trichloroethylene (TCE) 0.56 4/23/2004 Trichloroethylene (TCE) 0.67 10/26/2004 Trichloroethylene (TCE) 0.76 NZ-06 11/5/1999 Trichloroethylene (TCE) 4.5 4/11/2000 Trichloroethylene (TCE) 4.9 10/4/2000 Trichloroethylene (TCE) 4.9 M 4/19/2001 Trichloroethylene (TCE) 4 10/18/2001 Trichloroethylene (TCE) 4.9 4/10/2002 Trichloroethylene (TCE) 8.8 10/3/2002 Trichloroethylene (TCE) 8.3 9/24/2003 Trichloroethylene (TCE) 5.6 4/28/2004 Trichloroethylene (TCE) 7.7 11/1/2004 Trichloroethylene (TCE) 8.2 NZ-07 5/5/1999 Trichloroethylene (TCE) 26.1 M 5/5/1999 Chloroform 1.1 5/4/2000 Trichloroethylene (TCE) 33.9 M 5/4/2000 Chloroform 0.57 9/25/2003 Trichloroethylene (TCE) 14.6 4/28/2004 Trichloroethylene (TCE) 14.6 4/28/2004 Chloroform 0.31 11/3/2004 Trichloroethylene (TCE) 12.8 NZ-10 5/5/1999 Trichloroethylene (TCE) 2.9 M 5/5/1999 Chloroform 1.3 5/5/2000 Trichloroethylene (TCE) 3.3 9/25/2003 Trichloroethylene (TCE) 4.2 4/28/2004 Trichloroethylene (TCE) 4.7 11/1/2004 Trichloroethylene (TCE) 5.4 NZ-11 5/7/1999 cis-1,2-Dichloroethylene 16.5 5/7/1999 Trichloroethylene (TCE) 322 M 5/7/1999 Chloroform 1.5 B 11/5/1999 cis-1,2-Dichloroethylene 12.1 11/5/1999 Chloroform 0.9 11/5/1999 Trichloroethylene (TCE) 361 4/5/2000 cis-1,2-Dichloroethylene 9.5 4/5/2000 Chloroform 0.8 4/5/2000 Trichloroethylene (TCE) 217 10/4/2000 Trichloroethylene (TCE) 327 M 4/19/2001 cis-1,2-Dichloroethylene 6.8 4/19/2001 Trichloroethylene (TCE) 220 10/16/2001 cis-1,2-Dichloroethylene 5 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 8 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

10/16/2001 Trichloroethylene (TCE) 292 10/16/2001 Chloroform 0.6 5/9/2002 Chloroform 0.58 5/9/2002 Trichloroethylene (TCE) 308 5/9/2002 cis-1,2-Dichloroethylene 5.9 10/14/2002 cis-1,2-Dichloroethylene 4.9 10/14/2002 Trichloroethylene (TCE) 209 10/14/2002 Chloroform 0.58 10/6/2003 Trichloroethylene (TCE) 306 5/6/2004 NAPHTHALENE 0.82 5/6/2004 Trichloroethylene (TCE) 104 11/3/2004 Benzene 0.4 11/3/2004 cis-1,2-Dichloroethylene 3.4 11/3/2004 M,P-XYLENE 1.6 B 11/3/2004 Trichloroethylene (TCE) 194 NZ-12 5/7/1999 cis-1,2-Dichloroethylene 2 5/7/1999 Trichloroethylene (TCE) 148 M 5/7/1999 Chloroform 1.5 B 11/4/1999 Trichloroethylene (TCE) 80.8 R 11/4/1999 Chloroform 1.1 4/5/2000 Trichloroethylene (TCE) 54.3 4/5/2000 Chloroform 0.7 10/4/2000 Trichloroethylene (TCE) 58.1 M 10/4/2000 Chloroform 0.75 4/20/2001 Trichloroethylene (TCE) 79.5 4/20/2001 Chloroform 0.79 10/16/2001 Trichloroethylene (TCE) 87.4 10/16/2001 Chloroform 0.5 5/9/2002 Trichloroethylene (TCE) 110 10/14/2002 Trichloroethylene (TCE) 59 10/14/2002 Chloroform 0.38 10/2/2003 Trichloroethylene (TCE) 70.6 M 5/5/2004 Dibromochloromethane 0.55 B 5/5/2004 Trichloroethylene (TCE) 29.6 11/11/2004 Trichloroethylene (TCE) 34.2 NZ-13 4/28/1999 Trichloroethylene (TCE) 2.4 M 4/28/1999 Chloroform 0.78 11/8/1999 Trichloroethylene (TCE) 2 J 5/1/2000 Trichloroethylene (TCE) 2.5 10/9/2000 Trichloroethylene (TCE) 2.3 4/23/2001 Trichloroethylene (TCE) 2.3 10/22/2001 Trichloroethylene (TCE) 1.8 4/18/2002 Trichloroethylene (TCE) 3.5 M 4/18/2002 Chloroform 0.34 12/16/2002 Trichloroethylene (TCE) 2.4 6/21/2003 Benzene 0.54 B 6/21/2003 Trichloroethylene (TCE) 1.5 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 9 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

8/19/2003 Isopropylbenzene (Cumene) 0.82 8/19/2003 Trichloroethylene (TCE) 1.9 8/19/2003 1,3,5-trimethylbenzene 0.62 8/19/2003 m,p-Xylene 1 12/10/2003 Trichloroethylene (TCE) 2 4/15/2004 Trichloroethylene (TCE) 2.2 7/15/2004 Trichloroethylene (TCE) 1.9 10/13/2004 Trichloroethylene (TCE) 2.5 12/14/2004 Trichloroethylene (TCE) 2.5 NZ-17 5/5/2000 Benzene 0.42 NZ-18 4/30/1999 Trichloroethylene (TCE) 10 M 4/30/1999 Chloroform 0.88 B 5/5/2000 Trichloroethylene (TCE) 6.7 10/18/2001 Trichloroethylene (TCE) 2.7 4/10/2002 Trichloroethylene (TCE) 4.9 9/25/2003 Trichloroethylene (TCE) 1.9 4/28/2004 Trichloroethylene (TCE) 3.4 11/1/2004 Trichloroethylene (TCE) 1.3 NZ-20 5/7/1999 cis-1,2-Dichloroethylene 1.3 J 5/7/1999 Trichloroethylene (TCE) 70.2 M 5/7/1999 Chloroform 1.3 B 4/27/2000 Trichloroethylene (TCE) 59.4 4/27/2000 Chloroform 0.53 10/16/2001 Trichloroethylene (TCE) 78.9 10/16/2001 Chloroform 0.5 5/9/2002 Trichloroethylene (TCE) 102 10/2/2003 Trichloroethylene (TCE) 115 M 5/5/2004 Trichloroethylene (TCE) 53.1 11/11/2004 Trichloroethylene (TCE) 70.4 NZ-21 5/5/1999 Trichloroethylene (TCE) 29.1 M 5/5/1999 Chloroform 1.2 5/4/2000 Trichloroethylene (TCE) 22.8 M 5/4/2000 Chloroform 0.53 10/3/2003 Trichloroethylene (TCE) 31.7 5/6/2004 Dibromochloromethane 0.55 5/6/2004 Trichloroethylene (TCE) 27.6 11/11/2004 Trichloroethylene (TCE) 30.2 NZ-22 11/4/1999 Trichloroethylene (TCE) 20.6 R 4/5/2000 Trichloroethylene (TCE) 20.5 10/2/2000 Trichloroethylene (TCE) 22.1 10/2/2000 Chloroform 0.31 4/17/2001 Trichloroethylene (TCE) 18.5 10/29/2001 Trichloroethylene (TCE) 20.2 4/29/2002 Trichloroethylene (TCE) 18.9 10/3/2003 Trichloroethylene (TCE) 22.8 5/6/2004 Trichloroethylene (TCE) 15.8 11/11/2004 Trichloroethylene (TCE) 17.2 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 10 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

NZ-23 5/4/2000 Chloroform 2.7 5/4/2000 Trichloroethylene (TCE) 74.2 M 10/18/2001 Trichloroethylene (TCE) 34.3 10/18/2001 Chloroform 0.66 4/10/2002 Trichloroethylene (TCE) 41.6 4/10/2002 Chloroform 2 9/30/2003 Trichloroethylene (TCE) 17 9/30/2003 Chloroform 0.88 5/3/2004 Trichloroethylene (TCE) 18.5 5/3/2004 Chloroform 1 11/4/2004 Trichloroethylene (TCE) 13.9 11/4/2004 Chloroform 0.83 NZ-24 5/5/1999 Trichloroethylene (TCE) 9.8 M 5/5/1999 Chloroform 0.59 4/26/2000 Trichloroethylene (TCE) 5 11/11/2004 Trichloroethylene (TCE) 42.7 11/11/2004 Chloroform 1 NZ-25 5/6/1999 Trichloroethylene (TCE) 119 M 5/6/1999 Chloroform 0.8 B 11/4/1999 Trichloroethylene (TCE) 104 R 11/4/1999 Chloroform 0.7 4/25/2000 Trichloroethylene (TCE) 39.5 4/25/2000 Chloroform 1.1 10/2/2000 Trichloroethylene (TCE) 58.9 10/2/2000 Chloroform 0.73 4/17/2001 Chloroform 0.62 4/17/2001 Trichloroethylene (TCE) 73.3 11/5/2001 Trichloroethylene (TCE) 60.8 11/5/2001 Chloroform 0.51 5/8/2002 Chloroform 0.56 5/8/2002 Trichloroethylene (TCE) 68.1 10/11/2002 Trichloroethylene (TCE) 51.9 10/11/2002 Chloroform 0.57 9/30/2003 Trichloroethylene (TCE) 37.1 9/30/2003 Chloroform 0.35 5/3/2004 Trichloroethylene (TCE) 28.3 5/3/2004 Chloroform 0.36 11/5/2004 Trichloroethylene (TCE) 22.9 NZ-27 4/26/1999 Trichloroethylene (TCE) 128 M 4/27/2000 Trichloroethylene (TCE) 122 11/7/2001 cis-1,2-Dichloroethylene 8.4 11/7/2001 Trichloroethylene (TCE) 348 11/7/2001 Chloroform 0.83 11/7/2001 m,p-Xylene 2.3 B 4/30/2002 Benzene 2.7 B 4/30/2002 Toluene 10.4 B 4/30/2002 cis-1,2-Dichloroethylene 8.6 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 11 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/30/2002 Ethylbenzene 5.7 B 4/30/2002 Isopropylbenzene (Cumene) 0.89 B 4/30/2002 Naphthalene 1.1 B 4/30/2002 N-propylbenzene 1.2 B 4/30/2002 Chloroform 0.75 4/30/2002 1,2,4-Trimethylbenzene 6.3 B 4/30/2002 1,3,5-trimethylbenzene 2.5 B 4/30/2002 m,p-Xylene 22.7 B 4/30/2002 o-Xylene 6.9 B 4/30/2002 Trichloroethylene (TCE) 235 10/15/2002 cis-1,2-Dichloroethylene 7.1 10/15/2002 Chloroform 0.84 10/15/2002 Trichloroethylene (TCE) 236 10/7/2003 cis-1,2-Dichloroethylene 6.2 10/7/2003 Trichloroethylene (TCE) 280 5/10/2004 cis-1,2-Dichloroethylene 4.1 5/10/2004 Trichloroethylene (TCE) 177 11/4/2004 cis-1,2-Dichloroethylene 5.9 11/4/2004 M,P-XYLENE 0.71 11/4/2004 Trichloroethylene (TCE) 232 NZ-28A 11/4/1999 Trichloroethylene (TCE) 55.3 R 11/4/1999 Chloroform 1.1 J 4/3/2000 Trichloroethylene (TCE) 64.5 4/3/2000 Chloroform 0.81 10/2/2000 Trichloroethylene (TCE) 88.6 10/2/2000 Chloroform 1 4/16/2001 Chloroform 1.1 4/16/2001 Trichloroethylene (TCE) 57.9 11/5/2001 Trichloroethylene (TCE) 45.2 11/5/2001 Chloroform 0.85 5/8/2002 Trichloroethylene (TCE) 41 5/8/2002 Chloroform 0.84 10/11/2002 Trichloroethylene (TCE) 25.5 10/11/2002 Chloroform 0.87 10/1/2003 Trichloroethylene (TCE) 28.3 10/1/2003 Chloroform 0.55 5/4/2004 Trichloroethylene (TCE) 31.7 5/4/2004 Chloroform 0.34 11/5/2004 Trichloroethylene (TCE) 26.9 NZ-29 11/3/1999 Trichloroethylene (TCE) 1 R 4/4/2000 Benzene 13.7 10/6/2000 Trichloroethylene (TCE) 1.1 4/20/2001 Trichloroethylene (TCE) 2.1 B 10/23/2001 Trichloroethylene (TCE) 0.96 J 4/25/2002 Trichloroethylene (TCE) 4.8 9/29/2003 Trichloroethylene (TCE) 5 4/30/2004 Trichloroethylene (TCE) 2 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 12 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

11/3/2004 Trichloroethylene (TCE) 0.9 11/3/2004 Chloroform 0.34 M NZ-30 5/6/2000 1,1-Dichloroethane 1.4 5/6/2000 cis-1,2-Dichloroethylene 8.3 5/6/2000 Methylene chloride 13.1 B 5/6/2000 Chloroform 0.7 5/6/2000 Trichloroethylene (TCE) 359 10/17/2001 cis-1,2-Dichloroethylene 4.9 10/17/2001 Trichloroethylene (TCE) 244 5/9/2002 Trichloroethylene (TCE) 296 10/6/2003 Trichloroethylene (TCE) 321 11/3/2004 Benzene 0.72 11/3/2004 cis-1,2-Dichloroethylene 3.5 11/3/2004 M,P-XYLENE 2.3 B 11/3/2004 Trichloroethylene (TCE) 164 NZ-31 5/7/1999 Trichloroethylene (TCE) 28.7 M 5/7/1999 1,1-Dichloroethane 0.95 4/14/2000 Trichloroethylene (TCE) 19.8 11/5/2001 Trichloroethylene (TCE) 31.5 5/9/2002 Trichloroethylene (TCE) 43.5 10/1/2003 Trichloroethylene (TCE) 42.4 5/3/2004 Trichloroethylene (TCE) 46.4 11/12/2004 Trichloroethylene (TCE) 41 NZ-32 5/6/1999 Trichloroethylene (TCE) 46.7 M 5/6/1999 Chloroform 1.2 B 4/3/2000 Trichloroethylene (TCE) 70.1 4/3/2000 Chloroform 0.77 11/5/2001 Trichloroethylene (TCE) 47.9 11/5/2001 Chloroform 0.8 5/8/2002 Trichloroethylene (TCE) 50.2 5/8/2002 Chloroform 0.83 10/1/2003 Trichloroethylene (TCE) 43.4 10/1/2003 Chloroform 0.7 5/4/2004 Trichloroethylene (TCE) 50.4 5/4/2004 Chloroform 0.57 11/11/2004 Trichloroethylene (TCE) 40.9 NZ-34 4/30/1999 Trichloroethylene (TCE) 46 M 4/30/1999 Chloroform 1.1 B 4/11/2000 Trichloroethylene (TCE) 125 NZ-35 5/3/1999 Trichloroethylene (TCE) 14.1 M 5/3/1999 Chloroform 0.84 B 11/5/1999 Trichloroethylene (TCE) 9.7 4/11/2000 Trichloroethylene (TCE) 16.4 10/16/2000 Trichloroethylene (TCE) 15.1 10/16/2000 Chloroform 0.33 5/4/2001 Trichloroethylene (TCE) 12.6 5/4/2001 Chloroform 0.47 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 13 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

10/29/2001 Trichloroethylene (TCE) 13 10/29/2001 Chloroform 0.39 4/29/2002 Trichloroethylene (TCE) 10.4 10/2/2002 Trichloroethylene (TCE) 11.4 10/2/2002 Chloroform 0.33 9/25/2003 Trichloroethylene (TCE) 6.3 4/28/2004 Trichloroethylene (TCE) 9.9 4/28/2004 Chloroform 0.4 11/3/2004 Trichloroethylene (TCE) 7.4 NZ-36 5/6/1999 Trichloroethylene (TCE) 23.4 M 5/6/1999 Chloroform 0.66 B 11/4/1999 Trichloroethylene (TCE) 24 R 4/13/2000 Trichloroethylene (TCE) 28.3 10/3/2000 Trichloroethylene (TCE) 24.6 10/3/2000 Chloroform 0.47 5/1/2001 Trichloroethylene (TCE) 22.4 M 10/30/2001 Trichloroethylene (TCE) 26.2 M 4/30/2002 Trichloroethylene (TCE) 27.6 10/11/2002 Trichloroethylene (TCE) 26.8 10/1/2003 Trichloroethylene (TCE) 27.6 5/4/2004 Trichloroethylene (TCE) 33.4 11/5/2004 Trichloroethylene (TCE) 27.1 NZ-37 4/26/1999 Benzene 0.92 4/26/1999 Chloroethane 4.2 4/26/1999 1-chlorohexane 1.8 4/26/1999 Trichloroethylene (TCE) 30.4 M 4/26/1999 Chloroform 0.57 B 11/2/1999 Trichloroethylene (TCE) 27.5 4/4/2000 Trichloroethylene (TCE) 24.7 10/2/2000 Trichloroethylene (TCE) 35.5 10/2/2000 Chloroform 0.41 4/16/2001 Trichloroethylene (TCE) 19.2 4/16/2001 Chloroform 0.34 10/18/2001 Trichloroethylene (TCE) 21.7 NZ-39 5/7/1999 Trichloroethylene (TCE) 162 M 5/7/1999 Chloroform 0.7 B 11/16/1999 Trichloroethylene (TCE) 106 R 11/16/1999 Chloroform 0.4 11/16/1999 m,p-Xylene 1.5 4/13/2000 Trichloroethylene (TCE) 154 10/12/2000 Chloroform 0.5 10/12/2000 Trichloroethylene (TCE) 179 M 4/30/2001 Chloroform 0.52 M 4/30/2001 Trichloroethylene (TCE) 46.3 M 11/1/2001 Trichloroethylene (TCE) 145 11/1/2001 Chloroform 0.34 4/30/2002 Trichloroethylene (TCE) 148 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 14 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/30/2002 Chloroform 0.52 10/11/2002 Trichloroethylene (TCE) 103 10/11/2002 Chloroform 0.49 10/6/2003 Chloroform 0.55 10/6/2003 Trichloroethylene (TCE) 193 5/10/2004 Chloroform 0.38 5/10/2004 Trichloroethylene (TCE) 93.3 11/5/2004 Chloroform 0.9 11/5/2004 Trichloroethylene (TCE) 110 NZ-40 4/27/2000 cis-1,2-Dichloroethylene 14.6 4/27/2000 Chloroform 1 4/27/2000 Trichloroethylene (TCE) 516 11/7/2001 cis-1,2-Dichloroethylene 10.4 11/7/2001 Trichloroethylene (TCE) 341 11/7/2001 Chloroform 0.8 5/1/2002 Benzene 1.2 B 5/1/2002 Toluene 4.7 B 5/1/2002 cis-1,2-Dichloroethylene 8.6 5/1/2002 Ethylbenzene 2.9 B 5/1/2002 Naphthalene 0.66 B 5/1/2002 N-propylbenzene 0.74 B 5/1/2002 Chloroform 0.76 5/1/2002 1,2,4-Trimethylbenzene 3.9 B 5/1/2002 1,3,5-trimethylbenzene 1.5 B 5/1/2002 m,p-Xylene 11.9 B 5/1/2002 o-Xylene 3.4 B 5/1/2002 Trichloroethylene (TCE) 220 10/6/2003 Trichloroethylene (TCE) 342 5/7/2004 cis-1,2-Dichloroethylene 2.2 5/7/2004 Trichloroethylene (TCE) 157 8/25/2004 Styrene 0.72 8/25/2004 Trichloroethylene (TCE) 56.3 8/25/2004 Benzene 0.76 8/25/2004 Toluene 1.3 8/25/2004 cis-1,2-Dichloroethylene 2.3 NZ-41 9/25/1999 Trichloroethylene (TCE) 21.7 11/2/1999 Trichloroethylene (TCE) 12.9 1/10/2000 Trichloroethylene (TCE) 24.1 4/7/2000 Trichloroethylene (TCE) 17 7/18/2000 Trichloroethylene (TCE) 13.8 10/3/2000 Trichloroethylene (TCE) 14.7 10/3/2000 Chloroform 0.51 12/6/2000 Trichloroethylene (TCE) 17.1 4/25/2001 Trichloroethylene (TCE) 15 7/18/2001 Trichloroethylene (TCE) 17.4 11/1/2001 Trichloroethylene (TCE) 8.7 12/21/2001 Trichloroethylene (TCE) 12.4 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 15 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

5/3/2002 Trichloroethylene (TCE) 22.1 7/17/2002 Trichloroethylene (TCE) 15.3 10/10/2002 Trichloroethylene (TCE) 5.3 12/17/2002 Trichloroethylene (TCE) 5.4 6/14/2003 Trichloroethylene (TCE) 2.9 9/29/2003 Trichloroethylene (TCE) 4.1 12/10/2003 Trichloroethylene (TCE) 5.6 4/30/2004 Trichloroethylene (TCE) 6.8 7/15/2004 Trichloroethylene (TCE) 7.7 11/3/2004 Trichloroethylene (TCE) 9.3 12/15/2004 Trichloroethylene (TCE) 13.3 NZ-42 4/26/2000 Trichloroethylene (TCE) 15.5 10/3/2003 Trichloroethylene (TCE) 10.3 5/6/2004 Trichloroethylene (TCE) 6.4 11/12/2004 Trichloroethylene (TCE) 11 NZ-43 4/27/2000 Trichloroethylene (TCE) 5.7 NZ-46 5/5/1999 Trichloroethylene (TCE) 21.1 M 5/5/1999 Chloroform 0.7 4/25/2000 Trichloroethylene (TCE) 17.7 4/19/2002 Tetrachloroethylene (PCE) 1.6 4/19/2002 Trichloroethylene (TCE) 17.3 4/19/2002 Chloroform 0.46 10/1/2002 Tetrachloroethylene (PCE) 1.5 10/1/2002 Trichloroethylene (TCE) 17.1 10/1/2002 Chloroform 0.48 5/3/2004 Trichloroethylene (TCE) 15.8 5/3/2004 Chloroform 0.45 11/5/2004 Trichloroethylene (TCE) 16.7 NZ-48 4/22/1999 Trichloroethylene (TCE) 2.4 M 11/1/1999 Trichloroethylene (TCE) 3 R 4/7/2000 Trichloroethylene (TCE) 2.9 10/3/2000 Trichloroethylene (TCE) 5.2 10/3/2000 Chloroform 0.62 4/25/2001 Trichloroethylene (TCE) 5.8 4/25/2001 Chloroform 0.41 10/31/2001 Trichloroethylene (TCE) 15.9 5/3/2002 Trichloroethylene (TCE) 19.7 5/3/2002 Chloroform 0.42 10/3/2003 Trichloroethylene (TCE) 26.9 5/5/2004 Trichloroethylene (TCE) 41.5 11/12/2004 Trichloroethylene (TCE) 15.8 NZ-49 4/25/2000 Trichloroethylene (TCE) 1.6 10/19/2001 Methylene chloride 4.9 M 10/19/2001 Trichloroethylene (TCE) 1.7 4/19/2002 Trichloroethylene (TCE) 1.8 10/1/2002 Trichloroethylene (TCE) 1.8 9/19/2003 Trichloroethylene (TCE) 1.4 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 16 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/22/2004 Trichloroethylene (TCE) 1.8 10/25/2004 Trichloroethylene (TCE) 2.3 NZ-50 9/19/2003 Trichloroethylene (TCE) 0.55 4/21/2004 Trichloroethylene (TCE) 0.59 10/25/2004 Trichloroethylene (TCE) 0.68 NZ-51 4/29/1999 Tetrachloroethylene (PCE) 3.2 4/29/1999 Trichloroethylene (TCE) 5.2 M 4/21/2000 Tetrachloroethylene (PCE) 3.7 4/21/2000 Trichloroethylene (TCE) 4.8 10/10/2000 Tetrachloroethylene (PCE) 3.1 10/10/2000 Trichloroethylene (TCE) 4.3 10/10/2000 Chloroform 0.38 5/2/2001 Tetrachloroethylene (PCE) 2.5 5/2/2001 Trichloroethylene (TCE) 3.2 5/2/2001 Chloroform 0.34 5/2/2001 m,p-Xylene 1.8 B 11/8/2001 Methylene chloride 5.3 B 11/8/2001 Tetrachloroethylene (PCE) 1.8 R 11/8/2001 Trichloroethylene (TCE) 2.9 4/29/2002 Benzene 5.7 B 4/29/2002 Toluene 24.4 B 4/29/2002 Ethylbenzene 9.6 B 4/29/2002 Isopropylbenzene (Cumene) 0.98 B 4/29/2002 Naphthalene 0.81 B 4/29/2002 N-propylbenzene 1.4 B 4/29/2002 Tetrachloroethylene (PCE) 2.1 4/29/2002 Trichloroethylene (TCE) 4.8 4/29/2002 Chloroform 0.39 4/29/2002 1,2,4-Trimethylbenzene 8.5 B 4/29/2002 1,3,5-trimethylbenzene 3.3 B 4/29/2002 m,p-Xylene 40.7 B 4/29/2002 o-Xylene 10.8 B 10/17/2002 Tetrachloroethylene (PCE) 2 10/17/2002 Trichloroethylene (TCE) 3.4 10/17/2002 Chloroform 0.33 9/25/2003 Tetrachloroethylene (PCE) 1.5 9/25/2003 Trichloroethylene (TCE) 2.7 4/27/2004 Tetrachloroethylene (PCE) 2.2 4/27/2004 Trichloroethylene (TCE) 3.2 4/27/2004 Chloroform 0.33 11/1/2004 Tetrachloroethylene (PCE) 2.1 11/1/2004 Trichloroethylene (TCE) 3.9 11/1/2004 Chloroform 0.36 NZ-52 5/2/2001 m,p-Xylene 1.5 B 11/6/2001 Benzene 0.42 4/29/2002 1,2,4-Trimethylbenzene 7 B 4/29/2002 1,3,5-trimethylbenzene 2.8 B TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 17 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/29/2002 m,p-Xylene 31.5 B 4/29/2002 o-Xylene 8.1 B 4/29/2002 Benzene 3.8 B 4/29/2002 Toluene 16.9 B 4/29/2002 Ethylbenzene 7.3 B 4/29/2002 Isopropylbenzene (Cumene) 0.77 B 4/29/2002 Naphthalene 0.78 B 4/29/2002 N-propylbenzene 1.2 B 4/29/2002 Trichloroethylene (TCE) 0.69 4/27/2004 Trichloroethylene (TCE) 0.57 10/29/2004 Trichloroethylene (TCE) 0.81 NZ-54 5/3/1999 Chloroform 0.8 B 4/21/2000 Trichloroethylene (TCE) 1.6 5/2/2001 Ethylbenzene 0.74 B 5/2/2001 Trichloroethylene (TCE) 3.6 5/2/2001 Chloroform 0.43 5/2/2001 1,2,4-Trimethylbenzene 1.6 B 5/2/2001 1,3,5-trimethylbenzene 0.64 5/2/2001 m,p-Xylene 2.5 B 11/8/2001 Trichloroethylene (TCE) 2.8 4/29/2002 Ethylbenzene 6.4 B 4/29/2002 Isopropylbenzene (Cumene) 0.74 B 4/29/2002 Naphthalene 0.67 B 4/29/2002 N-propylbenzene 1.1 B 4/29/2002 Trichloroethylene (TCE) 4.1 4/29/2002 Chloroform 0.49 4/29/2002 1,2,4-Trimethylbenzene 6.5 B 4/29/2002 1,3,5-trimethylbenzene 2.6 B 4/29/2002 m,p-Xylene 28.2 B 4/29/2002 o-Xylene 7.1 B 4/29/2002 Benzene 3.5 B 4/29/2002 Toluene 14.8 B 9/25/2003 Trichloroethylene (TCE) 2 4/27/2004 Trichloroethylene (TCE) 2.6 4/27/2004 Chloroform 0.37 11/1/2004 Trichloroethylene (TCE) 2 NZ-55 4/27/1999 cis-1,2-Dichloroethylene 5.5 4/27/1999 Trichloroethylene (TCE) 210 M 11/12/1999 cis-1,2-Dichloroethylene 39.2 11/12/1999 Trichloroethylene (TCE) 530 R 4/18/2000 cis-1,2-Dichloroethylene 65.5 4/18/2000 1,1,2-Trichloroethane 3.2 4/18/2000 Chloroform 1.8 4/18/2000 Trichloroethylene (TCE) 1280 B 10/18/2000 cis-1,2-Dichloroethylene 60.7 J 10/18/2000 1,1,2-Trichloroethane 2.7 10/18/2000 Chloroform 1.2 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 18 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

10/18/2000 Trichloroethylene (TCE) 738 5/4/2001 Trichloroethylene (TCE) 395 5/4/2001 cis-1,2-Dichloroethylene 48.6 5/4/2001 1,1,2-Trichloroethane 2.3 5/4/2001 Chloroform 1.2 7/18/2001 1,2-Dichloroethane 0.8 7/18/2001 cis-1,2-Dichloroethylene 64.3 J 7/18/2001 1,1,2-Trichloroethane 2.6 7/18/2001 Chloroform 1.5 B 7/18/2001 Trichloroethylene (TCE) 771 11/8/2001 cis-1,2-Dichloroethylene 44.3 11/8/2001 Methylene chloride 6.2 B 11/8/2001 1,1,2-Trichloroethane 1.3 11/8/2001 Trichloroethylene (TCE) 618 11/8/2001 Chloroform 0.79 1/3/2002 cis-1,2-Dichloroethylene 38.2 1/3/2002 1,1,2-Trichloroethane 1.1 1/3/2002 Chloroform 0.91 1/3/2002 Trichloroethylene (TCE) 419 1/10/2002 cis-1,2-Dichloroethylene 40.8 M 1/10/2002 Trichloroethylene (TCE) 479 M 1/17/2002 cis-1,2-Dichloroethylene 39.4 1/17/2002 Trichloroethylene (TCE) 536 1/31/2002 cis-1,2-Dichloroethylene 52.5 1/31/2002 1,1,2-Trichloroethane 1.4 1/31/2002 Chloroform 1.4 B 1/31/2002 Trichloroethylene (TCE) 518 B 2/14/2002 cis-1,2-Dichloroethylene 35.1 2/14/2002 Chloroform 1.1 B 2/14/2002 Trichloroethylene (TCE) 521 3/14/2002 cis-1,2-Dichloroethylene 38.6 M 3/14/2002 Trichloroethylene (TCE) 653 M 4/18/2002 cis-1,2-Dichloroethylene 35.2 M 4/18/2002 Trichloroethylene (TCE) 543 M 5/16/2002 cis-1,2-Dichloroethylene 31.7 M 5/16/2002 Trichloroethylene (TCE) 442 J 6/13/2002 cis-1,2-Dichloroethylene 35.7 6/13/2002 Trichloroethylene (TCE) 485 M 10/9/2002 cis-1,2-Dichloroethylene 22.5 10/9/2002 Trichloroethylene (TCE) 281 8/27/2004 Chloroform 0.46 8/27/2004 Trichloroethylene (TCE) 171 8/27/2004 cis-1,2-Dichloroethylene 14.6 NZ-56 4/28/1999 Chloroform 1.2 4/18/2000 Trichloroethylene (TCE) 4.7 B 10/18/2000 Trichloroethylene (TCE) 31.9 5/5/2001 Trichloroethylene (TCE) 87.7 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 19 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

5/5/2001 cis-1,2-Dichloroethylene 5.6 5/5/2001 Chloroform 0.45 7/18/2001 cis-1,2-Dichloroethylene 9.4 7/18/2001 Dichlorodifluoromethane 1.6 7/18/2001 Chloroform 0.51 B 7/18/2001 Trichloroethylene (TCE) 194 11/8/2001 Trichloroethylene (TCE) 289 11/8/2001 Chloroform 0.41 11/8/2001 cis-1,2-Dichloroethylene 12.9 4/29/2002 Benzene 3.4 B 4/29/2002 Toluene 13.6 B 4/29/2002 cis-1,2-Dichloroethylene 30.8 4/29/2002 Ethylbenzene 6.1 B 4/29/2002 Isopropylbenzene (Cumene) 0.7 B 4/29/2002 Naphthalene 0.68 B 4/29/2002 N-propylbenzene 1.1 B 4/29/2002 Chloroform 0.9 4/29/2002 1,2,4-Trimethylbenzene 6.1 B 4/29/2002 1,3,5-trimethylbenzene 2.5 B 4/29/2002 m,p-Xylene 26.2 B 4/29/2002 o-Xylene 6.5 B 4/29/2002 Trichloroethylene (TCE) 415 10/14/2002 cis-1,2-Dichloroethylene 12.7 10/14/2002 Trichloroethylene (TCE) 200 10/14/2002 Chloroform 0.43 10/7/2003 Benzene 0.47 B 10/7/2003 cis-1,2-Dichloroethylene 45.7 10/7/2003 1,1,2-Trichloroethane 1.7 10/7/2003 Chloroform 0.68 10/7/2003 m,p-Xylene 1.8 B 10/7/2003 Trichloroethylene (TCE) 509 5/10/2004 cis-1,2-Dichloroethylene 13.1 5/10/2004 Trichloroethylene (TCE) 170 11/4/2004 cis-1,2-Dichloroethylene 6.1 11/4/2004 Trichloroethylene (TCE) 78.4 NZ-57 6/21/2003 Benzene 0.81 B 6/21/2003 Isopropylbenzene (Cumene) 1.2 B 6/21/2003 N-propylbenzene 1.5 B 8/19/2003 Sec-butylbenzene 1.4 8/19/2003 Ethylbenzene 1.1 8/19/2003 Isopropylbenzene (Cumene) 1.3 8/19/2003 N-propylbenzene 1.5 8/19/2003 1,2,4-Trimethylbenzene 5.6 8/19/2003 1,3,5-trimethylbenzene 3 8/19/2003 m,p-Xylene 3.8 NZ-58 4/28/1999 Trichloroethylene (TCE) 1 M 4/28/1999 Chloroform 0.7 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 20 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/23/2001 Trichloroethylene (TCE) 0.81 4/18/2002 Trichloroethylene (TCE) 0.96 M 12/17/2002 Trichloroethylene (TCE) 0.71 6/22/2003 Trichloroethylene (TCE) 0.56 8/20/2003 Trichloroethylene (TCE) 0.61 12/11/2003 Trichloroethylene (TCE) 0.74 4/16/2004 Trichloroethylene (TCE) 0.73 7/14/2004 Trichloroethylene (TCE) 0.82 10/14/2004 Trichloroethylene (TCE) 0.92 12/15/2004 Trichloroethylene (TCE) 1.1 NZ-59 4/12/2000 Chloroform 0.63 11/2/2001 Chloroform 0.58 5/7/2002 Chloroform 0.57 NZ-60 4/29/1999 Chloroform 0.96 B 11/9/1999 Methylene chloride 3 B 12/18/2002 Methylene chloride 13.2 NZ-61 12/18/2002 Methylene chloride 15.2 NZ-62 12/18/2002 Methylene chloride 16.6 NZ-63 4/19/2000 Chloroform 0.79 NZ-66 4/19/2000 Chloroform 0.94 NZ-67 5/7/1999 cis-1,2-Dichloroethylene 6.3 5/7/1999 Trichloroethylene (TCE) 324 M 5/7/1999 Chloroform 1.2 B 11/5/1999 cis-1,2-Dichloroethylene 10.9 11/5/1999 Chloroform 0.9 11/5/1999 Trichloroethylene (TCE) 411 4/5/2000 cis-1,2-Dichloroethylene 16.8 J 4/5/2000 Chloroform 1 J 4/5/2000 Trichloroethylene (TCE) 425 10/4/2000 cis-1,2-Dichloroethylene 14.7 10/4/2000 Chloroform 0.96 10/4/2000 Trichloroethylene (TCE) 580 M 4/20/2001 cis-1,2-Dichloroethylene 12.4 4/20/2001 Chloroform 1.1 4/20/2001 Trichloroethylene (TCE) 337 11/7/2001 Benzene 0.51 11/7/2001 cis-1,2-Dichloroethylene 9.1 11/7/2001 Trichloroethylene (TCE) 303 11/7/2001 Chloroform 0.77 11/7/2001 m,p-Xylene 2 B 5/1/2002 Trichloroethylene (TCE) 206 5/1/2002 Benzene 1.6 B 5/1/2002 Toluene 6.7 B 5/1/2002 cis-1,2-Dichloroethylene 7.4 5/1/2002 Ethylbenzene 4.1 B 5/1/2002 Isopropylbenzene (Cumene) 0.7 B 5/1/2002 Naphthalene 0.86 B TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 21 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

5/1/2002 N-propylbenzene 0.93 B 5/1/2002 Chloroform 0.65 5/1/2002 1,2,4-Trimethylbenzene 4.7 B 5/1/2002 1,3,5-trimethylbenzene 1.9 B 5/1/2002 m,p-Xylene 16.5 B 5/1/2002 o-Xylene 4.8 B 10/15/2002 cis-1,2-Dichloroethylene 5.3 10/15/2002 Chloroform 0.56 10/15/2002 Trichloroethylene (TCE) 218 10/6/2003 Trichloroethylene (TCE) 299 5/7/2004 cis-1,2-Dichloroethylene 1.9 5/7/2004 Trichloroethylene (TCE) 138 11/3/2004 Benzene 0.66 11/3/2004 cis-1,2-Dichloroethylene 4.4 11/3/2004 M,P-XYLENE 2.6 B 11/3/2004 Trichloroethylene (TCE) 224 NZ-68 5/3/1999 1,1-Dichloroethane 0.58 5/3/1999 Trichloroethylene (TCE) 13.2 M 5/3/1999 Chloroform 0.75 B 5/6/2000 Trichloroethylene (TCE) 6 5/5/2001 Trichloroethylene (TCE) 4.5 B 5/5/2001 Chloroform 0.4 B 10/31/2001 Trichloroethylene (TCE) 2.9 10/31/2001 m,p-Xylene 1.4 5/6/2002 Trichloroethylene (TCE) 2.7 9/24/2003 Trichloroethylene (TCE) 1.6 4/27/2004 Trichloroethylene (TCE) 2.3 4/27/2004 Chloroform 0.37 10/29/2004 Trichloroethylene (TCE) 2.9 10/29/2004 Chloroform 0.37 NZ-69 4/27/2000 Trichloroethylene (TCE) 17.1 10/31/2001 Trichloroethylene (TCE) 16.2 4/19/2002 Trichloroethylene (TCE) 18.3 9/17/2003 Trichloroethylene (TCE) 3.7 4/23/2004 Trichloroethylene (TCE) 0.93 4/23/2004 Chloroform 0.88 10/26/2004 Chloroform 0.9 NZ-70 4/27/1999 Trichloroethylene (TCE) 15.2 M 11/3/1999 Trichloroethylene (TCE) 12.8 R 4/4/2000 Trichloroethylene (TCE) 14.9 10/6/2000 Trichloroethylene (TCE) 13.2 4/20/2001 Trichloroethylene (TCE) 15.3 10/23/2001 Trichloroethylene (TCE) 9.9 4/19/2002 Trichloroethylene (TCE) 14.7 9/19/2003 Trichloroethylene (TCE) 3.1 4/23/2004 Chloroform 0.93 10/26/2004 Chloroform 1.1 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 22 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

NZ-71 9/22/2003 Trichloroethylene (TCE) 1.7 4/23/2004 Trichloroethylene (TCE) 0.6 10/26/2004 Chloroform 0.52 NZ-72 1/14/2000 Trichlorofluoromethane 2.1 1/14/2000 Dichlorodifluoromethane 2.8 B 12/17/2001 m,p-Xylene 0.51 7/15/2002 m,p-Xylene 1.3 B NZ-73 4/23/1999 Trichloroethylene (TCE) 31.4 M 9/25/1999 Trichloroethylene (TCE) 27.2 11/1/1999 Trichloroethylene (TCE) 17.6 R 1/14/2000 1,1-Dichloroethene 1.8 1/14/2000 Trichlorofluoromethane 2.1 1/14/2000 Dichlorodifluoromethane 2.6 B 1/14/2000 Trichloroethylene (TCE) 19.7 4/6/2000 Trichloroethylene (TCE) 11.4 7/20/2000 Trichloroethylene (TCE) 19.1 10/3/2000 Trichloroethylene (TCE) 12.3 10/3/2000 Chloroform 0.45 12/4/2000 Trichloroethylene (TCE) 9.5 4/25/2001 Trichloroethylene (TCE) 9 7/16/2001 Trichloroethylene (TCE) 10.7 10/31/2001 Trichloroethylene (TCE) 9 12/19/2001 Benzene 0.4 12/19/2001 Trichloroethylene (TCE) 11.5 5/3/2002 Trichloroethylene (TCE) 8 7/16/2002 Trichloroethylene (TCE) 3.5 10/10/2002 Trichloroethylene (TCE) 1.5 12/17/2002 Trichloroethylene (TCE) 2.1 9/16/2003 Trichloroethylene (TCE) 1.5 12/9/2003 Trichloroethylene (TCE) 1.6 4/20/2004 Trichloroethylene (TCE) 2.3 7/15/2004 Trichloroethylene (TCE) 3 10/18/2004 Trichloroethylene (TCE) 3.7 12/14/2004 Trichloroethylene (TCE) 4.5 NZ-74 4/25/2002 Methylene chloride 3.7 B NZ-75 5/7/1999 1,1-Dichloroethane 0.56 5/7/1999 Trichloroethylene (TCE) 41.9 M 5/7/1999 Chloroform 1.8 B 4/25/2000 Trichloroethylene (TCE) 32 4/25/2000 Chloroform 1.3 10/6/2003 Trichloroethylene (TCE) 58.8 10/6/2003 Chloroform 0.59 5/10/2004 Trichloroethylene (TCE) 31 11/3/2004 Trichloroethylene (TCE) 51.4 11/3/2004 M,P-XYLENE 0.62 B NZ-76 1/14/2000 Dichlorodifluoromethane 2.4 B 7/15/2002 m,p-Xylene 0.75 B TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 23 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/20/2004 Trichloroethylene (TCE) 2.7 7/15/2004 Trichloroethylene (TCE) 4.2 10/18/2004 Trichloroethylene (TCE) 0.75 12/14/2004 Trichloroethylene (TCE) 5.4 NZ-77 9/24/1999 Methylene chloride 0.366 7/16/2002 m,p-Xylene 0.69 NZ-79 9/17/2003 Chloroform 1.4 4/19/2004 Chloroform 1.2 NZ-80 4/11/2000 Tetrachloroethylene (PCE) 2.2 4/11/2000 Trichloroethylene (TCE) 3 5/5/2001 Trichloroethylene (TCE) 1.9 10/31/2001 Tetrachloroethylene (PCE) 1.8 10/31/2001 Trichloroethylene (TCE) 2.2 5/2/2002 Tetrachloroethylene (PCE) 1.6 5/2/2002 Trichloroethylene (TCE) 1.9 10/8/2002 Trichloroethylene (TCE) 1.3 9/22/2003 Trichloroethylene (TCE) 1.1 4/22/2004 Trichloroethylene (TCE) 1.6 10/25/2004 Trichloroethylene (TCE) 1.7 NZ-81 7/17/2000 Dichlorodifluoromethane 1.1 10/12/2000 Dichlorodifluoromethane 2.2 4/26/2001 Dichlorodifluoromethane 2.5 4/26/2001 Trichloroethylene (TCE) 6.4 11/6/2001 Dichlorodifluoromethane 2.1 11/6/2001 Trichloroethylene (TCE) 24.9 4/29/2002 Trichloroethylene (TCE) 94.4 4/29/2002 Benzene 10.6 B 4/29/2002 Toluene 39.1 B 4/29/2002 cis-1,2-Dichloroethylene 3 4/29/2002 Ethylbenzene 14.1 B 4/29/2002 Dichlorodifluoromethane 3.1 R 4/29/2002 Isopropylbenzene (Cumene) 1.4 B 4/29/2002 Naphthalene 1.4 B 4/29/2002 N-propylbenzene 1.7 B 4/29/2002 Chloroform 0.41 4/29/2002 1,2,4-Trimethylbenzene 10.6 B 4/29/2002 1,3,5-trimethylbenzene 4 B 4/29/2002 m,p-Xylene 56.1 B 4/29/2002 o-Xylene 16.7 B 10/17/2002 cis-1,2-Dichloroethylene 2.9 10/17/2002 Dichlorodifluoromethane 1.2 10/17/2002 Trichloroethylene (TCE) 68 10/17/2002 Chloroform 0.3 10/2/2003 cis-1,2-Dichloroethylene 3.7 10/2/2003 Trichloroethylene (TCE) 105 M 5/5/2004 Trichloroethylene (TCE) 40.4 11/11/2004 Trichloroethylene (TCE) 36 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 24 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

NZ-82 7/17/2000 Dichlorodifluoromethane 1.1 7/17/2000 Trichloroethylene (TCE) 137 10/12/2000 Trichloroethylene (TCE) 174 M 4/26/2001 Chloroform 0.84 J 4/26/2001 Trichloroethylene (TCE) 238 J 11/7/2001 cis-1,2-Dichloroethylene 34.6 11/7/2001 Trichloroethylene (TCE) 530 11/7/2001 Chloroform 1.2 5/1/2002 Trichloroethylene (TCE) 474 5/1/2002 Benzene 1 B 5/1/2002 Toluene 3.8 B 5/1/2002 cis-1,2-Dichloroethylene 47.4 5/1/2002 Ethylbenzene 2.4 B 5/1/2002 Naphthalene 0.64 B 5/1/2002 N-propylbenzene 0.64 B 5/1/2002 Chloroform 1.3 5/1/2002 1,2,4-Trimethylbenzene 3.3 B 5/1/2002 1,3,5-trimethylbenzene 1.3 B 5/1/2002 m,p-Xylene 9.9 B 5/1/2002 o-Xylene 2.8 B 10/16/2002 cis-1,2-Dichloroethylene 39.9 10/16/2002 Chloroform 0.68 10/16/2002 Trichloroethylene (TCE) 587 10/7/2003 cis-1,2-Dichloroethylene 28.2 10/7/2003 Chloroform 0.67 10/7/2003 Trichloroethylene (TCE) 572 5/10/2004 cis-1,2-Dichloroethylene 19.6 5/10/2004 Trichloroethylene (TCE) 57.5 J 5/10/2004 Chloroform 0.34 8/25/2004 cis-1,2-Dichloroethylene 10.1 8/25/2004 TRANS-1,2-DICHLOROETHENE 0.66 8/25/2004 Trichloroethylene (TCE) 162 8/25/2004 Benzene 0.78 8/25/2004 Toluene 1.6 8/25/2004 Styrene 1.9 8/25/2004 M,P-XYLENE 0.79 NZ-83 7/17/2000 cis-1,2-Dichloroethylene 8.7 7/17/2000 Chloroform 0.58 7/17/2000 Trichloroethylene (TCE) 210 10/12/2000 cis-1,2-Dichloroethylene 20.4 M 10/12/2000 Methylene chloride 21 10/12/2000 Chloroform 0.9 10/12/2000 Trichloroethylene (TCE) 383 M 4/26/2001 cis-1,2-Dichloroethylene 1.2 J 4/26/2001 Chloroform 1.3 J 4/26/2001 Trichloroethylene (TCE) 412 J 11/7/2001 cis-1,2-Dichloroethylene 24 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 25 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

11/7/2001 Trichloroethylene (TCE) 436 11/7/2001 Chloroform 0.9 5/1/2002 Trichloroethylene (TCE) 267 5/1/2002 Benzene 1 B 5/1/2002 Toluene 4 B 5/1/2002 cis-1,2-Dichloroethylene 20.9 5/1/2002 Ethylbenzene 2.6 B 5/1/2002 Naphthalene 0.58 B 5/1/2002 N-propylbenzene 0.69 B 5/1/2002 Chloroform 0.78 5/1/2002 1,2,4-Trimethylbenzene 3.3 B 5/1/2002 1,3,5-trimethylbenzene 1.3 B 5/1/2002 m,p-Xylene 10.7 B 5/1/2002 o-Xylene 3 B 10/16/2002 Trichloroethylene (TCE) 202 J 10/16/2002 cis-1,2-Dichloroethylene 10.6 J 10/16/2002 Chloroform 0.51 J 10/7/2003 cis-1,2-Dichloroethylene 10.2 10/7/2003 m,p-Xylene 1 B 10/7/2003 Trichloroethylene (TCE) 285 5/10/2004 cis-1,2-Dichloroethylene 2.3 5/10/2004 Trichloroethylene (TCE) 101 8/26/2004 cis-1,2-Dichloroethylene 4.5 8/26/2004 Chloroform 0.36 8/26/2004 Trichloroethylene (TCE) 190 M NZ-84 7/17/2000 Trichloroethylene (TCE) 6.3 10/9/2000 Trichloroethylene (TCE) 5.5 4/23/2001 Trichloroethylene (TCE) 5.7 10/22/2001 Trichloroethylene (TCE) 5.1 4/18/2002 Trichloroethylene (TCE) 10.1 M 12/17/2002 Trichloroethylene (TCE) 2.7 8/20/2003 Trichloroethylene (TCE) 9.8 12/11/2003 Trichloroethylene (TCE) 14.6 4/19/2004 Trichloroethylene (TCE) 19.6 7/14/2004 Trichloroethylene (TCE) 17.5 7/14/2004 Chloroform 0.4 10/14/2004 Trichloroethylene (TCE) 23.9 12/13/2004 Trichloroethylene (TCE) 26.4 NZ-85 7/18/2000 Trichloroethylene (TCE) 1.3 10/12/2000 Trichloroethylene (TCE) 2 M 4/26/2001 Trichloroethylene (TCE) 2.2 11/8/2001 Trichloroethylene (TCE) 1.8 5/7/2002 Trichloroethylene (TCE) 2.6 12/16/2002 Trichloroethylene (TCE) 0.64 6/21/2003 Benzene 0.42 B 6/21/2003 Trichloroethylene (TCE) 0.81 8/19/2003 Isopropylbenzene (Cumene) 0.76 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 26 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

8/19/2003 Trichloroethylene (TCE) 0.86 8/19/2003 m,p-Xylene 0.55 12/10/2003 Trichloroethylene (TCE) 0.87 4/16/2004 Trichloroethylene (TCE) 0.78 10/13/2004 Trichloroethylene (TCE) 1.1 12/15/2004 Trichloroethylene (TCE) 1.2 NZ-86 6/21/2003 Benzene 0.48 B 6/21/2003 Isopropylbenzene (Cumene) 1.2 B 8/19/2003 Isopropylbenzene (Cumene) 0.76 8/19/2003 m,p-Xylene 0.62 7/14/2004 Trichloroethylene (TCE) 0.86 NZ-92 1/30/2001 Trichloroethylene (TCE) 16.6 NZ-93 10/19/2001 Methylene chloride 4.7 M 10/19/2001 Trichloroethylene (TCE) 7.2 4/17/2002 Trichloroethylene (TCE) 19.7 10/1/2002 Trichloroethylene (TCE) 17.6 9/29/2003 Trichloroethylene (TCE) 27.7 4/30/2004 Trichloroethylene (TCE) 32.7 11/4/2004 Trichloroethylene (TCE) 31.3 NZ-94 5/5/2001 Trichloroethylene (TCE) 20.5 B 5/5/2001 Chloroform 0.42 B 10/31/2001 Trichloroethylene (TCE) 8.2 10/31/2001 Chloroform 0.37 5/6/2002 Trichloroethylene (TCE) 8.4 10/17/2002 Trichloroethylene (TCE) 7.7 10/17/2002 Chloroform 0.42 10/2/2003 1,1-Dichloroethane 0.64 10/2/2003 Trichloroethylene (TCE) 13.3 M 5/4/2004 Trichloroethylene (TCE) 10.5 11/11/2004 1,1-DICHLOROETHANE 0.74 11/11/2004 Trichloroethylene (TCE) 7.8 NZ-95 5/4/2001 Chloroform 0.4 5/7/2002 Benzene 0.66 B 5/7/2002 Toluene 3.5 B 5/7/2002 Ethylbenzene 2.1 B 5/7/2002 N-propylbenzene 0.42 B 5/7/2002 Trichloroethylene (TCE) 1.9 B 5/7/2002 Chloroform 0.43 B 5/7/2002 1,2,4-Trimethylbenzene 2.2 B 5/7/2002 1,3,5-trimethylbenzene 1 B 5/7/2002 m,p-Xylene 9.1 B 5/7/2002 o-Xylene 2.4 B 10/18/2002 Trichloroethylene (TCE) 0.66 4/26/2004 Trichloroethylene (TCE) 0.51 10/27/2004 Trichloroethylene (TCE) 0.68 NZ-96 5/5/2001 1,1-Dichloroethane 0.63 5/5/2001 Trichloroethylene (TCE) 11.1 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 27 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

5/5/2001 Chloroform 1 B 10/31/2001 1,1-Dichloroethane 0.55 10/31/2001 Trichloroethylene (TCE) 5.1 10/31/2001 Chloroform 1.1 5/6/2002 1,1-Dichloroethane 0.46 5/6/2002 Trichloroethylene (TCE) 4.3 5/6/2002 Chloroform 0.91 9/24/2003 1,1-Dichloroethane 0.41 9/24/2003 Trichloroethylene (TCE) 2.9 9/24/2003 Chloroform 0.63 4/27/2004 1,1-DICHLOROETHANE 0.84 4/27/2004 Trichloroethylene (TCE) 5.5 4/27/2004 Chloroform 0.66 10/29/2004 1,1-DICHLOROETHANE 2.3 10/29/2004 1,1-DICHLOROETHENE 2.3 10/29/2004 Trichloroethylene (TCE) 6 10/29/2004 Chloroform 0.5 NZ-97 10/19/2001 Methylene chloride 4.6 M NZ-98 2/6/2001 Chloroform 0.48 4/30/2002 Benzene 2.9 B 4/30/2002 Toluene 11.5 B 4/30/2002 Ethylbenzene 6.2 B 4/30/2002 Isopropylbenzene (Cumene) 0.9 B 4/30/2002 Naphthalene 1.4 B 4/30/2002 N-propylbenzene 1.2 B 4/30/2002 Trichloroethylene (TCE) 2.7 B 4/30/2002 1,2,4-Trimethylbenzene 6.6 B 4/30/2002 1,3,5-trimethylbenzene 2.6 B 4/30/2002 m,p-Xylene 24.9 B 4/30/2002 o-Xylene 7.6 B NZ-99 1/22/2001 Trichloroethylene (TCE) 5 3/8/2001 Trichloroethylene (TCE) 9.8 11/7/2001 Ethylbenzene 0.6 11/7/2001 Naphthalene 0.4 R 11/7/2001 Trichloroethylene (TCE) 10.1 11/7/2001 1,2,4-Trimethylbenzene 3.3 B 11/7/2001 1,3,5-trimethylbenzene 1.7 J 11/7/2001 m,p-Xylene 9.5 B 11/7/2001 o-Xylene 2.6 J 4/30/2002 Isopropylbenzene (Cumene) 1.1 B 4/30/2002 Naphthalene 1.6 B 4/30/2002 N-propylbenzene 1.4 B 4/30/2002 Trichloroethylene (TCE) 17.3 B 4/30/2002 1,2,4-Trimethylbenzene 7.8 B 4/30/2002 1,3,5-trimethylbenzene 3 B 4/30/2002 m,p-Xylene 31.1 B 4/30/2002 o-Xylene 9.9 B TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 28 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/30/2002 Benzene 4 B 4/30/2002 Toluene 15.4 B 4/30/2002 Ethylbenzene 7.9 B 10/15/2002 Trichloroethylene (TCE) 14.4 9/29/2003 Trichloroethylene (TCE) 26.6 4/30/2004 Trichloroethylene (TCE) 24 11/3/2004 Trichloroethylene (TCE) 25.3 NZ-100 3/7/2001 Toluene 13.9 10/15/2001 Toluene 1.1 10/15/2001 Vinyl chloride 0.79 NZ-101 5/23/2001 Trichloroethylene (TCE) 49.6 7/19/2001 cis-1,2-Dichloroethylene 5.2 7/19/2001 Chloroform 0.81 B 7/19/2001 Trichloroethylene (TCE) 191 11/6/2001 cis-1,2-Dichloroethylene 4.6 11/6/2001 Trichloroethylene (TCE) 176 11/6/2001 Chloroform 0.66 5/10/2002 cis-1,2-Dichloroethylene 5.1 5/10/2002 Chloroform 0.96 5/10/2002 Trichloroethylene (TCE) 223 10/1/2003 cis-1,2-Dichloroethylene 1.2 10/1/2003 Chloroform 0.44 10/1/2003 Trichloroethylene (TCE) 109 5/7/2004 Trichloroethylene (TCE) 75.4 11/4/2004 Trichloroethylene (TCE) 98.5 NZ-102 5/30/2001 cis-1,2-Dichloroethylene 7 5/30/2001 Trichloroethylene (TCE) 259 5/30/2001 Chloroform 0.94 7/19/2001 Trichloroethylene (TCE) 239 7/19/2001 cis-1,2-Dichloroethylene 6.6 7/19/2001 Chloroform 0.83 B 11/6/2001 cis-1,2-Dichloroethylene 5.5 11/6/2001 Trichloroethylene (TCE) 225 11/6/2001 Chloroform 0.69 5/10/2002 cis-1,2-Dichloroethylene 5.8 5/10/2002 Chloroform 0.89 5/10/2002 Trichloroethylene (TCE) 274 10/14/2002 cis-1,2-Dichloroethylene 3.9 10/14/2002 Trichloroethylene (TCE) 193 10/14/2002 Chloroform 0.63 10/2/2003 Trichloroethylene (TCE) 256 M 5/7/2004 Trichloroethylene (TCE) 124 11/4/2004 cis-1,2-Dichloroethylene 2.4 11/4/2004 Trichloroethylene (TCE) 147 NZ-103 6/8/2001 Trichloroethylene (TCE) 19.3 6/8/2001 Chloroform 1.5 6/25/2001 Trichloroethylene (TCE) 2.9 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 29 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

7/19/2001 cis-1,2-Dichloroethylene 1.6 7/19/2001 Chloroform 0.92 B 7/19/2001 Trichloroethylene (TCE) 102 11/6/2001 cis-1,2-Dichloroethylene 1.3 11/6/2001 Trichloroethylene (TCE) 75.2 11/6/2001 Chloroform 0.75 5/10/2002 Chloroform 1 5/10/2002 Trichloroethylene (TCE) 90.9 6/14/2003 Chloroform 0.57 J 6/14/2003 Trichloroethylene (TCE) 68.8 10/6/2003 Chloroform 0.34 10/6/2003 Trichloroethylene (TCE) 134 5/6/2004 Trichloroethylene (TCE) 50.7 11/4/2004 Trichloroethylene (TCE) 73.1 NZ-104 6/5/2001 Trichloroethylene (TCE) 16.5 7/19/2001 Chloroform 0.39 B 7/19/2001 Trichloroethylene (TCE) 65.1 11/7/2001 Trichloroethylene (TCE) 93.4 11/7/2001 Chloroform 0.41 4/30/2002 Benzene 1.8 B 4/30/2002 Toluene 6.7 B 4/30/2002 Ethylbenzene 4 B 4/30/2002 Isopropylbenzene (Cumene) 0.63 B 4/30/2002 Naphthalene 0.84 B 4/30/2002 N-propylbenzene 0.92 B 4/30/2002 1,2,4-Trimethylbenzene 4.7 B 4/30/2002 1,3,5-trimethylbenzene 1.8 B 4/30/2002 m,p-Xylene 16.2 B 4/30/2002 o-Xylene 4.8 B 4/30/2002 Trichloroethylene (TCE) 84.7 10/15/2002 Trichloroethylene (TCE) 49.8 10/1/2003 Trichloroethylene (TCE) 17.8 5/4/2004 Trichloroethylene (TCE) 18.3 11/11/2004 Trichloroethylene (TCE) 14.1 NZ-105 7/19/2001 Trichloroethylene (TCE) 1.4 8/9/2001 Trichloroethylene (TCE) 42.6 M 8/9/2001 Chloroform 0.39 B 11/6/2001 Trichloroethylene (TCE) 39.1 11/6/2001 Chloroform 0.39 5/9/2002 Trichloroethylene (TCE) 44.9 5/9/2002 Chloroform 0.51 10/14/2002 Trichloroethylene (TCE) 27.2 10/14/2002 Chloroform 0.31 6/14/2003 Trichloroethylene (TCE) 21 NZ-105R 11/26/2003 Trichloroethylene (TCE) 11.6 5/6/2004 Trichloroethylene (TCE) 6.2 11/12/2004 Trichloroethylene (TCE) 7.4 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 30 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

NZ-106 11/6/2002 cis-1,2-Dichloroethylene 6.1 11/6/2002 Trichloroethylene (TCE) 99.8 11/6/2002 Chloroform 0.43 12/20/2002 Bromoform 1.3 12/20/2002 Trichloroethylene (TCE) 37.2 12/20/2002 Benzene 14.5 12/20/2002 cis-1,2-Dichloroethylene 1.3 6/22/2003 Trichloroethylene (TCE) 11.6 8/20/2003 Trichloroethylene (TCE) 9.9 12/10/2003 Trichloroethylene (TCE) 8.9 4/16/2004 Trichloroethylene (TCE) 6.8 7/14/2004 Trichloroethylene (TCE) 7.6 7/14/2004 Chloroform 0.34 10/14/2004 Trichloroethylene (TCE) 9.5 12/15/2004 Trichloroethylene (TCE) 13.8 NZ-107 12/19/2002 Trichloroethylene (TCE) 1.4 6/22/2003 Trichloroethylene (TCE) 1.3 8/20/2003 Isopropylbenzene (Cumene) 0.76 8/20/2003 Trichloroethylene (TCE) 1.5 12/9/2003 Trichloroethylene (TCE) 2.6 4/16/2004 Trichloroethylene (TCE) 3 7/14/2004 Trichloroethylene (TCE) 4.3 10/12/2004 Trichloroethylene (TCE) 7.3 12/15/2004 Trichloroethylene (TCE) 9.6 NZ-108 12/19/2002 Dibromochloromethane 1.6 12/19/2002 Bromoform 3.7 NZ-109 2/13/2003 Trichloroethylene (TCE) 0.96 2/13/2003 m,p-Xylene 0.57 NZ-111 2/18/2003 Dibromochloromethane 4.7 2/18/2003 Bromoform 9.8 2/18/2003 Trichloroethylene (TCE) 7.5 NZ-112 3/11/2003 Trichloroethylene (TCE) 1.2 5/1/2003 Methylene chloride 7.7 R 5/1/2003 Tetrachloroethylene (PCE) 2.2 5/1/2003 Trichloroethylene (TCE) 2.7 9/19/2003 Tetrachloroethylene (PCE) 2.4 9/19/2003 Trichloroethylene (TCE) 2 4/22/2004 Tetrachloroethylene (PCE) 2.6 4/22/2004 Trichloroethylene (TCE) 2.4 10/25/2004 Tetrachloroethylene (PCE) 2.6 10/25/2004 Trichloroethylene (TCE) 2.5 NZ-113 5/1/2003 Methylene chloride 6.1 R 4/22/2004 Tetrachloroethylene (PCE) 1.4 4/22/2004 Trichloroethylene (TCE) 0.76 10/25/2004 Tetrachloroethylene (PCE) 1.4 10/25/2004 Trichloroethylene (TCE) 0.72 NZ-114 3/13/2003 Trichloroethylene (TCE) 1.4 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 31 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

3/13/2003 Chloroform 0.6 5/1/2003 Methylene chloride 7.5 R 5/1/2003 Chloroform 1.3 9/17/2003 Chloroform 0.91 4/21/2004 Chloroform 0.6 NZ-115 3/13/2003 Chloroform 1 5/1/2003 Chloroform 1.2 9/17/2003 Chloroform 1.2 4/21/2004 Chloroform 0.5 NZ-116 3/14/2003 1,1-Dichloroethane 1.3 3/14/2003 1,1-Dichloroethene 1.4 3/14/2003 Trichloroethylene (TCE) 6.2 3/14/2003 Chloroform 0.38 5/2/2003 1,1-Dichloroethane 1.7 5/2/2003 1,1-Dichloroethene 1.9 5/2/2003 Trichloroethylene (TCE) 17.4 5/2/2003 Chloroform 0.64 9/24/2003 1,1-Dichloroethane 1.2 9/24/2003 1,1-Dichloroethene 1.6 9/24/2003 Trichloroethylene (TCE) 16.2 9/24/2003 Chloroform 0.46 4/27/2004 1,1-DICHLOROETHANE 1.8 4/27/2004 1,1-DICHLOROETHENE 2.1 4/27/2004 Trichloroethylene (TCE) 12.9 4/27/2004 Chloroform 0.5 10/29/2004 1,1-DICHLOROETHANE 3.7 10/29/2004 1,1-DICHLOROETHENE 3.6 10/29/2004 Trichloroethylene (TCE) 8.9 10/29/2004 Chloroform 0.46 SP1 11/4/2004 Chloroform 0.3 SP2 11/4/2004 Chloroform 0.41 SP3 11/4/2004 Chloroform 0.61 SP4 11/4/2004 Chloroform 0.5 SZ-10 11/11/1999 Benzene 0.67 WZ-04 4/30/2001 Naphthalene 0.96 M WZ-06 4/17/2000 Toluene 1.5 4/17/2000 Benzene 0.72 4/17/2000 Toluene 3.2 4/17/2000 m,p-Xylene 2.4 4/17/2000 o-Xylene 1.8 4/17/2000 Benzene 18.8 4/17/2000 Toluene 60.5 4/17/2000 Ethylbenzene 12.2 J 4/17/2000 Isopropylbenzene (Cumene) 2.1 4/17/2000 N-propylbenzene 1.5 4/17/2000 1,2,4-Trimethylbenzene 1.9 4/17/2000 1,3,5-trimethylbenzene 4.6 TABLE 4-4

DETECTED VOLATILE ORGANIC COMPOUNDS JANUARY 1999 THROUGH DECEMBER 2004 FORMER GEORGE AIR FORCE BASE, CALIFORNIA

(Page 32 of 32)

Result Well ID Sample Date Compound (µg/L) Flag

4/17/2000 m,p-Xylene 47.1 4/17/2000 o-Xylene 28.4

Notes: µg/L - micrograms per liter B - The compound was found in an associated blank as well as in the sample. J - Estimated concentration M - Results of associated quality control indicates possible matrix interference. R - Data are rejected due to quality control non-conformance. APPENDIX A

DOCUMENT LIST Five-Year Review Report Former George Air Force Base

LIST OF DOCUMENTS REVIEWED

Boyle, 1987. Alter Base Water Supply, George Air Force Base, Victorville, California, Well Field Analysis. San Bernardino, California.

Department of Toxic Substances Control (DTSC), 2003. Memo from Patty W. Wong-Yim, Ph.D, Staff Toxicologist, Human and Ecological Risk Division: Trichloroethylene Toxicity Criteria for Use at California Military Sites. 19 February.

DTSC, 2004. Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air. California. December.

HydroGeoLogic, 1998. Final Basewide Sampling and Analysis Plan, George Air Force Base. August.

International Technology Corporation (IT), 1995. Final Remedial Investigation/Feasibility Study, OU 3 TCE/PCE Study Area, George Air Force Base. San Bernardino, California. January.

IT, 1999. Draft Feasibility Study Report, Operable Unit 2, George Air Force Base. San Bernardino, California. January.

James M. Montgomery Consulting Engineers Inc. (JMM), 1992. Remedial Investigation, Operable Unit 1, George Air Force Base. Walnut Creek, California.

LUFT Task Force, State of California, 1989. Leaking Underground Fuel Tank Manual: Guidelines for Site Assessment, Cleanup, and Underground Storage Tank Closure. October.

Malcolm Pirnie, 2005. Final Site WP-17 Closure Report, George Air Force Base, California. Emeryville, California. April.

Mojave Basin Watermaster, 2005. Eleventh Annual Report of the Mojave Basin Area Watermaster, Water Year 2003-04. 1 April.

Mojave Water Agency (MWA), 2004. 2004 Regional Water Management Plan. September.

Montgomery Watson, 1994. Operable Unit 1 Record of Decision, George Air Force Base. Walnut Creek, California. March.

Montgomery Watson, 1996. Final Remedial Investigation Report, Operable Unit 3, George Air Force Base, California. Walnut Creek, California. April.

Montgomery Watson, 1996. Bioventing and Soil Vapor Extraction Operations and Maintenance Manual, George Air Force Base, California. Walnut Creek, California. February. Five-Year Review Report Former George Air Force Base

LIST OF DOCUMENTS REVIEWED (continued)

Montgomery Watson, 1998. Final Operable Unit 3 Record of Decision, George Air Force Base, California. Walnut Creek, California. November.

Montgomery Watson, 1999. Operation and Maintenance Manual, OU 1 Groundwater Extraction/Treatment System, George Air Force Base, California. April.

Montgomery Watson, 2000. Draft Five-Year Review for Operable Units 1, 2, and 3 at George Air Force Base, California. October.

Montgomery Watson, 2003. Final Long-Term Maintenance and Monitoring Plan, George Air Force Base, California. Walnut Creek, California. January.

MWH 2001. Final Confirmation Sampling Event Report, Sites WP-17 and FT-19a, George Air Force Base, California. Walnut Creek, California. September.

MWH, 2002. Final Explanation of Significant Difference for Site OT-51, George Air Force Base, California. Walnut Creek, California. July.

MWH, 2003. Proposed Approach to Post-Closure Landfill Groundwater Monitoring at OU-3 Landfills Technical Memorandum, George Air Force Base, California. March.

MWH, 2003. Final Sampling and Analysis Plan Addendum for Basewide Groundwater Monitoring Events, George Air Force Base, California. Walnut Creek, California. May.

MWH, 2004. Final Operable Unit 3 Site FT-19 Closure Work Plan, George Air Force Base, California. Walnut Creek, California. February.

MWH, 2004. 2002 Annual Basewide Groundwater Monitoring Report, George Air Force Base, California. Walnut Creek, California. June.

MWH, 2004. Semiannual Report for Remedial Activities at Sites FT-19a, FT-19c, OT-51 and Landfills DP-03, DP-04, LF-12, LF-14, and the SEDA, George Air Force Base, California. Walnut Creek, California. October.

MWH, 2005. Final Hydrogeologic Conceptual Site Model, George Air Force Base, California. Sacramento, California, May.

MWH, 2005. Data Gaps Well Installation Report, Operable Unit 1, George Air Force Base. Walnut Creek, California. March.

MWH, 2005. Process Monitoring Report, OU 1 Groundwater Extraction/Treatment System, First Quarter 2003. Walnut Creek, California. March. Five-Year Review Report Former George Air Force Base

LIST OF DOCUMENTS REVIEWED (continued)

MWH, 2005. Semiannual Report for Remedial Activities at Sites FT-19a, FT-19c, OT-51 and Landfills DP-03, DP-04, LF-12, LF-14, and the SEDA, George Air Force Base, California. Walnut Creek, California. April.

MWH, 2005. Final 2003 Annual Basewide Groundwater Monitoring Report, George Air Force Base, California. Walnut Creek, California. April.

MWH, 2005. Draft 2004 Annual Basewide Groundwater Monitoring Report, George Air Force Base, California. Walnut Creek, California. July.

Regional Water Quality Control Board (RWQCB), 2003. Memo from Stephen Hill, Toxics Cleanup Division: Status of Cancer Slope Factors for Trichloroethylene. San Francisco Region, 3 March.

Science Application International Corporation (SAIC), 1987. Installation Restoration Program Phase II – Confirmation/Quantification Stage 2, George Air Force Base California. January.

United States Air Force (USAF), 1989. Closure of George Air Force Base, San Bernardino County, California, Draft Environmental Impact Statement. December.

United States (U. S.) Census Bureau, 2000. http://quickfacts.census.gov.

United States Environmental Protection Agency (USEPA), 2001. Comprehensive Five-Year Review Guidance. June. APPENDIX B

INTERVIEWS INTERVIEW RECORD

Site Name: George AFB EPA ID No.: Subject: 5 Year Review Interviews Time: Date: April 05 Type: Telephone Visit X Other Incoming Outgoing Location of Visit: Written Interview Questionnaire Contact Made By: Name: Brian Sytsma Title: Community Relations Organization: MWH Individual Contacted: Name: Bob Field Title: Water Quality Supervisor Organization: Victor Valley Water District Telephone No: Street Address: 17185 Yuma Street Fax No: City, State, Zip: Victorville, CA 92395 E-Mail Address: [email protected] Summary Of Interview

Mr. Field has been in his position for three years. He is aware that there is contamination at George AFB, and that jet fuel has leaked into the soil at the airbase.

Mr. Field has attended a public meeting held by the Air Force in the fall of 2004. He does not have any major concerns about the ongoing cleanup, nor is he aware of any community concerns.

He indicated that he would like to receive more information and updates to better understand the status of the cleanup.

Page 1 of 1 USEPA, Comprehensive Five-Year Review Guidance, June 2001 INTERVIEW RECORD

Site Name: George AFB EPA ID No.: Subject: 5 Year Review Interviews Time: Date: April 05 Type: Telephone Visit X Other Incoming Outgoing Location of Visit: Written Interview Questionnaire Contact Made By: Name: Brian Sytsma Title: Community Relations Organization: MWH Individual Contacted: Name: Barbara Loux Title: Former Apple Valley Organization: Council Member Apple Valley City Council Telephone No: (760) 243-1515 Street Address: 9843 SVL Box Fax No: N/A City, State, Zip: Victorville, CA 92394 E-Mail Address: N/A Summary Of Interview

Ms. Loux has lived/worked in this area for 25 years. She is aware that there is contamination at former George Air Force Base, and understands that chemicals and buried debris are in the water moving toward the river. She believes there are no effects on the community as these contamination issues are being addressed.

Ms. Loux has not received any updates in many years either directly or indirectly through the media. She does not have any major concerns about the ongoing cleanup, nor is she aware of any community concerns.

She indicated that she is not interested in receiving any additional information and does not have any questions or concerns about the site.

Page 1 of 1 USEPA, Comprehensive Five-Year Review Guidance, June 2001 INTERVIEW RECORD

Site Name: George AFB EPA ID No.: Subject: 5 Year Review Interviews Time: 4:36 p.m. Date: April 05 Type: Telephone Visit X Other Incoming Outgoing Location of Visit: Written Interview Questionnaire Contact Made By: Name: Brian Sytsma Title: Community Relations Organization: MWH Individual Contacted: Name: Robert Mall Title: Environmental Specialist, Organization: Principal M&M Environmental, Inc. Telephone No: (760) 951-0700 Street Address: 15487 Seneca Road STE 201-B Fax No: N/A City, State, Zip: Victorville, CA 92392 E-Mail Address: [email protected] Summary Of Interview

Mr. Mall has lived/worked near George for 15 years. He is aware that there is contamination at the former George AFB, and that jet fuel and Trichloroethylene have leaked into the lower and upper aquifer at the former base and the surrounding area. He understands that there are no plans to extract water from the upper aquifer and that the contamination of the lower aquifer may affect the Mojave river basin. Mr. Mall believes that despite the contamination there are no known effects on the community of Victorville, CA.

Mr. Mall obtains information about the site and cleanup program directly from individuals involved with the cleanup program and through personal experience/professional knowledge. He is concerned that the groundwater extraction and treatment system has been shut down for over 2 years, indicating that there are no current efforts to cleanup and treat TCE contaminated groundwater. He is unaware of any community concerns regarding the cleanup program at George.

Mr. Mall indicated that he would like to receive more information about the effectiveness of the treatment program. He also questions if there are plans to install additional extraction wells to remove jet fuels from the OU-2 area. He notes that there were several new extraction wells installed at OU-1 and OU-3 TCE impact zone but that the Air Force has not commenced treatment at the air stripping system.

Page 1 of 1 USEPA, Comprehensive Five-Year Review Guidance, June 2001 APPENDIX C

INSPECTION DOCUMENTS AND LANDFILL INSPECTION AND MONITORING DESCRIPTION OU 1 PUMP AND TREAT INSPECTION DOCUMENTS

OU 3 INSPECTION DOCUMENTS AND DESCRIPTION 1.1 OU 3 LANDFILLS

Groundwater monitoring, visual site inspections, and burrows management inspections are performed as part of O&M activities at the OU 3 landfills.

1.1.1 Groundwater Monitoring

Groundwater monitoring at the landfills is conducted under the Basewide Long-Term Groundwater Monitoring Plan for GAFB (Montgomery Watson, 1996c) and the Site Closeout Report for DP-03, DP-04, LF-12, LF-14, and the SEDA (Montgomery Watson, 1997b). Several rounds of groundwater monitoring have been completed under these plans. Groundwater samples are collected from monitoring wells upgradient and downgradient of the landfills and are analyzed for halogenated volatile organic compounds (USEPA Method SW8260) and landfill metal surrogates (total dissolved solids by USEPA Method E160.1 and chloride, sulfate, and nitrate by USEPA Method SW9056). The sampling frequency and target compounds are modified as the program progresses.

Groundwater monitoring is used to assess whether contaminants have migrated into the groundwater. A detailed description of the landfill groundwater monitoring and analysis program is presented in the Technical Memorandum, Proposed Approach to Post-Closure Groundwater Monitoring at Operable Unit 3 Landfills (MWH, 2003c).

1.1.2 Landfill Inspection

The maintenance activity schedule for the landfills is presented in the Site Closeout Report for DP-03, DP-04, LF-12, LF-14, and the SEDA (Montgomery Watson, 1997b) and is revised in the Final Long-Term Maintenance and Monitoring Plan (LTMMP) (MWH, 2003d). A visual site inspection includes checking the condition of access roads, fencing, gates, signs, final cap, vegetative cover, and perimeter drainage channels. The schedule to implement any recommended repairs noted during the routine maintenance inspections will vary depending on the type and complexity of repair. The subsequent routine maintenance inspection will note if the recommended repairs were made. Inspections were last conducted in July 2004 and are discussed in the Second 2004 OU 3 Semiannual Report (MWH, 2004).

The procedure for landfill inspections is presented below. The inspection at each site addresses five components: access roads, security fencing/gates/signs, final cap, vegetative cover, and perimeter drainage channels. For each component, a summary of current conditions, recommended actions, and actions taken are noted. The detailed procedures for inspection of the landfill are taken from the closure plan and are as follows:

Access Roads: Note the condition of the access roads that lead to the site gates. Note if ruts, debris, or vegetation obstruct the access to the site by vehicles. Recommend immediate repairs if access is obstructed.

Security Fencing/Gates/Signs: Walk the perimeter of the site and note the condition of the perimeter fencing. Note any areas where animals have burrowed under the fence, areas where surface water has eroded under the fence, and areas where the fence has been damaged or vandalized. Note signs of unauthorized site access and where debris or tumbleweeds have accumulated along the perimeter fencing. Check the condition of the access gates and the warning signs posted at the site access. Recommend immediate fencing repairs if chain links, fence post, or gate is broken and if warning sign is damaged or missing.

Final Cap: Walk around a significant portion of the cap to check the condition of the final soil cover, concentrating the visual cap inspection in areas where the cap has drainage swales built into the soil cover (Sites LF-14 and SEDA only). Note all areas where erosion is evident on the soil cover, any evidence of animal burrows, and locations where tumbleweeds have accumulated on the cap. Note any areas where settlement is evident and where surface water has ponded. Recommend immediate cover repairs in areas where the cap has eroded (i.e., greater than 6 inches), where debris has been uncovered, surface water ponds, and where large animal burrows are identified.

Vegetative Cover: Following grading, the sites were seeded with native vegetation. Because GAFB is a desert environment, the vegetation will be sparse, similar to the undisturbed areas outside of the perimeter fencing. Check the condition of the vegetation, and note any areas where vegetation does not appear to be growing.

Perimeter Drainage Channels: Walk the length of the perimeter drainage channels, and note areas where erosion of the channels or accumulation of sediments is evident. Because the perimeter drainage channels are located outside of the cap boundary, erosion in the base of the channels is not a great concern. However, note all areas where the perimeter channel is eroding towards the landfill boundary and all areas where erosion has uncovered landfill debris. Also note any areas where debris has accumulated in the channel bottom. Recommend immediate drainage channel repairs if debris is accumulating in the channels, the slopes show signs of significant erosion toward the landfill, or the channels show signs of accumulated sediments.

Terraces: Site LF-12 is the only site with terraces. Walk the length of the terraces and note any erosion problems.

Riprap-Lined Cap Channels/Slope Inspection: Site LF-14 is the only site with riprap- lined cap channels. Walk the length of the cap channels and note any erosion problems. Note the condition of the channel running down the slope and check the slope for evidence of settlement or slope failure.

Monitoring Wells/Benchmarks: Check well surface completions and benchmarks for damage. 1.1.3 Burrows Management Inspection

The landfill remedial actions included actions that would minimize exposure of landfill wastes to ecological receptors (e.g., installation of a 12-inch to 24-inch thick native soil cover), compaction of the soil cover, and installation of a site perimeter fence.

Although the soil was compacted during construction, the landfills provide potential habitat for burrowing animals that can burrow under or move through small openings in the fence. Burrowing animals could potentially compromise the effectiveness of the cap that is acting as a barrier between the waste and the surrounding ecosystem. Burrowing animals that could potentially enter the area include special-status species such as the Mojave ground squirrel, Mojave vole, desert tortoise, San Diego horned lizard, and burrowing owl. Other species that may impact the soil cover include the coyote, badger, and kangaroo rat. The soil cover at each site is monitored by visually surveying for animal burrows. The LTMMP for the landfill sites (Montgomery Watson, 2003d) includes measures to address the potential presence of burrowing animals. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 1 of 6 GEORGE AIR FORCE BASE

Inspected By: Chris Glenn, Elena Birch-Carl Corporation: MWH Weather: Sunny, warm Date and Time: 7/12/04, 7:00 AM Reason for Site Inspection: Annual Inspection

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

ACCESS ROADS: Access Road Conditions: Access roads are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 2 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

SECURITY FENCING, GATES AND SIGNS: Conditions of Security Fencing, Gates and Signs: The fence and gate are in good condition. Tortoise fencing has been placed across the gate. A fence post is bent near the ground surface at the northeast corner of the landfill (photo DP03-1). There is a dugout area at the western fence corner and a 4” by 4” opening is bent in the fence (photo DP03-2). A small 1- inch opening at the fence post was observed at the northeast corner of the landfill. Small burrows are located along the entire perimeter fence. A few tumbleweeds have collected outside the landfill entrance gate. All warning signs list the AFRPA contact number, 1-800-655-7200 x. 103.

Recommendations: Repair the dugout area under the western fence corner by filling in with soil and manually compacting. Repair the opening at the fence post at the northeastern corner of the landfill. Remove the tumbleweeds from the landfill entrance gate.

Action Taken: The dugout area at the western fence corner was repaired by using stainless steel wire to reattach the fence fabric to the fence post and by filling the dugout area with rocks and soil and manually compacting. The opening at the northeastern fence post was repaired by filling in with rocks. The tumbleweeds were removed from outside the DP-03 entrance gate and placed inside the landfill fence. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 3 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

FINAL CAP: Final Cap Conditions (including Cap Channels or Terraces if applicable): The condition of the final cap is good. Small burrows (1/2” to 1”) are located throughout the cap. No evidence of erosion or settlement is present.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 4 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

VEGETATIVE COVER: Vegetative Cover Conditions: Vegetation is well established throughout the landfill cap (photo DP03-3).

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 5 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

PERIMETER DRAINAGE CHANNELS: Perimeter Drainage Channel Conditions: The perimeter drainage channels are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 6 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

WELLS AND BENCHMARKS: Wells and Benchmark Conditions: No problems.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 1 of 6 GEORGE AIR FORCE BASE

Inspected By: Chris Glenn, Elena Birch-Carl Corporation: MWH Weather: Sunny, warm Date and Time: 7/12/04, 8:00 AM Reason for Site Inspection: Annual Inspection

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

ACCESS ROADS: Access Road Conditions: Access roads are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 2 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

SECURITY FENCING, GATES AND SIGNS: Conditions of Security Fencing, Gates and Signs: The fence and gate are in good condition. There is a dug out area at the fence post near the easternmost corner of the fence (photo DP04-1). A few tumbleweeds have collected within the landfill fence at the eastern side, and outside the landfill fence near the entrance gate. Warning signs list 1-800-655-7200 x. 103 as the AFRPA contact number.

Recommendations: Repair the dugout area at the easternmost corner of the eastern fence. Recommended repair is fill and manual compaction. Remove tumbleweeds that have collected outside the entrance gate.

Action Taken: The dugout area at the easternmost corner was repaired by using stainless steel wire to reattach the fence fabric to the fence post, filling in the dugout area with rocks and soil, and manually compacting. The tumbleweeds were removed from outside the landfill entrance gate and placed inside the landfill fence. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 3 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

FINAL CAP: Final Cap Conditions (including Cap Channels or Terraces if applicable): Approximately 10 rill erosion channels are forming along the steeper portion of the cap (northern and northeastern portion of the cap. The channels are up to 80 feet long, 8 inches deep, and 18 inches wide. A rill erosion channel is forming on the east side of the landfill along the perimeter fence (approximately 32 feet long, 4 inches deep, 1 foot wide). Water run-off has caused minor erosion near the fence at west side of the landfill. Small burrows are located throughout the site (1/2” to 1” wide).

Recommendations: Continue to monitor the rill erosion in the northern and northeastern portion of the landfill cap during annual landfill inspections.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 4 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

VEGETATIVE COVER: Vegetative Cover Conditions: Well-established vegetation is located throughout the site.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 5 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

PERIMETER DRAINAGE CHANNELS: Perimeter Drainage Channel Conditions: The perimeter drainage channels are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 6 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

WELLS AND BENCHMARKS: Wells and Benchmark Conditions: No problems.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 1 of 6 GEORGE AIR FORCE BASE

Inspected By: Chris Glenn, Elena Birch-Carl Corporation: MWH Weather: Sunny, hot Date and Time: 7/12/04, 9:00 AM Reason for Site Inspection: Annual Inspection

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

ACCESS ROADS: Access Road Conditions: Access roads are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 2 of 6 GEORGE AIR FORCE BASE SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

SECURITY FENCING, GATES AND SIGNS: Conditions of Security Fencing, Gates and Signs: There is a dugout area in the southeast corner of the landfill. There is a small gap (2” by 6”) under the fence at the northwest end of the landfill. Small burrows are present near the fencing throughout the site (½” to 1” wide). The entrance gate generates static electricity and sparks when opened and closed. Tumbleweeds have collected outside the perimeter fence along the southern side, and on the inside of the perimeter fence at the northeastern corner. All warning signs list the AFRPA contact number, 1-800-655- 7200 x. 103.

Recommendations: Repair the dugout area at the southeastern fence post by filling with rocks and soil and manually compacting. Repair the gap under the fence at the northwest end of the landfill by filling with rocks and soil. Remove tumbleweeds that have collected outside the perimeter fence along the southern side and inside the perimeter fence at the northeastern corner and eastern side. Place grounding rods at entrance gate to reduce static electricity and sparks.

Action Taken: The dugout area at the southeastern fence post was repaired by reattaching the fence fabric to the fence post with stainless steel wire, filling the dugout area with rocks and soil, and manually compacting. The gap under the fence in the northwest end of the landfill was repaired by filling in with rocks and soil and manually compacting. Tumbleweeds were removed from outside the perimeter fence and placed within the landfill fence. Tumbleweeds collected at the northeast corner and eastern side of the landfill were removed and placed outside the landfill. Two copper grounding rods were placed at each side of the entrance gate and attached to the gateposts. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 3 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

FINAL CAP: Final Cap Conditions (including Cap Channels or Terraces if applicable): Rill erosion channel “LF-12A” (1 channel, maximum 25 feet long, 2 feet deep, and up to 4 feet wide) is located on the north side of the landfill (photo LF12-1). Several smaller rill erosion channels (approximately 4 channels up to 2 inches deep, 3 inches wide, and 25 feet long) are also forming on the north side of the landfill. Rill erosion is located at the eastern side of the landfill near the fence (one channel approximately 10 feet long, 5 inches deep, and 10 inches wide). The tire tracks and wheel ruts observed during the October 2002 inspection appear weathered and are filling in with vegetation. A portion of the landfill cap near the northeastern corner of the landfill appears to be settling, indicated by cracks in the cap surface forming a circle approximately 14 feet in diameter and by a sunken area (approximately 4 inches lower than the surrounding area) in the landfill berm (photos LF12-2 and LF12- 3). Some paper and plastic litter was observed on the landfill cap. Small burrows are located throughout the site (½” to 1” wide).

Recommendations: Repair the rill erosion channel “LF-12A” (up to 16 inches deep, 24 inches wide, and 25 feet long) at the northern portion of the landfill by cut and fill of channel and placement of a geomembrane and rip-rap. Continue to monitor the minor rill erosion channels forming at the eastern and northern portions of the landfill cap during annual inspections. Continue to monitor the region of cap settlement during annual inspections. Remove litter from the surface of the landfill cap.

Action Taken: Litter was removed from the surface of the landfill cap. A small flag was placed in the landfill cap to mark the location of rill erosion channel “LF-12A”. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 4 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

VEGETATIVE COVER: Vegetative Cover Conditions: Well-established vegetation is located throughout the site.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 5 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

PERIMETER DRAINAGE CHANNELS: Perimeter Drainage Channel Conditions: The perimeter drainage channels are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 6 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

WELLS AND BENCHMARKS: Wells and Benchmark Conditions: No problems.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 1 of 6 GEORGE AIR FORCE BASE

Inspected By: Chris Glenn, Elena Birch-Carl Corporation: MWH Weather: Sunny, hot Date and Time: 7/12/04, 10:45 AM; 7/13/04, 10:00 AM Reason for Site Inspection: Annual Inspection

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

ACCESS ROADS: Access Road Conditions: Access roads are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 2 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

SECURITY FENCING, GATES AND SIGNS: Conditions of Security Fencing, Gates and Signs: A dug out area is located under the access gate fence post (photo LF14-1). Rill erosion (about 7 channels) is present along and underneath the fence at the western end of the landfill. The channels have been filled in with asphalt pieces and rip-rap on the outside of the fence (photo LF14-2). There is an opening in the fence post at ground level (10 inches tall by 6 inches wide) where the chainlink fabric has been pulled away from fence at the north end of the landfill near well NZ-13 (photo LF14-3). At the north end of the landfill, a rill erosion channel is undercutting the fence and an 8-inch gap is exposed. Soil is dugout beneath fence at southeast corner of the landfill, creating an opening 9 inches tall. Fence fabric does not reach the ground surface at several locations on the eastern side of the landfill; some gaps covered with razor wire (photo LF14-4). There is a 6-inch gap under the western side of the northeastern access gate. Some tumbleweed has collected outside the landfill perimeter fence on the southern side of the landfill. All warning signs list the AFRPA contact number, 1-800-655-7200 x. 103.

Recommendations: Portions of the landfill fence that do not reach the ground (approximately 1,050 linear feet on the eastern side of the landfill) should be replaced with new fencing. The four locations (at the western access gate, near NZ-13, under the northern fence, and at the southeast corner) where an animal has dug under the fence should be repaired by filling with soil and manually compacting. Tumbleweeds collected along the southern perimeter fence should be removed.

Action Taken: The dugout area near NZ-13 and at the southeast corner were repaired by attaching the fence fabric to the fence post with stainless steel wire, filling in the dugout area with rock and soil, and manually compacting (photo LF14-5). Tortoise fencing (small mesh, 3-foot-wide fence fabric) was placed along the entire length of the eastern fence and buried approximately 18-inches under ground to cover the gaps under the fence (photo LF14-6). The undercut area under a portion of the northern fence was filled in with rock. The tumbleweeds collected along the southern perimeter fence were removed and placed within the landfill fence. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 3 of 6 GEORGE AIR FORCE BASE SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

FINAL CAP: Final Cap Conditions (including Cap Channels or Terraces if applicable): Desert tortoise burrows discovered in the LF-14 cap during July 2003 were determined to be inactive during the July 2004 biological inspection. Additionally, no desert tortoises were encountered on the cap surface (“Focused Biological Assessment Report,” attached). Small burrows are located throughout the landfill cap (½ inches to 1 inch wide). Rip-rap drainage channels and other low-lying landfill cap areas are filling with sediment. Rill erosion channels of varying lengths, widths, and depths were encountered throughout the landfill cap (as shown on landfill maps in “Maps and Photos”, attached). Descriptions of rill erosion channels with depths greater than two feet are as follows:

• North side of landfill, 4 channels “LF-14A”, 2 feet deep (one channel consistently 3 feet deep), 1 to 2 feet wide, 400 feet total length, photo LF14-7.

• East-facing slope at east side of landfill, near well NZ-03, 1 channel “LF-14B”, up to 2 feet deep, 2 feet wide, and 100 feet long, photo LF14-8.

• East-facing slope at east side of landfill, several channels “LF-14C”, up to 2 feet deep, 1 foot wide, 40 feet long, photo LF14-9

• East-facing slope north of drainage channel and dirt road, 2 channels “LF-14D” greater than 2 feet deep, 1 foot wide, 300 feet long, photo LF14-10.

• South side of landfill near dirt road, 2 channels “LF-14E”, up to 2 feet deep, 1 to 2 feet wide, 50 feet long, photo LF14-11.

Recommendations: The rill erosion channels listed above are recommended for repair by cut and fill of the channels and placement of geomembrane and rip-rap, or by reworking the landfill cap and compacting. Rill erosion channels not listed above but shown on the LF-14 landfill maps are recommended for continued annual monitoring.

Action Taken: Small flags were placed in the landfill cap to mark the location of rill erosion channels “LF-14A”, “LF- 14B”, “LF-14C”, “LF-14D”, and “LF-14E”. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 4 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

VEGETATIVE COVER: Vegetative Cover Conditions: Vegetation is well established throughout except at areas of erosion.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 5 of 6 GEORGE AIR FORCE BASE SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

PERIMETER DRAINAGE CHANNELS: Perimeter Drainage Channel Conditions: The perimeter drainage channels are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 6 of 6 GEORGE AIR FORCE BASE SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

WELLS AND BENCHMARKS: Wells and Benchmark Conditions: No problems.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 1 of 6 GEORGE AIR FORCE BASE

Inspected By: Chris Glenn, Elena Birch-Carl Corporation: MWH Weather: Sunny, warm Date and Time: 7/13/04, 6:30 AM Reason for Site Inspection: Annual Inspection

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

ACCESS ROADS: Access Road Conditions: Access roads are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 2 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

SECURITY FENCING, GATES AND SIGNS: Conditions of Security Fencing, Gates and Signs: The fence fabric is pulled slightly away from the fence post near the ground surface on the south side of the landfill. At the southeast corner, soil is dug out from under the fence, with fence fabric pulled away from the post. A few tumbleweeds have collected inside the landfill perimeter fence at the northeastern corner of the landfill. A new center gatepost has been installed at the entrance gate on the eastern side of the landfill; however, gaps exist underneath the gate. There are small burrows (up to 1” diameter) along the entire perimeter of the fence. All warning signs list the AFRPA contact number, 1-800-655-7200 x. 103.

Recommendations: Repair the dug out areas under the southern and southeastern fence corners by filling with rock and soil and manually compacting. Remove the tumbleweeds that have collected at the northeastern corner of the perimeter fence.

Action Taken: The two dugout areas at the southern and southeastern fence posts were repaired by using stainless steel wire to reattach the fence fabric to the post, filling in with rock and soil, and manually compacting, (photo SEDA-1). Tumbleweeds collected at the northeast corner of the landfill were removed. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 3 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

FINAL CAP: Final Cap Conditions (including Cap Channels or Terraces if applicable): Small burrows (up to 1 inch in diameter) are located throughout the cap. Rill erosion channels (less than 2 feet deep) are located throughout the cap in locations as shown on the landfill maps attached. Several silted areas were observed along the cap channels and at low-lying areas in the landfill cap.

Recommendations: Rill erosion channels observed at the SEDA are recommended for continued annual monitoring.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 4 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

VEGETATIVE COVER: Vegetative Cover Conditions: Vegetation is well established throughout except at areas of erosion.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 5 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

PERIMETER DRAINAGE CHANNELS: Perimeter Drainage Channel Conditions: The perimeter drainage channels are in good condition.

Recommendations: None.

Action Taken: None. FORM E-1 LANDFILL SITE INSPECTION POST-CLOSURE MAINTENANCE AND MONITORING Page 6 of 6 GEORGE AIR FORCE BASE

SITE NAME: SITE DP-03 SITE DP-04 SITE LF-12 SITE LF-14 SEDA CHECK (See attached map)

WELLS AND BENCHMARKS: Wells and Benchmark Conditions: No problems.

Recommendations: None.

Action Taken: None. APPENDIX D

ARAR TABLES OU 1 ROD ARAR TABLES

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,_' N!_,. , ,_ ,','m, _.._, , c ,_: _. APPENDIX E

HISTORICAL LANDFILL GROUNDWATER MONITORING DATA PLOTS FOR LANDFILLS Landfill DP-03 Groundwater Monitoring Chloride Landfill DP-03 Groundwater Monitoring Nitrate 100 8 90

7 80

70 6 ) L / g ) 60 L 5 m / ( g n m e (

g e

50 o d r i

t 4 r i o n l

s h a C 40 e t

a 3 r t i

30 N

2 20

1 10

0 0 3/15/2000 10/1/2000 4/19/2001 11/5/2001 5/24/2002 12/10/2002 6/28/2003 1/14/2004 8/1/2004 2/17/2005 3/15/2000 10/1/2000 4/19/2001 11/5/2001 5/24/2002 12/10/2002 6/28/2003 1/14/2004 8/1/2004 2/17/2005 Date Date

Background Well NZ-84 Compliance Well NZ-106 Background Well NZ-84 Compliance Well NZ-106

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005

Landfill DP-03 Groundwater Monitoring Landfill DP-03 Groundwater Monitoring Sulfate Total Dissolved Solids

120 600

100 500 ) L /

80 g 400 m (

s ) d L i / l g o S m

(

60 d 300 e e t v a l f l o u s S s i D

l a

40 t 200 o T

20 100

0 0 3/15/2000 10/1/2000 4/19/2001 11/5/2001 5/24/2002 12/10/2002 6/28/2003 1/14/2004 8/1/2004 2/17/2005 6/23/2000 1/9/2001 7/28/2001 2/13/2002 9/1/2002 3/20/2003 10/6/2003 4/23/2004 11/9/2004 5/28/2005 Date Date

Background Well NZ-84 Compliance Well NZ-106 Background Well NZ-84 Compliance Well NZ-106

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005 Landfill DP-04 Groundwater Monitoring Landfill DP-04 Groundwater Monitoring Chloride Nitrate

70 10

9 60 8

50 7 ) L / g m ) (

L 6 / n

g 40 e g m ( o

r e t 5 i d i N r o s l

30 a h

e 4 C t a r t i N 20 3

2 10 1

0 0 3/15/2000 10/1/2000 4/19/2001 11/5/2001 5/24/2002 12/10/2002 6/28/2003 1/14/2004 8/1/2004 2/17/2005 3/15/2000 10/1/2000 4/19/2001 11/5/2001 5/24/2002 12/10/2002 6/28/2003 1/14/2004 8/1/2004 2/17/2005 Date Date Background Well NZ-84 Compliance Well NZ-85 Compliance Well NZ-86 Background Well NZ-84 Compliance Well NZ-85 Compliance Well NZ-86

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005

Landfill DP-04 Groundwater Monitoring Landfill DP-04 Groundwater Monitoring Sulfate Total Dissolved Solids

100 700

90 600 80

) 500

70 L / g m (

s ) 60 d L i /

l 400 g o S m

(

50 d e e t v a l f l o u

s 300 S s

40 i D

l a t

30 o T 200

20 100 10

0 0 3/15/2000 10/1/2000 4/19/2001 11/5/2001 5/24/2002 12/10/2002 6/28/2003 1/14/2004 8/1/2004 2/17/2005 3/15/2000 10/1/2000 4/19/2001 11/5/2001 5/24/2002 12/10/2002 6/28/2003 1/14/2004 8/1/2004 2/17/2005 Date Date Background Well NZ-84 Compliance Well NZ-85 Compliance Well NZ-86 Background Well NZ-84 Compliance Well NZ-85 Compliance Well NZ-86

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005 Landfill LF-12 Groundwater Monitoring Landfill LF-12 Groundwater Monitoring Chloride Nitrate

90 5

80 4.5

4 70

3.5 ) L

60 / g m ) (

L 3 / n g 50 e g m ( o

r e t 2.5 i d i N r o 40 s l a h

e 2 C t a r t 30 i N 1.5

20 1

10 0.5

0 0 4/11/1995 8/23/1996 1/5/1998 5/20/1999 10/1/2000 2/13/2002 6/28/2003 11/9/2004 7/24/1998 12/6/1999 4/19/2001 9/1/2002 1/14/2004 Date Date Background Well NZ-108 Compliance Well NZ-60 Background Well NZ-108 Compliance Well NZ-60 Compliance Well NZ-61 Compliance Well NZ-62 Compliance Well NZ-61 Compliance Well NZ-62

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005

Landfill LF-12 Groundwater Monitoring Landfill LF-12 Groundwater Monitoring Sulfate Total Dissolved Solids

180 700

160 600

140

) 500 L /

120 g m (

s ) d L i / l 400 g

100 o S m

(

d e e t v a l f l

80 o u

s 300 S s i D

l a

60 t o

T 200

40

100 20

0 0 9/23/1994 2/5/1996 6/19/1997 11/1/1998 3/15/2000 7/28/2001 12/10/2002 4/23/2004 7/15/1992 11/27/1993 4/11/1995 8/23/1996 1/5/1998 5/20/1999 10/1/2000 2/13/2002 6/28/2003 11/9/2004 3/24/2006 Date Date Background Well NZ-108 Compliance Well NZ-60 Background Well NZ-108 Compliance Well NZ-60 Compliance Well NZ-61 Compliance Well NZ-62 Compliance Well NZ-61 Compliance Well NZ-62

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005 Landfill LF-14 Groundwater Monitoring Landfill LF-14 Groundwater Monitoring Chloride Nitrate

100 14

90 12 80

70 10 ) L / g m ) (

L 60 / n

g 8 e g m ( o

r e 50 t i d i N r o s l

a 6 h

e

C 40 t a r t i N 30 4

20 2 10

0 0 10/28/1995 3/11/1997 7/24/1998 12/6/1999 4/19/2001 9/1/2002 1/14/2004 10/28/1995 3/11/1997 7/24/1998 12/6/1999 4/19/2001 9/1/2002 1/14/2004 Date Date Background Well NZ-107 Compliance Well NZ-13 Background Well NZ-107 Compliance Well NZ-13 Compliance Well NZ-57 Compliance Well NZ-58 Compliance Well NZ-57 Compliance Well NZ-58

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005

Landfill LF-14 Groundwater Monitoring Landfill LF-14 Groundwater Monitoring Sulfate Total Dissolved Solids

200 800

180 700

160 600 )

140 L / g m (

500 s ) 120 d L i / l g o S m

(

100 d 400 e e t v a l f l o u s S s

80 i

D 300

l a t

60 o T 200 40

100 20

0 0 10/28/1995 3/11/1997 7/24/1998 12/6/1999 4/19/2001 9/1/2002 1/14/2004 5/28/2005 1/31/1993 6/15/1994 10/28/1995 3/11/1997 7/24/1998 12/6/1999 4/19/2001 9/1/2002 1/14/2004 5/28/2005 Date Date Background Well NZ-107 Compliance Well NZ-13 Background Well NZ-107 Compliance Well NZ-13 Compliance Well NZ-57 Compliance Well NZ-58 Compliance Well NZ-57 Compliance Well NZ-58

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005 SEDA Groundwater Monitoring SEDA Groundwater Monitoring Chloride Nitrate

35 3

30 2.5

25 ) L

/ 2 g m ) (

L / n

g 20 e g m ( o

r e t 1.5 i d i N r o s l

15 a h

e C t a r t i 1 N 10

0.5 5

0 0 6/28/2003 10/6/2003 1/14/2004 4/23/2004 8/1/2004 11/9/2004 2/17/2005 6/28/2003 10/6/2003 1/14/2004 4/23/2004 8/1/2004 11/9/2004 2/17/2005 Date Date

Background Well SZ-17 Compliance Well SZ-16 Compliance Well SZ-15 Background Well SZ-17 Compliance Well SZ-16 Compliance Well SZ-15

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005

SEDA Groundwater Monitoring SEDA Groundwater Monitoring Sulfate Total Dissolved Solids

160 350

140 300

120

) 250 L / g m (

100 s ) d L i / l 200 g o S m

(

80 d e e t v a l f l o u

s 150 S s i

60 D

l a t o

T 100 40

50 20

0 0 6/28/2003 10/6/2003 1/14/2004 4/23/2004 8/1/2004 11/9/2004 2/17/2005 6/28/2003 10/6/2003 1/14/2004 4/23/2004 8/1/2004 11/9/2004 2/17/2005 Date Date

Background Well SZ-17 Compliance Well SZ-16 Compliance Well SZ-15 Background Well SZ-17 Compliance Well SZ-16 Compliance Well SZ-15

George Air Force Base George Air Force Base OU3 Landfill WQPS Update OU3 Landfill WQPS Update January 25, 2005 January 25, 2005 APPENDIX F

RESPONSE TO COMMENTS REVIEW COMMENTS ON: DRAFT FIVE-YEAR REVIEW FORMER GEORGE AIR FORCE BASE, CALIFORNIA

From: Booz Allen Hamilton (BAH)

Comments from Calvin Cox, BAH, Dated 14 December 2005.

SPECIFIC COMMENTS

Comment No. 1: Executive Summary, Page ES-2, Operable Unit 2 section. Move IRP Sites FT-20 and ST-56 to the Operable Unit 3 section because they are closed out in the OU3 Record of Decision. They were never a part of OU2.

MWH Response: The text has been adjusted as requested.

Comment No. 2: Executive Summary, Page ES-3, Operable Unit 4 section. Area of Concerns (AOCs) Facility 749 Aircraft Ground-Support Equipment Fuel Station (AOC 79), Monitoring Well (MW)-32 Area, and Railroad Fueling System, Building 671 (AOC 81) need to be moved into the Operable Unit 2 section.

MWH Response: The text has been adjusted as requested.

RTC_BAH.doc

1 of 1 REVIEW COMMENTS ON: DRAFT FIVE-YEAR REVIEW FORMER GEORGE AIR FORCE BASE, CALIFORNIA

From: United States Environmental Protection Agency (USEPA)

Comments from James Chang, USEPA, Dated 3 November 2005.

GENERAL COMMENTS

Comment No. 1: The report should briefly highlight and address the general regulatory concerns from the last FYR to provide an organized reference starting point for this FYR.

MWH Response: The following has been appended to the 2nd paragraph, page 1-1.

The USEPA did not concur with the protectiveness statements presented in the first Five-Year Review document. Specifically, the following deficiencies were identified:

• Data gaps in OU 1 limit the understanding of the behavior of the TCE plume movement in the subsurface. • A more defined understanding of the hydrogeologic controls within OU 1 is essential to designing a more effective remediation system that will bring performance expectations to the level agreed to in the Record of Decision (ROD).

Comment No. 2: While conditions may exist for short-term protectiveness, the long-term protectiveness is an issue from the following concerns.

a. OU1 issues - The AF’s statement about OU1's remedy is not operating as effectively as predicted, but that it is protective of human health and the environment is not supported by adequate documentation; The remedial action objectives (RAO) have not been met for site CG-70 to eliminate or reduce TCE migration; OU1’s off-base protectiveness referenced on page 4-18 is uncertain as land use controls are not in place for the lower aquifer plume.

b. RAOs for some landfills have not been achieved: Landfill caps at Site LF-12 and Southeast Disposal Area (SEDA) to control erosion and surface water runoff and run-on have not been met; The Recurring repairs to LF-14 from a poorly designed cap is problematic and the AF needs to evaluate for long term solutions; The ICs relied upon for protectiveness are not clearly described.

RTC_USEPA.doc

1 of 15 MWH Response: a. OU 1 Protectiveness

Short-Term Protectiveness – The remedy at OU 1 is currently (short- term) protective of human health and the environment because there are no complete exposure pathways that pose an unacceptable risk, specifically:

• Upper Aquifer water is prohibited from use via lease restrictions. • Upper Aquifer and Lower Aquifer waters do not reach surface water; therefore there are no complete exposure pathways. • Lower Aquifer water use is restricted on and off-base. (See land use controls discussion below.) • The Lower Aquifer plume migration is limited to the north and east due to losing stream conditions of the Mojave River. Confirmation of the extent of the plume to the northeast is under investigation. Based on the historic plume configuration and magnitude it is not anticipated to have reached the northern VVWRA boundary.

Long-Term Protectiveness – Long-term protectiveness to human health and the environment and compliance with the RAO to eliminate or reduce TCE migration is being addressed through extensive optimization actions, specifically:

• Conducting data gap investigations, • Developing a comprehensive Geologic conceptual site model, • Converted 4 monitoring wells to extraction wells, • Conducted extensive aquifer tests for development of a comprehensive hydrogeologic conceptual site model • Conducting additional source area investigations and planning for implementation of a vadose zone remedy to eliminate TCE mass loading to the Upper Aquifer. • Groundwater modeling based on detailed data documented in the Geologic and Hydrogeologic CSMs is in progress. The groundwater modeling results will be used to optimize the OU 1 remedy to continue to achieve compliance with the RAOs ensuring long term protectiveness of human health and the environment. Specific remedy modification tasks such as; reconfiguration and/or expansion of the extraction and groundwater monitoring well networks, alteration of treated water discharge location and/or modification of the remedy, will be determined after completion and acceptance of the results of the simulation scenarios.

Off-base Protectiveness/Land Use Controls – Remedies are in place to address off-base protectiveness, specifically:

RTC_USEPA.doc

2 of 15 • The AF has a good working relationship with VVWRA ensuring water use restrictions are communicated and implemented. • The OU-1 remedy is protective in the short-term and the AF is performing significant effort towards long-term protectiveness. These future efforts may include a State Land Use Covenant and other ICs in the Lower Aquifer. If this is required, AF may need the assistance of EPA and the State. • Groundwater monitoring continues to be performed to monitor the extent of the plume. • Additionally, a subsurface investigation is underway to confirm the extent of the plume in the lower aquifer. Based on historic TCE concentrations in groundwater and the fact that the Mojave River is a losing stream it is not anticipated that the TCE plume in the lower aquifer has reached the northern boundary of the VVWRA property.

b. Compliance with Landfill RAOs

The landfill RAOs have been met. Larger erosion channels, created by heavy rainfall, were repaired in June 2005 and converted into permanent channels for faster drainage of rainwater off the landfills. Furthermore, no surface water run-on is occurring at the noted landfills. Additional repairs are scheduled in 2006 for other minor erosion channels.

The landfill cap at LF-14 is believed to be well designed. Four areas contained channels created by heavy rains. These areas were repaired into permanent channels in the summer of 2005. The EPA may be referring to the significant erosion that can be seen at the east of the site. However, that erosion is occurring away from the landfill cap and buried materials, thus not affecting the protectiveness of the remedy.

To provide clarity the text has been modified to state the Landfill ICs more definitively in the “Implementation of ICs and Other Measures” Sections.

Comment No. 3: Institutional Controls (IC) - the document lacks consistency for specific discussions of the ICs. The ICs should be identified (not just a comment that ICs remain in place) and discussed specifically as to whether they remain protective of human health and environment.

MWH Response: The document has been edited for the landfill sites. The sections entitled “Implementation of ICs and Other Measures” have been edited to consistently be clear about what ICs are in existence at each site. Furthermore, the text has been modified to state that the ICs are protective.

RTC_USEPA.doc

3 of 15 Comment No. 4: The ARARs Tables in Appendix D only contains those from OU3's ROD as ARARs from OU1's ROD are missing. Merely listing the ARARs is not enough, as they should be evaluated for any changes that may impact protectiveness.

MWH Response: The ARAR’s table from the OU 1 ROD has been included in Appendix D. ARARs were evaluated for changes and the results are listed as answers to Question B under “Changes in Standard and To Be Considered” throughout the document.

Comment No. 5: All Rail Service Project concerns should be identified, and the following additional concerns should be addressed where appropriate:

a. The project’s potential impact to the following landfills was omitted: LF-12, DP-03, DP-04.

b. If the project grading requirements cause ground surface to be less than 100 feet from the TCE in groundwater, the AF must re-evaluate the baseline risk assessment for indoor air concerns.

MWH Response: a. DP-03 and DP-04 are all approximately 1,000 to 1,500 feet away from the rail project footprint. The impact to LF-12 has been discussed in section 5.3.4 under Changes in Land Use. Landfill LF-12 will be impacted by the new road associated with the rail project.

b. Plans for the Rail Project are still preliminary. Final grading plans have not been issued. AF and regulatory agencies are in close communication with the Land Reuse Development Agency and will evaluate future human health issues as necessary.

Comment No. 6: While EPA agrees that the OU2 petroleum groundwater site may be omitted for protective evaluation because it was removed from the CERCLA process, the approach for OU4 is not consistent with EPA guidance regarding FYR reviews which directs all OUs be addressed for remedial actions that have been initiated at the time of review. Accordingly, the report should include

MWH Response: No remedial actions have been initiated for OU 4 and all work has been performed as removal actions. No ROD exists for OU 4 at this time.

RTC_USEPA.doc

4 of 15 SPECIFIC COMMENTS

Comment No. 1: FYR Cover and Title Page: Suggest adding the word “Second” before “Five-Year Review Report” for ease of report sequence identification.

MWH Response: The text has been modified accordingly.

Comment No. 2: Page ES-2, Operable Unit 2: Include a brief narrative of the AF’s letter that provides the date and rationale for removing OU-2 from CERCLA process. Also cite EPA and RWQCB has agreed to allow only State oversight.

MWH Response: The text has been modified accordingly.

Comment No. 3: Page ES-3, OU-4: Include a narrative citing the completed removal actions for appropriate sites.

MWH Response: The text has been modified accordingly.

Comment No. 4: Page 1-2, Second Paragraph: The narrative states that OU-4 site remedies have not been selected, but removal actions for the Skeet Ranges have been completed and should be cited accordingly.

MWH Response: The text has been modified accordingly.

Comment No. 5: The “Lead agency” field in the FYR Summary Form should be marked with “Other Federal Agency” vice “EPA.”

MWH Response: The text has been modified accordingly.

Comment No. 6: The second page of the FYR Summary form is missing and the appropriate entries for issues, recommendations, follow up actions, and protective statements should be completed. The following protective statement should be made separately for OU1 and OU3:

“The remedy at OU X currently protects human health and the environment because (describe the elements of the remedy that protect human health and environment in the short term). However, in order for the remedy to be protective in the long term, the following action need to be taken (describe the action needed to ensure long-term protectiveness).”

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5 of 15 MWH Response: The second page of the FYR Summary was not included, as it is redundant with the text. The information is clearly stated in the document and a Content Checklist Table was provided to easily find the information. Providing the same information twice has the risk of adding confusion.

Text has been modified to state: The remedy at OU 1 currently protects human health and the environment because: • Upper Aquifer water is prohibited from use via lease restrictions. • Upper Aquifer water does not reach surface water; therefore there are no exposure pathways. • Lower Aquifer water use is restricted on and off-base. (See land use controls discussion below) • The Lower Aquifer plume migration is limited to the north and east due to losing stream conditions of the Mojave River. Definition of the extent of the plume to the north and east is under investigation. Based on historic concentrations it is not anticipated to have reached the northern VVWRA boundary

However, in order for the remedy to be protective in the long-term, the following actions have and/or are being taken:

• Conducting data gap investigations, • Developing a comprehensive Geologic conceptual site model, • Converting 4 monitoring wells to extraction wells, • Conducting extensive aquifer tests for development of a comprehensive hydrogeologic conceptual site model • Conducting additional source area investigations and planning for implementation of a vadose zone remedy to eliminate TCE mass loading to the Upper Aquifer. • Groundwater modeling based on detailed data documented in the Geologic and Hydrogeologic CSMs is in progress. The groundwater modeling results will be used to optimize the OU 1 remedy to meet the RAOs ensuring long term protectiveness of human health and the environment. Specific remedy modification tasks such as; reconfiguration and/or expansion of the extraction and groundwater monitoring well networks, alteration of treated water discharge location and/or modification of the remedy, to achieve compliance will be determined after completion and acceptance of the results of the simulation scenarios.

OU 3 consists of landfill sites and VOCs/fuel sites. The text for each site has been modified as follows:

Landfill sites – The remedy for the “OU-3 LF-X” is protective of human health and the environment in the short-term, because the landfills caps

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6 of 15 and institutional controls effectively mitigate risk. The landfill caps and institutional controls will continue to be maintained to ensure long-term protectiveness.

VOCs/Fuel Sites – These include FT-19, OT-51, OT-69 and WP-17. The text for each site has been modified as follows:

Site FT-19 – The first sentence of section 5.7.7 has been modified as follows: “The remedy at Site FT-19 is currently and in the long term protective of...

Site OT-51 - The first sentence of section 5.8.7 has been modified as follows: “The remedy at Site OT-51 is currently and in the long term protective of...

Site OT-69 – The first sentence of section 5.9.7 has been modified as follows: “The remedy of natural attenuation is currently and in the long term protective of…”

Site WP-17 – The first sentence of section 5.10.7 has been modified as follows: “The remedy at Site WP-17 is currently and in the long term protective of…”

Comment No. 7: Page 4-10, Second bullet under Groundwater: The second sentence refers to the treatment system discharge effluent level at 2.5 µg/L. The narrative should clarify if this value is on an average or median basis.

MWH Response: The cited effluent level of 2.5 µg/L is on a median basis. The text has been modified accordingly.

Comment No. 8: Page 4-13, TCE Table: The Table shows that the TCE mass in the upper aquifer increased significantly in September 2004 from May 2004. The report should provide an explanation for the increase.

MWH Response: The following paragraph has been added for clarification.

The increase in TCE mass from May of 2004 to September of 2004 is likely the result of the Upper Aquifer rebounding after groundwater extraction ceased in March of 2003. This rebound of TCE concentrations may result from a combination of the continuing source of TCE to groundwater from the newly discovered CG-70 source area and TCE mass no longer being recovered through groundwater extraction.

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7 of 15 Comment No. 9: Pages 4-14/15/16, RAOs: The RAO descriptions to prevent exposure, reduce the TCE contamination in the groundwater, etc, outline the goals to be met but the related bullets do not specifically address if the RAOs have been achieved. The AF should be more candid about identifying whether there are problems with the remedy and then state what it plans to do about it. The TCE mass increase problem shown in the report should be clearly stated instead of vaguely stating that the "ongoing optimization will assist in this objective." The recurring vague and opaque discussions need to be replaced with on-point narratives.

MWH Response: There are 5 RAOs, and compliance with each has been fully or partially achieved. The RAOs have been numbered in the text (1 through 5) and text clarifying full or partial achievement included on pages 4-14/4-15/4- 16 as follows.

RAO 1: Achieved. RAO 2: Partially Achieved. TCE concentrations in the groundwater in the Upper Aquifer near the new percolation ponds were reduced to less than 5 µg/L during system operation. Continuing actions to achieve full compliance with this RAO. RAO 3: Achieved. RAO 4: Partially Achieved. As data continues to be collected and evaluated, actions have been taken as described in text to achieve full compliance with this RAO. RAO 5: Achieved.

Optimization of the OU 1 remedy to maintain compliance and achieve full compliance with the RAOs is in progress. See responses to General Comment #2 and Specific Comment #6 for specific optimization tasks.

Comment No. 10: Page 4-16, Implementation of ICs and Other Measures: The report states the OU-1 ROD did not contain ICs, but the OU-1 ROD selected “Alternative 2" remedy includes implementation of deed restrictions to prohibit groundwater usage until cleanup levels are achieved. Please clarify the discrepancy.

MWH Response: The text has been modified to state the ICs from the OU 1 ROD.

Comment No. 11: Page 4-17, Current -On-Base: This lists the restrictions on the lessee, but it lacks an outright prohibition on use of the groundwater. The AF should add this specific clause to the list and require the lessee to abide by it also.

MWH Response: The lease terms and conditions do not allow a lessee or sublessee to construct or permit any alterations that impede activities under the IRP or

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8 of 15 FFA without written consent. There is no scenario where a lessee could use groundwater without breaking this restriction. Furthermore, the AF has an on-base presence and is in close communication with the lessee. The lessee is very aware of current groundwater conditions.

Comment No. 12: Page 4-18, Current -On-Base: On the list of actions the AF is taking, no sentinel wells are identified. The AF should cite plans for sentinel wells or explain why they are not needed

MWH Response: The AF is currently evaluating the best means of optimizing the OU 1 Plume. As part of the evaluation, sentinel wells may be included in the future. However it is too early to assess this issue. Currently, the AF is sampling 10 perimeter Lower Aquifer wells on a quarterly basis as part of the Focused Monitoring Program. The text has been modified accordingly.

Comment No. 13: Page 4-18, Future: The first paragraph states that the deed covenants will be identified in the FOST, but they should be identified now.

MWH Response: FOSTs identify conditions at the time of the deed and that is the appropriate time to state deed covenants. Some examples of deed covenants would be that one cannot extract groundwater or that one cannot impound water that would cause migration.

Comment No. 14: Page 4-19, Changes in Exposure Pathway: The first paragraph states that the baseline risk assessment has not been recalculated because there are no complete exposure pathways. Although this is currently acceptable, potential indoor air concerns from the LRA’s Rail Service Project could require a recalculation if their grading activities cause the depth to groundwater to be less than 100 feet from the TCE groundwater plume, and should be stated in the narrative.

MWH Response: Plans for the Rail Project are still preliminary. Final grading plans have not been issued. AF and regulatory agencies are in close communication with the Land Reuse Development Agency and will evaluate future human health issues as necessary.

Comment No. 15: Page 4-20, Changes in Toxicity & Other Contaminate Characteristics: Replace entire existing text with following paragraphs:

“In 2001, EPA released a draft toxicity evaluation for TCE following the current cancer guidelines and incorporating current data and

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9 of 15 physiological/biochemical understanding. This review concluded TCE was "highly likely to produce cancer in humans.” With this determination a range of cancer slope factors were developed some of which would result in more stringent cleanup levels than the current MCL. This toxicity evaluation is under review by several external scientific panels. This issue will need to be updated in subsequent 5-year reviews.

The toxicity value and carcinogenicity assessment for 1,4 dioxane is under review as of August 2005, as part of USEPA’s IRIS reassessment program. The reassessments may result in changes to the health-based screening levels for assessing potential health impacts of 1,4 dioxane. This issue will need to be updated in subsequent 5-year reviews.

These potential toxicity changes at the site do not affect the protectiveness of the remedy.”

MWH Response: The AF used published risk values to evaluate this Five-year review. The AF believes it is not valuable to conjecture on future risk reassessments in a Five-year review. However, the published risk values will be evaluated every 5 years in future ROD 5-Year Reviews. The current text discussing the cancer slope factor for TCE was included as background of which factors were evaluated. This text has been adjusted to only reflect current standards.

Comment No. 16: Page 4-22/23, CG-70 Recommendations: Address the Rail Project’s potential grading depth concern as cited in specific comment #14 above.

MWH Response: The following recommendation has been added: “Monitor planning for the SCLA rail center and multimodal complex project to determine impact on indoor air exposure pathways (on-going); responsible party, USAF.”

Comment No. 17: Page 4-23, CG-70 Protectiveness Statement: While the remedy may be protective in the short term, it is not protective in the long term. Accordingly, the narrative should be replaced with following text: “The remedy at OU1 currently protects human health and the environment because (describe the elements of the remedy that protect human health and environment in the short term). However, in order for the remedy to be protective in the long term, the following action need to be taken (describe the action needed to ensure long-term protectiveness).”

MWH Response: See responses to General Comment #2 and Specific Comment #6, which have been incorporated into the protectiveness statement.

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10 of 15 Comment No. 18: Page 5-9, Implementation of ICs: The narratives state the ICs are in place for various landfills. As stated in our general comment #3, the ICs should be listed specifically and analyzed as to their protectiveness (e.g., what are they, if they are landfill regulations, etc.).

MWH Response: The text has been edited as discussed in the response to General Comment #3.

Comment No. 19: Page 5-9, Last Full Paragraph: The narrative states the Rail Project footprint allows landfill DP-03 to remain in place unaffected. However, EPA understands that a new road with the project may be constructed over the landfill and the narrative should be revised accordingly.

MWH Response: DP-03 is approximately 1,500 feet away from the rail project footprint. AF and regulatory agencies are in close communication with the Land Reuse Development Agency and will evaluate future human health issues as necessary. Monitoring of the SCLA rail center and multimodal complex is included as a recommendation.

Comment No. 20: Page 5-10, Changes in Toxicity and Other Contaminants Characteristics: Replace entire section with following text.

“The toxicity value and carcinogenicity assessment for benzo(a)pyrene and polycylic aromatic hydrocarbon (PAH) mixtures is under review as of August 2005, as part of USEPA’s IRIS reassessment program. The reassessments may result in changes to the health-based screening levels for assessing potential health impacts of benzo(a)pyrene. This issue will need to be updated in subsequent 5-year reviews. These potential toxicity changes at the site do not affect the protectiveness of the remedy.”

MWH Response: The AF used published risk values to evaluate this Five-year review. The AF believes it is not valuable to conjecture on future risk reassessments in a Five-year review. However, the published risk values will be evaluated every 5 years in future ROD 5-Year Reviews.

Comment No. 21: Page 5-20, Early Indicators of Potential Issues: The narrative should reference the Rail Project and its potential impact from the planned road construction over landfill DP-04.

MWH Response: DP-04 is approximately 1,500 feet away from the rail project footprint. AF and regulatory agencies are in close communication with the Land Reuse Development Agency and will evaluate future human health issues as necessary. Monitoring of the SCLA rail center and multimodal complex is included as a recommendation.

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11 of 15 Comment No. 22: Page 5-21, Changes in Toxicity and Other Contaminants Characteristics: Replace entire section with following text.

“The toxicity values and carcinogenicity assessment for PCBs was revised in 1997, as part of USEPA’s IRIS reassessment program. The reassessment resulted in changes to the health-based screening levels for assessing potential health impacts of PCBs in soils. These toxicity changes do not affect the protectiveness of the remedy.”

MWH Response: The text has been adjusted as requested.

Comment No. 23: Page 5-33, Changes in Toxicity and Other Contaminants Characteristics: Replace entire section with following text.

“EPA's draft dioxin reassessment was developed over many years with the participation of scientific experts in EPA, the National Institutes of Health's National Institute of Environmental Health Sciences, and other federal agencies, as well as scientific experts in the private sector and academia and followed the current cancer guidelines and incorporating current data and physiological/biochemical understanding. This review concluded a number of chemicals have dioxin-like activity including some PCBs, different dioxin congeners have varying levels of toxicity, and dioxins are approximately 10 times more potent than previously understood to be the case. This change has not been adopted into ARAR standards. Residual risk is higher. EPA's draft dioxin reassessment is currently under review from the National Academy of Sciences (NAS). This issue will need to be updated in subsequent 5-year review. These potential toxicity changes do not affect the protectiveness of the remedy.”

MWH Response: The AF used published risk values to evaluate this Five-year review. The AF believes it is not valuable to conjecture on future risk reassessments in a Five-year review. However, the published risk values will be evaluated every 5 years in future ROD 5-Year Reviews.

Comment No. 24: Page 5-48, Remedy Implementation: It states that LF-44 was a no further action site, but ICs for this site are discussed on the next page. Since ICs are considered an action, please clarify this discrepancy.

MWH Response: LF-44 is incorrectly stated as a No Further Action Site. A remedial action objective of the ROD indicates that deed restrictions must be implemented in accordance with Alternate 2. Since the property has not been transferred, these deed restrictions have not been completed. The site is protective, as the removal action has been completed, the site is fenced,

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12 of 15 and terms and conditions of the lease are in place. The text has been modified accordingly.

Comment No. 25: Page 5-52, Implementation of ICs: The last paragraph refers to a deed restriction, but the narrative should also describe the deed restriction, note if the site has been transferred, and if the deed transferring the property contains a covenant prohibiting current and future owners from use of the groundwater. Please discuss specific IC language here.

MWH Response: LF-44 is incorrectly stated as a No Further Action Site. A remedial action objective of the ROD indicates that deed restrictions must be implemented in accordance with Alternate 2. Since the property has not been transferred, these deed restrictions have not been completed. The site is protective, as the removal action has been completed, the site is fenced, and terms and conditions of the lease are in place. The text has been modified accordingly.

Comment No. 26: Page 5-74, Second full paragraph: The first sentence refers to a "base case scenario," but we suspect it should read “best case scenario.”

MWH Response: Base case scenario defines the groundwater model results prior to performing sensitivity analysis. A definition of this term was added to provide clarity.

Comment No. 27: Page 5-79, Changes in Toxicity and Other Contaminants Characteristics: Replace entire section with following text.

“In 2001, EPA released a draft toxicity evaluation for TCE following the current cancer guidelines and incorporating current data and physiological/biochemical understanding. This review concluded TCE was "highly likely to produce cancer in humans.” With this determination a range of cancer slope factors were developed some of which would result in more stringent cleanup levels than the current MCL. This toxicity evaluation is under review by several external scientific panels. This issue will need to be updated in subsequent 5 year reviews.”

MWH Response: The AF used published risk values to evaluate this Five-year review. The AF believes it is not valuable to conjecture on future risk reassessments in a Five-year review. However, the published risk values will be evaluated every 5 years in future ROD 5-Year Reviews.

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13 of 15 Comment No. 28: Page 5-75, Second Paragraph: The statement “...emerging chemicals at Site FT-19 is an issue...,” should be further explained as to the specific chemicals and their related risk concerns.

MWH Response: The text was modified to provide clarity. Emerging chemicals are not an issue at Site FT-19.

Comment No. 29: Pages 5-90/91, Implementation of ICs: Last paragraph in page 5-90 and first paragraph in page 5-91 discuss ICs in specific detail. This is a good IC discussion that should be applied to all IC sites. There is a reference to an existing deed restriction on page 5-90, 4th sentence, last paragraph, which is confusing as site OT-51 has not been transferred and the narrative should be clarified.

MWH Response: OT-51 has not been transferred, and therefore deed restrictions are not in place. The language has been modified to state the terms and conditions of the lease and not deed.

Comment No. 30: Page 5-104, Changes in Cleanup Levels: The State’s Resolution 68-16 is cited in this narrative but it is unclear how it applies here. The narrative should cite what is the current cleanup level if there has been a change.

MWH Response: The text has been adjusted to remove the reference to Resolution 68-16 and instead cites the current cleanup levels for TCE and PCE.

Comment No. 31: Page 5-105, Changes in Toxicity and Other Contaminants Characteristics: Replace entire section with following text.

“In 2001, EPA released a draft toxicity evaluation for TCE following the current cancer guidelines and incorporating current data and physiological/biochemical understanding. This review concluded TCE was "highly likely to produce cancer in humans.” With this determination a range of cancer slope factors were developed some of which would result in more stringent cleanup levels than the current MCL. This toxicity evaluation is under review by several external scientific panels. This issue will need to be updated in subsequent 5-year reviews.

The toxicity value and carcinogenicity assessment for PCE is under review as of August 2005, as part of USEPA’s IRIS reassessment program. The reassessment may result in changes to the health-based screening levels for assessing potential health impacts of PCE. This issue will need to be updated in subsequent 5 year reviews.”

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14 of 15 MWH Response: The AF used published risk values to evaluate this Five-year review. The AF believes it is not valuable to conjecture on future risk reassessments in a Five-year review. However, the published risk values will be evaluated every 5 years in future ROD 5-Year Reviews. The current text discussing the cancer slope factor for TCE was included as background of which factors were evaluated. This text has been adjusted to only reflect current standards.

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