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to UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION VIII ADMINISTRATIVE RECORD IN THE MATTER OF: CALIFORNIA GULCH SUPERFUND SITE, FILE PLAN ASARCO INCORPORATED, Q.7 RESPONDENT. EPA Docket No. CERCLA-VI11-91 - PROCEEDING UNDER SECTION 106(a) OF THE COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT, AS AMENDED, 42 U.S.C. § 9606(a)

ADMINISTRATIVE ORDER FOR CERTAIN REMEDIAL INVESTIGATION STUDIES

TABLE OF CONTENTS I. INTRODUCTION ...... 4 II. JURISDICTION ...... 4 III. PARTIES BOUND ...... 4 IV. DEFINITIONS ...... 4 V. GENERAL PROVISIONS ...... 5 VI. FINDINGS OF FACT ...... 6 VII. CONCLUSIONS OF LAW AND DETERMINATIONS ...... 7 VIII. NOTICE TO STATE ...... 8 I.. PERFORMANCE OF WORK ...... 8 .. MODIFICATION OF WORK PLANS ...... 9 XI. QUALITY ASSURANCE, SAMPLING, DATA ANALYSIS, AND AVAILABILIT...... Y ...... 9 . XII. ACCESS ...... 11 XIII. PUBLIC COMMENT, ADMINISTRATIVE RECORD...... 12 XIV. REPORTING REQUIREMENTS ...... 13 XV. SUBMISSIONS REQUIRING AGENCY APPROVAL ...... 13 XVI. REMEDIAL PROJECT MANAGER...... 14 XVII. ASSURANCE OF ABILITY TO COMPLETE WORK ...... 15 XVIII. CERTIFICATION OF COMPLETION, TERMINATION ...... 16 XIX. EMERGENCY RESPONSE ...... 16 XX. INSURANCE AND INDEMNIFICATION ...... 17 XXI. DELAY IN PERFORMANCE ...... 18 XXII. UNITED STATES NOT LIABLE ...... 19 XXIII. ENFORCEMENT AND RESERVATIONS ...... 19 XXIV. ACCESS TO INFORMATION ...... 20 XXV. RETENTION OF RECORDS ...... 21 XXVI. EFFECTIVE DATE ...... 21 XXVII. COMMUNITY RELATIONS ...... 21 XXVIII. MODIFICATION ...... 21 XXIX. OPPORTUNITY TO CONFER ...... 22 XXX. NOTICE OF INTENT TO COMPLY ...... 22 XXXI. ORDER ...... 23 Appendix A. Changes to Exhibits 2, 4, 5, and 6. Exhibit 1. Demographics Work Plan. Exhibit 2. Final Sampling Plan for Sampling and Analysis of Lead Occurrence Within and Immediately Adjacent to Residences. Exhibit 3. Soil Investigation Work Plan. Exhibit 4. Mine Waste Pile Remedial Investigation Work Plan. Exhibit 5. Tailing Disposal Area Remedial Investigation Work Plan. Exhibit 6. Surface Water, Bed Material and Aquatic Ecosystem Data Collection Program Work Plan. I. INTRODUCTION 1. This Administrative Order directs Respondent to perform certain studies toward the eventual completion of a Remedial Investigation/Feasibility Study ("RI/FS") in connection with the California Gulch Superfund Site near Leadville, Lake County, Colorado. II. JURISDICTION 2. This Order is issued under the authority vested in the President of the United States by section 106(a) of the Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C. § 9606(a), as amended by the Superfund Amendments and Reauthorization Act of 1986, Pub. L. No. 99-499, 100 Stat. 1613 (1986) (CERCLA). This authority was delegated to the Administrator of EPA on January 23, 1987, by-Executive Order 12,580, 52 Fed. Reg. 2,926 (1987), and further delegated to Regional Administrators on September 13, 1987, by EPA Delegation No. 14-14-C. This authority has been further delegated to the Director of the Hazardous Waste Management Division. III. PARTIES BOUND 3. This Order shall apply to and be binding upon Respondent, its agents, successors, and assigns. Respondent is responsible for carrying out all actions required of it by this Order. No change in the ownership or corporate or other legal status of Respondent or of the facility or site shall alter Respondent's responsibilities under this Order. 4. During the period in which this Order is in effect, Respondent shall provide a copy of this Order to any subsequent owners or successors before property rights, stock, or assets are transferred. Respondent shall provide a copy of this Order to all contractors, subcontractors, laboratories, and consultants retained to conduct any work performed under this Order, within 14 days after the effective date of this Order or at least 7 days before retaining their services, whichever is later. Respondent shall condition any such contracts upon satisfactory compliance with this Order. Notwithstanding the terms of any contract, Respondent is responsible for compliance with this Order and for ensuring that its employees, contractors, consultants, subcontractors, agents, and attorneys comply with this Order. IV. DEFINITIONS Unless otherwise expressly provided herein, terms used in this Order which are defined in CERCLA or in regulations promulgated under CERCLA shall have the meaning assigned to them in CERCLA or such regulations. For purposes of this Order, the following terms shall have the meanings set forth below: 5. "Contractor" means any person, including the contractors, subcontractors, or agents, retained or hired by Respondent to undertake any work under this Order. 6. "Day" means calendar day, unless otherwise specified. 7. "Deliverable" means any written product, including, but not limited to, technical reports, data reports, technical memoranda, and other documents describing the work performed or to be performed, required to be submitted under the terms of this Order or the accompanying workplans. 8. "NCP" means the National Oil and Hazardous Substances Pollution Contingency Plan promulgated under Section 105 of CERCLA, 42 U.S.C. § 9605, codified at 40 C.F.-R. Part 300, including, but not limited to, any amendments thereto. 9. "Order" means this Order, attachments to this Order, and all documents which are incorporated into this Order according to the procedures set forth herein. 10. "Site" means the California Gulch Superfund Site, including the areal extent of contamination and all suitable areas in very close proximity to the contamination necessary for implementation of the response action. 11. "Work" means all tasks required by this Order, including all activities related to the performance of such activities. 12. "Work plan" means one of the work plans affixed hereto as Exhibits 1 through 6, including changes as outlined in Appendix A. "Work plan" also includes any sampling and analysis plan prepared under this Order, and any other plans or modifications to any such work or sampling and analysis plan approved by EPA pursuant to this Order. 13. All other terms not otherwise defined herein, shall have their ordinary meaning unless defined in CERCLA or the NCP, in which case the CERCLA or NCP definition shall control. V. GENERAL PROVISIONS 14. EPA's objective in issuing this Order is to require the performance of certain RI studies in accordance with CERCLA and the NCP to assess site conditions. 15. The activities conducted under this Order are subject to approval by EPA and must be sufficient to provide all necessary information for the RI work to be performed under this Order, and for a record of decision that is consistent with CERCLA and the NCP. The activities conducted under this Order shall be conducted in compliance with CERCLA, the NCP, and all applicable EPA guidance, policies, and procedures. VI. FINDINGS OF FACT 16. The Site is listed on the National Priorities List and is located near Leadville, Colorado. 17. ASARCO Incorporated ("ASARCO") is a New Jersey corporation with its corporate headquarters in the State of New York. Respondent owns or operates or has owned or operated portions of the Site. 18. The Site discharges or has the potential to discharge various metals, including arsenic, cadmium, copper, lead and zinc as follows: Soil resources of residential, commercial, industrial, and undeveloped lands within the Site have been and continue to be subject to impact by mining and related activities. Smelter slag, tailings piles, and waste rock piles containing high levels of metals are found throughout the Site. Metals migration can occur from these sources to nearby surface and vadose soils by wind dispersion, precipitation and surface water runoff, and reworking of these surface sources. Mill tailings are the rock debris remaining after milling and separation has removed the metal as concentrates from the ore. Tailings are generally fine-grained, silt-sized particles. Many piles and ponds (where water is decanted from the tailings), are located on the Site. These tailings piles and ponds are a potential source of metals contamination as shown in previous studies. Mine waste rock consists of mine development rock and low grade ore taken from below ground and deposited near adit or shaft openings. Many of the mine waste rock piles contain high concentrations of arsenic, cadmium, copper, lead, nickel, and zinc, which may be leached from the mining waste during times of rain or snowfall. There are hundreds of waste rock piles on the Site. Surface water acts as the primary transport mechanism for both soluble metals and metal-laden sediments. The Site is drained by several gulches tributary to the Arkansas River, including: Evans, California, Iowa, and Empire gulches. These gulches flow mostly in response to precipitation events and snowmelt. , The intermittent flow of surface water over, through, and around mining waste rock and tailings piles, into the gulches, and ultimately into the Arkansas River is a potential source of metals contamination. Groundwater acts as a transport mechanism for soluble metals. Groundwater is found in both bedrock and alluvial systems at California Gulch, and recharge is principally from infiltration of precipitation and surface water drainage. Groundwater in upper California Gulch, occurs primarily in the bedrock formations including granite, limestone, porphyry, and sandstones. Groundwater in the bedrock system east and southeast of Leadville discharges directly to California Gulch surface water, into the mine workings and the Yak Tunnel, or into downgradient groundwater systems. In lower California Gulch, groundwater flows through high terrace gravels, lake bed sediments, or bedrock units. Much of the groundwater in the area eventually reaches California Gulch and Arkansas River surface water or associated alluvial groundwater systems. Stream sediments may be affected by migration, alteration, absorption, and precipitation of contaminants from sources upstream. Air is affected by fugitive dust generated by wind erosion, earth movement during construction, off-road vehicles, and vehicular traffic on dirt and gravel roads. Significant pathways exist for ingestion, inhalation, and contamination of indoor environments with hazardous elements found in mining, processing, and smelting wastes at the Site. Flora and fauna may be threatened by metals contamination of the environment. System studies confirm the presence of metals in soils, sediments, and surface water. These metals affect vegetation, livestock, wildlife, and macroinvertebrates. 19. Arsenic, cadmium, copper, lead, and zinc are "hazardous substances" pursuant to section 101(14) of CERCLA, 42 U.S.C. § 9601 . VII. CONCLUSIONS OF LAW AND DETERMINATIONS 20. The site is a "facility" as defined in section 101(9) of CERCLA, 42 U.S.C. § 9601(9). 21. Various metals found at the Site are "hazardous substances" as defined in section 101(14) of CERCLA> 42 U.S.C. § 9601(14), or constitute "any pollutant or contaminant" that may present an imminent and substantial danger to public health or welfare under section 104(a)(1) of CERCLA, 42 U.S.C. § 9604(a). 22. The past, present, or potential future migration of hazardous substances described in section VI of this Order constitutes an actual and/or threatened "release" as defined in section 101(22) of CERCLA, 42 U.S.C. § 9601(22). 23. Respondent is a person as defined in section 101(21) of CERCLA, 42 U.S.C. § 9601(21). 24. Respondent is a responsible party under sections 104, 107, and 122 of CERCLA, 42 U.S.C. §§ 9604, 9607, and 122. 25. The actions required by this Order' are necessary to protect the public health or welfare or the environment and are consistent with CERCLA and the NCP. VIII. NOTICE TO STATE 26. By providing a copy of this Order to the State of Colorado, EPA has notified the state that this Order is being issued and that EPA is the lead agency for coordinating, overseeing, and enforcing the response action required by this Order. EPA will provide for state involvement with development of the RI studies in accordance with section 121(f) of CERCLA, 42 U.S.C. § 9621(f ). 27. Any document, notice, material, or deliverable, which Respondent is required under this Order to submit to EPA, shall also be submitted by Respondent to the State. 28. The State and its authorized representatives shall be provided the same rights of access to areas to which this Order applies as is provided for EPA in Section XII. IX. PERFORMANCE OF WORK 29. All Work performed under this Order shall be under the direction and supervision of qualified personnel. Within 30 days of the effective date of this Order, and before the Work begins, Respondent shall notify EPA in writing of the names, titles, and qualifications of the personnel, including contractors, subcontractors, consultants, and laboratories, to be used in carrying out such Work. The qualifications of the persons undertaking the Work for Respondent shall be subject to EPA's review for verification that such persons meet minimum technical background and experience requirements. If EPA disapproves in writing of any person(s)' technical qualifications, Respondent 8 shall notify EPA of the identity and qualifications of the replacement(s) within 7 days of the written notice. -If EPA subsequently disapproves of the replacements), EPA reserves the right to terminate this Order, conduct the Work, and seek reimbursement for costs and penalties from Respondent. During the course of the Work, Respondent shall notify EPA in writing 7 days in advance of any changes or additions in the personnel used to carry out such Work, providing their names, titles, and qualifications. EPA shall have the same right to approve changes and additions to personnel as it has hereunder regarding the initial notification. 30. Respondent shall conduct activities and submit deliverables as provided by this Order and the attached exhibits, which are incorporated by reference. All Work performed is to be conducted in accordance with the schedules, standards, specifications, and other requirements of this Order, and the attached work plans, as initially approved or- modified by EPA, and as may be amended or modified by EPA from time to time. 31. Respondent shall, prior to any off-site shipment of hazardous substances from the site, provide written notification to the appropriate state environmental official in the receiving state and to EPA's Designated Remedial Project Manager (RPM) of such shipment of hazardous substances. (a) The notification referred to above shall be in writing, and shall include the following information: (1) the name and location of the facility to which the hazardous substances are to be shipped; (2) the type and quantity of the hazardous substances to be shipped; (3) the expected schedule for the shipment of the hazardous substances; and (4) the method of transportation. Respondent shall notify the receiving state of major changes in the shipment plan, such as a decision to ship the hazardous substances to another facility within the same state, or to a facility in another state. (b) The identity of the receiving facility will be determined by Respondent following the award of the contract or contracts for the Work. Respondent shall provide all relevant information, including information under the categories noted in paragraph (a) above, on the off-site shipments, as soon as practical after the award of the contract and before the hazardous substances are actually shipped. 32. All activities undertaken by Respondent shall be in compliance with all Federal, State and local laws and regulations, including permit requirements, unless an exemption is provided by section 121(e) of CERCLA, 42 U.S.C. § 9621(e). Respondent shall identify and obtain all permits, licenses, and approvals required for performance of Work in sufficient time to perform Work as scheduled. 33. The Exhibits identify deliverables to be produced under the terms of this Order along with due dates for those deliverables. Tasks referred to are those set forth in this Order and the Exhibits. X. MODIFICATION OF WORK PLANS 34. If at any time during performance of the Work as required herein, Respondent identifies a need for additional data, a memorandum documenting the need for additional data shall be submitted to the designated RPM within 7 days of such identification. EPA in its discretion will determine whether the additional data will be collected by Respondent and whether it will be incorporated into reports and deliverables. 35. In the event of conditions posing an immediate threat to human health or welfare or the environment, Respondent shall notify the RPM and the state immediately. In the event of unanticipated.or changed circumstances at the site, Respondent shall notify the RPM by telephone within 24 hours of discovery of the unanticipated or changed circumstances. In addition to the authorities in the NCP, in the event that EPA determines that the immediate threat or the unanticipated or changed circumstances warrant changes in any work plan, EPA shall modify or amend such work plan in writing accordingly. Respondent shall perform the work plan as modified or amended. 36. EPA may determine that in addition to tasks defined in any initially approved work plan, other work may be necessary to accomplish the objectives of the Work. EPA may require that Respondent perform these response actions in addition to those required by any initially approved work plan, including any approved modifications, if it determines that such actions are necessary to adequately complete the Work. Respondent shall confirm its willingness to perform the additional work in writing to EPA within 7 days of receipt of the EPA request. Respondent shall implement the additional tasks which EPA determines are necessary. The additional work shall be completed according to the standards, specifications, and schedule set forth or approved by EPA in a written modification to any work plan or written supplements thereto. EPA reserves the right to conduct the Work itself at any point, to seek reimbursement from Respondent, and/or to seek any other appropriate relief. XI. QUALITY ASSURANCE, SAMPLING, DATA ANALYSIS, AND AVAILABILITY 37. Respondent shall assure that work performed, samples taken, and analyses conducted conform to the requirements of the work plans and guidance identified therein.

10 38. In the event that the Respondent fails to use the QA/QC practices and procedures as outlined in the work plans approved hereunder, EPA reserves the right to conduct all Work identified herein, including a complete RI/FS or any portion thereof pursuant to its authority under CERCLA, to seek reimbursement from Respondent, and/or to seek any other appropriate relief. 39. All results of sampling, tests, modeling, or other data (including raw chemical analytical data) generated by Respondent, or on Respondent's behalf, during implementation of this Order, shall be submitted to EPA in an electronic file format using the EPA contract laboratory program (CLP) format A (as described in Exhibit H of the EPA CLP Statement of Work for Inorganic Analysis, Multi-media, Multi-concentrate) or an ASCII file format, along with the monthly progress report as described in Section XIV of this Order. EPA will make available to the Respondent validated data generated by EPA unless it is exempt from disclosure by any federal or state law or regulation. 40. Respondent will notify EPA in writing at least 15 days prior to conducting significant field events as described in any work plan, or sampling and analysis plan. At EPA's verbal or written request, or at the request of EPA's oversight assistant, Respondent shall allow split or duplicate samples to be taken by EPA (and/or its authorized representatives) of any samples collected by the Respondent in implementing this Order. 41 . If Respondent objects to data relating to the RI Work identified herein, Respondent shall submit to EPA a report that identifies and explains its objections, describes the acceptable uses of the data, if any, and identifies any limitations to the use of the data. The report must be submitted to EPA within 15 days of the monthly progress report containing the data. XII. ACCESS 42. EPA and its authorized representatives may enter and freely move about all property at the site and off-site areas where Work, if any, is being performed, for the purposes of inspecting conditions, activities, the results of activities, records, operating logs, and contracts related to the site or Respondent and its contractor(s) pursuant to this Order; reviewing the progress of Respondent in carrying out the terms of this Order; conducting tests as EPA or its authorized representatives deem necessary; using a camera, sound recording device, or other recording equipment; and verifying the data submitted to EPA by Respondent. Respondent shall allow these persons to inspect and copy all records, files, photographs, documents, sampling and monitoring data, and other writings related to work undertaken in carrying out this Order. Nothing herein shall be interpreted as limiting or affecting any EPA 1 1 representative's right of entry or inspection authority under federal law. 43. If for proper performance of the Work, it is necessary to enter property owned in whole or in part by parties other than those bound by this Order, Respondent will obtain, or use its best efforts to obtain, site access agreements from the owner 30 days prior to the time such access is needed. Such agreements shall provide access for EPA, its contractors and oversight officials, the State of Colorado and its contractors, and the Respondent or its authorized representatives. Such agreements shall specify that Respondent is not EPA's representative with respect to liability associated with site activities. Copies of such agreements shall be provided to EPA prior to Respondent's initiation of field activities. 44. If access agreements are not obtained within the time referenced above, Respondent shall promptly notify EPA of its failure to obtain access. EPA may obtain access for the Respondent, perform those tasks or activities with EPA contractors, or terminate the Order in the event that Respondent cannot obtain access agreements. In the event that EPA performs those tasks or activities with EPA contractors and does not terminate the Order, Respondent shall perform all other activities not requiring access to that site, and shall reimburse EPA for all costs incurred in performing such activities. Respondent additionally shall integrate the results of any such tasks undertaken by EPA into its reports and deliverables. Respondent shall reimburse EPA for all costs and attorney fees incurred by the United States in obtaining access for the Respondent. XIII. PUBLIC COMMENT, ADMINISTRATIVE RECORD 45. EPA retains the responsibility for the release to the public of any reports based upon the Work. 46. EPA may provide Respondent with copies of any report based upon the Work and the final RI/FS report. 47. EPA will determine the contents of the administrative record file for selection of the remedial action. Respondent must submit to EPA documents developed during the course of the Work upon which selection of the response action may be based. Respondent shall provide copies of plans, task memoranda including documentation of field modifications, recommendations for further action, quality assurance memoranda and audits, raw data, field notes, laboratory analytical reports, and other reports. Respondent must additionally submit any previous studies conducted under state, local, or other federal authorities relating to selection of the response action, and all communications between Respondent and state, local, or other 12 . federal authorities concerning selection of the response action. At EPA's discretion, Respondent may establish a community information repository at or near the site, to house one copy of the administrative record. XIV. REPORTING REQUIREMENTS 48. Respondent shall make presentations at and participate in meetings at the request of EPA during the initiation, conduct, and completion of the Work. In addition to discussion of the technical aspects of the Work, topics will include anticipated problems or new issues. Meetings will be scheduled at EPA's discretion. 49. In addition to the deliverables set forth in this Order, Respondent shall provide to EPA monthly progress reports by the 1Oth day of each month during which this Order is in effect. At a minimum, with respect to the preceding month, these progress reports shall: (1) describe the actions which have been taken to comply with this Order during that month; (2) include all results of sampling and tests and all other data collected or received by Respondent; (3) describe work planned for the next two months with schedules relating such work to the overall project schedule for completion or Work; and (4) describe all problems encountered and any anticipated problems, any actual or anticipated delays, and solutions developed and implemented to address any actual or anticipated problems or delays. XV. SUBMISSIONS REQUIRING AGENCY APPROVAL 50. EPA reserves the right to comment on, modify, and direct changes for all deliverables. When EPA comments on or directs changes to deliverables, the following procedures shall apply: a. Respondent must fully correct all deficiencies and incorporate and integrate all information and comments, as directed by EPA, within seven (7) days of receipt of EPA comments, unless otherwise specified in any schedule in the work plans approved hereunder. b. Respondent may request, and EPA shall grant, a meeting to discuss any comments or instructions from EPA, prior to resubmitting the deliverable. If EPA, in consultation with the state of Colorado, agrees that its comments or instructions are incorrect or should be modified, Respondent may resubmit the deliverables in accordance with EPA's decision. c. At the time any revised deliverable is submitted, Respondent shall submit a cover letter describing how each substantive EPA comment was addressed, and a 13 description of any additional substantive changes or additions in the resubmittal along with a•justification for those changes or additions. The cover letter shall also include a certification that no substantive changes other than those identified in the cover letter were made. Failure to address EPA comments or directions as described in this paragraph, or failure to identify additional substantive changes or additions is a violation of this Order. d. If Respondent disagrees with the substantive changes required by EPA, Respondent may include a disclaimer in the cover letter identifying the portion(s) of such documents with which the Respondent disagrees and the reasons for the disagreement. Whenever and to whomever the document is disseminated, EPA will include such cover letter with the deliverable. Such cover letter shall be included in the Administrative Record for the Site as provided under Section XIII. 51. If Respondent fails to comply with the preceding paragraph, or if EPA determines that additional changes or additions were included in a resubmittal without sufficient justification, EPA retains the right to seek statutory penalties, perform its own studies, or complete or modify the deliverable or any portion thereof and seek reimbursement from Respondent for its costs. To the extent that EPA conducts or takes over some of the Work, Respondent shall incorporate and integrate information supplied by EPA into any report on such Work. 52. In the event that EPA takes over some of the tasks, Respondent shall incorporate and integrate information supplied by EPA into any reports prepared by it. 53. Neither failure of EPA to expressly approve or disapprove of Respondent's submissions within the specified time periods, nor the absence of comments, shall be construed as approval by EPA. Whether or not EPA gives express approval for Respondent's deliverables, Respondent is responsible for preparing deliverables acceptable to EPA. XVI. REMEDIAL PROJECT MANAGER 54. All communications, whether written or oral, from Respondent to EPA shall be directed to one of EPA's RPMs. Respondent shall submit to EPA three copies of all documents, including plans, reports, and other correspondence, which are developed pursuant to this Order, and shall hand deliver or send these documents return receipt requested.

14 EPA's RPM concerning Exhibits 1-5 is: Ken Wangerud, 8HWM EPA Remedial Project Manager Hazardous Waste Management Division EPA Region VIII 999 18th Street, Suite 500 Denver, CO 80202-2405 EPA's RPM concerning Exhibit 6 is: Denise Link, 8HWM EPA Remedial Project Manager Hazardous Waste Management Division EPA Region VIII 999 18th Street, Suite 500 Denver, CO 80202-2405 55. EPA has the unreviewable right to change its RPMs. If EPA changes either of its RPMs, EPA will inform Respondent in writing of the name, address, and telephone number of the new RPM. 56. EPA's RPMs shall have the authority lawfully vested in RPMs and On-Scene Coordinators (OSCs) by the NCP, 40 C.F.R. Part 300. EPA's RPMs shall have authority, consistent with the NCP, to halt any work required by this Order, and to take any necessary response action. 57. Within ten (10) days after the effective date of this Order, Respondent shall designate a Project Coordinator and shall submit the name, address, and telephone number of the Project Coordinator to EPA for review and approval. Respondent's Project Coordinator shall be responsible for overseeing Respondent's implementation of this Order. If Respondent wishes to change its Project Coordinator, Respondent shall provide written notice to EPA, five (5) days prior to changing the Project Coordinator, of the name and qualifications of the new Project Coordinator. Respondent's selection of a Project Coordinator shall be subject to EPA approval. XVII. ASSURANCE OF ABILITY TO COMPLETE WORK 58. Respondent shall establish and maintain a financial instrument, trust account, or other financial mechanism such as one of those set forth at 40 C.F.R. Part 264.143, acceptable to EPA, funded sufficiently to perform the work and any other obligations required under this Order, including a margin for cost overruns. Within 15 days of the effective date of this Order, Respondent shall either fund the financial instrument or trust account or demonstrate to the satisfaction of EPA that its 15 financial resources are sufficient to perform the work required under this Order projected for the period beginning•with the effective date of the Order through the end of the current calendar year quarter. On or before the 15th calendar day of each calendar year quarter thereafter, Respondent shall either fund the financial instrument or trust account or demonstrate to the satisfaction of EPA that its financial resources are sufficient to perform the work and other activities required under this Order projected for the succeeding calendar year quarter. Within 5 days of the funding of any account or other mechanism or the demonstration of ability to perform Work, Respondent shall report such to the RPM. 59. If at any time the net worth of the financial instrument or trust account is insufficient or the other demonstration of financial ability is inadequate to assure performance of the Work and other obligations under the Order for the upcoming quarter, Respondent shall provide written notice to EPA within 7 days after the net worth of the financial instrument, trust account or other demonstration of financial ability becomes insufficient or inadequate. The written notice shall describe why the financial instrument, trust account or other demonstration of financial ability is insufficient and shall explain what actions have been or will be taken to fund the financial instrument or trust account adequately or to demonstrate to the satisfaction of EPA that it has the financial resources to continue the Work through the time period required. EPA reserves the right to terminate this Order if funding becomes or will become inadequate. XVIII. CERTIFICATION OF COMPLETION, TERMINATION 60. This Order shall terminate when Respondent demonstrates in writing and certifies to the satisfaction of EPA that all activities required under this Order, including any additional work, are complete. 61. The certification shall be signed by a responsible official representing Respondent. The representative shall make the following attestation: "I certify that the information contained in or accompanying this certification is true, accurate, and complete." For purposes of this Order, a responsible official is a corporate official who is in charge of a principal business function. XIX. EMERGENCY RESPONSE 62. In the event of any action or occurrence during the performance of the Work which causes or threatens a release of waste material that constitutes an emergency situation or may present an immediate threat to public health or welfare or the 16 environment, Respondent shall, subject to the following paragraph, immediately take all appropriate action to prevent, abate, or minimize such release or threat of release, and shall immediately notify the RPM. If this person is not available, the Respondent shall notify the EPA Emergency Response Branch, Region VIII. Respondent shall take such actions in consultation with the RPM and in accordance with all applicable provisions of the Health and Safety Plans, the Contingency Plans, or any other applicable plans or documents developed pursuant to this Order. In the event that Respondent fails to take appropriate response action as required by this Section, and EPA takes such action instead, Respondent shall reimburse EPA all costs of the response action not inconsistent with the NCP. 63. Nothing in the preceding paragraph or in this Order shall be deemed to limit any authority of the United States to take, direct, or order all appropriate action or to seek an order in a Court of competent jurisdiction to protect human health and the environment or to prevent, abate, or minimize an actual or threatened release of waste material on, at, or from the Site. XX. INSURANCE AND INDEMNIFICATION 64. (a) Prior to commencement of any work under this Order, Respondent shall secure, and shall maintain in force for the duration of this Order, and for two years after the completion of all activities required by this Order, Comprehensive General Liability (CGL) and automobile insurance, with limits of $2,000,000.00 dollars, combined single limit, naming as insured the United States. The CGL insurance shall include Contractual Liability Insurance in the amount of $2,000,000.00 per occurrence, and Umbrella Liability insurance in the amount of $2,000,000.00 per occurrence. Respondent may, in lieu of CGL insurance, provide to EPA a copy of its certificate of self insurance. (b) Respondent shall also secure, and maintain in force Professional Errors and Omissions insurance in the amount of $1,000,000.00 per occurrence for the duration of this Order and for two years after the completion of all activities required by this Order . * (c) For the duration of this Order, Respondent shall satisfy, or shall ensure that their contractors or subcontractors satisfy, all applicable laws and regulations regarding the provision of employer's liability insurance and workmen's compensation insurance for all persons performing work on behalf of Respondent, in furtherance of this Order. (d) If Respondent demonstrates by evidence satisfactory to EPA that any contractor or subcontractor maintains insurance equivalent to that described above, or 17 insurance covering the same risks but in a lesser amount, then with respect to that contractor or subcontractor, Respondent need provide only that portion of the insurance described above which is not maintained by the contractor or subcontractor. (e) At least 7 days prior to commencement of any work under this Order, and annually thereafter on the anniversary of the effective date of this Order, Respondent shall provide to EPA certificates of such insurance and a copy of each insurance policy. Respondent shall certify to EPA that the required insurance has been obtained by that contractor. 65. EPA shall not be liable for any injury or damages to persons or property resulting from acts or omissions of the Respondent or its Contractors in implementing the requirements of this Order or any EPA-approved work plan or planning documents. EPA shall not be considered a party to any contract entered into by Respondent for purposes of implementing this Order. 66. Respondent shall indemnify and hold the United States Government, its agencies, departments, agents, and employees harmless from any and all claims or causes of action arising from or on account of acts or omissions of Respondent, its employees, agents, servants, receivers, successors, or assigns, or any persons including, but not limited to, firms, corporations, subsidiaries, and contractors, in carrying out activities under this Order. XXI. DELAY IN PERFORMANCE 67. Any delay in performance of this Order that, in EPA's judgment, is not properly justified by Respondent under the terms of this paragraph shall be considered a violation of this Order. Any delay in performance of this Order shall not affect Respondent's obligations to fully perform all obligations under the terms and conditions of this Order. 68. Respondent shall notify EPA of any delay or anticipated delay in performing any requirement of this Order. Such notification shall be made by telephone to the RPM within forty eight (48) hours after Respondent first knew or should have known that a delay might occur. Respondent shall adopt all reasonable measures to avoid or minimize any such delay. Within five (5) business days after notifying EPA by telephone, Respondent shall provide written notification fully describing the nature of the delay, any justification for delay, any reason why Respondent should not be held strictly accountable for failing to comply with any relevant requirements of this Order, the measures planned and taken to minimize the delay, and a schedule for implementing the measures that will be taken to mitigate the effects of the delay. Increased costs or expenses associated 18 with implementation of the activities called for in this Order is not a justification for any delay in performance. XXII. UNITED STATES NOT LIABLE 69. The United States, by issuance of this Order, assumes no liability for any injuries or damages to persons or property resulting from acts or omissions by Respondent, or their directors, officers, employees, agents, representatives, successors, assigns, contractors, or consultants in carrying out any action or activity pursuant to this Order. Neither EPA nor the United States may be deemed to be a party to any contract entered into by Respondent or its directors, officers, employees, agents, successors, assigns, contractors, or consultants in carrying out Any action or activity pursuant to this Order. XXIII. ENFORCEMENT AND RESERVATIONS 70. EPA reserves the right to bring an action against Respondent under section 107 of CERCLA, 42 U.S.C.S 9607, for recovery of any response costs incurred by the United States related to this Order. This reservation shall include but not be limited to past costs, direct costs, indirect costs, the costs of oversight, the costs of compiling the cost documentation to support oversight cost demand, accrued interest as provided in section 107(a) of CERCLA, 42 U.S.C.§ 9607(a), and any and all other costs not inconsistent with the NCP. 71. Notwithstanding any other provision of this Order, at any time during the response action, EPA may perform its own studies, complete the response action (or any portion of the response action) as provided in CERCLA and the NCP, and may seek reimbursement from Respondent for its costs, or seek any other appropriate relief. 72. Nothing in this Order shall preclude EPA from taking any additional enforcement actions, including modification of this Order or issuance of additional Orders, and/or additional remedial or removal actions as EPA may deem necessary, or from requiring Respondent in the future to perform additional activities pursuant to CERCLA, 42 U.S.C. § 9606(a), et seq., or any other applicable law. Respondent shall be liable under CERCLA section 107(a), 42 U.S.C. § 9607(a), for the costs of any such additional actions. 73. Notwithstanding any provision of this Order, the United States hereby retains all of its information gathering, inspection and enforcement authorities and rights under CERCLA, RCRA and any other applicable statutes or regulations. 74. Respondent shall be subject to civil penalties under section 106(b) of CERCLA, 42 U.S.C. § 9606(b), of not more than 19 $25,000 for each day in which Respondent willfully violates, or fails or refuses to comply with this Order without sufficient cause. In addition, failure to properly provide response action under this Order, or any part hereof, without sufficient cause, may result in liability under section 107(c)(3) of CERCLA, 42 U.S.C. § 9607(c)(3), for punitive damages in an amount at least equal to, and not more than three times the amount of any costs incurred by the Fund as a result of such failure to take proper action. 75. Nothing in this Order shall constitute or be construed as a release from any claim, cause of action or demand in law or equity against any person for any liability it may have arising out of or relating in any way to the Site. 76. If a court issues an order that invalidates any provision of this Order or finds that Respondent has sufficient cause not to comply with one or more provisions of this Order, Respondent shall remain bound to comply with all provisions of this Order not invalidated by the court's order. 77. In the event of any inconsistency between the terms and conditions of this Order or those contained in any work plan approved hereunder, schedules, attachments, exhibits, or other documents incorporated herein, the terms and conditions of this Order shall take precedence. XXIV. ACCESS TO INFORMATION 78. Respondent shall provide to EPA upon request, copies of all documents and information within their possession or control or that of their contractors or agents relating to activities at the Site or to the implementation of this Order, including, but not limited to, sampling, analysis, chain-of-custody records, manifests, trucking logs, receipts, reports, sample traffic routing, correspondence, or other documents or information related to the Work. Respondent shall also make available to EPA, for purposes of investigation, information gathering, or testimony, their employees, agents, or representatives with knowledge of relevant facts concerning the performance of the Work. 79. Respondent may assert business confidentiality claims covering part or all of the documents or information submitted to EPA under this Order to the extent permitted by section 104(e)(7) of CERCLA, 42 U.S.C. § 9604(e)(7). Such claims shall be asserted in the manner described by 40 C.F.R. § 2.203(b) and substantiated at the time the claim is made. Documents or information determined to be confidential by EPA will be afforded the protection specified in 40 C.F.R. Part 2, Subpart B. If no claim of confidentiality accompanies documents or information when they are submitted to EPA, or if EPA has notified Respondent that the 20 documents or information are not confidential under the standards of section 104(e)(7) of CERCLA, 42 U.S.C. § 9604(e)('7), the public may be given access to such documents or information without further notice to Respondent. 80. No claim of confidentiality shall be made with respect to any data, including, but not limited to, all sampling, analytical, monitoring, hydrogeologic, scientific, chemical, or engineering data and materials or information submitted pursuant to this Order, or any other documents or information evidencing conditions at or around the Site. XXV. RETENTION OF RECORDS 81. All records and documents in Respondent's possession that relate in any way to the site shall be preserved while this Order is in effect and for a minimum of 10 years after commencement of construction of any remedial -action. Respondent shall acquire and retain copies of all documents that relate to the site and are in the possession of its employees, agents, accountants, contractors, or attorneys. After this 10-year period, Respondent shall notify EPA at least 90 days before the documents are scheduled to be destroyed. If EPA requests that the documents be saved, Respondent shall, at no cost to EPA, give EPA the documents or copies of the documents. XXVI. EFFECTIVE DATE 82. The effective date of this Order shall be the date it is signed by EPA. XXVII. COMMUNITY RELATIONS 83. EPA may prepare a community relations plan describing the activities it will undertake to disseminate information regarding the Work to the public. Respondent shall cooperate with EPA (and the State) in providing information regarding the Work to the public. As requested by EPA, Respondent shall participate in the preparation of such information for dissemination to the public and in public meetings which may be held or sponsored by EPA to explain activities at or relating to the Site. XXVIII. MODIFICATION 84. This Order may be amended by EPA. Amendments shall be in writing and shall be effective when signed by EPA. 85. No informal advice, guidance, suggestions, assurances, or comments by EPA or its authorized representatives shall modify the terms and conditions of this Order or relieve Respondent of its obligation under this Order. Any deliverables, plans, 21 technical memoranda, reports (other than progress reports), specifications, schedules, and attachments required by this Order are, upon approval by EPA, incorporated into this Order. XXIX. OPPORTUNITY TO CONFER 86. Respondent may, within five (5) days after the date this Order is signed, request a conference with the EPA Region VIII staff attorney responsible for this matter to discuss this •Order. 87. The purpose and scope of the conference shall be limited to issues involving the implementation of the response actions required by this Order and the extent to which Respondent intend to comply with this Order. This conference is not an evidentiary hearing, and does not constitute a proceeding to challenge this Order. It does not give Respondent a right to seek review of this Order, or to seek resolution of potential liability, and no official stenographic record of the conference will be made. At any conference held pursuant to Respondent's request, Respondent may appear in person or by an attorney or other representative. 88. Requests for a conference must be by telephone followed by written confirmation mailed that day to: Andrew J. Lensink, 8RC Assistant Regional Counsel Office of Regional Counsel EPA Region VIII 999 18th Street, Suite 500 Denver, CO 80202-2405 (303) 294-7574 XXX. NOTICE OF INTENT TO COMPLY 89. Respondent shall provide, not later than five (5) days after the effective date of this Order, written notice to the RPM stating whether it will comply with the terms of this Order. If Respondent does not unequivocally commit to perform the Work as provided by this Order, it shall be deemed to have violated this Order and to have failed or refused to comply with this Order. Respondent's written notice shall describe, using facts that exist on or prior to the effective date of this Order, any "sufficient cause" defenses asserted by Respondent under sections 106(b) and 107(c)(3) of CERCLA, 42 U.S.C. §§ 9606(b) and 9707(c)(3). The absence of a response by EPA to the notice required by this paragraph shall not be deemed to be acceptance of assertions by Respondent.

22 XXXI. ORDER 90. Based on the foregoing, Respondent is hereby ordered to comply with the provisions of this Order, including but not limited to all attachments to this Order, all documents incorporated by reference into this Order, and all schedules and deadlines in this Order, attached to this Order, or incorporated by reference into this Order.

IT IS SO ORDERED: ENVIRONMENTAL PROTECTION AGENCY, REGION VIII

BY: /£ •^XV5'/ / / "7T ^^xf DATE: Robert L. Duprey, Director// Hazardous Waste Manag4men^Division

23 APPENDIX A - WORKPLAN CHANGES The changes outlined below are hereby made in the referenced work plans, and with these changes, the referenced work plans are hereby approved. A. Changes to Work Plan for Sampling and Analysis of Lead Occurrence in and Immediately Adjacent to Residential Areas, July 1991, Exhibit 2. 1) The title is changed to read FINAL SAMPLING PLAN FOR SAMPLING AND ANALYSIS OF LEAD OCCURRENCE WITHIN AND IMMEDIATELY ADJACENT TO RESIDENCES. 2) Section 2.0, Page 2-1, Para. 3: Before "An effort will be made..." place the language: A minimum of 100 homes will be sampled according to the protocols set forth in this work plan. These 100 homes will be representatively distributed according to the age of each home and its geographic location within the Populated Remedial Investigation Study Area. A minimum of 50% of these homes will have children age 6 months to 72 months in residence. The sentence beginning "An effort will be made..." is changed to read: Additionally, an effort will be made... . 3) Section 4.1.1, Page 4-1: Create a new Section 4.1.1 and renumber subsequent sections. The new section is entitled Initial Visit and reads: Before sampling occurs, an initial visit will be conducted. The purpose of this visit will be to explain the objectives of EPA's remedial investigation and to request permission to release to EPA the results of sampling. 4) Section 4.1.3.1, Page 4-7, Para. 2: Item No. 1 is changed to read: A floor area directly inside the main entrance to the residence. 5) Section 4.1.3.1, Page 4-8, Para. 2: Item No. 1 is changed to read: If possible, an additional dust sample will be obtained from: 1) beneath carpets and 2) attic areas. 6) Section 4.1.3.1, Page 4-8, Para. 2: The first sentence is changed to read: Colocated samples will be collected from 20% of the houses and will be evaluated for speciation in accordance with the Metals Speciation Work Plan for this study. 1 7) Section 4.1.3.1, Page 4-8, Para. 4: When dust samples are collected, a tri-directional sweep pattern should be used where the second sweep is in a direction 90 degrees to the first, and the third direction is 45 degrees from the first sweep. All references to this technique throughout the work plan shall be corrected (e.g., p. 4-16, p. B-3. p. B-17). 8) Section 4.1.5, Page 4-19, Para. 1: The following action levels shall be stated for the analytical methods - All samples with lead detected at 20 ppm or less shall be re-analyzed by graphite furnace atomic absorption. 9) Section 4.1.6, Page 4-20, Sentence 1: The sentence is changed to read: Introduction, preliminary residential walk-through, and request to release results of sampling to EPA. 10) Section 6.0, Page 6-1: The second and third sentences are changed to read: For the minimum 100 homes sampled (they must be representatively distributed, no less than 50% of them with children age 6 to 72 months in residence) the environmental sampling forms contained in Appendix A (form numbers 05-08) will be completed and submitted to EPA along with the results of the sampling parameters prescribed in the work plan. For all other homes sampled, if permission has been received to release sampling results to EPA, the forms set forth in Appendix A will be completed and submitted to EPA along with the results of the sampling parameters prescribed in the work plan. 11) Appendix B,Section 9A, Page B-6: This procedure shall be modified to include the full acid digestion of the sample filter instead of the filter wash and discard step. 12) Appendix B, Section 9A, Page B-8: This procedure shall be modified to include: All samples with lead detected at 20 ppm or less shall be re-analyzed by graphite furnace atomic absorption. 13) Appendix B,Section 9A, Page B-20: All analytical calibration procedures within this work plan shall be modified to include a minimum of 5 calibration points, not 3 as stated in paragraph 7 of page B-20. 14) Appendix B, Section 9B, Page B-24, Table 5-3: The frequency of Calibration Verification and Instrument Blank samples shall be 1 per 10 samples instead of 1 per 20. In addition, the frequencies of Decon Blank samples, Duplicate samples, Replicate Analysis samples, and Interlaboratory Split samples will be analyzed every 1 per 20 samples or 1 per day which ever is more frequent. 15) The work plan shall be amended to require the use of Custody Seals on all sample containers prior to transportation off-site. 16) Appendix D, Section 5, Page D-3, Table 1: The Limit of Detection for the A.A.S. analysis shall be changed to 1 ppm (mg/kg). 17) Appendix D, Section 9B, Page D-11, Table 5-3: The frequency of Calibration Verification and Instrument Blank samples shall be 1 per 10 samples instead of 1 per 20. In addition, the frequencies of Decon Blank samples, Duplicate samples, Replicate Analysis samples, and Interlaboratory Split samples will be analyzed every 1 per 20 samples or 1 per day whichever is more frequent. B. Changes to Mine Waste Remedial Investigation Work Plan, July 1991, Exhibit 4. The Mine Waste Pile Remedial Investigation Work Plan is changed as follows: Within 30 days of the date of this Order, a flow diagram depicting the mine waste pile sampling and evaluation process and its relation to other RI procedures, along with an accompanying narrative description of that same process, shall be provided to EPA. C. Changes to Tailing Disposal Area Remedial Investigation Work Plan, July 1991, Exhibit 5. 1) Physical and chemical information characterizing Resurrection 1 and Resurrection 2 Tailings (Res 1 and Res 2) must be provided to EPA. Unless such information is presently available, a remedial investigation must be undertaken at Res 1 and Res 2 consisting of the collection of subsurface tailing samples, collection of groundwater samples, analytical testing, and geotechnical laboratory testing. Specifically, these activities will consist of: a. Drilling of three test holes, two at Res 1 and one at Res 2, to foundation material with sampling from the top 2 feet, at about 5-foot intervals, and at changes in material identified during drilling. i. Two test holes will be drilled through the buried tailing at Res 1—with one location at what is determined to be the thickest section of the tailing and another drilled at what is determined to be an upgradient location in the tailing. ii. One hole will be drilled at Res 2. This hole penetrate what is judged to be the thickest section of buried tailing. The locations of the test holes will be established in the field based on the site reconnaissance and review of historical data. Disturbed and relatively "undisturbed" samples in the test holes will be collected using shelby tubes, an Osterburg sampler, split spoons (SPT) or a California drive sampler. Water levels will be measured in the Res 1 test holes during drilling and 24 hours after drilling completion to allow for stabilization of water levels. b. Installation of monitor wells. Each of the holes will be completed as monitor wells in the tailings if water is encountered. The wells will be screened near the base of the tailings. The wells will be developed and sampled and the samples will be analyzed for the parameters listed in Table 2- 5. c. Chemical Analyses. All tailing and foundation samples from the Res 2 hole and the deeper hole at Res 1 will be analyzed for the parameters listed in Table 2-2. The remaining hole at Res 1 will be sampled at the following depths and submitted for chemical analysis: i. Within 5 feet above groundwater in the tailing if the groundwater is at a depth greater than 10 feet. ii. Within 5 feet below groundwater iii. Within 5 feet above the foundation material if the vertical distance between groundwater and the foundation material is greater than 10 feet. iv. Within the foundation material below the tailing. d. Geotechnical Analyses. Samples from the test holes will be tested for physical parameters. The testing may include: i. Moisture content; ASTM D2216 ii. Wet and densities; ASTM D2216 iii. Particle size distribution; ASTM D421 and D422 iv. Atterberg limits (liquid limit and plasticity index); ASTM D4318 The specific geotechnical testing program will be established based on the types of materials encountered, samples recovered, and engineering judgment. Other properties for design will be estimated from index properties or collected during remedial design, if needed. An amendment to the approved workplan addressing the above requirements shall be submitted to EPA no later than September 15, 1991. 2) Investigations of Hecla tailings. The investigations of Hecla tailings specified in Section 2.3.5, page 2-20, are approved. However, these investigations should not begin until September 16, 1991. In the event that an administrative order on consent or unilateral administrative order with an approved work plan for study of these tailings is issued to Hecla Mining Company by September 15, 1991, this section of the work plan shall be null and void. D. Changes to Surface Water, Bed Material and Aquatic Ecosystem Data Collection Program Work Plan, June 1991, Exhibit 6. 1) Page 2-1, Objectives: Remove the phrase, "Eliminate sampling at stations where contaminants of concern are not detected." 2) Section 4.2, Page 4-3: Correct the range for zinc concentrations to read 630 - 9150 mg/1. 3) Table 6-1: Change EPA GFAA method for lead to 239.2; Change method number for pH to 150.1; Change method number for bicarbonate and carbonate to SM403; Change method number for cyanide to 335.3. 4) Figure 6-1: Modify sample location numbering system to correspond to the USGS numbering system for surface water sampling locations on the Arkansas River and its tributaries. 5) Table 6-2: Add detection limits for parameters to be analyzed in bed material samples. See Attachment I, USEPA Contract Laboratory Program, Statement of Work For Inorganic Analysis, Multi-Media, Multi-Concentration, ILM01.0, July, 1988. However, the CRDL is dependent on the dry weight of the sample. The method to determine sediment detection limits is as follows: (Aqueous CRDL' s (ug/L) X 0.200D/1 gram (dry)*. * Dry weight = weight X % solids Antimony must be analyzed using the Furnace AA analysis, method 204.2. 6) SOP 2A, Page 6: Remove paragraph 1, since depth- integrated sampling is not appropriate in the Arkansas River Basin. 7) SOP 2A, Page 12, Paragraph 2: Samples for alkalinity, chloride, fluoride, and cyanide must be determined as totals (i.e., unfiltered). Add that samples will be checked for the presence of chlorine and sulfide, which may interfere with the cyanide analysis. 8) SOP 2A, Page 13 and 14, Rinsate Samples and Field Blanks: Modify last sentence to state that one rinsate sample will be collected for every twenty (20) water samples or once a day, whichever is more frequent. 9) SOP 4A, Page 7, Water Flea Toxicity Testing: Modify text to state that samples from California Gulch may require dilution to 0.25 percent, since toxicity below 1 percent has been observed in previous studies. 10) SOP 4A, Page 7, Fathead Minnow Toxicity Testing: Modify third sentence to state that the fathead minnow tests shall be conducted for forty-eight (48) hours at 20°C(+/-2°C). Modify next sentence to state that the minnows will be fed 0.1 milliliter brine shrimp prior to selection and at 24 hours. 11 ) SOP 4A, Page 8, Benthic Macroinvertebrates: Add the following: "At stations where the flows are too high for a standard D-frame kick-net sampler, a kick screen sampler will be used. A technician will be required to hold the sampler in place while a second technician agitates the streambed surrounded by the sampler. Samples will be put into white pans for pre-sorting and will be rinsed through a number 30 mesh screen prior to preservation. Samples will be preserved with 95% ethanol and placed in non-breakable (i.e., plastic) containers. Streamflow measurements will be conducted concurrently with sample collection." Add the stipulation that when a benthic sample cannot be identified to the Genus level for the chironomidae Family, the sample will be given to EPA for identification. 12) SOP 4A, Page 9, Fish: Add the sentence, "Fish age will also be confirmed by using a standard fish scale analysis." 13) SOP 4A, Page 10, Fish: Small fish must be collected to obtain a minimum weight of 300 - 500 grams. Add copper, chromium and arsenic to the list of parameters in the last paragraph. 14) SOP 4A, Page 12, Table 4-1: Table 4-1 must be modified as follows: Add an additional sampling station to sample the contaminant plume at station AR-3 for all parameters. The stations should be labeled as AR-3E and AR-3W to indicate east and west bank. Add a surface water sampling station downstream of AR-3. Immediately above the confluence of Half Moon Creek should be the approximate location. Add Station EM-2, EM-3, and EM-4 to be sampled for fish (total of 15 fish sampling stations). Add an additional station on California Gulch upstream of the Yak Tunnel discharge to the list of Benthic sampling stations. Add stations IG-1, HC-1, LF-1, and EF-1 to the toxicity testing list (total of 19 toxicity testing stations). 15) A storm event surface water sampling program must be implemented during the summer of 1991. Attachment 2 is a minimum requirements program that must be incorporated into the sampling program. Add language regarding the storm event sampling program indicating that EPA will be notified every time that a storm event sample is collected. ATTACHMENT I (page 1 of 1) USEPA CONTRACT LABORATORY PROGRAM STATEMENT OF WORK FOR INORGANIC ANALYSIS MULTI-MEDIA, MULTI-CONCENTRATION JULY, 1988

TARGET ANALYTE LIST

:^AQUEOUS> •-"'•• •::SOHL&- ^K^tfK-^-A: : '»QUEOUS.I JiSOILii •^Anatyte;.;; •£?CXDL- i" W-CKDL'-^: f SAnalyte - 1i%-CRDLi;ifi f!|lCRDLf!i: ,(ug/L,ppb) (mg/Kg,ppm): •:H"p'-:^ :-latug/L,ppb)::-

MINIMUM REQUIREMENTS FOR A STORM EVENT SAMPLING PROGRAM FOR SURFACE WATER AT THE CALIFORNIA GULCH SITE Purpose The storm event sampling program is designed to determine the chemical loading of metals to the Arkansas River from California Gulch during a rainfall storm event. The data will serve as a preliminary determination of the effects of a storm event on the aquatic biota in the surface water. The results will also be used to determine whether a detailed storm event monitoring program will be designed for California Gulch Site in the future. For purposes of this monitoring program, a storm event is defined as a rain event that results in at a minimum of 0.1 inches of rainfall to a surface. Data Quality Objectives The data quality objective of the storm event surface water data collection is to collect data of sufficient quality to determine the changes in water column chemistry and possible impacts to aquatic biota in the Arkansas Ri.ver from California Gulch during storm events. The data will be used to determine the chemical loading of metals during a storm event to the Arkansas River. Other potential uses of the data include: o environmental baseline risk assessment; o surface water modeling of contaminant transport from California Gulch; o and, screening and evaluation of remedial measures. Parameters flow copper pH iron conductivity lead total suspended sediment magnesium arsenic manganese cadmium silver calcium zinc Toxicity Sample Locations CG6: California Gulch above the confluence with the Arkansas River; AR2: Arkansas River upstream of California Gulch; AR3E: East Bank of the Arkansas River downstream of California Gulch; AR3A: Arkansas River downstream of ARSE. Frequency Samples must be collected during rainfall storm events that occur between August 1, 1991 and September 30, 1991. The sampling interval during the storm event should be designed to capture samples in the range of every 15 minutes to one half hour. Instrumentation Samples must be collected using precipitation-activated samplers or by personnel located near the site directed to collect samples when a storm event that results in 0.1 in. or more of precipitation occurs. Woodward-Clyde Consultants

TABLE OF CONTENTS (Concluded)

LIST OF TABLES TABLE 2-1 CRITERIA FOR LOCATION OF ALLUVIUM BACKGROUND MONITORING WELLS TABLE 2-2 ALLUVIAL BACKGROUND WELL LOCATIONS TABLE 3-1 ANALYTICAL METHODS FOR ANALYSIS OF WATER SAMPLES TABLE 3-2 SAMPLE ID NUMBER DATA FIELD CODE ENTRIES FOR SAMPLE LOCATION, MATRIX AND DATA LIST OF FIGURES FIGURE 2-1 APPROXIMATE LOCATION MAP OF EXISTING AND PROPOSED MONITORING WELLS AND PIEZOMETERS FIGURE 2-2 APPROXIMATE LOCATION MAP OF PROPOSED MINI-PIEZOMETERS FIGURE 2-3 DIAGRAMMATIC PRESENTATION OF GROUNDWATER 4 STUDIES FOR CONTAMINATION ASSESSMENT 4 LIST OF ATTACHMENTS ATTACHMENT A WELL SURVEY QUESTIONNAIRE f ATTACHMENT B SOP NO. HG-1 - MINI-PIEZOMETER INSTALLATION ATTACHMENT C SOP NO. HG-2 - MINI-PIEZOMETER WATER LEVEL MEASUREMENT AND SAMPLING ATTACHMENT D SOP NO. HG-3 - TUNNEL DISCHARGE AND SPRING RECONNAISSANCE AND SAMPLING I ATTACHMENT ESOP NO. HG-4 - SLUG TESTING I I f 22443-22327/R21.TC 08-10-91/RPT/6 -111- Woodward-Clyde Consultants

TABLE OF CONTENTS (Continued)

Section 3.1.5 Decontamination 3-7 3.1.6 Reporting 3-7 3.2 QUALITY ASSURANCE PLAN 3-7 3.2.1 Analytical Program 3-7 3.2.2 QA/QC Sampling 3-7 3.2.3 Precision, Accuracy, Representativeness, Comparability, and Completeness 3-8 3.2.4 Data Validation 3-8 3.3 STANDARD OPERATING PROCEDURES 3-9 4.0 REFERENCES 4-1

22443-22327/R21.TC 08-10-91/RPT/6 -11- Woodward-Clyde Consultants

TABLE OF CONTENTS Section 1.0 INTRODUCTION 1-1 1.1 SITE DESCRIPTION 1-1 1.2 WORK PLAN PURPOSE AND OBJECTIVES 1-1 1.3 WORK PLAN OVERVIEW 1-2 2.0 SCOPE OF WORK 2-1 2.1 DATA QUALITY OBJECTIVES 2-1 2.1.1 Data Needs/Data Gaps 2-2 2.1.2 Identification of Data Uses/Needs 2-4 2.2 PROPOSED WORK 2-7 2.2.1 Task 1 - Assess Previously Unidentified Groundwater Users and Uses 2-7 2.2.2 Task 2 - Tunnel Portal Discharge and Spring Reconnaissance Survey 2-8 2.2.3 Task 3 - Assess Groundwater Background Quality 2-11 2.2.4 Task 4 - Characterize Groundwater/Surface Water Interaction Along California Gulch 2-13 2.2.5 Task 5 - Characterize Groundwater Flow Directions and Hydraulic Gradients 2-16 2.2.6 Task 6 - Assess Groundwater Within the Bedrock Aquifer 2-18 2.2.7 Task 7 - Assess the Nature and Extent of Groundwater Contamination in the Alluvium 2-21 2.2.8 Task 8 - Data Analysis and Report 2-22 2.2.9 Task 9 - Additional Groundwater Contaminant Assessment Work 2-32 3.0 SAMPLING AND ANALYSIS PLAN 3-1 3.1 FIELD SAMPLING PLAN 3-1 3.1.1 Purpose 3-1 3.1.2 Sampling Objectives 3-1 3.1.3 Sampling Locations and Frequency 3-2 3.1.4 Sample Handling, Documentation, and Analysis 3-7

22443-22327/R21.TC 0&-10-91/RPT/6 -i- i I i i i • •••••• HYDROGEOLOGIC WORK PLAN CALIFORNIA GULCH j SITE ; LEADVILLE, COLORADO 1

AUGUST 1991

Prepared for ASARCO, Incorporated Leadville, Colorado Prepared by Woodward-Clyde 4582 South Ulster Street Parkway Stanford Place 3, Suite 1000 Denver, Colorado 80237

Project No. 22443E-3220