Prepared For: TCE RI/FS Coordinator Final TRICHLOROETHENE FEASIBILITY STUDY REPORT Former WACS Site / Joe Parent Vocational Education Center Aniak, Alaska Prepared By: 4101 Arctic Blvd., Suite 206 Anchorage, Alaska 99503 Geosyntec Project Number: PNG0712 March 2019 Final TRICHLOROETHENE FEASIBILITY STUDY REPORT Former WACS Site / Joe Parent Vocational Education Center Aniak, Alaska Prepared By: Geosyntec Consultants, Inc. 4101 Arctic Blvd., Suite 206 Anchorage, Alaska 99503 Ben Martich Bruce Marvin Principal Senior Principal Geosyntec Project Number: PNG0712 March 2019 TABLE OF CONTENTS EXECUTIVE SUMMARY .......................................................................................................... VI 1. INTRODUCTION .................................................................................................................... 1 1.1 Purpose and Objectives ....................................................................................................... 1 1.2 Regulatory Framework ....................................................................................................... 1 1.3 Organization of Report ....................................................................................................... 2 2. BACKGROUND INFORMATION ......................................................................................... 3 2.1 Site Location and Surroundings .......................................................................................... 3 2.2 Site Use ............................................................................................................................... 3 2.3 Investigation History ........................................................................................................... 4 2.4 Constituents of Potential Concern ...................................................................................... 5 2.5 Previous and Ongoing Remedial Activities ........................................................................ 5 2.5.1 Previous Remedial Studies and Activities .............................................................. 5 2.5.2 Ongoing and Planned Remedial Activities ............................................................. 8 2.6 Conceptual Site Model Overview ....................................................................................... 8 2.6.1 Geology and Hydrogeology .................................................................................... 8 2.6.2 TCE Sources ........................................................................................................... 9 2.6.3 Nature and Extent of TCE and Breakdown Products ........................................... 10 2.6.4 Fate and Transport of TCE ................................................................................... 13 2.6.5 Potential Exposure Pathways ................................................................................ 14 3. REGULATORY REQUIREMENTS AND REMEDIAL ACTION OBJECTIVES.............. 16 3.1 Applicable Requirements .................................................................................................. 16 3.2 Remedial Action Objectives ............................................................................................. 16 3.3 Target Areas for Remedial Response Actions .................................................................. 17 4. TECHNOLOGY IDENTIFICATION AND SCREENING ................................................... 18 4.1 Remedial Technologies ..................................................................................................... 18 4.2 Screening Criteria ............................................................................................................. 18 4.2.1 Effectiveness ......................................................................................................... 18 4.2.2 Implementability ................................................................................................... 19 4.2.3 Cost ....................................................................................................................... 19 4.3 Screening Results .............................................................................................................. 19 5. REMEDIAL RESPONSE ACTION ALTERNATIVES DEVELOPMENT AND EVALUATION....................................................................................................................... 21 Final FS Report i March 2019 5.1 Remedial Alternatives Development ................................................................................ 21 5.2 Alternatives Descriptions .................................................................................................. 21 5.2.1 Alternative 1 – No Action ..................................................................................... 22 5.2.2 Alternative 2 – Institutional Controls and Engineering Controls ......................... 22 5.2.3 Alternative 3 – Targeted Soil Vapor Extraction with ICs and ECs ...................... 23 5.2.4 Alternative 4 – Long-Term Groundwater Monitoring with ICs and ECs ............. 25 5.2.5 Alternative 5 – Targeted SVE and LTGM with Limited ICs and ECs ................. 25 5.2.6 Alternative 6 – Excavation and LTGM with Limited ICs and ECs ...................... 26 5.3 Alternatives Evaluation ..................................................................................................... 27 5.3.1 Evaluation Criteria ................................................................................................ 27 5.3.2 Comparative Discussion of Alternatives .............................................................. 28 6. RECOMMENDED REMEDIAL ALTERNATIVE ............................................................... 31 7. CONCLUSIONS..................................................................................................................... 32 8. REFERENCES ....................................................................................................................... 33 LIST OF TABLES – IN TEXT Table 4-1: List of Potential Remedial Technologies .................................................................... 18 LIST OF TABLES – APPENDED Table 1 Default Remedial Action Cleanup and Target Levels Table 2 TCE Mass Estimates by Geologic Unit Table 3 Technology Screening Table 4 Remedial Alternatives Evaluation Final FS Report ii March 2019 LIST OF FIGURES – APPENDED Figure 1 Site Location Figure 2 Site Vicinity Figure 3 1959 Aerial Photograph Figure 4 Extent of Removal Actions Figure 5 Plan View of Cross Sections Figure 5A Cross Section A-A’ Figure 5B Cross Section B-B’ Figure 5C Cross Section C-C’ Figure 5D Cross Section D-D’ Figure 5E Cross Section E-E’ Figure 6 Extent of TCE in Gravel Fill Layer Figure 7 Extent of TCE in Fine Silt Layer Figure 8 Extent of TCE in Groundwater Figure 9 Extent of TCE in Soil Figure 10 Unsaturated Zone – Institutional and Engineering Controls Figure 11 Saturated Zone – Institutional and Engineering Controls Figure 12 Unsaturated Zone – Targeted SVE with Institutional and Engineering Controls Figure 13 Saturated Zone – LTGM with Institutional and Engineering Controls Figure 14 Unsaturated Zone – Excavation with Institutional and Engineering Controls LIST OF CHARTS – APPENDED Chart 1 Alternatives Cost Comparison LIST OF APPENDICES Appendix A Spring 2018 Groundwater Monitoring Appendix B Remedial Response Action Alternatives Cost Estimates Appendix C Response to Comments Final FS Report iii March 2019 LIST OF ACRONYMS AND ABBREVIATIONS µg/kg ..........................micrograms per kilogram µg/L ............................micrograms per liter µg/m3 ..........................micrograms per cubic meter AAC ...........................Alaska Administrative Code ADEC .........................Alaska Department of Environmental Conservation ADOT&PF .................Alaska Department of Transportation & Public Facilities bgs ..............................below ground surface CD ..............................Consent Decree cDCE ..........................cis-1,2-dichloroethene CERCLA ....................Comprehensive Environmental Response, Compensation, and Liability Act COPC .........................constituent of potential concern CSM ...........................conceptual site model E&E............................Ecology and Environment, Inc. ECs .............................engineering controls FS ...............................feasibility study Geosyntec ...................Geosyntec Consultants, Inc. ICs ..............................institutional controls JPVEC ........................Joe Parent Vocational Education Center KSD............................Kuspuk School District LTGM ........................long-term groundwater monitoring mg/kg .........................milligrams per kilogram NAVD88 ....................North American Vertical Datum of 1988 NCP ............................National Contingency Plan O&M ..........................operations and maintenance OASIS ........................OASIS Environmental, Inc. PCBs ..........................polychlorinated biphenyls PCE ............................tetrachloroethene RAOs..........................remedial action objectives RI Report ....................Trichloroethene Remedial Investigation Report RI................................remedial investigation RI/FS Work Plan ........Trichloroethene Remedial Investigation and Feasibility Study Work Plan ROI .............................radius of influence Final FS Report