Final Report Use of Cometabolic Air Sparging to Remediate Chloroethene-Contaminated Groundwater Aquifers by Battelle 505 King Avenue Columbus, OH 43201 July 31, 2001 CONTENTS FIGURES....................................................................................................................................... iv TABLES ......................................................................................................................................... v ABBREVIATIONS AND ACRONYMS...................................................................................... vi ACKNOWLEDGEMENTS.........................................................................................................viii 1. Introduction................................................................................................................................ 1 1.1 Background Information.................................................................................................... 1 1.2 Official DoD Requirements Statements............................................................................. 2 1.3 Objectives of the Demonstration ....................................................................................... 3 1.4 Regulatory Drivers............................................................................................................. 3 1.5 Previous Testing of the Technology .................................................................................. 4 2. Technology Description............................................................................................................. 5 2.1 Description......................................................................................................................... 5 2.1.1 Technology Background, Development, Function, and Intended Use.................... 5 2.1.2 Theory of Operation ................................................................................................. 5 2.2 Process Description............................................................................................................ 7 2.2.1 Key Design Criteria................................................................................................. 9 2.2.2 Performance Criteria ............................................................................................. 10 2.3 Strengths, Advantages, and Weaknesses of the Technology........................................... 10 2.4 Factors Influencing Cost and Performance...................................................................... 11 3. Site/Facility Description .......................................................................................................... 13 3.1 Background and Test Site Selection ................................................................................ 13 3.2 Site/Facility Characteristics ............................................................................................. 13 4. Demonstration Approach......................................................................................................... 16 4.1 Performance Objectives................................................................................................... 16 4.2 Physical Set-Up and Operation........................................................................................ 16 4.2.1 System Equipment................................................................................................. 16 4.2.1.1 Sparge Wells ............................................................................................ 17 4.2.1.2 Soil Vapor Extraction System.................................................................. 18 4.2.1.3 Groundwater and Soil-Gas Multi-Level Monitoring Points .................... 20 4.2.1.4 Groundwater Monitoring Wells............................................................... 22 4.2.1.5 Air Injection System ................................................................................ 22 4.2.1.6 Propane Gas Storage and Injection System ............................................. 23 4.2.1.7 Field Analytical Trailer............................................................................ 24 4.2.2 System Operation .................................................................................................. 24 4.3 Sampling, Monitoring, and Analytical Procedures.......................................................... 24 4.3.1 System Testing ...................................................................................................... 24 4.3.1.1 Equipment Shakedown. ............................................................................ 25 4.3.1.2 Baseline Monitoring.................................................................................. 27 4.3.1.3 Helium Tracer Testing .............................................................................. 27 4.3.1.4 Pressure Transducer Test .......................................................................... 28 ii 4.3.1.5 SF6 Tracer Testing .................................................................................... 28 4.3.2 System Monitoring................................................................................................ 28 4.3.2.1 Groundwater Sampling ............................................................................ 28 4.3.2.2 Soil Gas Sampling.................................................................................... 31 4.3.2.3 Depth to Groundwater.............................................................................. 32 5. Performance Assessment ......................................................................................................... 33 5.1 Air Distribution Evaluation.............................................................................................. 33 5.1.1 Helium Tracer Testing........................................................................................... 33 5.1.2 Pressure Transducer Testing ................................................................................. 33 5.1.3 SF6 Tracer Testing................................................................................................. 34 5.2 CAS Study Results........................................................................................................... 41 5.2.1 Phase 1 Demonstration.......................................................................................... 41 5.2.1.1 Groundwater Results................................................................................ 41 5.2.1.1.1 Propane Uptake ....................................................................... 41 5.2.1.1.2 c-DCE and TCE Cometabolism .............................................. 49 5.2.1.1.3 Nitrate Limitations .................................................................. 49 5.2.1.2 Vadose Zone Results................................................................................ 49 5.2.2 Phase 2 Demonstration.......................................................................................... 58 5.2.2.1 Baseline Sampling and Rebound Effects................................................. 61 5.2.2.2 Groundwater Results ................................................................................ 62 5.2.2.3 Groundwater Kinetic Test Results ........................................................... 66 5.2.2.4 Vadose Zone Results................................................................................ 72 5.3 Data Assessment .............................................................................................................. 75 5.4 Technology Comparison.................................................................................................. 76 6. Cost Assessment ...................................................................................................................... 77 7. Implementation Issues ............................................................................................................. 82 7.1 Cost Observations ............................................................................................................ 82 7.2 Performance Observations............................................................................................... 82 7.3 Scale-up............................................................................................................................ 83 7.4 Lessons Learned............................................................................................................... 84 7.5 End-User Issues ............................................................................................................... 85 7.6 Approach to Regulatory Compliance and Acceptance .................................................... 85 8. References................................................................................................................................ 86 APPENDIX A: POINTS OF CONTACT.........................................................................................A-1 APPENDIX B: SCHEDULE OF OPERATING CONDITIONS AND FIELD OBSERVATIONS.................................................................................................B-1 APPENDIX C: GROUNDWATER MONITORING POINT DATA.............................................C-1 APPENDIX D: SOIL-GAS MONITORING POINT DATA..........................................................D-1 APPENDIX E: HISTORICAL FIGURES FOR THE GROUNDWATER MONITORING POINTS ................................................................................................................