Technical/Regulatory Guidance Optimizing Injection Strategies and In Situ Remediation Performance IMPORTANT: This guidance document was developed for use on the web. Please review the following disclaimers before using the PDF version of the web-based document: • Web-based formatting may not be optimal when using this document as a PDF. • Hyperlinks will send users to the web-based document. • Glossary terms are not hyperlinked. • The majority of the references are not hyperlinked. February 2020 Prepared by The Interstate Technology & Regulatory Council (ITRC) Optimizing Injection Strategies and In Situ Remediation Performance Team Table of Contents Home Page ................................................................................................................................ 1 1. Introduction ........................................................................................................................... 3 1.1 The Problem and the Need for Optimization ...................................................................... 3 1.2 Intended Audience ............................................................................................................. 5 1.3 Approaches to Optimizing an In Situ Remedy .................................................................... 5 1.4 Document Organization ..................................................................................................... 7 2. Remedial Design Characterization....................................................................................... 9 2.1 Cost Benefits of RDC ......................................................................................................... 9 2.2 Characterization Parameters for Refining the CSM ......................................................... 11 2.3 RDC Considerations ........................................................................................................ 14 3. Amendment, Dose, and Delivery Design ........................................................................... 21 3.1 The Design Wheel and Optimization Process .................................................................. 21 3.2 Design Considerations ..................................................................................................... 22 3.3 Design Support Elements ................................................................................................ 25 3.4 Amendment Selection Considerations ............................................................................. 30 3.5 Amendment Dose Requirements ..................................................................................... 34 3.6 Amendment Delivery Optimization ................................................................................... 38 3.7 Delivery Layout Design and Volume per Location ............................................................ 43 3.8 Delivery Strategies........................................................................................................... 46 4. Implementation and Feedback (Monitoring) Optimization ............................................... 49 4.1 Pre-implementation Considerations ................................................................................. 49 4.2 Adaptive Implementation and Feedback Optimization ..................................................... 49 4.3 Implementation and Optimization Staircase ..................................................................... 49 4.4 Monitoring ........................................................................................................................ 50 4.5 Implementation Optimization ........................................................................................... 73 4.6 Transition and Contingency Planning .............................................................................. 76 5. Regulatory Perspectives .................................................................................................... 79 5.1 Challenges ...................................................................................................................... 79 5.2 Traditional CERCLA Site Cleanup Process ..................................................................... 79 6. Community and Tribal Stakeholder Considerations ........................................................ 85 6.1 Background ..................................................................................................................... 85 6.2 Identifying Stakeholders .................................................................................................. 86 I 6.3 Stakeholder Concerns ..................................................................................................... 86 6.4 Approach to Stakeholder Engagement ............................................................................ 89 6.5 Communications .............................................................................................................. 92 Appendix A. Amendments and Other Additives ................................................................... 94 A1. Common Biotic Amendments .......................................................................................... 94 A2. Abiotic Amendments ..................................................................................................... 100 A3. Other Additives .............................................................................................................. 104 Appendix B. Commonly Encountered Issues with In Situ Remediation ........................... 106 Remedial Design Characterization ...................................................................................... 106 Amendment Delivery, Dose, and Design ............................................................................. 107 Amendment Delivery ........................................................................................................... 113 Field Implementation ........................................................................................................... 120 Regulatory Perspectives and Community and Tribal Considerations ................................... 124 Appendix C. Characterization Parameters for In Situ Treatment Remedies ..................... 125 Physical Properties .............................................................................................................. 125 Transport Properties ............................................................................................................ 126 Aqueous Geochemistry ....................................................................................................... 125 Degradation Potential .......................................................................................................... 130 Appendix D. Injection Fact Sheets ....................................................................................... 132 D1. Direct Push Delivery Methods ....................................................................................... 132 D2. Direct Push Delivery Methods ....................................................................................... 135 D3. Electrokinetics Delivery Methods ................................................................................... 136 D4. Solid Injection Principles ............................................................................................... 137 D5. Hydraulic Fracturing-Based Delivery Methods ............................................................... 139 D6. Pneumatic Fracturing-Based Delivery Methods ............................................................. 141 D7. Permeable Reactive Barrier Construction ..................................................................... 142 Appendix E. Case Studies .................................................................................................... 144 E1. In Situ Biological and Chemical Reduction of Hexavalent Chromium and Perchlorate .................................................................................................. 144 E2. Strontium-90 Apatite Permeable Reactive Barrier ......................................................... 145 E3. Rapid Site Closure of a Large Gas Plant Using In Situ Bioremediation Technology in Low Permeability Soil and Fractured Rock ................................................... 146 E4. Performance of Injected Powdered and Liquid Activated Carbon at a Petroleum Hydrocarbon Site ......................................................................................... 147 E5. Lawrence Livermore National Laboratory—Annual Groundwater Report ....................... 147 II E6. Oxidant Surface Eruption During Direct Push Injection .................................................. 148 E7. TerraVac Under EPA’s Demonstration Program Conducted SVE in the Source Area ........................................................................................................................ 149 E8. Unusual Dichloroethylene Isomerizations and External Nitrate Input to Help Decipher in Situ Pilot Test Outcomes ...................................................................... 150 E9. In Situ Bioremediation and Soil Vapor Extraction at the Former Beaches Laundry & Cleaners .............................................................................................. 151 E10. LNAPL Remediation Combining Mobile Dual Phase Extraction with Concurrent Injection of a Carbon-Based Amendment: Little Mountain