Results of initial proof of principle laboratory testing activities successfully demonstrated the viability of the in situ chemical treatment approach for remediation of soil and groundwater contaminated by hexavalent chromium. Testing activities currently in progress further indicate that soils contaminated with hexavalent chromium and uranium at concentrations of several hundred parts per million can be successfully treated with 100 ppM hydrogen sulfide gas mixtures. Greater than 90% immobilization of hexavalent chromium and 50% immobilization of uranium have been achieved in these tests after a treatment period of one day. Activities associated with further development and implementation of the in situ chemical treatment approach include conducting additional bench scale tests with contaminated geomedia, and undertaking scale-up laboratory tests and a field demonstration. This report discusses the testing and further development of this process.

The laboratory investigation was performed to evaluate the feasibility of utilizing in situ chemical oxidation for remediating the secondary source of groundwater contaminants at the Idaho National Engineering and Environmental Laboratory (INEEL) Test Area North (TAN) Site. The study involved trichloroethene (TCE) contaminated media (groundwater, soil, and sludge) from TAN. The effectiveness of the selected oxidant, potassium permanganate (KMn0(sub4)), was evaluated at multiple oxidant and contaminant concentrations. Experiments were performed to determine the oxidant demand of each medium and the rate of TCE oxidation. The experiments were performed under highly controlled conditions (gas-tight reactors, constant 12C temperature). Multiple parameter were monitored over time including MN04 and TCE concentrations and pH.

This volume provides comprehensive up-to-date descriptions of the principles and practices of in situ chemical oxidation (ISCO) for groundwater remediation based on a decade of intensive research, development, and demonstrations, and lessons learned from commercial field applications.

Laboratory scale soil treatment tests have been conducted as part of an effort to develop and implement an in situ chemical treatment approach to the remediation of chromate-contaminated soils through the use of reactive gases. These tests involved three different soil samples that were contaminated with Cr(VI) at the 200 ppM level. Treatment of the contaminated soils was performed by passing 100 ppM and 2000 ppM concentrations of hydrogen sulfide in nitrogen through soil columns until a S:Cr mole ratio of 10:1 was achieved. The treated soils were then leached with groundwater or deionized water and analyzed to assess the extent of chromium immobilization. Test results indicate>90% immobilization of chromium and demonstrate that the treatment process is irreversible. Ongoing developmental efforts are being directed towards the demonstration and evaluation of the gas treatment approach in a field test at a chromate-contaminated site. Major planned activities associated with this demonstration include laboratory testing of waste site soil samples, design of the treatment system and injection/extraction well network, geotechnical and geochemical characterization of the test site, and identification and resolution of regulatory and safety requirements.

These appendices support the results and discussion of the laboratory work performed to evaluate the feasibility of in situ chemical oxidation for Idaho National Environmental and Engineering Laboratory's (INEEL) Test Area North (TAN) which is contained in ORNL/TM-1371 l/Vol. This volume contains Appendices C-E. Appendix C is a compilation of all recorded data and mathematical calculations made to interpret the data. For the Task 3 and Task 4 work, the spreadsheet column definitions are included immediately before the actual spreadsheet pages and are listed as ''Sample Calculations/Column Definitions'' in the table of contents. Appendix D includes the chronological order in which the experiments were conducted and the final project costs through October 1998. Appendix E is a compilation of the monthly progress reports submitted to INEEL during the course of the project.

This appendix supports the results and discussion of the laboratory work performed to evaluate the feasibility of in situ chemical oxidation for Idaho National Environmental and Engineering Laboratory's (INEEL) Test Area North (TAN) which is contained in ORNL/TM-13711/V1. This volume contains Appendix F. Appendix F is essentially a photocopy of the ORNL researchers' laboratory notebooks from the Environmental Sciences Division (ESD) and the Radioactive Materials Analytical Laboratory (RMAL).