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r LFR Inc. • Nitrogen as nitrate • Sulfate concentration • Estimates of the competing hydrogen to form ferric iron, manganese (Mn"), and methane Processes other than reductive dechlorination compete for the hydrogen created by substrate injection. Nitrate reduction, ferric iron reduction, sulfate reduction, and the creation of methane all use hydrogen. Analytical data from the Site suggest that sulfate reduction may represent the largest competitive demand for hydrogen due to the relatively high (78 mg/1) sulfate concentration. The model predicts that sulfate reduction will take up an order of magnitude more hydrogen than any other competing process. When these demands of competing processes are accounted for, the required substrate load is increased to accommodate them and still provide sufficient hydrogen for the anaerobic dechlorination of targeted Hazardous Substances. LFR used a Hydrogen Demand/Groundwater Flux model spreadsheet provided by EOS Remediation, Inc., to perform this evaluation. The spreadsheet is presented as Appendix D in this report. Site data were put into the model and yielded an emulsified edible oil substrate requirement of 138 drums (7,590 gallons). Proposed Substrate Loading The two methods yielded similar recommended substrate loading, 8,580 and 7,690 gallons for the Empirical TOC approach and the Hydrogen Demand/Groundwater Flux model, respectively. To introduce a factor of safety for unforeseen competing processes and/or dispersion or transport of substrate away from the target area, and to minimize the likelihood that re-injection will be necessary, LFR proposes to roughly double the amount of substrate injected to approximately 15,000 gallons. 4.2.2 ERD Well Installation The proposed ERD injection wells will be installed using a hollow-stem auger drill rig. Eleven injection wells will be screened in the upper A zone and 11 injection wells will be screened in the lower A zone. Locations of the wells are shown on Figure 5. Based on historical site lithology data presented in Section 2.2 and shown on Figure 7, it is anticipated that the upper A-zone wells will be screened at approximately 45 to 60 feet bgs and the lower A-zone wells will be screened at approximately 65 to 80 feet bgs. An LFR geologist will record a description of the lithology as drilling progresses, based on drill cuttings, and the boring will be continuously cored and logged from approximately 40 feet bgs to 80 feet bgs for the deeper lower A-zone wells. Upper A-zone wells will not be continuously cored; these wells will be installed based on the lithology encountered in the adjacent lower A-zone wells. The ultimate depth of the injection well and screen interval will be determined in the field, based on lithologic and head- Page 22 wp-PhV IRA-Sep07-F1m1-06750.dx:IR