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LFR Inc. injection well layout is designed such that wells with the same screened intervals are spaced 30 feet apart, which will create overlap of the substrate-laden cylinders in the injection zone. Twenty-two wells will be installed for substrate injection. The wells will be placed along the western side of the Bank of Stockton on the frontage road adjacent to Pacific Avenue (see Figure 5). The wells will be configured such that they alternate between wells screened in the shallow A zone and wells screened in the deep A zone. The locations of the injection wells are positioned to create a line of injection points roughly perpendicular to the direction of the flow of groundwater. The injection wells in this line alternate between wells screened in the upper A zone and wells screened in the lower A zone. Upper A-zone wells will be installed to a total depth of approximately 60 feet bgs with a screened interval from approximately 45 to 60 feet bgs. Lower A-zone wells will be installed to a total depth of approximately 80 feet bgs with a screened interval from approximately 65 to 80 feet bgs. 4.2 ERD Substrate Selection The Substrate Evaluation portion of this report (Section 3.4) concluded with the recommendation that an emulsified edible oil product be selected as the substrate for the Phase V IRA. Evaluation criteria included the following: • Longevity in the aquifer; • Injection ROI; • Ease of handling, mixing, and injection in the field; and • Costs of the substrate, the delivery of substrate to the aquifer, and all field activities associated with the injection event(s). In this evaluation, emulsified edible oil was determined to be among the longest lasting substrates. While HRC-X may last as long or longer, it failed to meet the design ROI requirement and was among the most expensive substrates on a per-pound-of-hydrogen basis. Dilute emulsified edible oil has demonstrated the ability to produce ROIs in excess of 15 feet at other geologically similar sites. While soluble substrates also produce favorably large ROIs, their short life spans almost ensure that repeated injections would be required to maintain elevated TOC concentrations. Pre-emulsified edible oil mixes easily with water and can be pumped through well screens with inexpensive low- to moderate-pressure pumps using commonly available hoses, valves, and plumbing fittings. While the same is true of soluble substrates, HRC and HRC-X require a direct-push drill rig and high pumping pressure. HRC and HRC-X are commonly heated to reduce their viscosity and cannot be conveyed through common low- to moderate-pressure plumbing apparatuses. wp-P6V_1RASep07-Fim1-06750.dm:1fr Page 19