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• The lithologic properties of select intervals of soil cores. This will provide <br />information that is not available by CPT but may be critical to design of a successful <br />remedial system. Lithologic logging will conducted: <br />— Within depths and locations where gasoline contamination is inferred to be present. <br />— At depths and locations likely to have ambient groundwater flow disturbed by <br />active remediation (for example, any key sand zones). <br />— To evaluate select lithologic units that are inferred to be key aquitards or key zones <br />of higher flow. <br />DP borings will be abandoned in a manner similar to the UVIF-CPT borings. <br />3.3 Lateral and Vertical Extent and Site Conceptual Model <br />UVIF and CPT data will be synthesized with analytical laboratory data to develop a stratigraphic <br />model that will include locations of residual masses of hydrocarbons. The model will encompass <br />the subsurface from the lower vadose zone through the greatest depth of gasoline constituent <br />impact that is determined. <br />The model will present the inferred lateral and vertical limits of gasoline constituent impact. It <br />will be used to determine whether the potential zone of treatment may be considered a single <br />zone or whether treatment may need to address multiple discrete zones (for example, in separate <br />sands that are situated above and below a low -permeability unit). <br />3.4 Installation of Wells and Sparge Testing <br />DP technology will be used to install temporary wells for testing of air sparging. Some of the <br />wells may be converted to permanent status if permitting rationale and logistics are favorable for <br />doing so. Well installation and use will be as follows: <br />Installation of up to eight temporary wells. The depths and exact locations of the <br />wells will be determined at the time of the UVIF-CPT exploration and within the <br />constraints of county permitting requirements, safety, and logistics of operating at the <br />site. The wells will have 2 -inch diameter or smaller casings. <br />Performance of an air -sparge test. The test will address the feasibility, prospective <br />flow rates and well spacing for sparging of air or ozone into the saturated zone for the <br />direct oxidation, in-situ stripping and enhanced biodegradation of gasoline <br />hydrocarbons. Either air or helium will be used as a tracer gas for the test. <br />Temporary wells will be abandoned in accordance with county pennitting agency requirements. <br />UserName or Department -Z lswDA20051Pg108018000391A.5ad.doc 3-3 <br />