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easibility Testing Work Plan <br /> Jimco Truck Plaza <br /> C A M B R I A 1022 Frontage Road <br /> Ripon, California <br /> May 18, 2005 <br /> diameter augers and the well will be constructed of 2-inch diameter Schedule 40polyvinyl chloride <br /> (PVC)casing and 0.01-inch factory slotted PVC screen.The screened interval is anticipated to extend <br /> form 30 to 33 feet bgs. The annular space surrounding the screened section will be backfilled with <br /> 2/12 sand. The sandpack will be overlaid with at least 2 feet of hydrated bentonite chips and the <br /> remaining annular space will be sealed with cement grout. The wellhead will be completed below <br /> grade and will be protected by a traffic-rated well vault with a water-tight lid. <br /> 5.3 Well Elevation Survey <br /> Upon completing the drilling activities, Cambria will retain the services of a licensed surveyor to <br /> survey the coordinates and elevation of the new air sparge well. Survey data will be tied to a local <br /> benchmark. <br /> 5.4 Feasibility Testing <br /> A soil vapor extraction (SVE) and combined SVE and air sparge (AS) feasibility test will be <br /> performed in the vicinity of the former USTs. The SVE test will be performed on well EW-1 and a <br /> i <br /> combined SVE/AS test will be performed on wells EW-1 and AS-1 (Figure 3). The SVE test will <br /> assess the air flow and hydrocarbon mass removal rates of the unsaturated zone. Test data such as <br /> hydrocarbon vapor concentrations, vapor extraction flow rates, soil vapor chemistry, and radius of <br /> influence data will be collected. <br /> 5.4.1 SVE and Air Sparge Testing Protocol <br /> The SVE test will consist of a step test,a constant vacuum test,and a combined SVE/AS test. During <br /> the test,well EW-1 will be used as a vapor extraction well and new well AS-1 will be used as an air <br /> injection well.Observation wells will include wells MW-1,MW-2,and MW-9. The step test will be <br /> conducted using a vacuum pump connected to the extraction wellhead to obtain vapor extraction flow <br /> rate data. The step test will consist of a minimum of four steps to determine the optimal vapor flow <br /> rate. The optimal vapor flow rate is defined by the vacuum level that produces the maximum vapor <br /> flow rate. The applied vacuum, hydrocarbon concentrations, and vapor flow rate in EW-1 will be <br /> measured during and at the end of each step. The applied well vacuum will be increased sequentially <br /> starting at approximately 30 inches of water column (in. H2O), and rising by increments of <br /> approximately 10-15 in. H2O until the optimal vapor flow rate is determined. The timing of <br /> subsequent well vacuum steps will be predicated on data collected from the previous step including <br /> the stabilized vacuum response observed in nearby observation wells. <br /> J <br /> 8 <br />