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C A M B R I A <br /> Groundwater pumping and vapor extraction tests were conducted during March 1990 to obtain <br /> hydrogeologic data, hydrocarbon concentration levels, and flow parameters for remedial system <br /> design. <br /> A free product skimming system was installed to collect free product from well MW-2 in <br /> April 1990. The skimmer was later moved to well MW-7. Approximately 180 gallons of free <br /> product were removed from these wells. <br /> Off-site groundwater monitoring well MW-10 was installed in July 1991. <br /> A soil vapor extraction system was installed and operated full time from September 1992 to <br /> September 1993. The system operated intermittently through November 1996. The system <br /> removed an estimated 14,980 pounds of hydrocarbons from the subsurface during the first year <br /> of operation. <br /> During March 2000, four cone penetration test (CPT) borings were advanced onsite (CPT-1 <br /> through CPT-4). Cambria collected.depth-discrete groundwater samples from each of these <br /> borings. Total petroleum hydrocarbons as gasoline (TPHg) and benzene were detected in <br /> groundwater from all of the borings at concentrations ranging from 688 to 439,000 parts per <br /> billion (ppb) and from 1.52 to 13,200 ppb, respectively. The highest concentrations were from <br /> the sample collected at 47 feet below grade (fbg) from boring CPT4, located adjacent to the <br /> existing USTs. The complete results of this investigation may be found in Cambria's <br /> July 20, 2000 Site Investigation Report. The boring locations and TPHg, benzene, and methyl <br /> tertiary butyl ether(MTBE)results from the groundwater samples are shown on Figure 2. <br /> Based on results from this investigation, Cambria.recommended advancing additional CPT <br /> borings and SJCPHS/EHD requested submittal of this work plan. <br /> Technical Rational for Proposed Scope of Work <br /> Petroleum constituents were detected in deep groundwater samples collected from borings <br /> CPT-1 through CPT-4. Further assessment of the lateral extent of petroleum hydrocarbons in <br /> groundwater at depth.is warranted. <br /> 0778 2 <br />