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CAMBRIA concentrations were from the UST excavation with maximum concentrations of 19,000 ppm petroleum hydrocarbons volatile (PHV) and 280 ppm benzene This investigation is summarized in Aegis' June 18, 1990 Preliminary Subsurface InvestigationJTank Closure Report(Interim Soil Remediation Work Plan) During July 1990, Aegis installed monitoring wells MW-1 through MW-3 and vapor extraction wells VEW-1 and VEW-2 The highest concentrations in soil were from baring VEW-2 at 45 fbg, with 12,000 ppm PHV and 110 ppm benzene During the initial groundwater monitoring event, PHV and benzene were detected in all wells at concentrations ranging from 350 to 500,000 parts per billion (ppb) and 190 to 10,000 ppb, respectively These results are discussed in Aegis' January 4, 1991 Site Assessment Report In late 1991 and early 1992, Aegis performed a 75-day vapor extraction feasibility test at the subject site using wells VEW-1, VEW-2, and MW-3 Wells VEW-1 and VEW-2 were tested to evaluate their feasibility for removing petroleum hydrocarbons detected below the former UST location Well MW-3 was selected based on observed separate-phase hydrocarbons (SPH) in this well SPH has not been observed in well MW-3 since April 1993 i In September 1995,Fugro West,Inc (Fugro) of Roseville, California drilled four GeoProbeo soil borings Soil samples from the boring drilled in the former UST location contained total purgeable hydrocarbons as gasoline (TPHg) concentrations up to 7,000 ppm (at 16 fbg) and a benzene concentration of 10 ppm (at 49 fbg) TPHg and benzene were not detected in soil from the other borings Grab groundwater samples collected from these borings contained TPHg ranging from 14,000 to 60,000 ppb and benzene ranging from 4,100 to 9,800 ppb The complete results of this investigation may be found in Fugro's November 29, 1995 .Limited Subsurface Investigation Results In July 1997, Cambria drilled four onsite soil borings near the dispenser islands Petroleum constituents were delineated in soil in all the borings except one drilled near the northeastern dispenser In September 1997, Cambria installed monitoring wells MW-4 through MW-7 This investigation is described in Cambria's November 11, 1997 Site Investigation Report/Quarterly Monitoring Report—Fourth Quarter 1997 During May 2000, Cambria drilled two cone penetration test (CPT) borings and during November 2001, installed groundwater monitoring wells MW-10 and MW-11 Proposed wells MW-8 and MW-9 could not be installed at that time due to the presence of utilities The results 0854 2