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' Based on the initial data, the vertical and lateral limits of contamination were not sufficiently defined WHF proposed the installation of four (4) additional monitor wells (MW-5 through MW-8) to fully characterize the groundwater plume The PHS/EHD granted approval of the additional investigation on January 19, 1994 Between March 9 and 11, 1994, WHF installed MW-5 through MW-8 Moderate concentrations of gasoline were detected in the soil from MW-6 at 50 and 55 feet bgs and ' from MW-7 at 50 feet bgs Low to elevated concentrations of TPH-G and BTEX were detected in groundwater samples collected from MW-6, MW-7, and MW-8 A summary of the soil and groundwater analytical data are contained in Phase II Site Characterization, by WHF The wells were ' surveyed and gradient calculations indicated that a groundwater mound existed beneath the site indicating that recharge or leakage into the groundwater in the vicinity of MW-1 and MW-2 was occurring Three potential sources of recharge were identified 1) the car wash water recycling pit system under the building, 2) a leaking or broken sewer line that crosses the area, and 3) a leaking water supply line An MBAS (Methyl Blue Active Surfactants) test was conducted on groundwater samples collected at the site in July, 1994, to investigate the presence of detergents MBAS was not ' detected in the samples Aquifer testing (24-hour pump test) was conducted at the site by WHF on December 22 and 23, 1994 ' MW-I was used as a pumping well, and MW-4, MW-6, MW-7, and MW-8 were used as observation wells The results indicated an optimum pumping rate of 5 gpm with an effective radius of 140 feet Aquifer permeability was estimated at 126 gpd/f ' ' Quarterly groundwater monitoring has been conducted at the site by WHF through June, 1995 Historical groundwater analytical data indicates elevated concentrations of TPH-G and BTEX in MW- 1, MW-2, MW-6, and MW-7 Low to trace concentrations of TPH-G and BTEX have been detected in MW-3, MW-4, MW-5 and MW-8 The groundwater level has risen approximately 10 feet during the past three years A site investigation was conducted by Condor Earth Technologies, Inc (Condor) on July 31, 1996, at the Canepa's Car Wash facility The investigation included a review of existing investigative reports and an evaluation of the existing SVE system located at the site The fieldwork was conducted in ' accordance with Condor's proposal for SVE evaluation, dated April 8, 1996, and the addendum to the proposal, dated May 2, 1996 The report was titled Soil Vapor Extraction (SVE) System Evaluation, and dated September 23, 1996 ' Condor calculated that, based on the soil analytical data available for the site, the volume of hydrocarbons present in the soil beneath the site is estimated at approximately 13,000 pounds or ' 2,050-gallons (6 34 lbs/gal) Due to unknown variations in the lithology and contaminant concentrations, the actual volume of hydrocarbon beneath the site may vary by an order of magnitude or more from the estimate ' Based on the results of the SVE system evaluation and site background, Condor recommended that operation of the ICU be suspended since the system did not appear to meet APCD permit conditions (i e , 95% destruction efficiency) Condor further recommended that a 150 SCFM catalytic oxidation ionit (CAT-nX) he ,nct-lh-rl at the cite to Pxtrart and trent the gasoline contamination in the vadose zone It was detennmed that the configuration of the existing SVE wells appeared to be sufficient to remove a majority of the remaining gasoline contaminants in the vadose zone ' Condor has been conducting Quarterly Groundwater Monitoring at the site since August, 1996 Groundwater samples have been collected in various SVE wells and analytical data indicates that high levels of TPH-G and BTEX have been detected in SVE wells SV-1, SV-3, SV-5, SV-7, and SV-9 Installation of a new SVE system has been approved for this site 1 2