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. Site History
<br /> Canepa's Car Wash(Pacific Avenue)
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<br /> Status Report Phase II Investigation, by WHF. Based on the initial data, the vertical and lateral limits of
<br /> contamination were not sufficiently defined. WHF proposed the installation of four (4) additional monitor
<br /> wells (MW-5 through MW-8)to fully characterize the groundwater plume. The PHS/EHD granted approval
<br /> of the additional investigation on January 19, 1994. Between March 9 and 11, I994, WHF installed MW-5
<br /> through MW-8. TPH-G was detected in the soil sample collected from MW-6 at 50 and 55 feet bgs and from
<br /> MW-7 at 50 feet bgs. TPH-G and BTEX were detected in groundwater samples collected from MW-6, MW-
<br /> 7, and MW-8. A summary of the soil and groundwater analytical data is contained in Phase II Site
<br /> Characterization, by WHF. The wells were surveyed and groundwater elevation measurements indicated
<br /> that a groundwater mound existed beneath the site. This suggested that recharge or leakage into the
<br /> groundwater in the vicinity of MW-i and MW-2 was occurring. Three potential sources of recharge were
<br /> identified: 1) the car wash water recycling pit system under the building, 2) a leaking or broken sewer line
<br /> that crosses the area, and 3) a leaking water supply line. An MBAS (Methyl Blue Active Surfactants) test
<br /> was conducted on groundwater samples collected at the site in July, 1994, to investigate the presence of
<br /> detergents. MBAS was not detected in the samples.
<br /> Aquifer testing (24-hour pump test)was conducted at the site by WHF on December 22 and 23, 1994. MW-1
<br /> was used as a pumping well, and MW-4, MW-6, MW-7, and MW-8 were used as observation wells. The
<br /> results indicated an optimum pumping rate of 5 gpm with an effective radius of 140 feet. Aquifer
<br /> permeability was estimated at 126 gpd/ftz.
<br /> Quarterly groundwater monitoring was conducted at the site by WHF from March, 1994, through June, 1995.
<br /> . Historical groundwater analytical data indicated elevated concentrations of TPH-G and BTEX in MW-1,
<br /> MW-2, MW-6, and MW-7. Low concentrations of TPH-G and BTEX were detected in MW-3, MW-4, MW-
<br /> 5,and MW-8. Condor has been conducting quarterly groundwater monitoring at the site since August, 1996.
<br /> Analyses of groundwater samples collected from selected SVE wells (SVE-1, 2, 3, 5, 7, 8, and 9) indicated
<br /> that high concentrations of TPH-G, BTEX, and MTBE were present in the former location of the fuel
<br /> dispenser islands. The groundwater table has risen approximately 18 feet since quarterly monitoring of all
<br /> eight site monitor wells began in March, 1994.
<br /> A site investigation was conducted by Condor Earth Technologies, Inc. (Condor) on July 31, 1996, at the
<br /> Canepa's Car Wash facility. The investigation included a review of existing investigative reports and an
<br /> evaluation of the existing SVE system located at the site. The fieldwork was conducted in accordance with
<br /> Condor's proposal for SVE evaluation, dated April 8, 1996, and the addendum to the proposal, dated May 2,
<br /> 1996. The subsequent report was titled Soil Vapor Extraction (SVE) System Evaluation, dated September 23,
<br /> 1996.
<br /> Based on the soil analytical data available for the site, Condor estimated that the volume of hydrocarbons
<br /> present in the soil beneath the site was approximately 13,000 pounds or 2,050-gallons (6.34 lbs/gal). Due to
<br /> unknown variations in the lithology and contaminant concentrations, the actual volume of hydrocarbon
<br /> beneath the site may vary by an order of magnitude or more from the estimate.
<br /> Based on the results of the SVE system evaluation and site background, Condor recommended that operation
<br /> of the ICU be suspended since the system did not appear to meet APCD permit conditions (i.e., 95%
<br /> destruction efficiency). Condor further recommended that a 150 SCFM catalytic oxidation unit (CAT-OX)
<br /> be installed at the site to extract and treat the gasoline contamination in the vadose zone. -It was determined - —
<br /> that the configuration of the existing SVE wells appeared to be sufficient to remove a majority of the
<br /> remaining gasoline contaminants in the vadose zone.
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