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Site History
<br /> Canepa's Car Wash(Pacific Avenue)
<br /> Page 2 of 7
<br /> data is contained in Interim Status Report, Phase II Investigation, by WHF Based on the initial data, the
<br /> vertical and lateral limits of contamination were not sufficiently defined WHF proposed the installation
<br /> • of four (4) additional monitoring wells (MW-5 through MW-8) to fully characterize the groundwater
<br /> plume The PHS/EHD granted approval of the additional investigation on January 19, 1994 Between
<br /> March 9 and 11, 1994, WHF installed MW-5 through MW-8 TPH-G was detected in the soil sample
<br /> collected from MW-6 at 50 and 55 feet bgs and from MW-7 at 50 feet bgs TPH-G and BTEX were
<br /> detected in groundwater samples collected from MW-6, MW-7, and MW-8 A summary of the soil and
<br /> groundwater analytical data is contained in Phase II Site Characterization, by WHF The wells were
<br /> surveyed and groundwater elevation measurements indicated that a groundwater mound existed beneath
<br /> the site This suggested that recharge or leakage into the groundwater in the vicinity of MW-1 and MW-2
<br /> was occurring Three potential sources of recharge were identified 1) the car wash water recycling pit
<br /> system under the building, 2) a leaking or broken sewer line that crosses the area, and 3) a leaking water
<br /> supply line An MBAS (Methyl Blue Active Surfactants) test was conducted on groundwater samples
<br /> collected at the site in July I994, to investigate the presence of detergents MBAS was not detected in the
<br /> samples
<br /> Aquifer testing (24-hour pump test) was conducted at the site by WHF on December 22 and 23, 1994
<br /> MW-1 was used as a pumping well, and MW-4, MW-6, MW-7, and MW-8 were used as observation
<br /> wells The results indicated an optimum pumping rate of 5 gpm with an effective radius of 140 feet
<br /> Aquifer permeability was estimated at 126 gpd/ft2
<br /> Quarterly groundwater monitoring was conducted at the site by WHF from March 1994, through June
<br /> 1995 Historical groundwater analytical data indicated elevated concentrations of TPH-G and BTEX in
<br /> MW-1, MW-2, MW-6, and MW-7 Low concentrations of TPH-G and BTEX were detected in MW-3,
<br /> MW4, MW-5, and MW-8 Condor has been conducting quarterly groundwater monitoring at the site
<br /> since August 1996 Analyses of groundwater samples collected from selected SVE wells (SVE-1, 2, 3, 5,
<br /> 7, 8, and 9) indicated that high concentrations of TPH-G, BTEX, and MTBE were present in the former
<br /> location of the fuel dispenser islands The groundwater table has risen approximately 18 feet since
<br /> quarterly monitoring of all eight site monitoring 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
<br /> with Condor's proposal for SVE evaluation, dated April 8, 1996, and the addendum to the proposal, dated
<br /> May 2, 1996 The subsequent report was titled Soil Vapor Extraction (SVE) System Evaluation, dated
<br /> September 23, 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
<br /> to 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
<br /> operation of the IGU be suspended since the system did not appear to meet APCD permit conditions (i e ,
<br /> 95% destruction efficiency) Condor further recommended that a 150 SCFM catalytic oxidation unit
<br /> (CAT-OX) be installed at the site to extract and treat the gasoline contamination in the vadose zone It
<br /> was determined that the configuration of the existing SVE wells appeared to be sufficient to remove a
<br /> majority of the remaining gasoline contaminants in the vadose zone
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