ARCHIVED REPORTS_XR0006697 - Laserfiche WebLink

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Site History Canepa's Car Wash(Pacific Avenue) Page 2 of 10 vertical and lateral limits of contamination were not sufficiently defined W14F proposed the installation of four (4) additional monitoring 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 TPH-G was detected in the soil sample - collected from MW-6 at 50 and 55 feet bis and from MW-7 at 50 feet bgs 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-is-contamed-in-Phase-ff-Site-Characterization,-by-WHIF—The-wells-were surveyed and groundwater elevation measurements indicated that a groundwater mound existed beneath the site This suggested that recharge or leakage into the groundwater in the vicinity of MW-I and MW-2 was occurring Three potential sources of recharge were identified 1) the car wash water recycling pit system under_the_bilildifig, 2) a leaking 6r-broken sewer-line-that crosses the'area;and 3) a-leaking-water-supply line 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-1 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 gpd1W r Quarterly groundwater monitoring was conducted at the site by WHF from March 1994, through June 1995 Historical groundwater analytical-data indicated elevated concentrations of TPH-G and BTEX in MW-T, MW-2, MW-6, and MW-7 Low concentrations of TPH-G and BTEX were detected in MW-3, MW-4, MW-5, and MW-8 Condor has been conducting quarterly groundwater monitoring at the site since August 1996 Analyses of groundwater samples collected from selected SVE wells (SVE-1, 2, 3, 5, 7, 8, and 9) indicated that high concentrations of TPH-G, BTEX, and MTBE were present in the former location of the fuel dispenser islands The groundwater table has risen approximately I8 feet since quarterly monitoring of all eight site monitoring wells began in March 1994 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 subsequent report was titled Soil-Vapor Extraction (SVE)-System Evaluation, dated September 23, 1996 Based on the soil analytical-data available for the site, Condor estimated that the volume of hydrocarbons present in the soil beneath the site was 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 unit (CeAT-OX) be installed at the site to extract and treat the gasoline contamination in the vadose zone It -- -=---- =-was determined-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 During the fall of 1997, an Authority to Construct permit was applied for with the APCD for the installation of a SVE system Prior to granting approval of the installation of the SVE system, the