ARCHIVED REPORTS_XR0007688 - Laserfiche WebLink

Home Browse Search

URS • Mr Harlin Knoll Page 3 San Joaquin County Environmental Health Department ARCO 2093 February 24, 2005 gasoline (TPHg) concentrations were not reported above laboratory detection limits Maximum concen- trations of benzene, toluene, ethylbenzene, and xylenes (BTEX) were reported in the soil samples from ATR-7 at 93 ppb, 182 ppb, 31 ppb, and 177 ppb, respectively The soil analytical results for this investi- gation are summarized in Attachment D Groundwater samples were taken from the three new monitoring wells after their installation in March 1989 Maximum concentrations of TPHg and BTEX were reported in the groundwater samples collected from ATR-5 at 220 ppm, 693 ppb, 327 ppb, less than 5 ppb, and 7 ppb, respectively Groundwater analytical results for this investigation are summarized in Attachment D Supplemental Site Investigation-(October 1990) A supplemental site investigation was completed at the request of the RWQCB by Brown and Caldwell in October 1990 to further define the lateral extent of soil and groundwater contamination both on-site and off-site Five boreholes (ATR-9, ATR-10, ATR-12, BH-1, and BH-2) were drilled, and monitoring wells were completed in three of the boreholes In addition, a groundwater extraction well was installed (TEX-1)to provide a means of conducting an aquifer test Soil samples collected from the boreholes (except from TEX-1) were analyzed The following maximum concentrations were reported benzene less than 50 mg/kg, ethylbenzene less than 50 mg/kg, toluene less than 50 mg/kg, xylenes 270 mg/kg, and TPHg 1,300 mg/kg Soil analytical results for this investigation are presented in Attachment E Groundwater samples were collected in October 1990 from all 10 monitoring wells None of the off-site �f wells contained detectable concentrations of TPHg or BTEX compounds TPHg and BTEX compounds were identified in three of the on-site wells Groundwater analytical results from this sampling effort are surrunarized in Attachment E Under round Storage Tank Removal and Soil Sampling 1993 Four single-wall gasoline USTs and associated piping were removed and replaced with four double- wall, fiberglass USTs and double-containment piping by Roux Associates from July through September 1993 All of the tanks that were removed appeared to be in good condition The new USTs were t installed in the same general area of the site as the former USTs Prior to the installation of the new USTs, eight soil samples were collected from the sidewalls of the tank cavity excavation, and five soil samples were collected from the bottom of the product line trenches Sample locations and tabulated analytical results for this effort are presented in Attachment F During the UST removal activities, approximately 1,000 yards of contaminated soil were stockpiled on- site for disposal Analytical results for the 15 samples collected from stockpiled soil are presented in Attachment F �1 K 1WprocessV5 BP ARCo1020931Closure Report\Draft of 2093 Closure Report doc.