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r y 90 1 <br /> ]] AT <br /> GeoStrategies Inc. r �, 1;( € <br /> August 3, 1994 <br /> Mr Michael M Collins <br /> San Joaquin County Environmental Health Division <br /> P 0 Box 2009 <br /> Stockton, California 95201-2009 <br /> SUBJECT SOIL SAMPLING AT FORMER UNOCAL SERVICE STATION NO <br /> 0187, 437 EAST MINER AVENUE, STOCKTON, CALIFORNIA (SITE <br /> CODE 1 181) <br /> Mr Collins <br /> Attached please find Table 3 - Soil Chemical Analytical Data for the above <br /> referenced site This table summarizes metals analyses for the soil sample <br /> collected from well boring U-1 at a depth of approximately 6-6 5 feet below <br /> • ground surface (bgs) in the former waste oil underground storage tank (UST) <br /> excavation The location of the former waste oil UST excavation and well boring <br /> U-1 are shown on the attached Site Plan The base of the former waste oil UST <br /> excavation was at approximately 6 feet bgs, as discussed in GSI report no <br /> 782701-1 , Tank Removal Observation Report, dated September 11 , 1992 <br /> As discussed in GSI report number 782703-4, Work Plan, dated March 9, 1994, <br /> this soil sample was analyzed for the metals Cd, Cr, Pb, and Ni by the California <br /> Waste Extraction Test (WET) using a de-ionized water extractant As the <br /> attached table indicates, Cd and Pb were not detected above their respective <br /> laboratory detection limits of 0 020 and 0 10 milligrams per liter (mg/0 Cr was <br /> detected at a concentration of 0 056 mgh This concentration is below the <br /> current CCR Title 22 Soluble Threshold Lima Concentration (STLC) for Cr of 5 <br /> mg/l. Ni was also detected in this sample at a concentration of 0 13 mg/1 This <br /> concentration is below the current CCR Title 22 STLC for Ni of 20 mgll <br /> These data and data from previous subsurface investigations at the subject site <br /> indicate that soils at the base of the former waste oil UST excavation <br /> (approximately 6 feet bgs) do not contain the metals Cr, Cd, Ni, Pb, or Zn above <br /> 1482AIetter02 me <br /> 6747 Sierra Court, Suite G • Dublin, CA 94568•(510) 551-8777• Fax (510) 551-7888 <br /> 3035 Prospect Park Drive, Suite 80• Rancho Cordova, GA 95670 •(916) 631-1314• Fax (916) 631-1317 r <br />