ARCHIVED REPORTS_XR0005743 - Laserfiche WebLink

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IV/ y SECOR r International Incorporated December 11, 2001 Project 077 43029 330 ' Ms Lon Duncan San Joaquin County Environmental Health Division 304 East Weber Avenue, Third Floor Stockton, California 95202 DEC 14 2001 ' Re Site Assessment Report ENVIRONMENTAL HEALTH ARCO Service Station #595 PERMIT/SERVICES North Highway 99 ' Stockton, California Dear Ms Duncan ' SECOR International Incorporated (SECOR) has prepared this letter on behalf of Atlantic Richfield Company (ARCO) to document the installation of three offsite groundwater monitoring wells, drilling of two soil borings at the site referenced above ' (Figures I and 2), review of the previous '/2 mile radius well survey, and the performance of a 500-foot radius door-to-door well survey The purpose of this work was to evaluate r the horizontal and vertical extent of petroleum hydrocarbons in soil and groundwater beneath the site This work was performed as described in the Work Plan for Site Assessment, dated November 30, 2000 San Joaquin County Environmental Health ' Division (SJCEHD) approved the Work Plan as indicated in a letter dated December 20, 2000 (Attachment A) ' SITE BACKGROUND The site is located at 6100 N Highway 99 in Stockton, California, and is an operating ' AMIPM mini-mart and ARCO service station The site is bordered by orchards to the north, east, and south, and Highway 99 to the west The site currently contains three 12,000-gallon gasoline underground storage tanks (USTs), associated product lines, and ' dispensers Additionally, a domestic water supply well (WSW) is currently in operation at the service station and is located at the southwest corner of the property ' During September 1999, product lines and dispensers at the site were upgraded and replaced in the same trench locations Twenty-one soil samples were collected from beneath the product lines, vapor lines, dispensers, and previously abandoned-in-place ' product lines Total petroleum hydrocarbons as gasoline (TPHg) were reported in eighteen of the twenty-one samples, with concentrations ranging from 194 mg/kg to 11,300 mg/kg Benzene was reported in fifteen of the twenty-one samples at concentrations ranging from 0 0316 mg/kg to 48 3 mg/kg Methyl tert-butyl ether (MtBE) was reported in fourteen of the twenty-one samples ranging in concentration from 0 110 mg/kg to 6 47 mg/kg Tert-butyl alcohol (TBA), di-isopropyl ether(DIPE), ' 3017 Kilgore Road, Suite 100, Rancho Cordova, CA 95670 916 861 0400 916 861 0430 Fax wuw 6ecor com