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I ,California W�ional Water Quality Ontrol Board i <br /> vCentral Valley Region { <br /> Winston H.Hickox <br /> Steven T.Butler,Acting Chair Gray.Davis <br /> Secretaryfor d Governor <br /> Environmental Sacramento Main Officei <br /> Protection ,. Internet Address: httpl/wwwswrcb.ra.gov/—rwgc65 V <br /> 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3015 - � <br /> i <br /> TO: Gordon L. Boggs FROM: Mark R.List <br /> UST Program Manager Engineering Geologist (! <br /> p I <br /> DATE: 27 January 1999 . SIGNATURE: e <br /> a <br /> SUBJECT: FILE REVIEW FOR CLOSURE CONCURRENCE DETERMINATION,ANTIOCH <br /> - `TOYOTA, DISCOVERY`CHEVROLET SITE, 1615 WEST LITH STREET, TRACY,' <br /> SAN JOAQUIN COUNTY <br /> At the request of the San Joaquin County Environmental Health Division (SJCEHD), a file review was <br /> completed to determine if Regional Board staff concur with the SJCEHD determination of no further <br /> action required at this site. This information was obtained during my review of the Regional Board I <br /> casefile, and during discussions with Mr. Jeff Wong of San Joaquin County. <br /> ;V <br /> Background: <br /> On 2 April 1993, three underground storage tanks (USTs) were removed from the site, including two <br /> 1,000-gallon gasoline tanks and one 550-gallon waste oil tank. Petroleum hydrocarbons were noted in <br /> j all soil samples collected during UST removal activities. Site characterization activities began on <br /> 10 September 1994 with the installation of three groundwater monitoring wells. The analytical results, <br /> from monitoring well soil samples revealed TPHg and BTEX soil contamination near MW-1 and MW-2. <br /> Groundwater contamination was also identified in samples collected from MW-1 and MW-2. <br /> Two monitoring wells (MW-4 and MW-5) and 11 hand-auger borings were installed and soil samples <br /> were collected for laboratory analyses on 3 April 1997. On 19 February 1998, a total of 10 GeoProbe® <br /> borings,were installed between.14 and 25 feet below.ground surface.(bgs),with soil and groundwater,. <br /> sampling, to assess the lateral and vertical extent of contamination. A previously undocumented on-site <br /> domestic well was also discovered on 19 February 1998. The domestic well was sampled on 5 June <br /> 1998 and did not contain TPHg, BTEX or MTBE above laboratory reporting limits. <br /> Between 10 and 17 August 1998, corrective action and soil removal activities were conducted at the'fsite. <br /> Approximately 450 cubic yards of petroleum contaminated soil were overexcavated to 12 feet bgs and <br /> confirmation soil samples collected. During the soil excavation process, MW-1 was destroyed. <br /> Following excavation activities, approximately 5,750-gallons of petroleum impacted groundwater were <br /> pumped from the pit. The contaminated groundwater was stored on-site in a baker tank, treated by <br /> carbon adsorption, sampled (results show no detectable concentrations of petroleum constituents), then <br /> discharged to the city of Tracy Sanitary Sewer after approval from the City of Tracy Utilities <br /> Department. Contaminated soil was disposed of at Forward Landfill on 20 August 1998. Additionally, <br /> on 13 August 1998,the on-'site domestic well was destroyed by pressure grouting. <br /> California Environmental Protection Agency <br /> ped Recycled Paper <br />