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r California Regional Water Quality Control Board <br /> Central Valley Region <br /> Karl E.Longley,ScD,P.E.,Chair 0 <br /> Linda S.Adams Arnold <br /> Secretaryfor 11020 Sun Center Drive N200,Rancho Cordova,California 95670.6114 <br /> Phone(916)464-3291 •FAX(916)4644645 Schwarzenegger <br /> Environmental http://www.waterboards.ca.gov/centralval ley Governor <br /> Protection (� /� C I t tt i <br /> OCT 0 7 2008 <br /> 3 October 2008 ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> Mr. John Trinkle <br /> 24551 Kasson Road <br /> Tracy, CA 95304-9518 <br /> REVIEW OF LIMITED SUBSURFACE INVESTIGATION REPORT, TR/NKLE & BOYS, <br /> 31244 S. HIGHWAY 33, TRACY, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff have reviewed the 7 August 2008 Limited Subsurface Investigation Report <br /> prepared by Advanced GeoEnvironmental, Inc. The report describes a soil and grab <br /> groundwater investigation that you undertook in order to evaluate if the former airstrip is <br /> suitable to subdivide into residential lots. <br /> From 13 borings, three grab groundwater samples were obtained from about 15 feet below <br /> ground surface (bgs), 25 soil samples were obtained from depths of 1 and 3 feet below ground <br /> surface, and one soil sample was obtained from 15 feet bgs. All soil samples were analyzed <br /> for organochlorine pesticides, organophosphate pesticides, chlorinated herbicides, and diuron, <br /> and all soil samples positioned adjacent to the former runway were additionally analyzed for <br /> polynuclear aromatic compounds. All groundwater samples were analyzed for all of the above <br /> analytes and additionally for volatile organic compounds and fuel constituents. <br /> Of the soil samples, five samples contained one or two of the following compounds at these <br /> maximum concentrations: 2,4-D at 0.048 mg/kg, dicamba at 0.002 mg/kg, and dinoseb at <br /> 0.039 mg/kg. As seen in Table 1, these concentrations are substantially below concentrations <br /> of concern. <br /> Table 1. Detected Soil Constituents and Screening Levels <br /> Number of Detected Residential <br /> Constituent Detections Concentration Range Screening Level Source <br /> 2,4-D 1 0.048 mg/kg 690 mg/kg CHSSLs' <br /> Dicamba 2 0.002—0.0042 mg/kg 1,800 mg/kg EPA PRGS2 <br /> Dinoseb 4 0.005—0.039 mg/kg 61 mg/kg EPA PRG <br /> s2 <br /> Use of California Human Health Screening Levels (CHHSLs) in Evaluation of Contaminated Properties, <br /> California Environmental Protection Agency, January 2005. <br /> 2 Preliminary Remediation Goals, US EPA, 2004. <br /> Therefore, the portion of the property that you wish to develop with residential units does not <br /> contain pesticide residuals in soil that would impede residential development. However, grab <br /> groundwater samples from the operations area at the west end of the property contain 1,2-di- <br /> California Environmental Protection Agency <br /> Qv Recycled Paper <br />