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• 10 121 998 16209 9165360207 APEX ENVIROTECH PAGE 06 Workploo for Pilot Teat and lt'easibility,Analysis COlberg Bast Works,401 N Stockton St.,Stockton,California Pag�c 1 IiNTIMIUCTION PROJECT DESCRIPTION This workplan has been prepared in response to a recent meeting between representatives of the San Joaquin County Environmental Health Division(SJCEM), Ms Lynn Swanson and Apex Envirotech, Inn. (Apex)to discuss closure Options for the subject site; It was agreed for Apex to submit a closure request based for the farmer diesel tank area on the western portion of the site based on a mass balance assessment. In addition,Apex would submit;a pilot test workplan to evaluate the feasibMty of using oxygen release compound(ORC`)torenrediate the remaining gasoline-impacted groundwater on the eastern portion of site. The mass balance calculations were completed and submitted to SJCEHD to justify no further monitoring of the;monitoring wells in the former diesel tank area. The tasks required to complete the Pilot Test and Feasibility Analysis for the 0RC" application are discussed below. SITE LOCATION ANIS DESCRIPTION The subject site is located in the western portion.of Stockton, San.Joaquin County,California, t an elevation ofapp oxintately;10 feet above mean sea levet. The site contains several marine service warebouselstorage buildings on approximately three acres of land and is located in an industrial area ofStockton, Calif mia(Figure 1). The site is nearly level and is bordered by the Stockton Deep Water Channel to the south. The site is a former shipyard which is no longer active,with the exception of limited beat storage(Figure 2) SITE MISTORlt AND PREVIOUS SUBSURFACE INVESTIGATIONS x On;May 16, 1986,Jin1 Thorpe tail,.Inc. retrieved two 550-gallon diesel,one 8,000-gallon diesel, and one 1,000-gallon gasoline underground storage tames(U Ts)from the site. The area around N the former gasoline UST was over-excamvated in 1988. In February 1993,Telic<Engineering Corporation(TEC)of Stockton, California,performed-a A� `— Phase I investigation ofthe subject site and surrounding area within a cine-mite radius. TECs findings are summarized in their report,Phase I Pretiminm y Hazardous Materials Site Assessment,dated July 21, 1993, On December 12 and 13, 1994,Apex supervised the advancement of 11 subsurface probes to collect soil and groundwater samples at the site. The results of the subsurface investigation are summarized in the report,PhW Lf Site Assessment Report,dated January 23, 1995. The results Of the subsurface investigation indicated that areas around the former U Ts were mpacted by petroleum hydrocarbons. TIB:]D. x1PrcOOMXPI)QjcctstCl OLOI-00I1F+tas-bWtyWorkplan.doc