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T <br /> December 21, 2022 <br /> Ms. Vera Fischer <br /> Central Valley Regional Water Quality Control Board <br /> 11020 Sun Valley Drive, Suite 200 <br /> Rancho Cordova, California 95370 <br /> Subject: Subsurface Investigation Work Plan, Former Stockton City Taxi Cab <br /> Company, 2085 East Fremont Street, Stockton, California <br /> Dear Ms. Fischer: <br /> ATC Group Services LLC doing business as Atlas Technical LLC (Atlas) has prepared this work <br /> plan on behalf of the Ernest R. Foppiano Family Trust describing proposed subsurface <br /> investigation activities to be conducted in association with the above referenced site (Figures 1 <br /> and 2). The purpose of the subsurface investigation is to evaluate the horizontal extent of <br /> petroleum impacted groundwater off site to the east and to address data gaps with regard to the <br /> California State Water Resources Control Board's Low Threat Underground Storage Tank Case <br /> Closure Policy. The scope of work is described in detail in the following paragraphs. <br /> SITE HISTORY <br /> In 1998, two 10,000-gallon gasoline underground storage tanks (USTs) and associated product <br /> piping were removed from the site by Advanced GeoEnvironmental. Soil samples were collected <br /> from the tank pit and under product piping and analyzed for petroleum hydrocarbons. Analytical <br /> testing indicated the samples collected from the tank pit contained detectable concentrations of <br /> petroleum hydrocarbon constituents. <br /> In February 2000, WHF, Inc. (WHF) advanced two soil borings, B1 and B2, to depths of <br /> approximately 81.5 and 31.5 feet below ground surface (bgs), respectively. Soil and groundwater <br /> samples were collected from the borings and submitted for laboratory analyses. These soil and <br /> groundwater samples contained detectable concentrations of petroleum hydrocarbon <br /> constituents. <br /> In July 2003, WHF advanced six soil borings, four of which were completed as monitoring wells <br /> MW1 through MW4. Soil samples collected from these borings contained detectable <br /> concentrations of petroleum hydrocarbon constituents. Petroleum hydrocarbons were detected in <br /> groundwater samples collected from MW1 through MW4. <br /> From November 10 to November 12, 2004 and November 15 to November 17, 2004, an ATC <br /> Associates Inc. (ATC) geologist supervised the installation of monitoring wells MW5 through <br /> MW12. Soil samples were collected from the boreholes of MW5, MW6, MW7, MW8, MW9, MW10, <br /> MW1 1, and MW12 and selected soil samples were submitted for laboratory analyses. Each well <br /> was constructed with 2-inch diameter PVC casing, with MW8, MW9, MW10, and MW11 extending <br /> to a depth of 65 feet bgs in the shallow groundwater bearing zone, MW5, MW6, and MW12 <br /> extending to a depth of 90 feet bgs in the intermediate groundwater bearing zone, and MW7 <br /> extending to a depth of 121 feet bgs in the deep groundwater bearing zone. <br /> 1117 Lone Palm Avenue, Suite 201 B, Modesto, CA 95351 <br /> 209.579.2221 1 oneatlas.com <br />