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s <br /> Mr. Kenneth Earnest <br /> July 30, 1993 <br /> Page 2 <br /> grade from soil boring B-4 indicated the presence of TEH at a concentration of 42 mg/kg. <br /> Seven of the nine borings were completed as monitoring wells. Only one water sample collected <br /> from the monitoring wells has even contained measurable amounts of benzene. A ground water <br /> sample collected from monitoring well MW-4 on April 13, 19$7, contained .i.2 micrograms per <br /> liter (µg/1) of benzene. Ground water samples collected from the site in April 1993 did not <br /> contain measurable amounts of benzene or TPHg. (Data from SSB Environmental Consultants, <br /> Inc. report titled "Subsurface Investigation of Soil and Ground Water Quality at Beacon <br /> Cardlock Station #6.10, 3300 Waterloo Road, Stockton, California.") <br /> During the excavation work for the removal of the existing underground storage tanks at the:site, <br /> soils will be segregated if possible into "clean" and "dirty" stockpiles based on subjective <br /> analysis and readings taken with a photoionization detector (PID). Four soil samples will then <br /> be collected for every .50 cubic yards of excavated soil. Each set of four samples will be <br /> submitted to a state-certified laboratory where they will- be composited into one sample and <br /> analyzed for BTEX and TPHg using U.S. Environmental Protection Agency (EPA) and. <br /> California Environmental Protection Agency, Department of Toxic Substances Control <br /> (Cal-EPA) approved methods. All soil 'stockpiled on site will be completely covered with <br /> visqueen and ;secured so that the visqueen will remain in place. <br /> f Soil excavated from this site and determined to be "nonhazardous" will be transported to <br /> Ultramar's refinery facility in Hanford, California, for thin-spreading and aeration. Soil that <br /> is classified as "hazardous" (as defined by Title 22, California Code of Regulations), will be <br /> transported to a Class I landfill in Kettleman Hills, California. <br /> Following removal of the existing underground storage tanks, soil`samples will be collected at <br /> approximately 2 feet into native soil below the former tank locations as outlined in the Central <br /> k Valley Regional Water Quality Control Board's.-(Regional Board's); Tri-Regional Guidelines. <br /> A minimum of six soil samples (two per tank) will be collected from native soil underlying the <br /> tank basin and submitted for-laboratory analysis of BTEX and TPHg. In addition, soil samples <br /> collected from below the former regular leaded gasoline storage tank will be analyzed for the <br /> presence of total lead (by the Waste Extraction.Test method using atomic absorption and <br /> inductively coupled plasma) and ethylene dibromide (EDB). - Additional soil samples may be <br /> collected at other locations if deemed desirable by the Ultramar representative at the site. <br /> Soils underlying the product distribution lines, which are to be'removed, will be sampled. <br /> Initially, one soil sample will be collected 2 feet below the former distribution lines for-each 20 <br /> lineal-feet of piping. Additional soil samples may be collected at greater depths or at other <br /> locations if deemed desirable by the Ultramar representative at the site. The collected soil <br /> IrPM8* <br /> ACTON MICKELSON van DAM,INC. Consulting Scientists, Engineers,and Geologists <br />