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Mr. Randall K. Stephenson <br /> August 24, 1992 <br /> Page 2 <br /> During the excavation work for the removal of the existing underground storage tank at the <br /> referenced site, soils will be segregated 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 100 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. Eight soil samples will be composited into one (equivalent to one <br /> sample per 200 cubic yards) and analyzed by a state-certified laboratory for chlorinated <br /> hydrocarbons and metals (arsenic, barium, cadmium, chromium, total cobalt, copper, lead, <br /> nickel, mercury, and zinc) using EPA and Cal-EPA approved methods. Additionally, any <br /> composite soil sample with a concentration of TPHg greater than 3,000 ppm wil'I be analyzed <br /> for aquatic toxicity by the 96-hour fish bioassay test. All soil stockpiled on site will be <br /> completely covered with visqueen and secured to insure that the visqueen will remain in place. <br /> Soil excavated from this site and determined to be "nonhazardous" will be transported to <br /> Forward Landfill in Stockton, California, for disposal as either Class II or Class III waste. Soil <br /> . that is classified as "hazardous" (as defined by Title 22, California Code of Regulations), will <br /> be 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 /> a maximum depth of 2 feet into native soil below the former tank locations as outlined in the <br /> Central Valley Regional Water Quality Control Board's (Regional Board's), Tri-Regional <br /> Guidelines. A minimum of six soil samples (two per tank) will be collected from native soil <br /> underlying the tank basin and submitted for laboratory analysis of BTEX and TPHg. In <br /> addition, soil samples collected from below the former regular leaded gasoline storage tank will <br /> be analyzed for the presence of total lead (Waste Extraction Test method using atomic absorption <br /> of inductively coupled plasma). Additional soil samples may be collected at greater depths if <br /> deemed desirable by the Ultramar representative at the site. <br /> Soils underlying the product distribution lines, which are to be removed, will be sampled. Initial <br /> soil samples will be collected 2 feet below the former distribution lines for each 20 lineal feet <br /> of piping. Additional soil samples may be collected at greater depths if deemed desirable by the <br /> Ultramar representative at the site. The collected soil samples will be submitted to the analytical <br /> laboratory for analysis of BTEX, TPHg, and total lead concentrations. <br /> Present soil sample analytical results indicate that overexcavation may not be necessary. <br /> However, upon receiving results of the soil samples collected from beneath the product lines and <br /> the tank basin, soil at the limit of the excavation containing BTEX, TPHg, or lead above limits <br /> specified in the Tri-Regional Guidelines and Title 22 will be overexcavated and stockpiled on <br /> site until analytical results are obtained and transportation can be arranged for removal of the <br /> ACTON •MICKELSON 9 van DAM, INC. Consulting Scientists, Engineers,and Geologists <br />