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ENVIRONMENTAL INVESTIGATION REPORT <br /> Unocal Service Stanon No 5886 <br /> 2701 West March Lane <br /> Stockton Califortua <br /> Delta Project No D1191-066 <br /> ' Page 14 <br /> tA grab ground water sample was collected from the tank excavation following collection of the soil <br /> samples This sample was collected prior to the removal of impacted fill material, and is not considered <br /> ' representative of ground water conditions The ground water sample was collected by lowering a <br /> collection container into the excavation Once the container had filled, it was retrieved and the water <br /> ' sample placed in sampling containers <br /> ' On October 25, 1995, the excavation was enlarged to accommodate the three new 15,000 gallon USTs <br /> Soil was excavated from the north, south, and west sldewalls of the excavation The excavation was also <br /> ' deepened to approximately 16 feet bsg Provisional soil samples were collected at Unocal's request <br /> pending the receipt of the results of the sample collected at 12 feet bsg Analytical results from the 12 <br /> foot soil samples collected beneath the tanks were below the laboratory's limits of detection for all <br /> analytes Soil and the overlying pea-gravel removed from the tank cavity were stockpiled on-site in two <br /> piles The pea-gravel was stockpiled separately and covered with plastic sheeting Soil excavated from <br /> the tank cavity was placed in a bermed area lined with plastic sheeting and covered <br /> ' In preparation for the installation of the new tanks, ground water in the tank cavity was pumped into an <br /> above ground Baker tank Approximately 5,000 gallons of water was removed from the excavation This <br /> ' water was removed from the site by RUST on October 26, 1995, and recycled at Unocal's facility in <br /> Rodeo, California A copy of RUST's transport/disposal information is presented in Appendix H An <br /> ' additional grab water sample was collected from the excavation after the removal of the soil and water <br /> to assess any changes in hydrocarbon concentrations in the ground water The ground water sample was <br /> ' collected using the same methods described previously <br /> 1 <br /> RPT160 SJs <br />