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Case Closure Report <br /> Former Tosco(Unocal) SS No 5421, Stockton,California <br /> July 8, 1998 <br /> At the request of Harlin Knolls of the SJCPHS, GR sampled down-gradient P g ent well MW-2 one <br /> last time to verify groundwater conditions at the site On June 22, 1998, GR collected <br /> groundwater samples from MW-2 and were submitted to and analyzed by Sequoia <br /> Analytical, located in Redwood City, California Analytical results were reported as non <br /> detected for TPHg, BTEX, MtBE and the five additional oxygenated compounds These <br /> data are summerized in a table presented in Appendix D along with a copy of the laboratory <br /> analytical report <br /> Environmental Remedial Activities <br /> Approximately 3,180 cubic yards of impacted soil has been excavated from the two <br /> generations of UST and associated piping removals and from the removal of the septic <br /> tank and associated leach lines/field The excavated soil was stockpiled on-site, sampled <br /> and characterized for appropriate disposal Approximately 1,175 cubic yards from the <br /> first generation UST removal was transported and disposed at the Redwood Landfill <br /> facility located in Novato, California, along with approximately 25 cubic yards of soil <br /> transported and disposed at the Laidlaw Environmental Services facility located in <br /> Buttonwillow,California in January 1990 Another 630 cubic yards of soil from the <br /> second generation of USTs was transported and disposed at Forward Landfill located in <br /> Stockton, California, in May 1998 Approximately 1,350 cubic yards of soil generated <br /> from the removal of the septic tank and associated leach field was transported to Laidlaw <br /> . Environmental Services in August 1992 In addition to soil, approximately 1,000 gallons <br /> of sludge removed from the septic tank was also characterized and transported to the <br /> Laidlaw Environmental Services facility <br /> Groundwater Monitoring and Sampling <br /> A groundwater monitoring and sampling program was initiated in October 1990 and <br /> conducted through December 1997 The purpose of this program was to monitor and <br /> characterize the groundwater quality beneath the site Quarterly monitoring was <br /> performed in site wells from October 1990 through December 1991, semi-annual <br /> sampling during the period of June 1992 through December 1995, and annual monitoring <br /> and sampling from December 1996 until the present At the request of Mr Harlan Knoll <br /> of the SJCPHS,down-gradient Well MW-2 was monitored and sampled on June 22, <br /> 1998 Collected groundwater samples were analyzed for TPH as gasoline, TPH as diesel, <br /> BTEX and MtBE, and most recently (December 1997), for five additional oxygenates, <br /> ethanol, tertiary butyl alcohol (TBA), Di-isopropyl ether (DIPE), ethyl tertiary butyl ether <br /> (ETBE) and tertiary amyl methyl ether(TAME) Well MW-1 has also been historically <br /> sampled for total oil and grease (TOG) and EPA Method 8270 constituents <br /> A review of the historical groundwater analytical data (presented in Appendix E), <br /> indicates the groundwater beneath the site is not impacted by petroleum hydrocarbons <br /> Based on the last groundwater sample collected from the existing down-gradient well <br /> 140162 03 10 <br />