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US r Closure Rt,port NovernbLr 10 2000 <br /> 6425 Pa' lL Avenue Project No 3954 <br /> Stockton r aliforn:� <br /> Page 1 <br /> 1.0 Site Location and Description <br /> The Mason Center L L C property ("the Site") is located at 6425 Pacific Avenue, in Stockton, <br /> California (Figure 1) The Site is owned by Lincoln Center Properties L L C and was formerly <br /> operated as a gas station by Wickland Oil Company and Exxon USA Corporation At present, <br /> Mason Center L L d is redeveloping the site for use as a gas station and mini-mart Three <br /> 10,000-gallon underground storage tanks (USTs) will be removed from the Site These USTs <br /> will be replaced with two 20,000-gallon USTs <br /> The topography on and around the Site is relatively flat and covered with pavement The <br /> regional topography slopes very gently to the west The surface elevation at the Site is <br /> approximately 12 feet above mean sea level Reportedly, groundwater in monitoring well PZ- <br /> 001A, located about 30 feet north of the gas station property, is approximately 30 feet below <br /> grade (bg) (pers cam, Farr Associates, October 3, 2000) The Site is located within the Lincoln <br /> Center Shopping Center, operated by Sims-Grupe Management Corp , Inc <br /> 2.0 UST Removal and Disposal <br /> Wickland Oil Company installed the three double-walled fiberglass 10,000-gallon USTs in 1998 <br /> All three tanks failed a pressure test in August 2000 On November 1, 2000 these USTs were <br /> • removed under a permit from the San Joaquin County Environmental Health Division (SJC- <br /> EHD) A copy of the UST Closure Permit from San Joaquin County is included in Appendix A <br /> Mr Kent Miller, City of Stockton Deputy Fire Marshal, observed measurement of the lower <br /> explosive limit(LEL) and oxygen concentrations in all tanks Ms Letitia Briggs of the SJC-EHD <br /> was present during removal of the USTs <br /> W A Craig, Inc destroyed the USTs onsite under the supervision of the City of Stockton Fire <br /> Department W A Craig also transported and disposed of the USTs as non-hazardous solid <br /> waste at the Forward Landfill in Stockton on November 2nd and 3rd, 2000 Certification that the <br /> USTs were free of flammable vapors prior to removal is provided in Appendix R Weigh tickets <br /> from Forward Landfill for the disposal of the USTs are included in Appendix C <br /> 3.0 Soil Sampling and Analysis Methods and Procedures <br /> A work plan describing methods and procedures to collect soil samples beneath the three USTs <br /> waJ prVparl.d and s.bramed to tale SJC-GTL'il! oil O(.tuber 6, 200000 The workplan was required <br /> because pea-gravel in the UST backfill at depths up to 25 feet bg Due to the depth of the pea- <br /> gravel, native soil samples could not be collected with an excavator After the USTs were <br /> removed, the excavation was backfilled to within 4 feet of surface grade On November 3, 2000, <br /> a hydraulically operated drilling rig was used to collect native soil samples beneath the former <br /> USTs Precision Sampling Inc of Richmond California, a C-57 licensed contractor, provided <br /> . the XD-1 hydraulic drilling rig and operators Mr Tim Cook of W A Craig, Inc supervised <br /> drilling and sampling activities Ms Letitia Briggs of the SJC-EHD was present to observe <br /> sampling activities <br /> 11 romW\Central Project File13954 Mason Stmkton\UST Closure Roport\UST Closure PUPOrt cion <br /> I <br />