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1 Report on Additional Site Assessment and Soil Vapor Extraction Test 3 7-Eleven Store No 17334,4501 North Pershing Avenue, Stockton,CA August 21,2002 ' 32 Soil Boring and SVE/AS Well Installation On April 3 and 4, 2002, vertical delineation soil boring SB-1 was drilled to a depth of 50 feet bg with a ' truck-mounted Geoprobe hydraulic drill rig Continuous soil samples were collected from 5 to 30 feet bg using Macrocore techniques Groundwater samples were then taken using a HydropunchTm at a depth of 50 feet bg No soil samples were collected in the 30- to 50-foot interval during repeated attempts to collect groundwater samples using HydropunchTm equipment Two double-nested SVE/AS wells (SPV-1 and SPV-2)were installed to 30 feet bg The deep well segments are screened from 25 to 30 feet bg ' The shallow well segment In SPV-1 is screened from 7 to 17 feet bg, while the shallow segment in SPV-2 is screened from 12 to 22 feet bg A sand filter pack was placed to a height of 2 feet above the top of the shallow well screens Each well annulus was sealed with approximately 2 feet of bentonite pellets saturated in place on top of the sand pack, and neat-cement grout to approximately 10 inches bg The wellheads are protected at the surface by locking, water-tight well caps and traffic-rated street boxes (with watertight bolted lids) set in concrete Both wells were constructed using 2-inch-diameter Schedule 40 ' PVC casing with flush threads and 0 010-inch-slot well screen All soil and rinse water generated during the drilling were placed in labeled Department of Transportation (DOT)-approved 55-gallon drums and subsequently removed following proper transportation and disposal procedures 33 Soil Sample Collection Boring SB-1 was installed using Macrocore continuous-core sampling methods Continuous soil samples were also taken at 25-30 feet bg while drilling wells SPV-1 and SPV-2 Soil samples from the total depth ' of wells SPV-1 at 30 feet and SPV-2 at 30 feet were collected for analysis The samples were then sealed using Teflon septum caps, labeled with the job identification number, the sample number, date, and sampler name The samples were stored on ice and transported with a chain-of-custody record to a ' state-certified laboratory for analysis Soil samples were analyzed for benzene, toluene, ethylbenzene, and total xylenes (BTEX), and TPH-G using EPA Method 8015/8020 and for MTBE and other oxygenates by EPA Method 82606 Samples were also analyzed for ethylene dibromide (EDB) and 1,2- ' dichloroethane (1,2-DCA) by EPA Method 8260 Copies of the drilling logs can be found in Appendix A 34 Groundwater Sample Collection 1 A HydropunchTM groundwater sample from 50 feet bg was collected in boring SB-1 to vertically delineate the dissolved hydrocarbon plume in the source area The groundwater sample was collected into ' 40-milliliter vials, filled to zero headspace, acidified to a pH of 2, capped, labeled, and placed on ice for transport under chain-of-custody to a state-certified laboratory for analysis The samples were analyzed for BTEX and TPH-G by EPA Method 8015/8020, and for MTBE, other oxygenates, EDB, and 1,2-DCA tby EPA Method 8260 17334sar doc