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1 <br /> 2.3 Remaining Underground Storage Tanks <br />' Two fill ports are located on the north side of the gas station office Two inactive <br /> (approximately 100-gallon capacity) USTs are believed to be located in this area The fill <br /> ports are blocked at depths of approximately eighteen inches below surface grade It is <br />' understood that the active USTs are located on the south side of the gas station office <br />' 3.0 PROCEDURES <br /> 31 Drilling and Sampling <br />' On December 28 and 29, 1994, five soil borings (B-1 through B-5) were drilled at the site. <br /> B-1, B-3 and B-5 were drilled to depths of 35 feet B-2 and B-4 were drilled near the center <br />' of the former underground storage tanks (USTs), and advanced to a depths of 50 and 65 <br /> feet, respectively Because hydrocarbon-impacted soil was encountered during the drilling, <br /> three monitoring wells were installed at the site The locations of the borings are shown on <br />' Figure 2. <br /> On January 8 and 9, 1995, four additional borings (B-6, MW-1, MW-2 and MW-3)were <br /> I drilled at the site B-6 was drilled to a depth of 65 feet Borings MW-1, MW-2 and MW-3 <br /> were drilled to depths of 80 feet and completed as 2-inch diameter groundwater monitoring <br /> wells Borings B-1 through B-6 were each backfilled from total depth to surface grade with <br /> Portland cement <br /> All borings were drilled using a truck-mounted CME 75-HT drill ng The drill rig and two- <br /> man crew were supplied by Soils Exploration Services (SES) of Benicia, California During <br /> drilling, samples were collected at five-foot intervals in each boring using a split tube <br /> sampler loaded with three clean, 2-inch by 6-inch brass sleeves A 140-pound hammer was <br /> Iused to advance the sampler 18 inches, the number of blows required to advance the <br /> sampler in 6-inch increments was recorded on the boi ing logs All sampling equipment was <br /> washed in an Alconox solution and rinsed twice with water prior to each sampling run <br /> I For each sample, both ends of the lead sleeve were covered with aluminum sheets capped <br /> p PP <br /> and sealed with tape The samples were then stored on ice and transported under chain-of- <br /> custody to ABC Laboratory, Pan-Agricultural Division (Pan-Ag) in Madera, CA <br /> During drilling, auger returns were monitored for the presence of organic vapors using a <br /> Iphoto-ionization detector (PID Thermo Environmental 580A, 10 0 eV, calibrated to <br /> isobutylene) Auger returns were then placed on plastic sheeting and stored on-site <br /> 3.2 Logging <br /> Soil was extruded from the second brass sleeve and screened for the presence of organic <br /> �epml Ada S­cM lee. 2 <br /> T-P PW-8 pifiW10.Wh.1995 <br /> I ~ <br />