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• Preliminary Environmental Assessment Report Pittman Elementary School,Stockton,CA December 10,2003 Page 5 The paint chip samples were collected by removing the paint layers from the surface of the building. The paint on the warehouse building was chipping and peeling; therefore it was not necessary to use additional equipment to collect the paint chip samples. The paint chip samples were immediately placed in a resealable bag and shipped to EMSL Analytical, Inc. of Milpitas, California, which forwarded the samples to LA Testing of South Pasadena, California for analyses. 5.3 NATURAL GAS FIELD SAMPLES Soil vapor borings were installed at 15 locations on the site in a grid-like pattern, one location per acre. The borings were completed to approximately 20 feet bgs. Soil vapor.samples were collected at depths of 10 and 20 feet bgs in each boring for a total of 30 soil,vapor samples. Sample locations are indicated on Figure 6,Appendix A. The borings were advanced and samples collected using direct push technology. The borings were advanced using a Geoprobe percussion hammer driven sampler equipped with a two-inch outside diameter, four-foot long core barrel. Soil gas samples were collected from each direct push boring from a sample barrel fitted with a three-inch long, screened, expendable air sampling tip. The soil gas sampling tip was advanced to the target depth, opened, and the sample tubing purged of ambient air with a vacuum pump. One-liter Tedlar bags were checked for vacuum seal integrity, then connected to the purged sampling tube with a 10-micron filter and a soil gas sample was collected. Each Tedlar bag was labeled for sample identification. The soil vapor samples were analyzed for methane and hydrogen sulfide. The samples were shipped under chain-of-custody procedures via overnight carrier to Air Toxics Ltd. in • Folsom, Califomia, for analyses. Upon completion of the drilling and sampling, the borings were grouted with cement slurry containing three to five percent bentonite. The soil gas sampling equipment was cleaned prior to collecting each sample. The cleaning procedures consisted of washing in a solution of laboratory-grade, non-phosphate detergent and deionized water, and double rinsing with deionized water. 5.4 EASTERN FORMER UNDERGROUND STORAGE TANKS SITE SAMPLES Soil vapor borings (VB-5 through VB-6) were installed at four locations along the eastern site boundary. Three borings were installed approximately 30 feet apart from each other starting at the northern side of the warehouse building. One boring was installed approximately 30 feet west of the other borings. The borings were completed to groundwater, approximately 40 feet bgs..Soil vapor samples were collected at depths of five and 15 feet bgs in each boring for a total of eight soil vapor samples. Groundwater samples were also collected from the borings. Sample locations are indicated on Figure 5, Appendix A. The borings were advanced and samples collected using direct push technology. The borings were advanced using a Geoprobe percussion hammer driven sampler equipped with a two-inch outside diameter, four-foot long core barrel. Soil gas samples were collected from each direct push boring from a sample barrel fitted with a three-inch long, screened, expendable air sampling tip. The soil gas sampling tip was advanced to the target depth, opened, and the sample tubing purged of ambient air with a vacuum pump. Six-liter Summa canisters were checked for vacuum seal integrity, then connected to the purged sampling tube with a 10-micron filter and a soil gas sample was collected. The Summa canisters were checked for appropriate vacuum pressure after sample collection. Each Summa canister was labeled for sample identification. 4M , IL 41 CONDOR