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19 October 2012 <br /> AGE-NC Project No. 97-0312 <br /> Page 15 of 22 <br /> Typically, groundwater would represent the migration medium for contaminants over <br /> significant horizontal distances. However, sites located in up-gradient or cross-gradient <br /> directions from the site are not likely to be negatively impacted. The domestic well <br /> designated DW-L (large) is located somewhat down -gradient of the UST area, yet on the <br /> site. In addition, first encountered groundwater is not used for drinking or irrigation, <br /> although all groundwater in the State of California is considered to be of potential beneficial <br /> use. The nearest surface water feature in the vicinity of the property is the Stockton <br /> Diverting Canal, located approximately 2,500 feet southwest of the site. It is unlikely that <br /> water in the canal is contaminated by impacted groundwater based on its distance and <br /> direction (up-gradient) from the site. <br /> 6.0. EIGHT-HOUR HIGH VACUUM SOIL VAPOR EXTRACTION (SVE) PILOT TEST <br /> On 18 February 2010, an eight-hour high vacuum SVE pilot test was conducted at the site <br /> using vapor well VW-1 (screened 10 feet to 30 feet) as the extraction well. The high <br /> vacuum SVE system consisted of utilizing a portable, 25-horsepower, oil-sealed (Dyna <br /> Seal) liquid ring pump (Travaini Pump) to extract soil-vapor from on-site soil vapor <br /> extraction well VW-1 (4-inch diameter well screened 10 to 30 feet bsg). <br /> Influent, soil-vapor was sampled within a Tedlar sampling bag and carbon-charcoal tubes, <br /> and vapor was monitored for the presence of organic vapor using an organic vapor meter <br /> equipped with a photo-ionization detector (PID: Thermo Environmental 580, 10.0 eV, <br /> calibrated to isobutylene). An effluent vapor sample was also collected and OVM <br /> measurements were collected to monitoring the destruction of the hydrocarbons. During <br /> the test, soil-vapor flow was monitored at the well head of VW-1 utilizing a Blue White flow <br /> rotometer/totalizer. The flow rate was recorded in standard cubic feet per minute (SCFM). <br /> 6.1. EIGHT-HOUR HVSVE PILOT TEST SAMPLING AND ANALYSIS <br /> u <br /> A total of three soil-vapor samples were collected during the pilot test. Soil-vapor samples <br /> were collected at three intervals (10:00, 13:00 and 16:00)from a sample port near the inlet <br /> of the vacuum blower to measure hydrocarbon concentrations in the extracted soil-vapor. <br /> The samples were collected in Tedlar bags using an electric air pump. Samples were <br /> transported in a chilled container under chain-of-custody to McCampbell Analytical Inc. <br /> r, (MAI) a California Department of Public Health (CDPH)-certified laboratory. Each sample <br /> was analyzed within 72 hours for: <br /> • TPH-g, BTEX, MTBE, tert-amyl methyl ether (TAME), di-isopropyl ether (DIPE), <br /> ethyl tert-butyl ether (ETBE), TBA, ethylene di-bromide (EDB) and 1,2-DCA in <br /> accordance with EPA Methods 8015M and 826013; and <br /> V <br /> Advanced GeoEnvironmental,Inc. <br /> u <br />