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Second Semiannual 2011 Groundwater Monitoring Report <br /> Former Texaco Service Station <br /> Chevron Site ID 309075 <br /> February 28, 2012 <br /> 3.3 Waste Disposal <br /> Purge water and equipment decontamination water generated during the sampling event was <br /> collected by G-R, transported by G-R to their temporary storage facility in Dublin, California and <br /> staged until it could be properly disposed of by Integrated Wastestream Management, Inc. <br /> (IWM). <br /> 4.0 MONITORING AND SAMPLING DATA <br /> 4.1 Groundwater Monitoring Data Analysis <br /> CURRENT MONITORING DATA <br /> Chevron wells monitored and sampled: MW-1, MW-2, MW-3, MW-4, MW-5, MW-6, <br /> and MW-6D <br /> Monitoring and sampling dates: October 14, 2011 <br /> Were SPH observed this event? No <br /> DTW range (ft below TOC): 50.91 —52.24 <br /> Average change in groundwater elevation 0.02 foot decrease <br /> since last event (ft): <br /> Groundwater flow direction and gradient East-northeast at an approximate horizontal <br /> foot per foot ft/ft hydraulic gradient 0.001 ft/ft <br /> 4.2 Groundwater Sample Analysis <br /> Subsequent to collection, samples were packed on ice, cooled to approximately 4 degrees <br /> _ Celsius (°C) and shipped under appropriate chain-of-custody protocols for analysis to Lancaster <br /> Laboratories, Inc. (Lancaster) of Lancaster, Pennsylvania, a California Department of Public <br /> Health certified analytical laboratory. All groundwater samples were screened for the following <br /> analytes per the parameters listed: <br /> • Total petroleum hydrocarbons as motor oil (TPH-MO) [C16-C361 by United States <br /> Environmental Protection Agency (USEPA) Method 8015B modified <br /> V <br /> • TPH-MO [C16-C361 with silica gel cleanup (SGC [10-gram column]) by USEPA Method <br /> 8015B <br /> • Total petroleum hydrocarbons as diesel (TPH-DRO) [C10-C281, total petroleum <br /> hydrocarbons as gasoline (TPH-GRO) [C6-C121 by USEPA Method 8015B <br /> • TPH-DRO [C10-C281 with SGC (10-gram column) by USEPA Method 80158 modified <br /> • Benzene, toluene, ethylbenzene and total xylenes (BTEX) by USEPA Method 82608 <br /> V <br /> g:\aproject\env\chevron\309075\6 del iverables\periodic monitoring\2011\2sa11\temppdf\1ext\309075 2sa11 9mr tin 02262012.doc 3 <br />