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ATC Associates Inc. <br /> YA�� 1117 Lone Palm Avenue, Suite 201 <br /> Modesto, Califomia95351 <br /> 209-579-2221 <br /> Fax: 209-579-2225 <br /> ASSOCIATES INC. � jd ql _t <br /> slurry mixture using i tremmie pipe. ATC estimates to collect two groundwater samples from each <br /> boring after evaluating the CPT logs for potential water bearing zones separated by suspected <br /> overlying confining layers. <br /> Groundwater samples will be collected using a Hydropunch® type groundwater sampling system. <br /> The system includes an expendable drive point attached to poly vinyl chloride (PVC) or stainless <br /> steel filter screen threaded onto the leading end of the direct push rods. While the sampler is <br /> advanced, O-ring seals and the expendable drive point will provide a watertight system to ensure <br /> sample integrity. <br /> When the Hydropunch®type groundwater sampling system has been advanced to the desired depth, <br /> the expendable drive point is held in place by the surrounding soil while the direct push rods are <br /> retracted. Once retracted, up to 60-inches of PVC or stainless steel filter screen with slot sizes of <br /> 0.010 inches will be exposed allowing for groundwater infiltration. A stainless steel bailer will be <br /> lowered inside the hollow push rods until it is immersed in groundwater. <br /> Following soil characterization and groundwater sample collection, the borings will be backfilled <br /> with neat cement grout to the ground surface. Investigative derived wastes (IDW) will be stored on <br /> site in 55-gallon drums pending laboratory results. The IDW will be disposed of off-site pending <br /> laboratory results. <br /> Sample Analysis\ <br /> FI 1 <br /> Selected Asamples will be immediately placed on ice and delivered under chain-of-custody <br /> documentation to a State-certified analytical laboratory for chemical analysis. Soil and groundwater <br /> samples will be analyzed for Gasoline Range Organics (GRO) by EPA method 8015M and for <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX), methyl tertiary butyl ether (MTBE), tertiary <br /> butyl ether (TBA), tertiary amyl ether (TAME), di-isopropyl ether (DIPE), and ethyl tertiary butyl <br /> ether(ETBE), 1,2-dichloreathane (1,2-DCA), and dibromoethane (EDB) by EPA Method 8260. <br /> Preparation of Subsurface Investigation Report <br /> Upon completion of the additional subsurface investigation activities, a summary report will be <br /> prepared and will include a description of field activities, data presented in tabular form, and an <br /> evaluation of the lateral and vertical extent of groundwater impacted by petroleum hydrocarbons. <br /> The subsurface investigation report will be prepared in accordance with California Regional Water <br /> Quality Control Board and PHS/EHD reporting guidelines. <br /> S:\environmental\6205UReports\additional subsurface investigation workplan.wpd <br /> 4 <br />