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ATC Associates Inc. <br /> `rte/ <br /> 1117 Lone Palm Avenue, Suite B <br /> Modesto,California 95351 <br /> 209-579-2221 <br /> Fax: 209-579-2225 <br /> A S S O C I A T E S; I N C. <br /> When the tool has been advanced to the desired depth, extension rods will be sent down hole to <br /> brace the bottom of the sample screen as the tool casing is retracted. When the casing is <br /> retracted, up to 41-inches of screen with slot sizes of 0:004 inches will be exposed. Teflon <br /> tubing with a check valve attached to one end will be inserted down the casing until it is <br /> immersed in groundwater. Water will then be retrieved from the tubing by oscillating the tubing <br /> up and down. <br /> Following soil and groundwater sample collection, the borings will be backfilled with neat <br /> cement grout to the ground surface. Drill.cuttings,.if any, will be stored on-site in a 55-gallon <br /> container pending laboratory:results. <br /> Sample Analysis <br /> Selected soil samples will be immediately placed on ice and delivered under chain-of-custody <br /> documentation to a State-certified laboratory for. analysis. Samples will be analyzed for TPHg <br /> by EPA Method 8015, and for BTEX and oxygenate fuel additives by EPA Method 8260B. <br /> Groundwater Sampling <br /> Groundwater samples collected from the borings will be submitted using chain-of-custody record <br /> to a State-certified laboratory. Groundwater samples will be analyzed for TPHg by EPA Method <br /> 8015.and for BTEX and oxygenate fuel additives by:EPA Method 8260B. <br /> Advancement of Soil Vapor Borings and Sample Collection <br /> To evaluate the potential and risk associated with subsurface vapor intrusion into indoor air <br /> space.of the exiting site building, two to four vapor point borings (noted as VP on Figure 2)will <br /> be advanced to approximately five feet bgs depending on the depth to.water. <br /> The vapor point borings will be advanced using :a Geoprobe or Strataprobe drilling rig <br /> employing direct push technology. Drilling will be conducted by a State-licensed (C57) drilling <br /> company. Each vapor point boring will be. advanced to approximately five feet bgs or deeper,. <br /> possibly to seven feet bgs, depending on the capillary,fringe and water bearing zone depths. In <br /> the event that these two horizons exceed 10. feet bgs, then one. boring will be completed to ten <br /> feet bgs and one will be completed to ten feet bgs, totaling four vapor point boring locations. <br /> Two vapor point borings would then be advanced at each location (VP-1 and VP-2) (one to five <br /> feet and one ten feet) and drilled within a few feet of each other. In the event that there.are four <br /> vapor points competed they will be recorded as VP-la, VP-lb, VP-2a, and VP-2b. The two VP <br /> locations are depicted on Figure 2; note that the depth intervals will be determined based on <br /> Page8 (Nk <br /> w:\17861\WP for Additional Subsurface Investigation <br /> Soil Vapor Study,and Modeling .... <br /> i <br />