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EarthTec t Ms.Violeta Mislang A lyra Inlemalianzl❑d.CznDary 01/19/2006 Page 2 of 2 additional characterization is presented below. • A total of eight borings (SB40 through SB47) will be advanced at the site, four in and around the former drill room at 1856 Field Avenue, and four in the vicinity of S85 at 1848 Field Avenue. • In the 1856 Field Avenue site, one boring will be located near the former soil boring SV-2 in the former drill room, and two borings will be located north of SV-2, in the nominally downgradient direction, within 15 to 25 feet of the SV-2 location. These two borings may be advanced inside the building adjacent to the north wall of the building, or outside the building in the planter area between the north wall of the building and Field Avenue, depending on access. A fourth boring will be placed on Field Avenue to potentially delineate the northern extent of phthalate-impacted groundwater beneath the drill room in 1856 Field Avenue site. • In the 1848 Field Avenue site, two soil borings will be advanced north of former soil boring location SB-5 and two soil borings will be advanced to the south, one inside the building and the other one outside the building. • All borings will be advanced by a direct-push technology (DPT) drill rig equipped with a dual-tube coring system for the collection of continuous core. Borings will be advanced to the maximum depth of groundwater. At one location, S840, located adjacent to former soil boring SV-2, soil samples will be collected at approximately 2 and 10 feet below grade. The purpose of the soil samples at this location is to evaluate for potential source area. Please note that the soil borings will not be logged, and the soil will not be screened or sampled (except for SB40). • Grab groundwater samples will be collected from all borings.,A slotted PVC casing with a filter sock will be inserted into each boring, after which the outer casing of the coring system will be removed. Grab groundwater samples will be collected in laboratory- supplied containers using a peristaltic sampling pump. A duplicate groundwater sample will also be collected for quality control and assurance purposes. • All soil and groundwater samples will be delivered to a certified laboratory in an iced cooler and analyzed for bis(2-ethylhexyl)phthalate using EPA Method 8270C. Assuming a sufficient groundwater volume can be obtained from each boring, each groundwater sample will be analyzed for bis(2-ethylhexyl)phthalate prior to lab filtration and also following lab filtration (using a 45 micrometer pore size filter). • Upon completion of soil and grab groundwater sample collection, the borings will be abandoned with neat cement grout to the surface in accordance with local and State regulatory requirements. If you have any questions, please do not hesitate to call the undersigned at (408) 232-2839. Very truly yours, Earth Tech Inc. Zeynep G. Ungun, P.E. Program Director CC: Mr. Robert Senga (DTSC) Mr. Glen Foster(Tyco Electronics) Mr. Chuck Katz(Earth Tech)