SITE INFORMATION AND CORRESPONDENCE

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FIELD INVESTIGATION To investigate the extent of residual soil contamination at the site, three soil borings were advanced to 20 feet below ground surface (bgs). All field activities were performed in accordance with Smith Technology's Workplan for Subsurface Investigation,at Tracy Rural Fire Station #1, 22484 South Seventh Street, Banta, California, dated August 4, 1997. This workplan was approved by PHS/EHD on August 6, 1997 with slight modifications. Soil Sample Collection On August 21, 1997, a Smith Technology geologist supervised the advancement of three soil borings to 20 feet bgs. A site plan showing,soil boring locations is included as Figure 2. Fisch Environmental, California License C57 683865, advanced the borings using a truck mounted Geoprobe® narrow diameter rig employing direct push technology. Soil samples were collected at five-foot intervals in acetate sampling tubes beginning at four feet below the ground surface and were described according to the Unified Soil Classification System. Descriptions of soil types encountered and sample collection intervals are presented on the boring logs contained in Attachment 1. Each soil sample was field screened with a Photoionization Detector -(PID) for the presence of volatile organic compounds. No petroleum hydrocarbons were observed during field activities in borings SBI, S112, or S133. PID readings of collected soil samples did not exceed background levels_of approximately 0 to 2 parts per million (ppm). Sample tubes were then sealed at each end using Teflon tape and plastic end caps, labeled, and placed on ice. Selected soil samples were kept on ice and delivered under chain-of-custody documentation to a State-certified NEI/GTEL Environmental Laboratories, Inc. (DOHS Cert. No. 2147) for chemical analysis. Field notes and PID readings are contained in Attachment 2. Groundwater Sample Collection One groundwater sample was collected from each boring at the depth groundwater was first encountered, approximately 12 feet bgs. A Geoprobe® Screen Point 15 Groundwater Sampler was threaded onto the leading end of the Geoprobe after groundwater had been encountered. When the sampler was advanced, O-ring seals and an expendable drive point provided a watertight system to ensure sample integrity. - When the tool was advanced to the desired depth, extension rods were sent downhole to brace the bottom of the sample screen as the tool casing was retracted. When.the casing was retracted, approximately 41-inches of screen with slot sizes of 0.004 inches was exposed. Teflon tubing with a check valve attached to one end was inserted down the casing until it was immersed in groundwater. Water was then pumped through the tubing and to the ground surface by oscillating the tubing up and down. Groundwater samples were placed on ice and delivered under chain-of-custody documentation to NEI/GTEL for chemical analysis. Following soil and w:197739Vgxw&sum.doc 2 SMTH E