SITE INFORMATION AND CORRESPONDENCE

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h� KLEINFELDER A total of eight Geoprobes were driven at the locations shown on Plate 2. Diesel was detected in the four samples and in the eight groundwater samples collected from the Geoprobes. Diesel concentration in the soil ranged from 330 to 930 mg/kg. Groundwater results varied significantly. High concentrations were found in GP-2, GP-3, and GP-5 (9,000,000, 29,000,000, and 380,000 ug/l, respectively) located along the west and east sides of the above-ground tank enclosure. Free product was visible in the groundwater samples from GP-2 and GP-3 during sample collection. The remaining Geoprobe groundwater sample concentrations ranged from 190 to 870 ug/1. Based on the results of the Geoprobe assessment, Meinfelder supervised the installation of three additional monitoring wells (MW-2, MW-3, and MW-4) on February 23, 1994 (see Plate 2). Drilling and well construction was performed by Spectrum Exploration of Stockton, California. Each well was screened from 10 to 25 feet below ground surface (bgs). Monitoring Wells MW-2, MW-3, and MW-4 were developed by hand bailing and surging on February 23 and 24, 1994. Depth to the static water level was measured prior to the initial development of each well on February 23, 1994 (about 2-3 hours after well installation), prior to the secondary development of each well on February 24, 1994 (14-16 hours after installation), and prior to sampling on February 28, 1994 (5 days after installation). Water levels were obtained with an electric conductivity-based meter with a calibrated sounding line. Product thickness measurements were also collected prior to the secondary development on February 24, 1994 and prior to sampling on February 28, 1994. Product thickness was obtained by slowly lowering a transparent, disposable, Teflon bailer approximately 2-1/2 feet into the fluid in the well casing. The bailer was then withdrawn and the layer of product, if present, was measured with a steel tape. Floating product was found in MW-1, MW-3, and MW-4. EW-1 had a centrifugal pump installed that was operating at an estimated flow rate of 3 gallons per minute throughout the course of the field investigation (2-23 through 2-28-94) and consequently, water levels and product thickness measurements were not obtained. Water samples were collected from EW-1 and MW-2 on February 28, 1994. Water samples were not collected from MW-1, MW-3, and MW-4 because floating product was present. Water was purged from MW-2 with a disposable bailer. Samples were collected with a disposable bailer with a low flow bottom emptying device. Water was pumped from EW-1 via a surface-mounted centrifugal suction pump with an intake submerged below the static water level. The pump was 24-220176-FOl/CR43-8 (1994) Page 4 of 13 June 3, 1994 Copyright 1994 Kleinfelder, Inc.