SITE INFORMATION AND CORRESPONDENCE_CASE 1

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Mr. Harlin Knoll December 17, 1992 Page 2 The three ground water wells have been monitored quarterly for five quarters. A summary of analytical results for ground water samples collected from the wells are presented in Table 1. Ouarterly monitoring results have shown Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) concentrations well below California Action Levels but for one exception. In August 1991 benzene was found at the California Action Level in MW-2 but was not confirmed during the next quarterly monitoring. This was the only occurrence of benzene in any quarter monitored. Based on results of soil and ground water samples, ESE does not believe that an additional well will find any hydrocarbon source at the site and that the area of B-2Y will always be questioned. Instead of installing one additional ground water well, ESE proposes to install two soil borings in the vicinity of boring B-2Y to depths of 20 feet bgs. During drilling activities, an ESE geologist will log the borings and utilize a Photoionization Detector (PID) to screen soil. In addition visual and olfactory indicators will be used to assess the presence of contaminated soil. If at a depth of 20 feet bgs, soil is found to be impacted based on field screening techniques, the boring will be continued to a depth where no apparent impact is observed or to ground water. A minimum of two soil samples per boring will be analyzed for TPH-D/BTEX. PIease respond in writing to this proposed work. We would like to address the letter from the County as soon as possible. Thank you for your assistance. Please contact Kerry Lefever or Sue Wickham at (510) 685-4053 with any questions or comments. Sincerely, ENVIRONMENTAL SCIENCE & ENGINEERING, INC. Kerry Lefever Susan S. Wickham, RG 3851 Senior Staff Geologist Senior Geologist KL/SSW:gm Attachments (2) pc: Mr. Art Romann, AT&T Communications, Pleasanton F:1...\S030\FURTHASS.L TR