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Mr. Harlin Knoll <br /> April 15, 1992 <br /> Page 2 <br /> Boring B-2Y was discontinued at a depth of 15 feet due to auger refusal (construction <br /> debris) and a grab sample of soil was collected from drill cuttings. Chips of asphalt were <br /> observed in these final cuttings and may have seriously impacted the laboratory analysis of <br /> this sample. Borings for MW-1, 2, and 3 are located within 11 feet of the former excavation. <br /> Boring MW-3, in particular, is within 28 feet of B-2Y, the location of detectable <br /> hydrocarbons. MW-2 was drilled to a depth of 48 feet. <br /> Based on these latest soil sample analyses all soil that might have ever contained any of the <br /> BTEX components at greater concentrations than five (5) ug/Kg or parts per billion (ppb) <br /> has been removed. <br /> Three ground-water wells have been monitored quarterly for five quarters. Quarterly <br /> monitoring results have shown BTEX concentrations well below California Action Levels <br /> but for one exception. In August 1991 benzene was found at the California Action Level <br /> in MW-2 but was not confirmed during the next quarterly monitoring. This was the only <br /> occurrence of benzene in any quarter monitored. Based on this evaluation ESE requests <br /> that the County reconsider and grant closure for this site. <br /> Please contact Neil Garrett or Sue Wickham at (510) 685-4053 with any questions or <br /> comments. <br /> Sincerely, <br /> ENVIRONMENTAL SCIENCE & ENGINEERING, INC. <br /> Neil R. Garrett Susan Wickham, RG 3851 <br /> Geologist Senior Geologist <br /> NRG/SSW:ng <br /> pc: Mr. Ron Tamoush/ Art Romann, AT&T Communications, Pleasanton <br /> Figure 1 - Worksite Plan <br /> Figure 2 - Cross-Section A - A' with TPH-d Concentrations <br /> F:\...\5030\RCNSD GR.LTR <br />