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KLEINFELDER <br />Kleinfelder in April 1991 (1). The two new borings were drilled to depths of 81.5 and 91.5 <br />feet. First encountered ground water was present at an approximate depth of 78 feet in each <br />boring. From each boring, four selected soil samples from 50 to 80 feet and 1 ground water <br />sample were analyzed for 1,2-DCP, nitrate and TKN. One additional ground water sample <br />collected from an on-site domestic well was also analyzed 1,2-DCP, nitrate and TKN. <br />Pertinent tables that summarize this data are included in Appendix H. <br />1,2-DCP and nitrate (reported as nitrogen) were detected in most soil samples collected from <br />the borings; however, their concentrations appeared to decrease with depth. 1,2-DCP was not <br />detected in soil samples collected just above ground water surface. The concentrations of TKN <br />in soil were substantially lower than concentrations detected in samples collected at shallower <br />depths during the preliminary soil assessment in April 1991. <br />1,2-DCP (27.0 and 8.8 ug/L) and nitrate as nitrogen (12.8 and 20.7 mg/L) were detected in <br />the two ground water samples. The concentration of 1,2-DCP is above the maximum <br />contaminant level (MCL) of 5 ug/L and the nitrate is above the MCL of 10 mg/L. These <br />MCLS are established by the California Department of Health Services (DHS). TKN was not <br />detected in the ground water samples collected from each boring. <br />1,2-DCP and TKN were not detected in the domestic well water sample. A low nitrate <br />concentration of 0.6 mg/L was detected in the domestic well sample. <br />Based on the analytical results, it appeared that ground water beneath the site is affected with <br />nitrate and 1,2-DCP which may have migrated downward from the subsurface soil. <br />Historically, 1,2-DCP has been found in ground water in this area (4). Both 1,2-DCP and <br />nitrate have appreciable water solubilities and can easily migrate vertically from the soil to <br />ground water. Kleinfelder recommended that monitoring wells be installed at the site to assess <br />and monitor ground water quality beneath the site and to estimate a ground water flow <br />direction. Details pertaining to the Phase II soil and ground water assessment are contained in <br />Kleinfelder's report dated August 8, 1991(3). <br />D29-91-351 5 of 19 <br />Copyright 1991 K[einfelder, Inc. <br />