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Ms Vicki McCartney Project No 8800401A 0201 <br /> October 26, 2004 <br /> Page 6 <br /> rShaw recommends that the cleanup level goals for this site be the California <br /> Department of Health Services Primary MCLS, which are 13 pg/l for MtBE, <br /> 1 0 µg/1 for benzene, 150 µg/1 for toluene, 300 µg/l for ethylbenzene, and <br /> 1,750 µg/l for xylenes Primary MCLS have not been established for TPHg <br /> • Cross sections based upon boreholes monitoring wells, trenches, and supporting <br /> geological mapping logs <br /> IFigures 6 and 7 illustrate the lithology encountered beneath the site during <br /> previous investigations and the approximate vertical and lateral extent of impact <br />' to groundwater as defined by MtBE to 5 µgd Appendix D includes boring logs <br /> showing soil encountered beneath the site during previous investigations <br /> ■ A site map showing sensitive receptors (i e local water supply wells, buildings or <br /> utilities impacted or potentially threatened) <br /> Figures 1 and 2 show pertinent features at the site and in the vicinity A water <br /> supply well survey previously conducted by Shaw indicated that no wells are h44'G AI r <br /> located within 2,000 feet of the site Based on the limited extent of groundwater wex -Wr'� <br /> impact beneath the site, no critical receptors appear to be impacted or threatened d IVA.- <br /> ■ A risk assessment will be necessary to demonstrate that the site poses no <br /> unacceptable risks to human health or the environment <br /> The hydrocarbon plume extends beneath an area that is currently being used for <br /> commercial purposes (gasoline sale) and transportation (West Hammer Lane) <br /> Most of this area is paved with asphalt or concrete No residential buildings are <br /> located within the probable extents of the plume No water producing wells are -- <br /> located within 2,000 feet of the subject site r' <br /> r <br /> Potential exposure receptors include current and future workers and customers of <br /> the subject station at 3250 West Hammer Lane, motorists, pedestrians, and utility <br /> maintenance workers The potential exposure mediums are ambient air and soil <br /> and groundwater in potential future excavation areas The mayor exposure <br />�I <br />' N 1sacDPQ004RJ188018800401A 4ad doc Shaw Environmental, Inc <br />