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1 <br /> I F� - <br /> TreadweIEJUlo <br /> r" extent of the groundwater impacts within the shallow and deep zones, to monitor the succession of <br /> r j natural attenuation, and to help evaluate the need for additional monitoring and remedial measures. <br /> Monitoring wells MW-5s, MW-6s and MW-7s will be screened from approximately 20 to 35 feet bgs in <br /> order to intersect with the top of the shallow zone. Monitoring wells MW-5d, MW-6d, and MW-8d will be <br /> screened from approximately 50 to 65 feet bgs in order to intersect with the top of the deep zone. Two <br /> sets of shallow and deep wells MW-5s and MW-5d, and MW-6s and MW-6d will be located adjacent to <br /> one another to establish vertical gradients ( Figure 9) . <br /> Wells MW-5s and MW-5d will be installed adjacent to the edge of the former 1,000 gallon UST excavation <br /> area . MW-6s and MW-6d will be adjacent to the former 8,000 gallon UST excavation area . MW-7s will <br /> be installed near the down-gradient edge of the shallow zone plume. Well MW-8d will be installed in a <br /> presumed down-gradient direction near the edge of the deep zone plume. In particular, the MW-5 and <br /> MW-6 shallow and deep wells will provide information on the source area . The MW-7s, and MW-8d wells <br /> will provide information on the extent of contamination within the shallow and deep zones respectively. <br />! 8. 1 Monitoring Well Installation and Development <br /> All drilling and well installation will be performed with the appropriate permitting and oversight of the <br /> SJCEHD. <br /> Prior to drilling, the following will be performed : <br /> • Drilling permits and encroachment permits will be obtained from the SJCEHD; <br /> • Underground Service Alert (USA) will be notified to mark buried utilities in the vicinity of the <br /> proposed drilling locations; and <br /> • A private utility locator will be retained to screen for buried utilities in the vicinity of the proposed <br /> drilling locations . <br /> Borings for the wells will be drilled using auger or direct push methods. The borings will be drilled to a <br /> depth 10 feet below the observed groundwater level (the anticipated depth to groundwater is 25 feet in <br /> the shallow zone and 55 feet deep in the deep zone) . During drilling, soil samples will be collected at <br /> minimum intervals of approximately 5 feet or detectable changes in lithology (whichever is more <br /> frequent) . Soil samples will be classified in the field in approximate accordance with ASTM Standard <br /> 13 <br /> 25971201 . DGD 6 February 2008 <br />