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the directg ush drill rig were collected in 1-m acetate sleeves Once the soil sample P was extracted from the sampler, the ends of the tubes were covered with Teflon and capped with plastic lids The samples were then placed in a cooler chilled to at least . 37 degrees Fahrenheit and submitted to a California-certified laboratory Select samples were analyzed by an on-site laboratory and by a fixed laboratory for analyses Copies of the Chain of Custodies (CDCs) and laboratory results are included in Appendix B ' 2.4.2 Groundwater Sampling Hydropunch groundwater samples were collected from HA-1 at 15 to 19 ft bgs, HA-2, HA-3, and HA-4 at 16 to 20 ft bgs, HA-5 and HA-6 at 20 to 24 ft bgs, and HA-7 at 15 to 19 ft bgs Unpreserved groundwater samples were collected in glass vials, capped, and placed in a cooler chilled to at least 37 degrees Fahrenheit and submitted to a California-certified laboratory for on-site analysis Copies of the COCl and laboratory results are included in Appendix B ' 2.5 Monitoring Well Installation Monitoring well MW-7 was installed on 15 April 2004 adjacent to the tank excavation area to assess groundwater quality in the deeper portion of the aquifer Monitoring well MW-7 was drilled to a total depth of 35 ft bgs The water table was encountered at a depth of approximately 15 ft bgs The well was constructed with a 2-in diameter Schedule 40 PVC well screen with 0 020-m slot size The screened interval was set cross the 30 to 35 ft bgs interval The sand pack for the screened interval consisted of#2-12 sand and was installed from the bottom of the borehole to 2 ft above the top of the screened interval The well was surged to settle the sand pack prior to continuing A 3-foot bentonite seal was emplaced and hydrated on top of the sand pack Following the final bentonite seal, the remaining annulus was backfilled with a Portland cementlGel-X mixture to 2 ft bgs Surface completion consisted of a flush mount traffic-rated well cover cemented around the wellhead A diagram of the well construction detail is included in Appendix C 2.6 Monitoring Well Development The newly installed groundwater monitoring well MW-7 was developed on 16 April 2004 by Blaine Tech Services, Inc The well development log is included in Appendix C Development consisted of swabbing the lower water column to flush out debris from the slots of the screen Using a stainless steel positive displacement pump, the well was purged at 0 5 to 1 0 gallons per minute (gpm) The pump was placed near the well bottom to remove ' accumulated sediment During purging, the pump was moved up and down through the screened interval until sediment was no longer observed Water quality parameter readings were taken at each casing volume removed Measurements included pH, temperature, electrical conductivity (EC), and turbidity (NTU) Approximately 10 case volumes of purge water were removed and water quality measurements were collected 1 and evaluated for stability 1 ' 5