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'! 2.0 SCOPE OF WORK The objectives of this investigation were to further assess the lateral extent of impacted groundwater and to expand the on-site groundwater monitoring network To achieve these objectives, three additional on-site groundwater table monitoring wells (MW-4, MW-5 and MW-6) ' were permitted, installed, surveyed, monitored and sampled 2.1 Project Planning ' Pnor to initiating fieldwork, a site-specific health and safety plan addendum was prepared ' according to 29 CFR 1910 120 The health and safety plan included safety procedures, chemical hazard information, site safety officers, and preferred medical emergency locations ' According to EHD, an existing monitonng well permit (SR#0028186), issued on November 28, 2001, remained active and was used for the project A copy of the permit is included in Appendix A At least two working days prior to drilling, EHD and Underground Service Alert (USA) were notified so that regulatory and utility clearance inspections could be scheduled Underground utilities were marked by USA member utilities under USA Ticket#418782 2.2 Groundwater Monitoring Well Installations On December 1 and 2, 2003, under the supervision of Ramage Environmental, Mitchell Drilling (C-57 License#672617) installed the three on-site groundwater table monitoring wells (MW-4, MW-5 and MW-6) to expand the groundwater monitoring network approximately 250 feet east, 175 feet south, and 50 feet west of former UST#3 (Figure 3) ' 2 2 1 Monitoring Well Construction Development and Surve Mitchell Drilling installed all three wells in 8-inch diameter soil borings, drilled to depths of 55 feet bgs, using a truck-mounted CME 75 drill ng and hollow stem augers All three wells consisted of 20 feet of two-inch diameter, Schedule 40, flush-threaded and machine-slotted (0 020-inch) ' polyvinyl chloride (PVC) well screens, spanning from approximately 35 to 55 feet bgs Blank PVC casings were threaded into the tops of the well screens and extended to the surface Filter packs of#3 graded and washed silica sand were placed through the hollow stem augers as they were slowly retrieved and until the sand packs reached approximately two feet above the tops of the ' screened intervals (i e , 33 feet bgs) 1 0 7