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WELL INSTALLATION AND CPT INVESTIGATION REPORT 54Q0 and 5606 Pacific Avenue Stockton California CAO NO 5-00707 FAI Project No 1232 . 2.2 Monitoring Well Construction The wells were constructed of two-inch inside diameter flush threaded Schedule 40 polyvinyl chloride well casing All casing materials were steam cleaned prior to installation The ground ' water monitoring wells were designed with a slotted section (0 020-inch x 1-inch slots) The annular space between the borehole wall and well casing was backfilled with grade #3 Monterey sand to about two feet above the slotted section An approximate three-foot thick ' layer of hydrated bentonite chips was placed on top of the sand pack and the borings grouted to the surface using a cement slurry Flush mounted traffic grates were placed on all wells Appendix D contains the specific well construction details for each well 23 CPT Investigation ' On November 15 and 16, 2001, CPT borings CPT-MW and CPT-UN were advanced to total depths of 150 feet bgs at the Site (see Figure 2) Note boring CPT-UN was originally to be drilled west of monitoring well MW-25D (see Figure 2) However, due to a washed out cavern under the sidewalk in this area, the location was moved, with approval of the RWQCB, to a location north of well MW-12 (see Figure 2) County Health permits to advance the CPT soundings are contained in Appendix A (SR#0028074 and SR#002$075) The CPTs were advanced, in accordance with ASTM standards (D3441), by Gi egg Di filling & Testing, Inc (Gregg) under the supervision of EAI staff (Brent Mecham) The following parameters were recorded by the cones at 5-centimeter depth intervals for each of the three soundings, tip resistance, sleeve friction, and dynamic pore pressure Appendix E contains a copy of the Gregg report documenting the results obtained from. the CPT soundings Each sounding was offset by approximately 4 feet and a second boring was advanced to a depth of approximately 86 feet bgs At this depth, the deepest sand in both soundings was identified Upon termination at 86 feet bgs, the CPT rods were retracted approximately three feet and a ground water sample obtained using a stainless steel bailer 24 Equipment Cleaning Protocol All augers and CPT rods were steam cleaned prior to drilling each well/sounding The sampler was disassembled and decontaminated prior to each sampling using the following procedure ■ All excess soil was scraped off the sampler p p parts ■ The sampler was washed in a solution of Alconox detergent and tap water ® The sampler was rinsed with tap water 2.5 Effluent Management All effluent generated during drilling and equipment decontamination activities was sealed in labeled 55-gallon drums The drums remained on the Site pending the results of the analytical testing, at which time the effluent vias tiansported to an approved disposal of recycling facility BHM WORD 123280191 4 ENVIRONMENTAL A UDIT, INC