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4L 5.0 METHODS AND PR0CEDURES <br /> To assess the contribution of the former underground tanks <br /> to groundwater contamination at the site, WaterWork proposes <br /> to drill, log, and sample two additional soil borings which <br /> will be completed as groundwater monitoring wel'.s. <br /> To define the lateral extent of soil and groundwater <br /> �- contamination, these wells will be situated with one well <br /> approximately upgradient and one approximately downgradient <br /> of the former tank location. The proposed boring/well <br /> locations are shown on Figure 2. <br /> Underground utilities will be located by Underground <br /> Services Alert prior to drilling at the site. <br /> Work will commence on the site within 30 days of receiving <br /> workplan approval. We anticipate it will take one to two <br /> days for soil boring and well installation and one day for <br /> groundwater well development and sampling. Drilling will be <br /> scheduled upon a <br /> p pproval of the workplan. The County of San <br /> Joaquin will be notified at least 48 hours in advance of <br /> site work. <br /> Two eight-inch soil borings will be drilled and completed as <br /> two inch diameter groundwater monitoring wells. All <br /> procedures and protocol for groundwater monitoring well <br /> construction will conform the the standards recommended by <br /> San Joaquin County and the Regional Water Quality Control <br /> Hoard (RWQCH) . <br /> : The wells will be completed to a depth of approximately 25 <br /> to 30 feet below grade. Well completion depth will be based i <br /> on placement of the screened interval five feet above and <br /> fifteen feet below the static water table. However, if a <br /> r� stratum of five continuous feet of relatively impermeable <br /> material is encountered below the zone of saturation, the <br /> well will be terminated without penetrating the stratum. <br /> Drilling will be conducted under a C57 license using a <br /> hollow stem auger drill rig. <br /> The well will be constructed of 2 inch diameter F480 <br /> threaded PVC screen/casing. No glues or solvents will be <br /> used. Screen slot size will be 0,010 inch. Sand pack <br /> material will be No. 2/12 pre-washed silica sand. A minimum <br /> two foot bentonite seal will be placed prior to grouting <br /> with neat cement or a 1; 1 cement-sand grout. Grout will be <br /> placed in the annulus using the tremmie method. Typical <br /> completion will be as shown on Figure 3. Actual completion <br /> depths will be determined in the field based on <br /> hydrogeologic conditions encountered. <br /> Drill cuttings will be logged continuously for <br /> characterization of contamination and soil type by an <br /> experienced staff geologist or civil engineer using the <br /> 5 <br /> i <br />