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Aquifer Testing Work Plan • • <br /> Former PureGro Facility <br /> ' Stockton, <br /> North Broadway Avenue - <br /> Stockton,California <br /> Sierra-Pacific Project No. 94-055.05 <br /> ' Potable tap water will be available at the site for hydrating bentonite, mixing grout, and washing <br /> sampling tools. Cuttings from the well borings are expected to be relatively free of contaminants. <br /> ' Regardless, drilling tools will be steam-cleaned on the subject site between borings and before being <br /> removed from the site. The cuttings will be placed in steel 55-gallon drums and staged on site pending <br /> analysis and disposal. Rinsate water for cleaning drilling tools and ground water from well development <br /> ' and well purging will be staged in drums or portable storage tanks on site. <br /> ' 4.3 Analyze Well Logs and Geologic Information <br /> Final decisions on the depths and screened intervals for the three new wells will be made after logging <br /> ' of the soil cores and receipt of laboratory test data. The three boring logs will be compared and <br /> contrasted with the existing MW-7 well log and other available geologic information. Laterally- <br /> continuous aquifers or aquitards will be identified and described. Sierra-Pacific will describe the <br /> sediments collected and assess how these sediments might affect future aquifer tests and remediation. <br /> ' Screened intervals will be selected on the.basis of sample lithologies and the inferred lateral continuity <br /> ' of beds penetrated by the drill holes. <br /> ' 4.4 Design Observation and Extraction Wells <br /> If fewer than two laterally-continuous aquifers are intercepted above 100 feet bgs,two standard 2-inch- <br /> diameter observation wells will be installed at the site,at locations OW-1 and OW-2 as shown on Figure <br /> 7. The screened intervals of the observation wells will extend from the base of the targeted aquifer zone <br /> ' to just above the highest measured water level. Screen types, slots, and filter sand will be selected on <br /> the basis of the core samples, field observations, and laboratory test results. <br /> ' If there are two or more laterally continuous aquifers with the upper 100 feet, nested test wells will be <br /> constructed with screened intervals positioned to isolate the separate aquifers. Each aquifer in the <br /> stratigraphic section will have a dedicated well screen. Screened intervals will be isolated within each <br /> ' well boring using hydrated bentonite seals. The well boring will be over-bored, if necessary, to <br /> accommodate two or three 2-inch-diameter observation well casings and screens. <br /> ' SIERRA-PACIFIC GROUP 7 <br />