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__4ww� _ <br /> Work Plan for Environmental Investigation May 18, 1989 <br /> Proposed ARCO Station Woodbridge,..California AGS 39044-1W <br /> CW <br /> MONITORING WELL- CONSTRUCTION <br /> Monitoring wells will be constructed in the borings using <br /> 4-inch-inner-diameter, thread-jointed, Schedule 40 PVC casing. <br /> No chemical cements, - glues, or solvents will be used in well' <br /> d, construction. Monitoring wells will be constructed using 4-inch- <br /> inner-diameter casing to facilitate possible future recovery of <br /> contaminated ground water. The slotted portion of each wellwil <br /> 161 consist of factory-perforated casing with 0. 020-inch-wide slots. <br /> The well screen will extend from total depth of the well to a- <br /> point approximately 5 feet above first encountered ground-water. <br /> .. This interval will allow sampling of water near the air-water, <br /> interface in the -wel-1s, which is .representative of the water: in <br /> the formation during seasonal fluctuations of the ground-water - <br /> ft;, level. The annular space in the well will be packed from the" <br /> bottom with sorted sand until it is approximately 2 feet above <br /> the slotted interval. A 3-foot-thick plug of bentonite pellets <br /> will be placed above the sand pack to keep out cement. The <br /> h <br /> 13 - <br /> A,vv/ied GeoSystems <br />