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Valley Water Treatment L../ Page 4 <br /> Work Plan-Monitoring Well Construction <br /> GPE Project No.480.2 <br /> June 16,2005 <br /> The detection limits for these analyses are summarized in the following <br /> table. <br /> Benzene Toluene Ethyl.- Xylene TPH-G <br /> benzene <br /> MDL 0.5 0.5 0.5 1 50 <br /> Units /K -pg/K /K /K _m/Kg <br /> 4.4 Monitoring Well Construction <br /> After drilling, the borings will be converted to monitoring wells. They will be <br /> cased with 2.0-inch diameter; schedule 40 PVC casing with flush threaded <br /> joints. The screened intervals will consist of 0.010 inch slotted schedule 40 <br /> PVC pipe. The casing will include a 15-foot slotted interval extending from <br /> total depth of 20 feet to 5 feet. Number three sand will be used to form a <br /> filter pack about the perforations and extending one foot above the screened <br /> interval. A transition seal will be constructed by installing sufficient <br /> bentonite to form a 2-foot thick seal. The remaining annulus will be filled <br /> with neat cement grout. <br /> The wells will be secured with a watertight locking cap encased within a <br /> traffic safe well box. The following table summarizes the construction details <br /> of these four wells. <br /> Boring Depth of Depth of Filter Transition Annular <br /> Depth Blank Scr( pack Seal Seal <br /> MW's 1-4 20' 5' - 0' 20' —5' 20'—4' 4' - 2' 2 - 0' <br /> LM All numbers are depths below grade. <br /> Lo 4.5 Well Development <br /> The new monitoring wells will be developed after the well sealing materials <br /> have set for at least 48 hours. The wells will be developed using mechanical <br /> LW surging and pumping, or bailing methods until a clear stream of water is <br /> generated. This will be done to assure the slots are clear and allow free fluid <br /> flow through the filter pack material. All development water will be <br /> '-' containerized in 55-gallon DOT approved containers and stored on site until <br /> its disposal can be arranged. <br /> 4.6 Groundwater Sampling <br /> Upon completion of the well development, the new wells will be sampled in <br /> 6.W accordance with standard sampling procedures. Thereafter, the wells will be <br /> placed on a normal quarterly monitoring schedule. <br /> �• 2937 Veneman Ave., #8240 Geo-Phase Environmental Inc. Phone(209) 569-0293 <br /> Modesto,CA 95356 Fax(209)569-0295 <br />