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34 Groundwater Monitor Well Installation <br /> ' Four groundwater monitor wells (MW-1, MW-2, MW-3, and MW-4) were constructed at the <br /> site A relatively large amount of screen was used to construct the each well because historical <br /> ' data for the area indicated a wide seasonal fluctuation of the water table elevation Each well is <br /> constructed of 2-inch diameter, 0 020-inch machine slot, Schedule 40 polyvinylchloride (PVC) <br /> ' well screen, installed from the bottom of the borehole (100 feet bgs) to 65 feet bgs Two-inch <br /> diameter blank PVC casing completed the well from the top of the screened interval to within <br /> 112-foot of surface grade A filter pack consisting of#3 Monterey sand was placed in the annular <br /> space from the bottom of the boring to approximately 3 feet above the screened interval A <br /> ' sanitary seal consisting of 3 feet of hydrated bentonite chips was placed on top of the filter pack, <br /> the remaining annulus was grouted with Portland cement to within 1 foot of ground surface The <br /> ' groundwater monitor wells were completed at ground surface with an 8-inch diameter water tight <br /> traffic rated street box set in cement, and a water tight, locking well cap <br /> 3 5 Groundwater Monitor Well Development and Surveying <br /> On January 16, 1995 the groundwater monitor wells were developed by using a PVC bailer to <br /> ' alternately surge the screened portion of the well bore and purge the sediment laden water <br /> Development continued until five to ten well volumes of groundwater was removed, the well <br /> ' went dry, or until the water produced was relatively sediment free The top of casing of the <br /> completed groundwater monitor well was then surveyed to an arbitrary datum (100 feet) and <br /> ' accurately located on a site map by Tom Morrow Inc of West Sacramento, California, a Iicensed <br /> professional survey company <br /> 3 6 Groundwater„Sampling <br /> ' On January 19, 1995 the four groundwater monitor wells were sampled by SEC OR Prior to <br /> sampling, depth to water in each groundwater monitor well was taken and subjective analyses <br /> ' performed The subjective analyses consisted of checking for floating product or a hydrocarbon <br /> sheen by lowering a clean Teflon' bailer down the well and collecting a Sample at the <br /> groundwater-air interface Wells not containing floating product were purged of approximatcIN I <br /> 1116 No 40005 001 of q <br /> I f)i k RPI 4 rl l Ilk <br />