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1 EVAX Project B239-02 April 7, 1992 <br /> 1� <br /> Well Construction <br /> The groundwater monitoring wells were constructed by Spectrum with <br /> flush thread pointed, Schedule 40, polyvinyl chloride (PVC) casing of <br /> 4-inch diameter. Well casing with machine manufactured 0.010-inch <br /> slots was used for the wells; however, solid casing was used in the top <br /> portion of the wells. The well casing for MW-1 was set at a depth of <br /> 17 feet below ground surface and was screened in the 7.0 to 17.0 feet <br /> depth interval . The well casing for MW-2 was set at a depth of 15 feet <br /> and screened in the 5 to 15 feet depth interval . MW-3 was set at a <br /> depth of 17 feet and screened in the 5 to 17 feet depth interval . A <br /> threaded bottom cap was fitted on the bottom of the well casing of MW-1 <br /> and MW-2; a slip cap secured by stainless steel screws was used for MW- <br /> 3 because of an odd sized screen casing. No glues or cements were used <br /> to join the well casing sections together. <br /> The annular space between the well casing and borehole wall was filled <br /> with the following materials. Lonestar 2/12 Sand was placed in the <br /> annular space between the base of the well and 0.5 to 2.0 feet above <br /> the top of the screened well casing. A layer of bentonite pellets, 0.5 <br /> to 1 .0 foot thick, was placed above the sand pack. A sanitary seal of <br /> neat cement was placed atop the bentonite layer to ground surface. The <br /> sanitary seal in each well is approximately 4 feet thick. A locking <br /> well cap was placed on the wellhead and the wellhead was enclosed in a <br /> traffic rated well box set in the neat cement seal . Well construction <br /> details are presented on the right hand column of the Logs of <br /> Borings/Wells, Appendix B. <br /> Well Development <br /> The wells were developed by Spectrum on the day of well installation. <br /> Prior to placement of the sanitary cement seal , each well was swabbed <br /> for approximately 15 minutes using a mechanically operated swabber <br /> attached to the drill rig. Later in the day, each well was purged <br /> using a mechanically operated bailer until the water in the well <br /> appeared to be relatively clear and free of fine suspended materials. <br /> Following well completion and development, the augers and other <br /> equipment were cleaned with a steam cleaner. <br /> i <br /> -4- <br />