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V}VokT 1<}Jmun,J If.rnwi,C fl.li..�I: in. tip.i4i: ('.1 3•+<-7 P,F..x- grade was installed at MW-2 and MW-3. Construction diagrams for monitor well MW-I, MW-2 and ' M\V-3, and M1V-4 are included in Figures 4. 5, and 6, respectively, Appendix A. I3.4 Monitor Well Development Approximately two weeks following installation, the monitor xvclls were developed h\ bailing ' and surging the groundwater in each well until the discharge eater was free of' sediment (clear of particles to the unaided eye). The water purged from MW-i, MW-2. and MW'-3 was brown in color Idue to the brown silt present in the peaty soil the wells -,vere screened in. The brown color did not diminish after between approximately S and 12 casing volumes of water were removed from the wells. MW-4 was purged dry after 4 easing volumes of water were removed. The water purged from MW-4 -.vas clear of sediment and color, however. All well-development equipment was cleaned prior to use ' in each well by washing in a solution of laboratory-grade, non-phosphate detergent and hydrocarbon- free water, and double-rinsing with hydrocarbon-free water. The purge water discharged from the wells during development %%as placed in drums, scaled, labeled. and left on site to await disposal ` pending results of laboratory analysis. Groundwater %ticll development logs are included in Appendix ' C. 3.5 Well Collar Survey ' A sunny was conducted by a licensed professional surveyor to determine the location and relative elevation of the well collars, following installation of the monitor wells. It was intended that ' the survey determine the elevation of the monitor well collars to mean sea level based on a United States Geological Survey (USGS) benchmark. Once the monitor well collar elevations were ' determined relative to a USGS benchmark, they were cross-checked against another USGS benchmark, (a standard survey method). A discrepancy between the two USGS benchmarks was discovered, ' however. Therefore, a temporary benchmark using the MW-1 well collar was established with an assumed elevation of 100 feet above mean sea level (amsl). The well collars were surveyed with a vertical accuracy of 0.01 foot and horizontal accuracy of 1.0 foot. A measuring point was also established for the Empire Tract drainage channel south of the site and for the Little Connection ' Slough west of the site. The elevations of monitor wells MW-2, MW-3. MW-4 and the two described water body measuring points were determined relative to the MW-1 well collar assumed elevation. The measuring point for water-level measurements was marked on each well collar and on walkways ' to CONDOR