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1 4.0 MONITOR WELL INS'T'ALLATION Page 5 AND DEVELOPMENT Soil borings B-1 through B-3 were converted into flinch diameter monitor wells MW-4 through MW-C,respectively.The wells were installed and developed in accordance with local regulatory guidelines using the Standard Operating Procedures included in Appendix A. Construction details are included on the boring logs for each of the wells(Appendix B). The wells were screened in the first shallow water-bearing zone. The top of the screened interval ranges from about 8.0 to 10.0 ft. V,,.low ground surface. Screened intervals are 15 ft. in length. Four inch inner diameter polyvinyl chloride(PVC)casing with a slot size of 0.010" was used for the well screen. A threaded end-cap was attached to the base of the well screen. After installing a Monterey#3 sand pack,a 4-inch bailer was used for up to 30 minutes per well to surge the screened . interval. After surging the screened interval,the sand pack compacted about 8 inches per well. Additional sand was added to bring the sand pack up to the proper depth. A 1 ft. bentonite seal was { constructed using about 1.5 buckets of pellets per well. Complete hydration of the bentonite seal was ensured by maintaining about 1/2 inch of water on top of the pellets during the hydration oprocess. A five percent bentonite cement grout was used as the surface sanitary seal. t During well development,from three to seven well volumes from each well (MW-4 through MW-5) were evacuated by using a 2-inch diameter submersible pump, allowing the pH, specific conductivity,temperature and sediment content of the water to stabilize. The pumps and hosing i were cleaned between wells using an alconox wash,a dionized water rinse and a dionized spray between wells. The development water was stored on-site in 55-gallon DOT drun:;pending "? laboratory analysis for appropriate disposal. c c