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3 <br /> F <br /> • The monitoring well will be screened across the water table. The screen <br /> length will extend approximately 5 feet above and 15 feet below the <br /> water table. <br /> • Schedule 40 PVC casing and the well screen will be installed through the <br /> hollow stem augers. A threaded PVC bottom cap will be placed below <br /> the screen. <br /> • Filter pack will be installed through the annular space between the well <br /> casing and the augers as the augers are removed. The filter pack depth <br /> will be sounded continuously to ensure a solid pack with no bridging. <br /> The filter pack will extend approximately 2 feet above the top of the <br /> screen. <br /> • At least 1 foot of bentonite pellets will be placed into_the.borehole to <br /> form a seal above the sand pack. If there is water in the well annulus <br /> an is:judged to be inappropriate, a:iine.satld, such'as"Lone <br /> y Star No:. U or its equivalent,may be tremmied in glace of the hen tonite <br /> pellets: sts-�1 .`-� cs <br /> • Cement-bentonite grout containing approximately 5 percent bentonite <br /> will be installed from the top of the bentonite/sand seal to the ground <br /> surface. he grout will be pumped through a tremmie pipe from the <br /> }. <br /> bottom of the remaining annulus to the surface. The grout will be a1- <br /> ]owed to set for at least 12 hours before well development. <br /> Wells will be developed by surging, pumping, and/or bailing until the <br /> pumped water is clear and free of sand and the pH, conductivity, and <br /> temperature are stabilized. Conductivity will be considered stabilized <br /> when two consecutive readings are within 10 percent and pH within <br /> 0.02 units. The well depths will be measured before developmeht com- <br /> pletion. Accumulated fine-sized materials will be removed from the well. r <br /> s <br /> Water level and flow rate measurements will be obtained while purging s <br /> the wells. <br /> Wells will be completed at grade. A Christie box will be installed with a <br /> 2-to 3-foot-diameter cement pad,mounded to direct surface water runoff <br /> t <br /> away from the monitoring well. <br /> The top elevation of the well casing will be surveyed to the nearest <br /> 0.01 foot. <br /> Uevelepment water, decontamination rinse water, and cuttings will be <br /> collected for disposal. <br /> - Figure 4-1-shows the typical..construction.details_of.a._monitoring well. <br /> F _ ...... ... <br /> " <br /> 4-5 <br /> SF031d011wP\M.51 <br />