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Mii <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 exten,� 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. <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. The grout will be pumped through a trenimie pipe from the <br /> bottom of the remaining annulus to the surface. The grout will be <br /> allowed 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, aad <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 treasured before development <br /> completion. Accumulated fine-sized materials will be removed from the <br /> well. Water level and flow rate measurements will be obtained while <br /> purging 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 dire,:t surface water runoff <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 /> • Development water, decontamination rinse water, :.na cuttings will be <br /> collected for disposal. <br /> Figure 4-1 shows the typical construction details of a monitoring well. <br /> Static water level measurements for each monitoring well will be taken and referenced <br /> to the top of the casing. The wetted tape method or the electric sounder method will <br /> be used to take the measurement to the nearest 0.01 foot. Sounder cable or tape will <br /> be decontaminated before and after use at each well. Soil borings and well locations <br /> will be surveyed. <br /> ---- <br /> i- <br /> # SI-031605%WP004.51 4-5 <br />