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April 23, 1987 <br />Project 116-1.5 <br />Monitoring wells #1, #2, and #7 were constructed with slotting from the <br />concrete seal to the bottom of the well. The slot size for all three wells <br />is 0.063 inches, and the filter pack is composed of pea gravel. These <br />wells should not require additional perforation before in-place pressure <br />grouting. A tremie pipe will be set within five feet from the bottom of <br />the well, and cement grout will be pumped into the well until it reaches <br />the ground surface. Additional grout will then be pumped into the casing <br />under pressure. The maximum grout pressure will be determined in the <br />field, and will be based on the well construction details. <br />The remaining wells were constructed with blank well casing below the <br />concrete seal, but the well diameters are all too small to perforate the <br />blank casing in-place. These monitoring wells will be drilled out using <br />hollow stem augers, and then filled with cement/bentonite grout using a <br />tremie pipe. The tremie pipe will be set within five feet of the bottom of <br />the borehole, and cement grout will be pumped into the well until it <br />reaches the ground surface. If a bentonite annular seal is encountered <br />around the blank casing below the concrete surface seal, drilling will be <br />stopped and the well will be pressure grouted in-place. The top of the <br />casing will not be damaged as long as the auger remains centered during <br />drilling. The annular space will be grouted to the depth where bentonite <br />was encountered using a tremie pipe. <br />Please inform us of your comments regarding this plan to permanently close <br />the existing monitoring wells at the Forward, Inc. Landfill. If you have <br />any questions, please call me at (408) 978-1514. <br />Sincerely, <br />BETA ASSOCIATES <br />Carrie Cummings <br />- 2 - <br />GBetac_lssociates <br />