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3.03 WELL INSTALLATION <br />A. The Contractor shall calculate volumes of sand pack, bentonite pellets, and grout <br />required, based on borehole and well casing dimensions. <br />B. The Contractor shall inspect the casing, screen, and any other well construction <br />materials prior to installation to assure that no damage has occurred. The well <br />screens, bentonite seals and neat cement seals shall be installed in accordance <br />with the following sequence: <br />The 15 -foot long screen shall be set below where the water level is <br />encountered. Screen length may be modified in the field based on site <br />conditions. <br />2. The annular space for the -screened interval shall be filled with a sand pack to <br />5 feet above the screen' <br />3. A 5 -foot bentonite seal above the sand, and a neat cement seal to the ground <br />surface. <br />C. The Contractor shall connect and carefully lower the well casing assembly to the <br />depth directed by the on-site geologist. A casing centralized shall be attached at <br />the top of each screened interval to assure that the well is centered in the borehole. <br />The well casing assembly should be suspended by the installation rig and should <br />not rest on the bottom of the borehole. The top of the well casing shall extend <br />approximately 2 to 3 feet above the ground surface. <br />D. In the event the well casing assembly was dropped, lowered abruptly, or for any <br />other reason suspected of being damaged during placement, the well casing <br />assembly shall be removed from the borehole and inspected. If the well casing <br />assembly rises after being placed in the borehole due to heaving formation <br />material, the Contractor shall not place any drilling equipment (drill pipe, <br />hammers, etc.) to prevent the casing from rising. The Contractor shall notify the <br />on-site geologist of the amount of rise. <br />E. The Contractor shall place the sand pack into the annular space around the <br />screened interval. Clean water and a tremie pipe may be used to assist with the <br />sand pack tremie operation. If the well assembly is installed through the hollow <br />stem augers, the augers shall be pulled slowly during sand pack installation. <br />F. The Contractor shall monitor the sand pack settlement by measuring the sand <br />level with a weighted tape. The Contractor shall also monitor the top of the well <br />casing to detect any movement due to settlement or from drive casing removal. If <br />the top of the well casing moves upwards at any time during the well installation <br />Corral Hollow EMP Man Rev2Mar 22-07.DOC Pag#s ae February 28, 2007 <br />