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�0� - 0 <br /> Amy SIERRA-PACIFIC GROUP <br /> Geologists+Engineers+Scientists+Compliance Specialists <br /> February 20, 2001 <br /> Mr. Michael Infurna <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 304 East Weber, Third Floor <br /> Stockton, California 95202 <br /> Subject: Well Permit Applications and Fee Payment, Vicinity of the Former PureGro Stockton <br /> Facility Additional Wells, 1905 North Broadway Avenue, Stockton, California: Sierra- <br /> Pacific Project No. 94-055.02 <br /> Dear Mr. Infiuna: <br /> On behalf of Unocal Corporation, Sierra-Pacific Group(Sierra-Pacific)has conducted contaminant plume <br /> characterization and ground water monitoring in the vicinity of the former PureGro Stockton facility (now <br /> Western Farm Service) at 1905 North Broadway Avenue, Stockton, California, since 1995. In order to <br /> establish both lateral and vertical limits on the contaminant plume, Sierra-Pacific proposes to install four <br /> nested monitoring wells(MW-15,MW-16,MW-17,and MW-18),install a single pumping well(E-2),and <br /> decommission an old domestic well in east Stockton,south of Waterloo Road. The well locations are listed <br /> in the enclosed summary table, and are shown on the attached figure. <br /> Sierra-Pacific intends to use the existing nested-well installation work plan. You received a copy of that <br /> installation work plan in 2000. The current scope of work includes: <br /> ■ Nested-Well MW-15 A/B Installation-A nested monitoring well(MW-15 A/B)will be installed <br /> in the southbound lane of Sutro Avenue, approximately 200 feet south of the intersection of <br /> Waterloo Road, Stockton. <br /> The nested well will be constructed using 2-inch-diameter Schedule 40 PVC well casings and well <br /> screens. The perforated intervals will consist of 2-inch(0.020) slotted PVC casing. One well will <br /> be screened from 95 to 110 feet below ground surface(bgs),the other nested well from 45 to 65 feet <br /> bgs. Threaded PVC caps will be secured to the bottoms of each casing. Factory cleaned two-inch- <br /> diameter Schedule 40 PVC well casing will be extended from the perforated casing to approximately <br /> 2 feet above the ground surface. The top of the well casings will be plugged with 2-inch expansible <br /> caps. <br /> After setting the lower screen and casing inside the hollow-stem auger,RMC Pacific Materials#2-12 <br /> well sand will be poured into the annular space to fill the boring to approximately 2 feet above the <br /> perforated intervals. The wells will be lightly surged to compact the filter-sand around the casings. <br /> If the filter-sand drops during surging, additional sand will be added to bring the sand level to <br /> 4911 Windplay Drive,Suite 4 E-Mail:mail@www.sierra-pacificgroup.com Phone:(916)933-1468 <br /> El Dorado Hills,CA 95762 Fax:(916)933-3197 <br />