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L <br /> June 2, 1992 <br /> -�� <br /> Beacon Station No. 492, Manteca, California <br /> WELL SEARCH <br /> It is our understanding from City of Manteca personnel that the City provides water and <br /> sewer service for the site. Locations of underground utilities within the boundaries of the <br /> site are shown on Plate 2; there are no known septic tanks or leachfields near the site. We <br /> conducted a well search to locate any municipal, domestic, or irrigation water wells within <br /> 2,000 feet of the site. Several ground-water supply wells are within 2,000 feet of the site. <br /> Data obtained from the California Department of Water Resources and the City of Manteca <br /> Public Works Department concerning these wells are presented in Table 1. Some of the <br /> wells noted are probably inactive, and other wells may exist near the site but do not appear <br /> in the records. <br /> MONITORING WELL INSTALLATION <br /> Field Methods <br /> The drilling operations, soil sampling, well construction and development, and water <br /> sampling are presented below and are discussed in more detail in our field methods (an <br /> attachment to this report). Copies of the Chain of Custody Records and laboratory reports <br /> for soil and water samples are also attached. Work was conducted according to field <br /> methods outlined in our Work Plan No. 86102-7W, dated December 11, 1991. <br /> Soil Borings, Soil Sampling, and Well Installation <br /> Y <br /> A geologist from RESNA was onsite on February 14, 1992, to observe Woodward Drilling <br /> of Rio Vista, California, drill one soil boring (B-8) and install a ground-water monitoring <br /> well (MW-4) in the boring at the location shown on Plate 2. The location of well MW-4 <br /> was chosen based on ground-water gradient data evaluated from depth-to-water <br /> measurements collected on October 1, 1991, from three monitoring wells at the site and five <br /> monitoring wells at the nearby former Jackpot gasoline station, immediately north of the <br /> site. Based on that data, well MW-4 was installed downgradient of the tank cavity. Soil <br /> samples were collected at approximately 5-foot intervals during drilling and were identified <br /> using visual and manual methods and classified according to the Unified Soil Classification <br /> System (Plate 3). Ground water was encountered at approximately 25 feet below grade. <br /> Descriptions of the sediments encountered and well construction details are presented on <br /> the Log of Boring (Plates 4 and 5). Sediments consisted predominately of fine- to coarse- <br /> grained sand and silt. <br /> > 0316kear <br /> �. 86102-7 2 <br />