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a n, <br /> W , "M Mg- <br /> I <br /> Problem Assessment Report December 5, 1989 <br /> USA Petroleum Station No. 65, Lodi, California AGS 87050-3 <br /> Srround Water I4ionitoring Wells <br /> Well Construction <br /> ! 3 <br /> i <br /> The monitoring wells were constructed with thread jointed,2-inch-inner-diameter.Schedule <br /> 40 polyvinyl chloride (PVC} casing. No chemical cements, glues, or solvents were used in <br /> r <br /> well construction. 'File screened portion of each well consists of factory-perforated casing <br /> with 0.020-inch-wide slots and extends from the total depth of Ilse boreholes at <br /> r r <br /> approximately 60 feet below grade to approximately 34 to 36 feet below grade. Blank <br /> (unperforated) casng was set from the top of the screen to several inches below surface i <br /> grade. <br /> The annular space of each well was packed with No.3 sorted Monterey sand from the total <br /> depth of i--e monitoring well to approximately 4 to 6 feet above file top of the screen (30 <br /> II <br /> to 32 feet below-surface grade). A 2-to 4-foot=th'sck plug consisting of bentonite pellets waste <br /> placed above the sand to prevent cement from entering the sand pack. The thicker <br /> bentonite seal was used when a known sand layer was encountered within 2 feet of the top <br /> ti of the screened interval. The remaining ann Ous was backfilled to the ground surface with t <br /> , <br /> a mixture of water, cement,and bentonite: The construction details of file individual wells <br /> i <br /> { are depicted on the Logs o:Borings. <br /> .isVStems <br /> 3 <br /> - _ - <br /> ,r. <br />