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A C-57 licensed contractor will install the nested well to a total depth of approximately 55 feet ' using a truck-mounted drill rig, and 10-inch diameter hollow stem augers The nested well will consist of three casings in the same borehole All of the wells will consist of two-inch diameter, Schedule 40, flush-threaded and machine-slotted (0 020-inch) PVC well screen and blank PVC ' casing The screen intervals will span from 12 to 22 feet, 28 to 38 feet , and 44 to 54 feet bgs ' The driller will place filter packs of Monterey #3 graded and washed sand around the screen intervals and approximately two feet above the tops of the screen intervals Overlying all three filter pack intervals, the driller will install four-foot thick seals of hydrated bentonite Overlying the ' upper bentonite layer, the driller will place a surface seat of neat cement grout To facilitate future underground soil vapor extraction piping connections, the top of the upper cement seal will be approximately three feet below surface grade Each of the well casings will be secured with watertight locking caps, and the well nest wili be covered with an 18-inch diameter, traffic-rated, flush-mount street box 4 3 2 Nested Air Sparge/Soil Va or Extraction Well ' The nested air spargelsoil vapor extraction well will consist of one air sparge well and one soil vapor extraction well in the same borehole, and will be located directly over the south end of the former UST#3 (Figure 2) ' A C-57 licensed contractor will install the nested well to a total depth of approximately 65 feet using a truck-mounted drill rig, and 10-inch diameter hollow stem augers The air sparge well will ' be constructed with a 3-foot macroporous bubbler (KVA spargepointTM) section, spanning from approximately 62 to 65 feet bgs, and one-inch PVC casing to the surface The soil vapor extraction well will consist of two-inch diameter PVC casing and (0 020-inch slot) PVC well ' screen, spanning from approximately 33 to 48 feet bgs ' The driller will place a filter pack of Monterey#3 graded and washed sand around the sparge point and soil vapor extraction well screen intervals, and approximately two feet above the tops of the spargepornt and screen intervals Between the two filter packs, the driller will install a 12-foot ' thick layer of hydrated bentonite from approximately 48 to 60 feet bgs A four-foot thick hydrated bentonite seal will also be placed over the top of the soil vapor extraction well filter pack Overlying this upper bentonite seal, the driller will place a surface seal of neat cement grout to within three feet of the surface The well casings will be secured with watertight locking caps, and the well nest will be covered with an 18-inch diameter, traffic-rated, flush-mount street box 14