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%WOO n <br /> San Joaquin Workplan <br /> ing at an approximate depth of five feet below the existing grade.Samples will <br /> be obtained by means of a California Modified sampler which was lined with <br /> brass sleeves or rings.The samples will be advanced by blows form a 140 pound <br /> hammer falling 30 inches. Soil will be classified according to the Unified Soil <br /> Classification System. <br /> Upon retrieval,samples retained for chemical analysis will be contained with <br /> a plastic cap over a teflon seal,and taped at each end.The samples will be placed <br /> into a cooler chest on "ice" under proper chain-of-custody protocol for <br /> shipment to the analytical laboratory. <br /> It is anticipated that four of the borings will be complketed as monitoring wells. <br /> Borings not completed as monitoring wells will be back-filled upon termina- <br /> tion with a sand-cement grout to the surface grade. <br /> 5.2 MONITORING WELL INSTALLATION <br /> Each monitoring well will be constructed through a ten-inch diameter,hollow- <br /> stem auger using 4-inch flush thread PVC schedlue pipe.Based upon our local <br /> experience, screened intervals will be constructed utilizing schedule 40 PVC <br /> flush thread 0.020 inch well screen. The screened interval will consist of <br /> sufficient screening to accommodate a minimum ten foot screened interval <br /> below and five feet above the encountered groundwater leve.A No. 3 gradded <br /> sand will be used a filter media around the screened intercal,and completed to <br /> an equivalent depth of 2 feet above the well screen. A seal composed of <br /> bentonite pellets will be placed to an approximate thickness of 3 feet atop the <br /> filter media and hydrated. <br /> The remaining annulus will be back-filled with a san/cement slurry with <br /> approximately 3%bentonite added from the seal to the surface vault.A locking <br /> well head will be installed, and a water-tight surface vault will be placed at <br /> grade for well security. The design of the groundwater monitoimg wells is in <br /> general compliance with the State of California Department of Water Re- <br /> sources Bulletin 74-90 Monitoring Well Standards (DWR 163907). <br /> 5.3 WELL DEVELOPMENT AND SAMPLING <br /> The following methodologies will be specified for the chemical analyses of soil <br /> and groundwater samples: <br /> Project Number: JOAQ22192 <br />