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Ms. Amy Terrell <br /> 20 August 2007 <br /> Page 5 <br /> Both MW-6R and MW-7 will be 2-inch diameter polyvinyl chloride (PVC) monitoring wells <br /> installed using hollow-stem augers and screened from a depth of 25 to 45 feet below ground <br /> surface (ft bgs). A California-licensed driller will drill and install the wells. Soil samples will be <br /> collected for geologic description using a split-spoon sampler (SPT) at five foot intervals from <br /> the ground surface to a depth of 25 ft bgs. Continuous cores will be collected from 25 ft bgs to <br /> the bottom of the borehole. Geologic logs for each well boring will be prepared. <br /> Figure 3 shows a diagram of the proposed monitoring wells that will be constructed as follows: <br /> • 20 ft of well screen constructed of Schedule 40 PVC with 0.02-inch factory-cut slots ; <br /> • Riser pipe constructed of blank, Schedule 40 PVC; <br /> • Filter pack in the annular space between the borehole and the PVC casing that consists of <br /> a#2/12 filter sand; <br /> • A 2-foot bentonite seal placed on top of the PVC the filter pack. <br /> Following hydration of the bentonite seal, cement grout will be used to seal the annular space up <br /> to the ground surface using a tremie pipe. The monitoring well will be sealed at the bottom with <br /> a threaded cap and at the top with threaded or friction caps. Surface completion will consist of <br /> an outer casing completed in a stove-pipe configuration with surrounding bollards to prevent <br /> damage to the well. <br /> Monitoring Well Development <br /> Following a minimum period of 48 hours after installation, the wells will be developed using a <br /> surging, bailing, and pumping method in order to stabilize the filter pack and remove fines from <br /> the filter pack and well screen. Pumping will be performed using a submersible pump and water <br /> quality parameters (e.g.. turbidity, ORP, conductivity, etc.) will be measured during pumping. <br /> Purge water will be temporarily stored in 55-gallon drums on wooden pallets at the Site pending <br /> analysis and disposed of with soil cuttings at an appropriate off-site facility. <br /> P:\PR]2003REM\WFS\VER\VERF\2007 Expanded Pilot Work Plan\Expanded_Pilot Test WP.doc <br /> engineers I scientists I innovators <br />