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Mr. James Barton,PG 24 April 2014 Page 6 Drilling and Installation of Groundwater Monitoring Wells The well borings will be drilled by National Exploration, Wells & Pumps (National) using sonic drilling methods to minimize the potential for cross-contamination between the water-bearing zones. The boring for DMW-6B will be continuously logged to obtain geologic information and to visually identify first-encountered groundwater. The remaining wells will be logged at approximately 5-ft intervals. Soil logging will be performed by a qualified Geosyntec engineer or geologist under the supervision of a California Professional Geologist or Engineer. Soil cuttings will be contained in 55-gallon drums. Soil samples will not be collected for chemical analysis unless unusual soil conditions are noted during drilling: The following general procedures will be followed in constructing the monitoring wells. After reaching total depth in each boring;well construction materials will be placed through the center of the drill rods. Well casing will consist of 2-inch diameter threaded joint Schedule 40 PVC pipe. Well screen will consist of the same PVC pipe with 0.01-inch slots. The bottom caps on each well will be threaded. The tops of the well casings will be fitted with expandable-gasket lockable caps. After installing the casing and screen, an appropriate sand filter pack will be placed to about 2 feet above the top of the well screen. As the sand is added, the drill rods will be pulled up to allow the sand pack to continuously fill the borehole annulus. A bentonite seal consisting of a minimum of 2 feet of compressed bentonite pellets will be placed above the sand pack. The pellets will be allowed to hydrate before grouting. Cement and bentonite grout will be used to seal the borehole annulus from the top of the bentonite seal to-the ground surface. The grout mix will consist of Type II/V Portland cement and potable water. The grout will be tremmied into place. The wells will be completed at the surface with flush mount well boxes. Locking well caps and locks will be installed on all wells. Surveying The north side of each well box and PVC well casing will be surveyed for elevation and location by a licensed surveyor. The wells will be surveyed to North American Datum (NAD) 83 and North American Vertical Datum (NAVD) 88, in accordance with the RWQCB GeoTracker database reporting requirements. Offsite Characterization Workplan engineers I scientists I innovators