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APPENDIX C 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 augers. 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 augers will be pulled up to allow the sand pack to 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 I/II Portland cement, bentonite powder,and potable water. The grout will be tremmied into place. The wells will be completed at the surface with flush mount well boxes or with an above ground locking well cover and guard posts. Locking well caps and locks will be installed on all wells. Site personnel will be consulted about whether completions need to be at-grade or above ground. Surveying The north side of each well box and PVC well casing will be surveyed for elevation and location by a licensed surveyor. This information will be used to develop a groundwater elevation contour map from which the groundwater flow direction beneath the Site can be inferred. 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. Well Development The new monitoring wells will be developed at least 48 hours after installation. The purpose of well development is to stabilize the filter pack and remove fines from the filter pack and well screen. Development will be completed according to the following general procedures: • All downhole equipment will be decontaminated by steam cleaning or washing in a solution of laboratory-grade detergent prior to,between, and after use; • The total depth of the well and the water level will be measured; • Approximately one casing volume of water will be removed from the well using a submersible pump or bailer; 0 The well will be surged for a period of 15 to 30 minutes;