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grout has settled, the ground surface will be restored to original grade using hand tools and surrounding soils to minimize depressions in the ground surface. 3.44 MONITORING WELL INSTALLATION Permanent monitoring wells will be constructed when the results of the VOC analyses from the HydropunchT"' samples indicate non-detectable concentrations. 3.4.1 Borehole Reaming and Soil Sampling At each site where the HydropunchTM sample indicates non-detectable VOC concentrations, the sampler and casing will be removed, and the borehole will be reamed in preparation for well construction. Boreholes will be reamed to 10 inches using hollow -stem auger methods. Once the ream advances to the original depth of the exploratory borehole, drilling will continue up to 20 feet, and soil samples will be collected continuously using split -spoon sampling and logging methods described above. All drilling operations will be continuously observed, and samples will be retained for geologic logging purposes. 3.4.2 Monitoring Well Construction Groundwater monitoring wells will be constructed using 2 -inch nominal inner diameter, Schedule 80 PVC blank casing and 20 feet of screen to the approximate depths indicated above. Well screens will be formed using machine cut 0.020 -inch slots. A one -inch nominal inner diameter sounding tube constructed of similar PVC casing and screen will also be installed to avoid future conflict between tubes and wires associated with the pump. All well materials, including blank and factory -slotted casing, will be virgin, decontaminated and factory sealed. All well materials will be covered in plastic or similar protective materials when delivered to the site and will remain so until used in construction. All well casing will be flush -threaded, including the bottom cap at the base of the wells. No glue or solvents will be used to join the sections. Because wells will be constructed through the hollow -stem of the auger, centralizers are not needed. The drillers will suspend the casing from the drill wire during construction to ensure that the casing remains centralized within the augers. Based on the grain size distribution of the shallow, perched aquifer encountered in past site investigations, the proposed filter pack material will consist of commercially available inert, washed and graded number 2/12 Monterey sand (or equivalent). Well filter packing will be ' accomplished by slowly pouring the sand down the auger flights, which act as a tremie pipe. As sand is introduced, the augers will be withdrawn to allow the sand to fill the annular spaced between the auger and borehole wall. The elevation of the sand will be measured periodically using a decontaminated weight to ensure that no bridging occurs. The filter pack installation will be deemed complete when the sand extends at least three feet above ' 9 2011-0115 CHSL EMP Workplan Geo -Logic Associates Revision 1- August 24, 2011