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the top of the screen. Following filter pack sand placement, the filter pack will be surged and allowed to settle with additional sand being added as necessary to bring the filter pack up to design depth. A minimum 5 -foot thick granular bentonite seal (chips or pellets) will be placed on top of the well filter pack. The bentonite will be hydrated after placement using a minimum 5 gallons of distilled or GLA -approved water for each 2.5 vertical feet of seal. After the seal has been hydrated, it will be allowed to cure for at least 30 minutes prior further well sampling or construction activities. The remainder of the borehole will be sealed with an expansive neat cement grout. The grout seal will consist of Portland Type 1/II cement (or equivalent) and bentonite mixture with a water -to -cement ratio that includes no more than 8 gallons of water per sack of cement and 5 percent bentonite by weight. The grout will be delivered to the borehole via tremie pipe and positive displacement techniques. After placement of the sand pack and prior to placement of the bentonite chips, all wells will be pre -developed using bailing or surging techniques to settle the sand pack and remove fines. The level of the sand pack within the annulus will be measured both before and after the predevelopment process, and additional sand will be added to the borehole, as necessary, to bring the sand pack to the design elevation. After the bentonite chip seal is constructed, the bentonite will be allowed to hydrate for at least one hour before additional well development. At that time each well will be developed using a bailer and surge block and, if necessary, by pumping and surging with a well development pump or bailer until visually clear, non -turbid (approximately 5 NTU) water is discharged from the well, and the temperature, pH, and specific conductivity of 10 2011-0115 CHSL EMP Workplan Geo -Logic Associates Revision 1- August 24, 2011 During their placement, depth soundings will be utilized to evaluate the thickness and uniformity of the sand pack and bentonite seal, and to assure that no bridging occurs. Well heads will be finished with locking stovepipe -type monuments embedded in concrete pads and protected by concrete -filled traffic posts (bollards). A steel bolt will be embedded in the concrete pad to serve as a reference point for the elevation survey. A representative well construction diagram is presented on Figure 4. 3.4.3 Surveying Surveying of completed monitoringwells will be conducted b the County. Wells will be Y Y surveyed using laser guided or global positioning system equipment, tying into the State Plane Coordinate system datum. Top of casing, top of monument, and ground surface elevations will be measured to the nearest 0.01 foot. The coordinates of the well survey bolt will also be surveyed to the nearest 0.1 foot. 3.4.4 Monitoring p Well Development After placement of the sand pack and prior to placement of the bentonite chips, all wells will be pre -developed using bailing or surging techniques to settle the sand pack and remove fines. The level of the sand pack within the annulus will be measured both before and after the predevelopment process, and additional sand will be added to the borehole, as necessary, to bring the sand pack to the design elevation. After the bentonite chip seal is constructed, the bentonite will be allowed to hydrate for at least one hour before additional well development. At that time each well will be developed using a bailer and surge block and, if necessary, by pumping and surging with a well development pump or bailer until visually clear, non -turbid (approximately 5 NTU) water is discharged from the well, and the temperature, pH, and specific conductivity of 10 2011-0115 CHSL EMP Workplan Geo -Logic Associates Revision 1- August 24, 2011