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casing. A bentonite seal (1 to 2 feet thick),consisting of one-quarter-inch bentonite pellets,will be placed above the filter pack and hydrated with 2 to 3 gallons of potable water. The remaining annular space will be filled with a cement/ bentonite grout mixture in the ratio of approximately 2 pounds of powdered bentonite (measured in the field),6.5 to 7 gallons of water, and 94 pounds (one bag) of Portland cement. The bentonite will be added to the water and allowed to hydrate by circulating the mixture through a grout pump or mixing apparatus. The cement will then be added to the bentonite/water mixture and thoroughly mixed. The cement/bentonite mixture will be added to the borehole through the augers. During grout placement, the augers will be extracted at 1-to 2-foot intervals, and additional grout will be added to fill the annulus until the grout is at the original ground surface. The wells will be finished with a water-tight,locking well cap housed within a traffic-rated road box at grade,or an aboveground stovepipe well box. All downhole drilling and sampling equipment will be appropriately decontaminated prior to arrival onsite and between each boring location (see Section 4.7). Residual materials generated from drilling activities (soil cuttings and decontamination water) will be containerized, as appropriate, until laboratory analytical results are received and evaluated. The materials will then be disposed of appropriately (see Section 4.10). Following installation,each boring or monitoring well location will be surveyed by a licensed surveyor,including ground level elevation and geographical survey coordinates. 4.4 MONITORING WELL DEVELOPMENT PROCEDURES After well installation is completed and the well seals have set for a minimum of 24 hours (as per the DTSC standards for construction of monitoring wells as described in the Draft Scientific and Technical Standards for Hazardous Waste Sites, Chapter 8),the wells will be developed. The depth to groundwater will be measured in each monitoring well and the well volume calculated. Development initially will be performed by using a bailer to remove coarse sediments that may have entered the well,after which a 2-inch surge block will be inserted into the casing. Surging will be performed by raising and lowering the surge block across the saturated portion of the screen approximately 20 times. The surge block will then be removed and the bailer used to remove coarse sediments. After surging, a submersible or surface pump will be used to remove approximately 5 to ERM 9 LISCO,INC./0067373.01-N.vm ZOO/