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t i Ms. Margaret Lagorio November 6, 1996 Page 3 Monitoring Well Construction During completion of the groundwater monitoring wells, the depth of saturation will be observed and used as a basis for establishing the required well depth. Upon reaching , approximately 30 feet of depth (or 5 feet below the el ti first encountered groundwater), the monitoring wells will be constructed by placin 10 feet o 2-inch diameter Schedule 40 polyvinyl chloride (PVC) 0.02-inch slot casing into the ore hole through the annulus of the hollow-stem augers. Above the slotted casing, and attached by pipe threading, approximately 20 feet of 2-inch diameter Schedule 40 blank PVC casing will be lowered into the bore hole. After the well casing is in place, RMC Lonestar size #3 sand will be tremmied through the augers to the bottom of the borehole to provide a permeable filter pack around the slotted well casing. As the sand level rises, the augers will be raised slowly and removed from the boring, one section at a time. The sand pack elevation will be monitored regularly by the drilling crew with a weighted tape that will be lowered from the ground surface to the top of the sand to ensure the sand level is always above the cutting head elevation. Once the sand pack has reached a level near the top of the slotted casing the well will be surged to induce settlement of the filter pack. The sand pack will then be refilled to the desired elevation of approximately 2 feet above the slotted section. After surging the well, medium-size bentonite chips will be tremmied through the augers to form a seal over the sand pack. The level of bentonite will be raised to approximately 2 feet above the sand pack. A concrete/bentonite slurry will then be used to backfill the remainder of the soil boring. A traffic-rated well cover will then be cemented into place at the ground surface to protect the wellhead. An illustration of a typical groundwater monitoring well configuration is presented on Figure 4. Well Development Initial development will be performed at the time of well installation using a 5-foot long bailer attached to cable from the drilling rig. Development will proceed until approximately five well volumes have been removed. Groundwater extracted from the wells will be stored in labeled drums on the property pending receipt of analytical results. na+0007-M-01 :ta r\nov-96\gw4 mu.pin