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Minor Revision No. 226 Page 2 September 12, 1997 The total depths of these holes will not be known until the completion of the core hole. However, they can be expected to be shallower than the core hole. Other Piezometers: Three piezometers (soil piezometers) will be drilled through overburden by hollow stem auger to refusal and then by rotary methods until 3-feet into competent bedrock. Split spoon samples will be collected every two feet in one hole. Minimal split spoon samples will be collected on the other two holes. All three piezometers will be completed with 2-inch diameter pipe and screened across the transmissive zone above bedrock. Two of these piezometers will be located below the substation. Access will be bladed from the substation to the holes. Again, this area has been previously disturbed. Pumping Test: A submersible pump will be installed in the well and cone-day step drawdown test will be performed to evaluate the sustainable pumping rate. In addition, a 96-hour pumping test will be conducted to determine the area of influence of the pumping well. A 96-hour recovery test will also be conducted. The six piezometers will be monitored throughout the tests. If successful, the well will be used to pump groundwater before it enters the slide area. This water is expected to be of good quality, similar to other springs in the area, and be dischazged to the MB- 1/FW-1 spillway. If the pumping test is favorable, designs for additional pumping wells will be completed, permitted, and installed. If the pumping test is unfavorable, the well will be abandoned and reclaimed as described below. MCC is in the process of obtaining the necessary permits from the State Engineers Office for this well. FW-I Piezometers: MCC suspects that FW-1 may be leaking, causing another source of water being added to the landslide. Three sets of nested piezometers are planned to determine if MCC's suspicions are correct. Each nest consists of one shallow and one deeper piezometer as shown on Figure 3. Piezometer locations 1 and 2 aze to be placed at a depth of approximately 25-feet in order to form a nest with PP-4 and PP-7, respectively. PP-4 and PP-7 are existing pneumatic piezometers located in the "cobble" layer below the colluvium. Piezometer location 3 will have a nest as shown in Figure 3, with a screen placed at a depth of 25 feet, and another screen placed within the zone of cobbles under the colluvium. The shallow piezometers will be completed to a depth of approximately 25-feet. The deeper piezometer will be completed to an approximate depth of SS-feet. All four new piezometers will be completed with 2-inches diameter pipe. Reclamation: MCC will reclaim all piezometers to comply with Rule 4.07.3(1) or 4.07.3(2), depending on whether water was encountered during drilling. The schedule for reclamation in unknown at this time, as the success of the pumping test will determine if the holes are immediately abandoned or not.