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HYDROLOGIC AP~ALYSES Williams Fork Alluvium Local Geology Empire Energy has located mine facilities and the portal for their Eagle Mine No. 5 on the valley floor of the Williams Fork River. In the vicinity of the mine the valley floor is approximately 800 to 1000 feet wide. The valley floor is underlain by approximately 10 to 15 feet of poorly sorted clay to cobble size material. The material generally becomes coarser with depth and is mantled with 2 to 4 feet of fine sandy to loamy soil. Bedrock is sandstones and shales of the Williams Fork Formation. Well Construction On 9 and 10 March 1982, 3 wells were completed in the Williams Fork Alluvium near existing monitoring well AVF-5. The well locations are shown on Figure 1 and summary loss are presented on Figure 2. Typical well construction is presented on Figure 4. The wells were drilled with air rotary drilling methods. Well WF-1 was drilled with an 11-3/4 inch bit and completed with 6-5/8 inch O.D., PVC casing and continuous slot ~~ screen (.030 inch slot size). Well WF-2 and WF-3 were drilled with a 7-7/8 inch bit and completed with 2-3/8 inch O.D. PVC casing and machine slot screen (.010 inch slot size). All screened intervals were gravel packed with 10-20 sieve size silica sand. A seal of bentonite pellets was placed above the gravel pack. The wells were developed with air and by pumping for 1 to 2 hours each. The maximum yield obtained from any well was approximately 1 gpm. None of the wells were pumping clear water at the end of development. Wells WF-1, WF-2 and WF-3 will be abandoned in accordance with the approved plan. Hydrogeology In the wells drilled near AVF-5 the thickness of the alluvium ranged from 10 to 12 feet. The depth to water was approximately 5 to 6 feet yielding a saturated thickness of approximately 5 feet. Oue to the low yields obtained during development and the small saturated thickness, it was decided not to pump test well WF-1. Instead, wells WF-2, WF-3 and AVF-5 were slug tested. The slug tests were performed on 11 March 1982. The tests were performed by removing 0.23 gallons of water with a bailer. The subsequent water level recovery was measured using a steel tape with a "popper" at the bottom. The popper (Ferris and Knowls, 1954), makes a relatively loud popping sound when it strikes the water surface. Generally, water levels can be measured to 10.01 feet. The results of the slug testing are pre- sented on Table 1. The data was analyzed using 3 methods referenced on the ~ table. Where the data did not appear to be in accordance with what the theory would indicate fora particular method, the results of that method were not used.