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east corner of the mine while the downstream alluvial well is located down gradient of the mine but up gradient of the Nucla waste water lagoons in Calamity Draws. Western Fuels acquired access to and began monitoring the cluster of wells located in the southwest corner of the project area (wells GW-N16P1, GW-N17P1, and GW-N18P1) in July, 1993. The two sets of wells, GV1~- . N36, GW-N37 and GW-N38 in the northeast corner of the permit area, and GW-N16PI, GW- N17PI and GW-N18PI in the southwest corner of the permit area will adequately monitor groundwater flow activity covering the GarveylBurbridge leases. Two other wells, GW-N6 and GW-N22, were investigated for inclusion in then monitoring program. Well GW-N6, located northeast of the permit boundary, was found to be unusable due to the casing being filled with rocks. Well GW-N22, located downgradient of the waste water lagoons on Calamity Draw, cannot be used due to access agreements and may not tie appropriate to monitor due to its downstream location from these treatment facilities. Well.> GW-N19, GW-N2t) and GW-N21 were also dropped from the monitoring program since they did not serve a practical purpose. All wells are monitored on a monthly basis for water levels. These levels are: adjusted to mean sea elevation. Water quality samples will be collected and analyzed for the parameters listed in 2.04.7.2 on asemi-annual basis. Semi-annual samplings will be conducted in February during the non-irrigation season and in August during the irrigation season. PROBABLE HYDROLOGICAL CONSEQUENCES A discussion of the probable hydrologic consequences and reclamation plan are contained in Section 2.O5.ES(3) and Section 2.05.6(3)(b)(v) of the permit application document. The following discussion is intended to supplement the description of potential impacts of mining and mitigatio i of these potential effects. The determination of significance has been made considering the impact on the quality of the human environment, existing water uses, and the intended post mining land use of the area. • Interruption of groundwater flow and drawdown. In order to develop the impact assessment for groundwater quantity, two different analyses techniques were utilized. First, pit inflow volumes were determined on an annual basis using an analytical approach developed by McWhorter, 1982. The second analysis involved the determination of annual pit inflow rates and annual drawdcwns in the adjacent overburden and coal aquifers as a result of the pit inflows. This analysis utilized the USGS 3-dimensional finite-difference groundwater flow model MODFLOW. Transient simulations were performed for alive-year period, using the maximum drawdown estimates for the overburden and coal. These drawdown results are expressed as a maximum at the pit and are expressed as a conical depression which results in decreased drawdown at further distance from the mine. For the overburden, the pit drawdown was 5 feet for years 1 and 2, a feet during year 3, 15 feet during year 4, and 30 feet during year 5. The drawdown for the coal simulation was 8 feet during year 1, 5.8 feet during year 2, 6 feet during year 3, 7.3 feet during year 4, and 8 feet during year 5. The zero impact contour for the overburden and coal after five years of mining is approximately 4,000 feet. The overburden and coal drawdown contours do not intersect any of the boundaries, therefore, no impact of the San Miguel River from drawdown in the deeper part of the overburden or coal is predicted. Shallow aquifer flow mto Tuttle and ~~alamity Draws in the vicinity of the pit will be decreased, but vdill be offset by pumpage from the pit. Simulated average daily pit inflow for the coal and overburden aquifers varied from 1,255 cubic feet per day in year 1 to 5,604 cubic feet per day in year 5. WFC's approach to these potential impacts is to monitor the aquifers and discharge from the pit to determine the extent of drawdown. The hydrological monitoring program should provide reasonably accurate measurements of effects of mining. Should the monitoring show that impacts to the groundwater aquifers are precluding its use, WFC will provide alternate water sources of comparable quantity and quality. As described in the water augmentation plan, WFC has a 114 acre foot consumptive use right on the Highline Canal which would be used to mitigate the potential 26 acre foot impact on surface water right users from pit inflow drawdown.