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Due to the confining nature and lateral discontinuity of the saturated zones, <br />only one well has shown a decrease in head attributable to mining operations. <br />Well GW-N8 is located adjacent to a mining pit and exhibits an expected loss <br />of head due to mining. It is expected that mining will continue to induce <br />Limited inflows from isolated aquifers throughout the permit area. This does <br />not appear to be a significant concern due to the small quantity of Inflow <br />expected and the limited impact area. <br />Observations of reclaimed portions of the Nucla Mine site indicate that a <br />limited spoils aquifer has developed and is expected to continue developing <br />within backfilled areas. Monitoring in parts of the backfilled area indicates <br />that the spoil aquifer is limited in extent. We11 GW-N10, completed in the <br />western portion of the previously mined area, has been dry since its <br />construction in January, 1981. However, springs discharging from the mine <br />indicate that some portions of the spoils do resaturate over time. In order <br />to document the future development and extent of spoils aquifers, Peabody <br />committed to completing three additional spoil monitoring wells during 1987. <br />These wells were installed and will be monitored so that an accurate <br />assessment of spoil aquifer development can be made. <br />The quality of the overburden, coal and underburden aquifers varies from <br />sodium bicarbonate type to calcium magnesium sulfate type. Generally, each <br />monitored unit tends to be high in sodium, sulfate, manganese, and total <br />dissolved solids. These units are a poor source of quality drinking water and <br />have not, in the mine area, been developed for domestic use. <br />The operation is in compliance with the requirements of this section. <br />VII. Alluvial Valley Floors - Rules 2.06.8, 2.07.6(2)(k} and 4.24 <br />Information pertaining to alluvial valley floors (AVF) is presented in Volume <br />3, Tab 7 (p. 7-189 to 7-191) of the permit application. <br />Peabody conducted a study in 1980 for the proposed permit area and adjacent <br />area entitled "Reconnaissance Investigation for the Identification of the <br />Potential Yalley Floors in the Direct Vicinity of the Nucla Mine". Only one <br />drainage, Tuttle Draw, was identified as a potential AVF. The San Miguel <br />River was not investigated in this study; therefore, the Division undertook a <br />study to determine if the San Miguel River's potential AYF could be considered <br />adjacent to the Nucla Mine. <br />The San Miguel River is located about 2.5 miles from the Nucla Mine. Based <br />only upon visual observations, it is likely that the San Miguel River would be <br />identified as an AYF. However, the distance separating the mine from the <br />river is probably sufficient to mitigate any impacts that may occur, In <br />addition, the amount of flow that is contributed by Tuttle Draw to the San <br />Miguel River is very small in comparison to the total flow in the river. No <br />mine-related hydrologic impacts are anticipated to occur in the San Miguel <br />River hydrologic system. Therefore, the San Miguel River is considered to be <br />located outside of the potentially affected area and will not be discussed <br />further in the AYF portion of this document. <br />-13- May 6, 1988 <br />