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Mine pit inflows from Nucla East will be pumped to Pond 007 and discharged to <br />Calamity Draw. Mine pit inflows from the Nucla mine area 1 (NW pit) are <br />pumped to Pond 001 and subsequently discharged to Tuttle Draw. As both the <br />overburden and the coal seam discharge along the Draws, this modification will <br />have little effect other than accelerating the discharge. Peabody has <br />predicted that the quality of this discharge will be similar to the quality of <br />water found in the overburden aquifer. <br />Backfilling of spoil material at surface coal mines results in a single, <br />pit-sized, partially saturated aquifer with higher horizontal and vertical <br />permeability than previously found in the material. Infiltration rates will <br />probably increase. A large proportion of the water in these aquifers <br />discharges at the surface as springs instead of recharging the existing <br />bedrock aquifers. Spoils springs have been observed at the Nucla site, and <br />are ultimately expected to discharge as much as 0.238 cfs during the <br />irrigation season and 0.076 cfs during the non-irrigation season, based on <br />calculations of recharge from the bedrock aquifers, which are recharged by the <br />irrigation ditches in the area. Similarly, predictions were developed for <br />mining at Nucla East, and it was estimated that 1.31 cfs of discharge would <br />occur during the irrigation season and 0.48 cfs would occur during periods of <br />non-irrigation. <br />Based upon data collected at the Nucla Mine, it is apparent that only a <br />portion of the spoils will resaturate. One well (GW-N10) is completed in a <br />backfilled mining pit and has been dry for the period of record (1981-1987). <br />Three additional wells were completed in 1987 and only one (GW-N27) has had <br />any water in it. Other portions of the backfilled pit have resaturated, as <br />evidenced by the presence of spoil springs located near Pond 001. <br />The re-establishment of sub-irrigation recharged by irrigation return flows <br />will be delayed until the backfilled pit has been filled with water. This <br />will follow backfilling and reclamation by five-to-fifteen years, depending on <br />precipitation and irrigation patterns throughout the tract. <br />The water quality of this aquifer is predicted to be similar to the overburden <br />aquifer, a calcium sulfate water with average total dissolved solids <br />concentrations of 3800 mg/1 at Nucla and 4600 mg/1 at Nucla East. Water of <br />this quality could increase the total dissolved solids levels found in the <br />Dakota sandstone aquifer fora short distance from the mine Di t. The quality <br />of the water discharging from the spoils near Pond 001 at the Nucla Mine is <br />poor; however, no significant off-site impacts are expected. Spoil springs <br />discharge to the irrigation return flow drainages which flow to the San Miguel <br />River. This impact is discussed in the surface water section below. <br />Water levels in the alluvial aquifers adjacent to Tuttle and Calamity Draws <br />will be affected by the changes in points of discharge of the coal and <br />overburden aquifers during mining. Water levels in the alluvium will be <br />influenced more by surface water volumes than by discharge from the bedrock <br />aquifers, as occurred prior to mining. Consequently, one may observe higher <br />than average water levels in the alluvium immediately adjacent to the streams, <br />and lower average levels in the alluvium further from the stream. This will <br />have an insignificant impact on agricultural production in the area. <br />-20- <br />