Laserfiche WebLink
<br />The Trout Creek alluvial aquifer roughly parallels the western boundary of the <br />permit area. Currently, the Trout Creek alluvial aquifer is monitored by 5 <br />wells which are used to observe depth-to-water and water quality trends above, <br />adjacent to and below the mine site. A slight degradation of the alluvial <br />water quality has, and will continue to occur in the alluvium adjacent to <br />portions of the Edna site which have been mined. <br />The resaturation of backfilled pits has been expressed as spoils aquifers. <br />When the elevation head of the aquifer which has developed exceeds the <br />topographic low point along the buried highwall, water is discharged at the <br />surface in the form of springs. Numerous springs and seeps have been <br />identified along the areas mined adjacent to Trout Creek. These springs and <br />seeps discharge water which is high in TDS and sulfates to the alluvial <br />aquifers, as well as directly to Trout Creek. <br />Recent measurements made at a well completed in the West Ridge spoils indicate <br />that TDS values approach 2900 mg/l, which is consistent with other Wadge <br />spoils water quality measured in the basin. <br />Surface Water <br />The permit area lies in the upper Yampa River basin and is drained by several <br />ephemeral streams which flow into Trout Creek and Oak Creek. These are both <br />perennial streams which flow in a northeasterly direction toward the Yampa <br />River. The ephemeral streams draining the permit area flow predominantly <br />west-northwest into Trout Creek, which follows the western permit boundary. <br />Oak Creek flows along the eastern limit of the permit area. The eastern <br />permit boundary is partially defined by the Trout Creek - Oak Creek drainage <br />divide, therefore, Oak Creek receives only a small portion of the runoff from <br />the permit area. Both perennial streams are incised into bedrock, with Trout <br />Creek draining approximately 54 square miles above the northern limit of the <br />mine, while Oak Creek drains approximately 32 square miles. Runoff events in <br />both these streams are dominated by snowmelt. Peak spring runoff occurs <br />slightly later in Trout Creek than in Oak Creek because the headwaters of the <br />former are located at a much higher elevation. <br />Mining operations facilities should not be significantly impacted by large <br />flood events from these streams. The Trout Creek floodptain is well below <br />proposed and existing mining activities. The loading facilities and office <br />area are adjacent to Oak Creek, but above the 100-year, 24-hour floodplain. <br />Trout Creek forms the western boundary of the permit area. The ephemeral <br />streams which drain the permit area flow west or northwest into Trout Creek. <br />Sediment ponds are located at the base of these tributaries above their <br />confluence with Trout Creek. The disturbed area is 4190 acres, or 8 percent <br />of the 54 Square mile Trout Creek drainage basin. The average annual runoff <br />in Trout Creek is 37,500 acre-feet. The mine area is estimated to yield <br />approximately 730 acre-feet of runoff annually, or about 2 percent of the <br />total annual stream flow of Trout Creek above the mine. Annual mean minimum <br />discharge is estimated at 10 cubic feet per second (cfs). <br />Only a small area of mine-related disturbance drains into Oak Creek. Although <br />no mining occurs within this watershed, the loadout, conveyor, access road, <br />-9- <br />