2012-07-02_REPORT - C1980007 (3)

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West Elk Mine 2011 Annual Hydrology Report 15 the area down - gradient of the Box Canyon B -seam panel area (Map 2). There is no flume or data logger in Box Canyon and data have been collected at this site since 1999. 3.1.1.4 North Fork Upper The North Fork of the Gunnison River is a major perennial stream that drains the northern mine site area. The North Fork Upper monitoring station is at the site of the USGS gaging station (North Fork Gunnison River near Somerset, CO, USGS 09132500) located up- gradient of the mine facilities area and up- gradient of the mine discharge points. The underground mine water discharge flows into Sylvester Gulch then into the North Fork of the Gunnison River. The mine surface water runoff is treated and routed to holding ponds and is then discharged to the North Fork, if necessary. All of the mine water discharge occurs between the North Fork Upper and North Fork Lower monitoring stations. The three temperature monitoring sites in North Fork of the Gunnison River are discussed in Section 3.1.5.1. 3.1.1.5 Sylvester Gulch (Upper, Middle, Lower) Sylvester Gulch is an intermittent stream that drains the north central mine area. Many of the active surface facilities of the mine are located within the Sylvester Gulch drainage basin area including: the main road to the mine facilities from Highway 133, the coal refuse piles, the mine ventilation shafts, and the mine water discharge facility. The three monitoring sites in Sylvester Gulch include: Upper Sylvester Gulch (9 -inch Parshall flume and staff gage), Middle Sylvester Gulch (12 -inch Parshall flume, staff gage, and data logger), and Lower Sylvester Gulch (no flume or data logger). These three sites monitor areas up- gradient of the mine surface facilities, areas down - gradient of the mine water discharge point and the mine facilities, and areas down - gradient of the coal refuse pile, respectively. Monitoring at these 3 sites began in 1977. The five temperature monitoring sites in Sylvester Gulch are described in Section 3.1.5.2. June 2012 HydroGeo, Inc.