2016-12-01_PERMIT FILE - C1980007A

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HYDROLOGIC CHARACTERIZATION AND MONITORING PLAN 17 4.1.1 Upper North Fork Drainage Basin Surface Water Monitoring Stations 4.1.1.1 Deep Creek (Upper, Lower) Deep Creek is a perennial stream drainage that is tributary to Raven Gulch (Plate 1). The Upper Deep Creek monitoring station does not have a flume or data logger and is located up -gradient of the southeast B -seam longwall panels area (southeast mine panels area) and down -gradient of the SOD E -seam longwall panels area (SOD mine panels area). The Lower Deep Creek monitoring station does not have a flume or data logger and is located down -gradient of the southeast mine panels area and is directly east of the West Flatiron and Box Canyon mine panels area (Plate 1). In 2006, the flow monitoring at the Deep Creek monitoring sites was changed from continuous flow recording to instantaneous recording three times a year. This change was made for two reasons: mining in this area was nearly complete and the Deep Creek stream channel is highly variable, resulting in continuous flow data that were unreliable and that did not represent actual conditions. Hydrologic monitoring at the Upper and Lower Deep Creek monitoring stations began in 1996. 4.1.1.2 Box Canyon Box Canyon is an ephemeral drainage. The upper reach of the drainage is typically dry and the lower reach of the drainage only flows during storm events and during the spring months in above average precipitation years. The Box Canyon monitoring station is located at the mouth of the drainage and was established to monitor the area down -gradient of the Box Canyon B -seam longwall panels area (Box Canyon mine panels area) (Plate 1). There is no flume or data logger in Box Canyon and hydrologic data have been collected at this site since 1999. 4.1.1.3 North Fork Upper The North Fork is a major perennial stream that drains the northern area of the mine site. 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 (Plate 1). The underground mine water discharge flows into Sylvester Gulch and then into the North Fork. 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 North Fork Upper site has been monitored since 1977. 4.1.1.4 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 are: 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 - Revised 09/07- PR12; 08/16- TR139 HydroGeo, Inc