2010-06-30_REPORT - C1980007 (5)

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West Elk Mine 2009 Annual Hydrology Report 16 • 3.1.4.3 South Pronk Creek South Prong Creek is an ephemeral stream that is tributary to upper Minnesota Creek. The north fork of South Prong Creek drains the southern portion of the SOD mine plan area. The monitoring station on South Prong Creek is located at the mouth of the drainage and does not have a flume or data logger (Map 2). Preliminary flow and water quality data were collected during a one time sampling round of this site in 2005 (HydroGeo, 2006). Baseline monitoring is scheduled to resume in 2017, or at least one year prior to when mining begins in the area to monitor potential mining induced impacts. 3.1.5 Temperature Monitoring Sites The surface lands of the West Elk Mine are drained to the north by the North Fork of the Gunnison River. Water from the mine water pumping facility (MWPF) discharge point enters the North Fork of the Gunnison River via Sylvester Gulch. In September 2007, MCC contracted GEI Consultants (GEI) to install temperature loggers (a.k.a. thermistors) in Sylvester Gulch and in the North Fork of the Gunnison River in order to monitor the effects of discharge from Sylvester Gulch on water temperature of the North Fork of the Gunnison River. Five temperature loggers (ONSET Corp. HOBO Water Temp Pro v2) were deployed within Sylvester Gulch, and three within the North Fork of the Gunnison River (Table 4). The loggers were installed by GEI on September 21, 2007 and were programmed to record temperature data at 15 minute intervals. The data loggers were re-programmed in WY 2009 to collect data at hourly intervals. Data from the temperature loggers are downloaded on-site monthly by HydroGeo (whenever snow/ice or dangerously high water levels do not prevent access to the loggers) using a laptop computer and an ONSET adapter cable. Each temperature logger was attached to a steel rebar rod using galvanized cable and stainless steel hose clamps. The rebar was driven into the streambed. In October, 2007 HydroGeo re-anchored each of the loggers to secure points on the shore using 1/16 inch aircraft grade galvanized steel cable. In the summer of 2008 or in WY 2009, all of the data loggers were reprogrammed to record temperature data at one-hour intervals, in order to increase the data logger battery life, and to increase the length of time it takes for the logger memory to become full and stop recording. The temperature logger sites were visited on a near monthly basis in WY 2009 and the loggers were downloaded whenever snow/ice or dangerously high water levels did not prevent access to the loggers. The locations of the temperature monitoring sites are shown on Figure 8. Water temperature data and graphs for the 8 temperature monitoring site in WY 2009 are presented in • June 2010 HydroGeo, Inc.