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HYDROLOGIC CHARACTERIZATION AND MONITORING PLAN 29 <br />4.4 Underdrain and Mine Water Monitoring <br />The monitoring program includes two underdrains. The underdrains are located at the lower <br />refuse pile (LRP) and at the refuse pile expansion (RPE) area (Plate 1). The LRP underdrain is <br />located above the sediment ditch at the base of the pile, east of the Stacktube #5 coal stockpile <br />area. The RPE underdrain is located just above the RPE sediment pond. <br />Mine inflows are monitored and sampled at sites in the mine where discernible flows are greater <br />than five gallons per minute (gpm) and/or where flows are present for more than seven <br />consecutive days. If mine inflows are continuous, they are sampled for laboratory analysis at <br />least annually. <br />Table 11. Summary of the Underdrain and Mine Inflow Monitoring Program <br />Monitoring Site <br />Flow <br />Measurement <br />Field WQ <br />H, EC, tem <br />Annual Lab Water <br />Quality <br />Underdrains <br />LRP <br />3 x Year <br />3 x Year <br />Low Flow Period <br />RPE <br />3 x Year <br />3 x Year <br />Low Flow Period <br />(1) Lab parameters include TDS, EC, pH, Ca, Mg, Na, K, SAR, hardness, bicarbonate, Cl, <br />Nitrite/Nitrate, PO4, SO4, Fe (tot & dissolved), Mn (tot & dissolved), Al, As (tot), Cd, Cu, Pb, Hg <br />(tot), Mb, Se (tot), Bo, Zn. <br />4.5 U.S. Forest Service Water Resources <br />MCC and the USFS District office in Paonia, Colorado have jointly agreed to formally monitor <br />the USFS-appropriated water resources that are located over mined and planned longwall panels <br />and within the angle -of -draw of potential surface impacts of the mining operations. <br />Observations are reported in the annual Fall Subsidence Reports submitted to CDRMS. The <br />applicable appropriated water resources are listed in Table 12. <br />Revised 09/07- PR12; 08/16- TR139 HydroGeo, Inc <br />