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In May 2006, a spring and seep survey was also conducted in the northem mining district to identify potential <br />discharges to Fish Creek. No new or significant springs were identified in 2006. The northern mining district is <br />located within the Twentymile Park Syncline. The predominant lithologic unit nearest the surface and occupying <br />most of the basin is the Lewis Shale, which can be upwards of 700 feet thick. The lack of significant bedding <br />planes, faulting, or fracture zones in this area may account for the lack of springs in the central portion of this <br />basin. The few seeps observed in the basin may be the result from surface weathering of the Lewis Shale, which <br />may allow some accumulation of water beneath overburden. This may result in a short period of seepage <br />immediately following spring runoff. <br />3.6 Mine Water Discharge Sites <br />Two mine water dischazge sites associated with the TCC operations are monitored. Site 109 requires quarterly <br />monitoring for flows, field parameters, and water quality samples (when flowing), and site 115 is monitored as a <br />CDPS discharge point in accordance with the requirements set forth under CDPS Permit No. CO-0042161. <br />There was no flow from site 109 to Foidel Creak in 2006. Site 115 has not discharged to Fish Creek since early <br />2005. Piping leading to the discharge channel to Fish Creek was closed off in 2006, Currently, water is pumped <br />from underground to the surface (from the former Western Mining District), and is treated via an electro- <br />coagulation process at the surface, where water enters the 3 former treatment ponds for site 115, and is eventually <br />pumped back into the mine for underground dust suppression. Additional overflow piping was added, so the <br />treatments ponds cannot overflow. Overflow water would be directed back into the mine via a former pump well. <br />Historically, when pumping mine water from the Fish Creek Borehole (mine discharge site 115) the flow <br />becomes a contributor to sulfate levels in Fish Creek. When pumping mine water from the EMD Dewatering <br />Well (mine discharge site 109) the flow becomes a contributor to sulfate levels in Foidel Creek. Fish Creek and <br />Foidel Creek, in turn, contribute to [he sulfate levels in Trout Creek. Trout Creek currently has a secondary <br />drinking water standazd limiting sulfate concentrations above 250 mg/I. The 2006 Water Year data for mine <br />water dischazge site 115 is presented on Table 53. Table 53a provides historical water quality data. Figures 110 <br />and 111 present graphical data for this site. <br />3.7 CDPS Discharge Sites <br />Under State of Colorado Department of Public Health and Environment (CDPHE), Colorado Discharge Permit <br />System (CDPS) permit No.'s CO-0027154, CO-0036684, and CO-0042161, eleven discharge points are <br />monitored throughout the yeaz. Note that CDPS has been referred to as the National Pollutant Discharge <br />Elimination System (NPDES) in previous AHRs. Monitoring results (CDPHE Colorado Discharge Monitoring <br />Reports, or DMRs) are copied to DRMS in accordance with CDPS requirements. Tables 54 through 60 provide <br />2006 and historical data summaries for those CDPS outfall points (other than mine dewaering site 115, which <br />did not discharge during the year). Figures 112 through 115 provide graphical representations of the 2006 flow <br />rate and field conductivity data for Pond D at the Foidel Creek Mine and for Pond E at the Fish Creek Tipple. <br />Figure 116 depicts period of record total recoverable iron data for Pond E. Pond F data is provided in Table 60. <br />12 <br />