2013-03-14_REPORT - C1982056 (3)

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3.4 Spoil Spring Monitoring Generally, groundwater migrates along bedding planes, faults, joints, or fracture zones. Given adequate head pressure, if these zones of water migration intercept the surface, a spring or seep results. The TC spoil spring monitoring program was initiated in 1986 and is conducted annually. In accordance with the approved plan, the annual mine wide survey is conducted during May, with springs measured for flow and field parameters. If a spring is discharging at or above 35 gallons per minute, it is monitored for the next year in accordance with the monitoring plan. A few samples are typically collected each year even when the 35 GPM mark is not met. Two spoil spring sites, 7 and the 303 series (303 -1 through 303 -3), require monitoring under Exhibit 14 -10. In addition to the spoil spring monitoring requirements, Spring 7 is monitored quarterly for field parameters, and sampled on a semi- annual basis for water quality (if flowing). In 2012, site 7 did not flow. The 303 Spring series is monitored/sampled semi- annually for field parameters and water quality. Tables 50 through 52 provide summaries of the 2012 Water Year data collected at each 303 series (303 -1 through 303 -3) spoils spring. Table 50a and 51a provide a period of record statistical summary of collected data at sites 303 -1, and 303 -2, respectively. 3.5 Natural Spring Monitoring Two natural springs, SW1 and SW2, located over previously mined areas in the Southwest Mining District required semiannual monitoring during 2012. Prior to mining, SW -1 typically flowed throughout the year, while SW2 flows were sporadic. In recent years flows at SW -1 have been minor, and in the case of SW -2, non- existent. No flow was observed in SW -1 in May or September of 2012. In May 2012, a spring and seep survey was also conducted in the northern mining district to identify potential discharges to Fish Creek. No new or significant springs were identified in 2012. The northern mining district is located within the Twentymile Park Syncline. The predominant lithologic unit nearest the surface and occupying most of the basin is the Lewis Shale, which can be upwards of 700 feet thick. The lack of significant bedding planes, faulting, or fracture zones in this area may account for the lack of springs in the central portion of this basin. The few seeps observed in the basin may be the result from surface weathering of the Lewis Shale, which may allow some accumulation of water beneath overburden. This may result in a short period of seepage immediately following spring runoff. 3.6 CDPS Discharge Sites Under State of Colorado Department of Public Health and Environment (CDPHE), Colorado Discharge Permit System (CDPS) permit No.'s CO- 0027154, CO- 0036684, and CO- 0042161, eleven discharge points are monitored throughout the year. Note that CDPS has also been referred to as the National Pollutant Discharge Elimination System (NPDES) in previous AHRs. Monitoring results ( CDPHE Colorado Discharge Monitoring Reports, or DMRs) are copied to DRMS in accordance with CDPS requirements. Tables 54 through 60 provide 2012 and historical data summaries for those CDPS outfall points. Figures 110 through 113 provide graphical 13