2017-05-08_REPORT - C1982056 (3)

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The southwest area of TC (Eckman Park area), has been reclaimed and has been released from bond. In addition, the Iforner surface mine area referred to s Area 1 was released from bond in January 2002. As a result, the Colorado Department of Public Health and Environment (CDPHE) subsequently approved eliminating Pohl}ds A (Eckman Park) and H (Area 1) from our ongoing NPDES monitoring program in 2002. Since mid -1987, hydrologic monitoring and reporting has primarily been conducted by TC personnel. In May of 1995, a private finn (Miller Water Monitoring Service) was contracted to assist with hydrologic monitoring at the TC sites, and continues to assist in monitoring to date. Prior to June 1986, water quality analyses were performed by the on-site CYCC laboratory. From 1987 to 2000, water quality analyses were primarily performed by ACZ Laboratories (fonnerly Bookcliffs) of Steamboat Springs, Colorado. From 2001 through 2005, water quality analysis was primarily been performed by SGS North America laboratory of Denver, Colorado. Since mid - 2005, analyses are again primarily performed by ACZ Laboratory of Steamboat Springs, Colorado. Whole Effluent Toxicity (WET) testing was historically conducted by SGS, but has been conducted by Aqua-Tox of Wheatridge Colorado, since the summer of 2009. Note that in 2003, DRMS approved TR03-42 (See Pen -nit Exhibits 14-5, 14-6, and 14-10), and PR 03-06 (See Pen -nit Exhibits 14-7 through 14-9), which eliminated several surface, alluvial, and bedrock well monitoring sites, and reduced the monitoring frequency of other sites, while adding additional monitoring requirements to existing surface site 305 (located downstream at the time of Twentymile Park subsidence ). Data from tenninated sites can be found in previous AHRs. Three former US Geologic Survey (USGS) surface water sites (USGS 09243700, USGS 09243800 and USGS 09243900) were monitored for flow by the USGS through the 2001 water year. Prior to the 1989 Water Year, the USGS had collected and analyzed water quality samples from these sites. From the 1989 water year to date, TC has collected water quality samples from these sites for laboratory analysis. Beginning with the 2002 water year, TC took over monitoring of these three sites (referred to as sites 700, 800, and 900, respectively) from the USGS. In 2003, TR03-42 eliminated site 700 on Middle Creek. 3.0 2016 HYDROLOGIC MONITORING PROGRAM Specific monitoring site locations and their elevations are shown on Figure 2 (Map pouch at back of report). Required monitoring frequencies are listed in Pen -nit No. C-82-056, under Exhibit 14. 2016 data tables and figures for each site are referenced in the following discussions. Statistical summaries of the historical data base are provided after presentation of the 2016 data. 3.1 Bedrock Groundwater Monitoring H dIro eolo : TC's underground Wade inin operations are loca ed roughly 1600 feet beneath the surfa e of -y � �v g g g p g y �. Twentyrnile Park Basin. This is an enc osed synclinal ground water basin, rimmed by outcrops of mayor lithologic units. Ground water in the Twentymile Park Basin exists primarily under confined conditions within the bedrock units. All ground water aquifers in the general area, except the alluvial aquifers, are recharged by