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Nine spoil springs have been identified, eight of which aze monitored by Seneca <br />Coal Company. In addition, Seneca Coal Company has historically monitored <br />thirteen spoil wells as part of the approved monitoring plan. <br />Water from the spoils exhibit elevated concentrations of sulfate, manganese, and <br />magnesium. TDS concentrations in water from spoil wells have generally risen <br />during the period of monitoring but seem to level out at about 4000 mg/1. Several <br />exceptions are S25-S, which has reached concentrations as high as 5700 mgll, S26-S <br />which reached levels as high as 4300 mg/1 but has dropped off to around 3500 mg/l, <br />and S27-S which has climbed gradually to about 3300 mg/1 TDS. Spoil springs <br />show the same range of concentrations as the wells. <br />In 1977, the Water Resources Division of the United States Geological Survey <br />(USGS) began a lysimeter study at the Seneca II Mine to determine spoil aquifer <br />dischazge quality, and how that quality changes over time. Stipulation No. 23 in the <br />original permit required the applicant to submit the USGS report to the Division <br />upon its completion. In 1994, the USGS published Water-Resources Investigations <br />Report 92-4187 titled, Hydrolagy and Geochemis'uv of a Surface Coal Mine in <br />Northwestern Colorado. The report describes the sources of hydrologic rechazge to <br />and from reclaimed spoil, the relative contributions of recharge to the reclaimed <br />spoil aquifer from identified source waters, and the water movement and <br />geochemical reactions that control water quality in reclaimed spoil. <br />Native Springs <br />Four native springs exist within the permit azea: Springs #1, 2, 3 and 5. Spring #4 is <br />outside the permit azea and is no longer sampled. Under this renewal application, <br />Seneca proposes to discontinue-monitoring of all natural springs at the Seneca fi <br />Mine. Springs #1 and #2 exist in a pre-SMCRA azea and springs #3 and #5 aze <br />poorly defined seeps in a seasonally mazshy azea. <br />Surface Water <br />The applicant will conduct monitoring of surface water in a manner approved by the <br />Division. The monitoring plan was submitted under 2.05.6(3)(b)(iv) and can be <br />found in Table 1 of this document. Surface water hydrology information can be <br />found in Volumes 4, 5, and 6, Tab 7 of the permit application, and in the Annual <br />Hydrology Reports submitted by Seneca Coal Company. <br />The Seneca II Mine is located between the drainage basins of Grassy Creek and Fish <br />Creek. Both of these aze sub-basins of the upper Yampa River basin in northwestern <br />Colorado. <br />20 <br />