2022-09-29_PERMIT FILE - C1980007 (2)

Home Browse Search

West Elk Mine Fork drainage is less than one acre-foot. The losses that do occur (as a consequence of infiltration into surface cracks) will eventually be discharged to the North Fork as either springs/seeps or shallow groundwater return flow. MCC recognizes that this may affect the "timing" of discharges into the North Fork, but the key point is that water will be returned to the river. Also, as described later in this section, given the large fault inflows in 1996 and early 1997, MCC has been a net exporter of water to the river. 2. Springs -As discussed at length in Section 2.05.6 (3) (b) (iii & viii) Springs/Seeps, there are no springs in the Apache Rocks and Box Canyon permit revision areas which are within the fracture zone above the B Seam or the combined caved/fractured zone above the B and E Seams. As such, no spring flow is expected to be lost to the mine workings. Surface cracks could disrupt some of the colluvial springs, but this would ultimately result in the downgradient displacement of the flows, and there would be no loss to the river. 3. Groundwater - There is extensive discussion in Section 2.05.6(3)(b)(iii & viii), Groundwater Quantity Effects, on groundwater impacts including fault system inflows and underground storage of water. There are no "aquifers" in the current permit area. Most of the groundwater resulting from primary porosity occurs in small, discontinuous "lenses." Fractures and faults within the stratigraphic column have provided secondary porosity, which contributes the majority of the groundwater into the mine. Most of the groundwater intercepted in the mine is collected, pumped to the surface, treated, if necessary, and released to the North Fork. Until 1996, this treated and released groundwater represented approximately 20 acre-feet of "new" water in the North Fork. This is based on the observation that most of the B Seam dips under the North Fork in a downgradient direction from West Elk Mine. Therefore, discharges to the North Fork of this "developed water" constitute new water in the North Fork system. In 1996 and 1997, MCC encountered inflows up to 2,500 gpm and 8,000 gpm, respectively, which exceeded the hydraulic capacity of their treatment facilities. This necessitated the subsurface storage of water in previously mined areas or sealed sumps (see discussion in Section 2.05.6(3)(b)(iii & viii), Groundwater Quantity Effects). Isotope analysis of tritium and carbon-14 (Mayo 1998) has been used to determine the groundwater "age" (or mean residence time) of the fault water to be at least 50 years (per 3H analysis) and between 5,000 and 20,000 years (per 14C analysis). This fact, coupled with no known claim of reliance or water rights on these fault inflows, suggests that this water has not been appropriated. MCC has appropriated the fault water and storage rights to these inflows. Water Rd ghts Aspects of?Vorth Fork Diversions, FamIt Inflows and Sealed Panels Sumps In light of the large fault inflows experienced by MCC in 1996 and 1997, in conjunction with MCC's utilization of sealed panels sumps, the following text has been prepared to summarize the resulting water In addition, MCC'S a t0= a___ _____.. rattern of diversions and return flows to the North oric are described. • 2.05-213 Revised Jane 2005 PRIO; Rev. March 2006; Rev. April 2006 PR 10; A1ay 2006 PRIO; Sep. 2007 PR12; Feb 2008 PR12