2013-04-18_PERMIT FILE - C2009087A

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RULE 2 - PERMITS Potentially Affected Surface Water Drainages and Drainage Characteristics Over the life of the mine, potentially affected surface eater drainages include the Yampa River, as the primary receiving dralllage: Grassy ('reek. a perennial tributary of the Yampa River, and its tributaries: and western tributaries of fish Creek, a perennial tributary to 1 rOUt Creek. The following small perennial and intermittent drainages Rithill this area were idelltllled 1roin streams present in the US(;S National l lydrograph} Dataset (NHI)) «ithin one mile ol' the PSCNI permit area. The} are listed bolo« in sequence front NNest to east. and north to south. Llnnanlecl ephemeral tributaries are not specifically identified. unless identified other\\isc. all listed streams are intermittent. • Grassy Creek ( perennial below Little Glassy Creek COnflUCllce at site SSG2. intermittent above at site SSGI ) • Unnamed tributary #1 to Grassy Creek. joining the main stream in T6N:R87W, Section 21 • SCotchrnan s Gulch • Annand Dray • Unnamed tributary 92 to Grassy Creek, joining the main stream in T5N:R87W, Section 21 • Unnamed tributary to Scotchman's Gulch, west of Grassy Creek and joining Scotchnlan's Gulch main stream in T6N:R87W, Section 28 • Little Grassy Creek (perennial below Pond 002) • Unnamed tributary #1 to Little Grassy Creek. joining the main stream in T6N:R87W, Section 34 • Unnamed tributary 42 to little Grassy Creek. joining the main stream in T5N:R87W, Section 3 • Unnamed tributary #3 to Little Grassy Creek. joining the main stream in T5N:R87V1', Section 3 • Unnamed tributary #1 to Fish Creek, joining the main stream in T5N:R87W, Section 24 • Unnamed tributary 92 to Fish Creek, joining the main stream in T5N:R86W, Section 19 • Cow Camp Creek The principal proposed surface disturbance for mine portals, facilities, stockpiles, and roads occurs in the Little Grassy Creek drainage. For the permit terns, in which no subsidence is anticipated, the proposed underground mining lies under both Grassy Creek and Little Grassy Creek, portions of their respective drainages, and a portion of the drainage of the unnamed tributary to Scotchman's Gulch. While a portion of its watershed will be undermined, the unnamed Scotchman's Gulch tributary stream reach itself is not proposed to be undermined in the permit term. Given the areal extent of the proposed mining- related surface disturbance and undermining, it is proposed that adjacent area for surface water hydrology for the permit term include the watershed of Grassy Creek (a perennial stream draining to the Yampa River) and its tributaries, upstream of a point just below its confluence with Scotchman's Gulch, an intermittent tributary. The definition of the adjacent area corresponds to monitoring station YSG5, located on Grassy Creek downstream of the mouth of Scotchman's Gulch, and encompasses all mining activities, both surface and underground, for the permit term. With the inclusion of inflows from the Scotchman's Gulch tributary, it is likely to encompass the effects of mining beyond the permit term, depending on actual coal production rates. Streamflow for individual monitoring points within this area is discussed below. Midterm Review 2.04 -63 Revision 04/2013