2010-05-07_PERMIT FILE - C2009087A (9)

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RULE 2 - PERMITS SSLG5 was originally established for the Seneca II Mine, and is located on Little Grassy Creek just • west of the Spring Creek Stock Pond, in Section 3, T5N R87W. It represents conditions on Little Grassy Creek just upstream of the existing Seneca II Mine and the proposed PSCM surface disturbance. Little Grassy Creek is intermittent at this location, going dry in the summer, but producing spring peak flows as high as 2.5 cfs, receding to zero or near -zero by late May or early June. Pond 002, also known as the Wadge Impoundment and discussed further below, is a permanent impoundment lying along the reclaimed Seneca II highwall, roughly one mile north of the proposed PSCM portals. Its outflow is monitored at station NPDES2, located in Section 34, T5N R87W. Due to inflow from the Seneca II spoils, which have enhanced recharge relative to natural terrain, discharge at NPDES2 is perennial, and Little Grassy Creek is perennial downstream of this location. Spring peak flows occur in April or May, and ranged from 3.0 to 4.2 cfs. Late summer low flows ranged from 0.06 to 0.4 cfs. Spoil Springs In addition to streamflow monitoring, five spoil springs within the Little Grassy Creek drainage have been monitored biannually since at least 1993 (some from 1985), to assess the impacts of the Seneca II Mine. Spoil spring locations are shown on Map 2.04.7 -M1, Hydrology, and hydrographs are shown on Figure 2.04.7 -F15. Recent spoil spring monitoring data (2005 through 2008) is discussed below, in order from south to north (upstream to downstream on Little Grassy Creek). Springs SSSPG4 and SSSPG3 are both located in Section 2, T5N R87W, on an unnamed tributary • to Little Grassy Creek, upstream of the Spring Creek Stock Pond. SSSPG4 flows ranged from 15 gpm to 108 gpm. SSSPG3 produced consistently lower flows than SSSPG4, with May peaks of up to 35 gpm, and a September low of 13 gpm. Spring SSSPG5, located in Section 3, T5N R87W is the discharge from the Pecoco Pond, and produced flows ranging from 54 gpm to 290 gpm during the reporting period. Spring SSSPG10 (consisting of a series of seeps), in Section 2 and northeast of Pecoco Pond, produced 10 to 16 gpm. Spring SSSPG6 is located in Section 35, T5N R87W, and contributes 0.4 to 5 gpm to an unnamed ephemeral tributary to Little Grassy Creek. Springs and Seeps SCCC performed a spring and seep inventory within and adjacent to the PSCM permit boundary during August of 2009. Maps and aerial phototgraphs were reviewed to determine potential locations of springs and seeps. Historical information related to the occurrence of springs and seeps within the Seneca II permit area was also reviewed, and it was determined that the only springs or seeps that exist within the PSCM permit area are limited to spoil springs that are discussed in the previous section. Based on this assessment, a search and survey of springs and seeps within a one - mile buffer around the PSCM permit boundary was conducted during August 20 and 25, 2008. Drainages emanating from the Tow Creek and Fish Creek Anticlines that are largely ephemeral (some may be intermittent) were emphasized, as well as water - righted springs based on data • obtained from the Colorado Division of Water Resources CDSS (Colorado Decision Support Systems) website. Two known water - righted springs, Gerte Spring No. 1, and Livestock Pond No. 2, were not surveyed due to lack of access permission from the local rancher. PSCM Permit App. 2.04 -67 Revision 12/17/09