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Runoff From Disturbed Areas <br />• Surface tlow from disturbed areas would carry higher sediment concentrations than natural runoff. However, Rule 4.05.2 requires that <br />all disturbed flow pass through a properly designed sediment control pond or an alternate treatment system approved as pan of a small <br />area exemption granted under Rule 4.05.2(3). Effluent from the ponds is required to meet NPDES limitations prior to discharge. <br />During operation, monitoring and inspection by the Division ensures that the sediment control system is maintained to function as <br />designed. At the close of operations, surface disturbances would be reclaimed and the sediment control system would be removed <br />following the ensuing liability period. As a result, [he increased sediment load carried by disturbed flows would not be expected to <br />reach receiving sveams. <br />Discharse of Mine Water from Underground Workin¢s '~.A P ""'' °- \ - - ~ ~~ , •' <br />t"- <br />i:. <br />CDMG performed a salinity analysis to determine the impact of mine water dischazges on the Nonh Fork of the Gunnison. This <br />assessment assumes concurtent maximum impact to the river when active mining is developed to its greatest extent throughout the <br />area and the valley experiences a low flow year. <br />Water quality data for water in the flooded workings is scarce. However, much of the data can be exvapolated from mine to mine. <br />Water quality samples have been taken at the old Somerset, Hawk's Nest and abandoned Oliver No. 2 Mines. Somerset recorded TDS <br />values ranging from 2,000 to 3,200 mg/I. CDMG staff recorded a TDS of 1,642 mg/I in the Hawk's Nest East Mine in 1987. TDS <br />concenvations ranged from 1,050 to 1,900 mg/I from the Oliver Mine. This seam is svatigraphically similar to seams being mined <br />at Somerset and Bowie No. 1. Inputs to [his analysis will be described from upsveam to downsveam, starting with the Hawk's Nest <br />Mine and ending with Bowie No. 1 Mine. <br />The Hawk's Nes[ Mine's permit has been forfeited and the bond revoked. Amine discharge of 200 gpm was projected for the <br />purposes of [his study. Water quality data reports showed a sample with a total dissolved solids (TDS) concenvation of 7,020 mg/L~ <br />However, this water was recycled through the Hawk's Nest coal wash plant, and therefore had a higher salinity than the mine inflow - <br />•: ~ water. Mine discharge water is expected to have a TDS of 2,500 to 3,000 mgA, and this quality is more representative of the wa[er~~~~z <br />quality which may enter the North Fork of the Gunnison River since the site is reclaimed. << - <br />hl <br />The West Elk Mine is the only operation in the valley dischazging mine water from the underground workings on a permanent basis. <br />Mine dischazge during the 1987 water year averaged 14.4 gpm but athree=month average was reported as high as 48.5 gpm. <br />Maximum mine dischazge from the West Elk Mine was estimated at 1,000 gpm (2.23cfs). Worst-case salinity was projected at 2,500 <br />mg/I TDS. These numbers will be evaluated following submittal of updated hydrologic analyses for the West Elk Mine due in April, <br />1997. <br />The portals of the old Somerset Mine were permanently sealed in 1986, and no mine flow discharge is predicted from [his portion <br />of the site. The Sanborn Creek and Sanbom Creek East Mines may involve mine water discharge of up to 425 gpm. The operator <br />has provided aworst-case projection of an additional 235 gpm which may reach the North Fork of the Gunnison River via the alluvial <br />system. This seems exvemely unlikely; however, the projection is used below [o derive aworst-case water quality prediction. Data <br />collected to date indicates that water dischazged from the Somerset and Sanbom Creek Mines will reach about 3,200 mg/1 TDS. <br />Bear Mines 1 and 2 were sealed in 1983. No mine inflow discharge was recorded at those mines since [hey opened in 1934. The <br />Bear No. 3 Mine, was historically dry, but an inflow of about 12-18 gpm has been encountered recently. As of February 1997, The <br />Bear No. 3 Mine is closed and in not dischazging. Any change to this condition will be assessed with a new cumulative impact <br />analysis. <br />The Blue Ribbon Mine portals were permanently sealed in 1985. Thus, no mine inflow dischazge is exvapolated from this site. <br />Activities at the Terror Creek Loadout are restricted to crushing, screening and loadout activities. Consequently, no discharge occurs <br />from [his site. <br />' l3 <br />