Laserfiche WebLink
A+4.' <br />-46- <br />f i~ ~~~~~':~~ <br />G. Summarv and Findings <br />This cumulative hydrologic assessment has considered the short-term and <br />long-term effects of mining to the surface water and ground water hydrologic <br />systems. The surface water assessment is based upon a modification of <br />previous studies. <br />Ground Water <br />The Division finds that the Eagle No. 5 and No. 9 Mine, with the proposed <br />stipulations, is designed to minimize ground water impacts, and has been <br />designed to prevent material damage to ground water quality and quantity <br />outside the permit area. <br />Surface Water <br />The cumulative assessment indicates that mining would increase the total <br />dissolved solids concentrations on the Yampa River at Maybell. Under average <br />flow conditions, the projected concentrations for both short-term (during <br />mining) and long-term (after mining) effects remain below 600 mg/1. Water of <br />this quality would remain suitable for both irrigation and domestic purposes <br />(EPA, 1976). <br />Under low flow conditions, the short-term and long-term effects of mining <br />would be more severe. During the summer months, the dissolved solids <br />concentrations may exceed irrigation water standards (page 208, EPA, 1976), <br />and depending on its sulfate concentrations, may not be suitable for domestic <br />purposes. However, a comparison of the projections from this CHIS with those <br />of the Kaman Tempo CHIS (Bishop et al., 1982, Table 8) indicate that the <br />dissolved solids concentrations would be somewhat reduced because of the <br />discharge of relatively good quality water (compared to spoil water quality} <br />from the underground workings both during and after mining. Therefore, the <br />water quality deterioration from the proposed Eagle No. 5 and No. 9 operations <br />is anticipated to be a minor component of the overall cumulative impact of <br />mining in the Yampa River Basin (assuming the Division's worst-case <br />assumptions are correct). <br />The cumulative hydrologic assessment indicates that, with the proposed <br />hydrologic stipulations, the proposed mining operations for the Eagle No. 5 <br />and No. 9 Mine have been designed to prevent material damage to the hydrologic <br />balance outside the permit area. <br />REFERENCES <br />Bishop, N., Kelly, R., Kimball, D., and Quinn, G., 1982, Cumulative <br />Hydrologic Assessment: Effects of Coal Nining on the Yampa River Basin, <br />Moffat and Routt Counties, Colorado: Kaman Tempo report submitted to <br />Office of Surface Mining and Colorado Mined land Reclamation Division, <br />83 p. <br />