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After the cessation of mining operations, mine water would no longer be pumped <br />from the underground workings. As a result, the mine workings would <br />eventually fill with water, and the natural flow pattern would be restored. <br />Ground water passing through the abandoned workings would eventually discharge <br />to the glacial/alluvial aquifer. Water passing through the mine workings <br />would be expected to have a degraded water quality. Water found in adjacent <br />old mine workings is degraded (TDS, 10,509 mg/1, and SAR, 27). If water of <br />this quality discharged to the stream/alluvial aquifer system at the same rate <br />as maximum ground water inflow to the mine workings, the resulting water <br />quality in the stream under low flow conditions would be a TDS concentration <br />of 698 mg/1, and an SAR of 4. Water of this quality has a moderate salinity <br />hazard and a low sodium hazard. It is suitable for irrigation, but slightly <br />higher application rates might be necessary. <br />Other possible effects would not be expected to be significant. Increased <br />runoff and erosion from the surface disturbances associated with the mine <br />would be routed to a sediment pond. Water released from the pond would have <br />low sediment concentrations and in some instances might be erosive. In this <br />case, however, surface flows are infrequent and the amount of water to be <br />released on a continuous basis is small (less than 0.17 cfs) and should not <br />cause significant downstream erosion. The pond contains 1.24 acre-ft. of dead <br />storage, but this would normally be filled with water from the underground <br />workings so the pond would not decrease surface flow from the site. <br />The applicant has proposed an extensive surface water monitoring plan in <br />Volume 8 of the application (Table 10, Kimball, et. al., 1982). The plan, as <br />modified in Section VII Alluvial Valley Floors of this document, will be <br />adequate with the addition of Stipulation No. 6, contained in Section VI - <br />Ground Water of this document. <br />Cumulative Hvdroloatc Impact <br />The Quinn Coal Tomahawk mine is located in the general area of the Red Canyon <br />Mine, approximately two miles to the west. The Tomahawk mine is currently <br />permitted as a surface mining operation. Life-of-mine operations would <br />include underground mining activities. <br />The current disturbances at the Tomahawk Mine are located primarily within the <br />Sand Creek watershed. Sand Creek is a tributary of Dirty George Creek which <br />joins Ward Creek to form Tongue Creek. Since the Red Canyon Mines are also <br />located within the Ward Creek drainage, surface water effects of the two mines <br />may be cumulative. Surface water in the Ward Creek drainage is extensively <br />used for irrigation. <br />-32- <br />