GENERAL39215 - Laserfiche WebLink

Home Browse Search

2000, inflows were entirely consumed by dust control operations, but beginning in May 2002, discharge via CDPS Outfall 002 was resumed. For the purposes of projecting the effect mine discharge will have on East Salt Creek, PHC projections in Appendix N have assumed a conservative maximum mine flow rate of 100 gpm, or 0.22 CFS. The quantity of inflows which have been observed to date and are projected upon resumption of mining in future permit terms are considered to be insignificant with respect to effects on flow in the ephemeral surface drainages, or with respect to recharge of the coal seam. Based on information provided in the permit application, ground water intercepted by the mine does not appear to be in communication with any aquifers being put to beneficial use, and there are no registered wells within two miles of the permit boundary. The quality of water discharged from the mine is similar or higher quality than water in East Salt Creek at the confluence with McClane Creek, and any discharge is required to meet NPDES discharge standards. For these reasons, no detrimental impact to ground water resources or to surface water quality downstream of the permit area is expected. Original ground water flow patterns in the mined area will ultimately be reestablished after the mine is sealed and the abandoned workings slowly fill with water. An alluvial aquifer has been identified along East Salt Creek. Monitoring wells established in the alluvium indicate that alluvial water levels fluctuate seasonally in response to flow in East Salt Creek. Data collected by the applicant from the Salt Creek alluvial aquifer indicate acarbonate- sulfate type water, similar to the characteristics of the surface water in the system as would be expected. No effects to alluvial ground water quality or quantity are anticipated. Surface Water Effects McClane Canyon is an ephemeral drainage which is normally dry. Flows that do occur are in response to snowmelt or intense rainstorms, and are usually of short duration. McClane Canyon drainage is tributary to East Salt Creek, which is an intermittent tributary of the Colorado River. Water quality is typical of arid climate, ephemeral and intermittent systems located in marine deposited sedimentary land forms. Dissolved constituents often reach very high levels following dry periods and during the winter, when stream flows are made up almost entirely of recharge from ground water and from stagnant or semi-stagnant pools. Suspended solids levels are high during spring runoff and following high intensity rainstorms, due to sparse vegetation and erodible soils. Due to the limited areal extent of surface disturbance, existence of effective sediment control measures, and small quantity and acceptable quality of projected minewater dischazge, operations at McClane Canyon have had little effect on tfie quality of water in McClane Canyon drainage or East Salt Creek, and no significant effects aze expected. A full suite analysis of mine discharge water presented in Table 6 of the 2002 AHR shows a total dissolved solids (TDS) value of 1810 mg/I, compared to TDS values of 3000 to 4000 mg/I documented for East Salt Creek, at monitoring sites SW-1 and SW-8, in Table 4 of the AHR. Following the conclusion of mining, all culverts and diversions will be removed, and a network of ephemeral drainages in geomorphic balance with adjacent areas will be reconstructed on the disturbed area. Following successful vegetation establishment it is expected that surface water hydrologic characteristics of the reclaimed area will approximate pre-mining conditions. 18