2011-01-13_REVISION - C1980006 (9)

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is composed of interbedded siltstones and shales of the Coalmont formation with permeabilities ranging from 0.37 gpd/ft2 to 7.5 gpd/ft2. Monitoring is focused on the coal unit and immediate overburden and the alluvial deposits. The physical hydrologic characteristics of the coal unit suggest that it is at best a poor aquifer except where it is faulted, as reflected by permeabilities of 3.8 gpd/ft2 in a well distant from a fault zone and 16.5 gpd/ft2 in a well near a fault. These two wells suggest yields of less than ten gallons per minute and 20 gallons per minute, respectively. The aquifer quickly becomes confined east of the outcrop, which results in artesian heads on wells completed in this zone. Original recharge on the undisturbed 50-foot-wide outcrop within the permit area was calculated to be 4.75 acre-feet per year, and storage capacity of a 3,200-acre area was 240 acre feet. The only discharge of this aquifer in the permit area appears to be a spring located at the Old Sudduth Mine, which discharges less than one gpm. The maximum mine pit inflow was projected to occur during the mining of Pit 2, amounting to 126 gpm. That area was never mined. The quality of the groundwater in the coal seam has been variable, with some wells showing sodium bicarbonate water and others reflecting calcium bicarbonate/sulfate water. It is slightly alkaline, and total dissolved solids range from 183 to 1,166 mg/1, averaging approximately 500 mg/l. Dissolved manganese concentrations exceed the domestic standard regularly. This water is acceptable for stock and limited domestic use. Mining of the Sudduth coal probably dewatered the coal seam in the vicinity of the mine. The quality of water in the overburden and within the spoils has been within the range of baseline values for the bedrock groundwater presented in Table 6 of the PAP. The overburden physical hydrological characteristics were derived from two USGS wells (DH-3B and DH-4) within the general area. Permeabilities at these two wells ranged from 0.37 to 7.5 gpd/ft2. The two overburden wells (79-1 and 79-2) in the monitoring program were chosen simply because the water was observed in the overburden during drilling. A saline, sodic, sodium bicarbonate water is derived from this aquifer. TDS ranges from 796 mg/l to 1,708 mg/l, averaging 1,216 mg/1. Dissolved manganese concentrations exceed the domestic standards regularly. A review of water quality analyses conducted as part of the Division's approval of Bond Release Request SL-01 found that mining had not adversely affected groundwater quality. Upland terrace deposits are found sporadically throughout the permit area, where they have not been eroded. They can achieve thicknesses of up to 70 feet thick within the permit area. A perched aquifer in one of these deposits has produced a spring in Section 22, T9N, R78W, which has an average flow of less than two gpm. This spring is located outside the area of reclaimed mine disturbance. Alluvium is found in places along all of the draws draining the mine site, along the Canadian River, and along the Illinois River adjacent to the loadout. The alluvium within 17