Laserfiche WebLink
Assessment)" is available for inspection at the offices of the Division. The assessment <br />was not revised for this renewal. The Division tinds that the operations proposed <br />under the application have been designed to prevent damage to the hydrologic balance <br />outside the proposed permit area. (2.07.6(2)(c)). <br />Probable Hydrologic Consequences <br />Groundwater <br />There are predominately three aquifers of interest in the Marr permit area: the Sudduth coal <br />aquifer, upland terrace deposits, and alluvial deposits. The underburden at the site is the <br />relatively impermeable Pierre shale, with a permeability of 0.15 gpd/ft2. The overburden <br />sequence is composed of interbedded siltstones and shales of the Coalmont formation with <br />permeabilities ranging from 0.37 gpd/ftz to 7.5 gpd/ftZ. Monitoring is focused on the coal <br />aquifer, alluvial deposits, and two wells that encountered water in the overburden. <br />The physical hydrological characteristics of the coal ayuifer suggest that it is a moderately <br />poor aquifer except where it is faulted, as reflected by permeabilities of 3.8 gpd/ftZ in a well <br />distant from a fault zone and 16.5 gpd/ft2 in a well near a fault. These two wells suggest <br />yields of less than ten (10) gallons per minute and twenty (20) gallons per minute, respectively. <br />The aquifer quickly becomes confined east of the outcrop, which results in artesian heads on <br />wells completed in this zone. <br />Original recharge on undisturbed fifty (50) foot wide outcrop within the permit area was <br />calculated to be 4.75 acre feet per year and storage capacity of a 3,200 acre area was 240 acre <br />feet. The only discharge of this aquifer in the permit area appears to be a spring located at <br />the Old Sudduth Mine, that discharges less than 1 gpm. The maximum mine pit inflow is <br />projected to occur during the mining of Pit 2 and would amount to 126 gpm. <br />The coal aquifer water quality is variable, with some wells showing a sodium bicarbonate <br />water and others reflecting a calcium bicarbonate/sulfate water. It is slightly alkaline and <br />total dissolved solids range from 183-1,166 mg/], averaging approximately 500 mg/1. Dissolved <br />manganese concentrations exceed the domestic standard regularly. This water is acceptable <br />for stock and limited domestic use. <br />Mining of the Sudduth coal aquifer will most likely dewater the coal seam in the vicinity of <br />the mine. The quality of water percolating through disturbed overburden is expected to be <br />poorer than water flowing through the undisturbed coal seam because of the leaching of <br />soluble salts. Kerr, if mining progresses to Pit 2, will mine through anon-adjudicated spring in <br />Section 15, T9N, R78W. This spring has a very low water quality due to high TDS <br />Marr Strip Mine, C-80-006 15 December 9, 1992 <br />