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<br />Due to the aforementioned concerns and the Division's requirements <br />resulting from those concerns, the following stipulation is placed <br />on the Division's decision to approve the permit renewal: <br />Stipulation No. 32 <br />Within 60 days of issuance of the renewed Edna Mine permit, <br />the permittee shall submit a complete technical revision <br />application to the Division. The revision shall update the <br />probable hydrologic consequences analysis in the permit to <br />incorporate results of past water monitoring in the permit <br />area and to evaluate those results in terms of impacts to the <br />hydrologic balance. The revision shall also amend the <br />hydrologic monitoring plan for the mine to ensure that <br />adequate data is obtained to continue to meet the <br />requirements of Rule 2.05.6(3). The modifications to the <br />monitoring plan shall, at a minimum, address collection of <br />adequate flow date, total dissolved solids and specific <br />conductivity data from surface and alluvial well sampling <br />locations along Trout Creek. <br />Ground Water Effects <br />Consolidated and unconsolidated aquifer systems have been <br />identified at and near the Edna Mine site. These aquifers may <br />potentially be affected by surface coal mining operations at this <br />site. <br />The lower-most consolidated unit which is considered to be an <br />aquifer in this area is the Trout Creek Sandstone. The Trout Creek <br />Sandstone underlies the Wadge Coal by 150 to 225 feet. The <br />confining interburden between the Trout Creek Sandstone and Wadge <br />Coal is composed of interbedded shale, siltstone, lenticular <br />sandstone and coal. The Trout Creek Sandstone does not outcrop <br />within disturbed portions of the Edna Mine permit area. <br />Furthermore, due to the confining nature and thickness of the <br />material which separates the Wadge Coal and Trout Creek Sandstone, <br />it is not thought that any disturbance to or disruption of this <br />unit will occur during or after mining. <br />The Wadge Coal and overburden are marginally useful as a source of <br />water at the Edna Mine site. The hydraulic characteristics of <br />these combined units preclude their development as a ground water <br />resource. Down-gradient within Twentymile Basin, however, the <br />Wadge Coal and overburden is locally used as a water source. <br />Furthermore, it is hypothesized by the operator that this unit may <br />contribute base flow to overlying alluvial systems within the <br />basin. Therefore, these units are considered hydrologically <br />important at the Edna Mine site. <br />Mining operations will remove the Wadge Coal and overburden. This <br />removal will, for a short period of time, interrupt the recharge of <br />water from the up-gradient outcrop areas to the down-gradient <br />portions of the aquifer within the basin. As mining pits are <br />_pq_ <br />