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ENVIRONMENT, INC. <br />APRIL 26, 201 O <br />PAGE 2 <br />overburden piles surrounding the active mining area on the <br />east side of Area 5 according to the description. <br />Exhibit D - Mining Plan (Rule 6.4.4) <br />It is the understanding of the Division that this will be a "dry mining- operation which will employ no clay <br />liners or slurry walls to isolate itself from the aquifer, therefore the cells will need to be continuously <br />pumped until they are reclaimed. <br />Yes, they will need to be pumped until reclamation is com <br />plete. Rebuilding the slopes with compacted overburden and <br />other materials generated at the mine will seal the area as <br />mining progresses. Under the Office of the State Engineer <br />directive these slopes will become a compacted liner that will <br />seal the excavated area. This should reduce the amount of <br />water that needs to be pumped daily during mining. <br />Depth of mining appears to be approximately 35' b.g.s. based on map contours. Is this the anticipated <br />depth to bedrock? What is the underlying strata- shale? Disturbance (unreclaimed area) will be limited to a <br />maximum of 100 acres. Please confirm if this is correct. <br />The average depth from our test holes show the depth to bed- <br />rock is 32 feet but the depth to the water table is 6 feet <br />average. The underlying bedrock is a blue shale that is,part <br />of the Laramie Foxhills formation found in this. area. The <br />changes to the bonding requirements do not change the maximum <br />disturbed area and it will stay at 100 acres for now.. <br />Also please note that temporary cessation is limited -to a maximum of two 5 year intervals, and that site <br />maintenance activities (weed control, etc) need to continue on-site even during periods of temporary <br />cessation. <br />Thank you for reminding us of the temporary cessation times <br />and requirements. We will be sure to incorporate weed control <br />on the old plant site as part of the continuing agricultural <br />activities taking place on the permit area. We do not believe <br />it is necessary to post a.large bond until just before we come <br />out of temporary cessation <br />Please specify what setbacks will be maintained from the Last.Chance Ditch, Sidehill Ditch and the gas/oil <br />well access roads, and confirm that these have been•accurately reflected on the site maps. <br />The setbacks as shown on the maps conform with our agreements <br />with the ditch owners and oil and gas facility owners. The <br />scale of the maps make it hard to measure the distances, so <br />for your edification, the minimum setbacks for the ditches are <br />35 feet each side from the centerline of the ditch (total <br />701), occasionally it is wider because-there is a gasline <br />lying along the ditch that increases the setback. Around each <br />gas/oil well we will maintain an 80--foot radius (? acre) <br />during mining but during reclamation it will be rebuilt to a <br />150-foot radius. For the'well gas/oil 2" supply lines we used <br />15 feet either side of the lines, physical location (total <br />301). For the Sinclair line the ROW is 25 feet from the <br />centerline (total 501) each side. Mining is allowed to begin <br />on the ROW line but in actuality our setbacks vary from 50 to <br />100 feet wide depending on other structures that run parallel <br />.to or near the lines.