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iiiiiiiiiiiiiiuiii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1713 Sherman St., Room ?15 <br />Denver, Colorado 80?03 <br />Phone: (303) 866-3567 <br />FAX (3031832-8106 <br />DATE: December 5, 2001 <br />TO: Kate Pickford <br />FROM: Allen Sorenson ~~ <br />RE: Gravel Mining in Proximity to Railroad Tracks, 9B Enterprises, <br />Deakins Pit, File .No. M-2001-060 <br />GEOLOGY <br />R E C L A M A T I O N <br />MINING•SAFETY <br />DIVISION OF <br />MINERALS <br />Bit l Owens <br />Governor <br />ereg E walcne~ <br />Eneculive Dheaor <br />Michael R. Lung <br />~Drv~s~on Director <br />Based on commitments included in [he letter and attachm=nt submitted by 3B Enterprises dated • <br />November l9; 2001, the Division can permit the gravel pii excavatiua at the Deakins Pit fo be ' <br />conducted to within r10 fee[ of the toe of the railroad embankment. The 40-foot setback is to be <br />measured from the toe of the railroad embankment to the crest of the gravel pit inslope. The rationale <br />for the Division's determination that 40 feet is a safe setback resC; primarily ou the Ope~ahar's <br />commitment to maintain the pit slope at an angle no steeper than 3H:1 V, It is impr.,rt.,:.rtt :hat the' <br />i~peratur be notified that it is the Division's position that any mining excavation within 4t) fart of the <br />toe of the railroad embankment will be considered a permit violation and that any l;il s.lopcs within 200 <br />feet of the toe of the railroad embankment found to be steeper than 3H:1`d will also he considered a . <br />permit violation. The requirement to maintain 3H:1 V slopes with 200 feet of the railroad embankment <br />is applicable both during the conduct of operations at the pit and at the ttme of reclamation. The <br />Operator may gain approval of less restrictive setbacks and pit slope requirements by securing an <br />agreement with the railroad in accordance with §34-32.5-115(4)(e), C.R.S. or by submitting <br />quantitative slope stability analyses demonstrating that less restrictive criteria will be protective of the <br />railroad. <br />As a general rule, the Division considers the stability of 3H:1 V cut slopes in a sand and gravel deposit <br />to be axiomatic. The Division will also typically approve setback distances from structures to near <br />vertical gravel pit highwalls that are at least two-times the maximum pit depth, without requiring any <br />quantitative slope stability analysis. There are site specific exceptions to these guidelines, but none <br />appear applicable to the slopes under consideration at the Deakins Pit. <br />ec: Carl Mount, DMG (vin e/ecrronic transmission) <br />c U1yDocumcnis\Deal:ins Pit Slopes.duc <br />