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<br />Memo to File C-81-019 <br />- 2 - <br /> <br />July 6, 1993 <br />(1) Rule 4.05.2(1) is designed to prevent surface drainage from <br />disturbed areas from leaving the permit area without first passing <br />through a sedimentation pond, a series of ponds, or a treatment <br />facility. Rule 4.05.5(1)(a) is designed to prevent additional <br />contributions of sediment to streamflow or to runoff outside the <br />permit area. Rule 4.05.5(1)(c) is designed to prevent excessive <br />erosion and thereby provide protection for topsoil, vegetation, <br />fish and wildlife, and the hydrologic balance. Rule 4.05.5(2)(c) <br />is designed to prevent the sedimentation storage capacity of <br />practices in, and downstream from, disturbed areas from not <br />reflecting the degree to which successful mining and reclamation <br />techniques are applied to reduce erosion and control sediment. <br />Rule 4.05.5(2)(c) is also designed to prevent sediment control <br />measures from consisting of the utilization of improper mining and <br />reclamation methods and sediment control practices, singly or in <br />combination. To accomplish both of these measures, Rule <br />4.05.5(2)(c) lists, as one way, retaining sediment within disturbed <br />areas. <br />It is apparent from staff comments, testimony and photographs that <br />disturbed area surface drainage had left the Colowyo Mine permit <br />area without being passed through a proper <br />facility. It is apparent that the runoff <br />topsoil areas contributed to the breach in <br />Ditch, and as a result caused erosion that <br />areas below both the topsoil stockpile are <br />Ditch. It is also apparent that this erns <br />undisturbed areas caused additional contri <br />runoff outside the permit area. As such, <br />events which Rules 4.05.2(1), 4.05.5(1)(a) <br />designed to prevent occurred. <br />sediment control <br />from the stockpiled <br />the South Collection <br />impacted undisturbed <br />a and the Collection <br />ive flow over these <br />butions of sediment to <br />it is apparent that <br />. and 4.05.5(1)(c) were <br />4lhile it is apparent that the South Collection Ditch is designed to <br />accommodate high hypothetical flows, it is also apparent that <br />installation of this ditch by itself is not an appropriate sediment <br />control measure, given the realities of the climatic environment of <br />the Colowyo Mine site (heavy snowfall that blocks the ditch) which <br />designs for the ditch apparently do not currently reflect. Rule <br />4.05.5(2)(c) is designed specifically to prevent the utilization of <br />improper sediment control practices, either singly or in <br />combination. As such, it is apparent that by designing this ditch <br />without reflecting actual environmental conditions, and <br />subsequently constructing it apparently while the Division and the <br />operator have yet to resolve issues regarding its design, it can be <br />construed that installation of this ditch appears to be an improper <br />sediment control practice. <br />