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C. Stream Channel Diversions - Rule 4.05.4 Minor realignments and changes in permanent stream channels profiles are permitted within reclaimed mined and excess spoil fill areas Maps 33, 33A, 41 and 41A. Pre-mining and post- mining alignments are similar. However, profiles deviate more markedly. The most significant example is Streeter Gulch. Streeter Gulch is an ephemeral drainage (PAP, page 2.04.7-27). It was (pre-mining) a steep-sided, 200-foot deep (near the mouth) incised draw (PAP, Map 11). Initial box cut material for mining south of the Gulch (Draw) (PAP, page 2.06-3) was placed near the mouth, first as an experimental practice and later recognized as excess spoil (overburden) fill. Upstream topography was, as a result, necessarily modified. The pre-mining 16,000-foot-long Streeter Gulch profile ranged from 5% near the lower end, increasing to 12.5 % for the upper 1800 feet (measurements, Map 18, PAP). The post-mining profile is 30% for the first 1000 feet up the face of the Streeter Spoil fill, and thence approximately 4 % across the nnnrooxiM nnet_minincr tonormn"Iyu r if r e-la:med land (m - c'µrement°i XAn" 10, DATA CUT b JV F.%, diversions are designed, and certified by a registered professional engineer, to accommodate the 100-year design storm [Rule 4.05.4(2)(a) and (b)]. These diversions comply with the requirements of Rules 4.05.3(1)(b) through (f) (they are in compliance with applicable statutes and regulations, are designed not to increase flooding or otherwise endanger property or public safety, are designed to be stable and not adversely impact to the hydrologic balance, and do not divert water into underground mines). Construction is still in progress. Riprap is used to control erosion. The channels are stable and require infrequent maintenance [Rules 4.05.4(2)(a) and (4.05.4(4)(b)]. In smaller tributaries, profiles have been altered to accommodate post-mining sides at lesser slopes (for stability) than original steep ravine slopes. 1. The Division proposes to approve the diversion of an ephemeral stream draining at least one square mile. This decision is based on a finding that the proposed diversion meets the requirements of 4.05.18 and 4.05.4, applicable local, State, and Federal statutes and regulations and that the diversion is designed to safeguard public safety and to minimize adverse impacts to the hydrologic balance. The reclaimed Streeter Gulch ditch will drain a watershed area of about 1280 acres. Streeter Gulch is an ephemeral drainage (PAP, page 2.04.7-27). It was (pre-mining) a steep-sided, 200-foot deep (near the mouth) incised draw (PAP, Map 11). Initial box cut material for mining south of the Gulch (Draw) (PAP, page 2.06-3) was placed near the mouth, first as an experimental practice and later recognized as excess spoil (overburden) fill. Upstream topography was, as a result, necessarily modified. The pre-mining 16,000-foot-long Streeter Gulch profile ranged from 5% near the lower end, increasing to 12.5 % for the upper 1800 feet (measurements, Map 18, PAP). The post-mining profile is 30% for the first 1000 feet up the face of the Streeter Spoil fill, and thence approximately 4 % across the approved post-mining topography of reclaimed land (measurements, Map 19, PAP) (4.05.4(1) and (4)). 2. Channel lining structures, retention basins, and artificial channel roughness structures are approved for use to control erosion. These means are proposed to be approved by the Division since they are necessary to control erosion, they are stable and will require infrequent maintenance. Riprap lining, permanent stock ponds, and dugout sediment traps on the spoil areas are the measures that will be used (4.05.4(2)(a)). Proposed Decision and Findings of Compliance 14 September 2009 Permit Renewal 05 Page 36