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compliance with the requirements of Rule 4.05. <br />A. Water Quality Standards and Effluent Limitations -Rule 4.05.2 <br />1. The Division proposes to grant a small area exemption from use of sediment ponds due to the <br />limited size ofthe area and due to the fact that ponds and treatment facilities aze not necessary for the <br />drainage to meet the effluent limitations of Rule 4.05.2 and applicable State and Federal water <br />quality standards for receiving streams and also due to the fact that no mixing of surface drainage <br />with a dischazge from underground workings will occur. The small areas to be exempted are the <br />topsoil stockpiles outside the Section 11 ditch, the topsoil stockpiles along the paved haul road, and <br />the East Taylor holding pond and pump station. Small azea exemptions aze shown on Map 11, <br />Hydrology, North Area and Map 12, Hydrology, South Area. All disturbed area surface drainage in <br />the South Taylor area will drain through sediment ponds and no small azea exemptions are approved <br />in the South Taylor azea (4.05.2(3)(b)(i)). <br />2. The Division has approved several small areas of disturbance to be exempt from the use of <br />sediment ponds to treat runoff. Typical of these small areas are topsoil stockpiles, electric power <br />substation installations, the lineaz fresh water line, and the rail loop [Rule 4.05.2(3)]. Colowyo <br />demonstrated that treatment facilities were not necessary for the drainage to meet the effluent <br />limitations of Rule 4.05.2 and applicable State and Federal water quality standards for receiving <br />streams. There is no mixing of surface drainage with a discharge from underground workings azeas <br />at the exempted areas. <br />B. Diversions and Conveyance of Overland Flow -Rule 4.05.3 <br />The Division approves the use of riprap channel lining for permanent diversions constructed on the <br />reclaimed area. Channel protection is warranted due to steep slopes and large watershed azeas that <br />exist and that are planned on the post-mining topography. Pre-mining bedrock control is removed by <br />the mining operation and channel protection is necessary to provide long-term stability on the <br />reclaimed area, especially until vegetation is established. These permanent diversions are shown on <br />Map 41, Watershed Boundaries for Hydrologic Modeling for the original Colowyo mining azea and <br />on Map 41 A for the South Taylor area. The riprap lining will provide stability in order to protect fills <br />and property and to avoid danger to public health and safety (4.05.3(3)).. <br />C. Stream Channel Diversions -Rule 4.05.4 <br />Minor realignments and changes in permanent stream channels profiles aze permitted within <br />reclaimed mined and excess spoil fill areas Maps 33, 33A, 41 and 41 A. Pre-mining and post-mining <br />alignments aze similaz. However, profiles deviate more mazkedly. The most significant example is <br />Streeter Gulch. Streeter Gulch is an ephemeral drainage (PAP, page 2.04.7-27). It was (pre-mining) a <br />steep-sided, 200-foot deep (near the mouth) incised draw (PAP, Map 11). Initial box cut material for <br />mining south of the Gulch (Draw) (PAP, page 2.06-3) was placed near the mouth, first as an <br />experimental practice and later recognized as excess spoil (overburden) fill. Upstream topography <br />Proposed Decision and Findings of Compliance 4 May 2007 <br />Permit Revision 02 Page 32 <br />