Laserfiche WebLink
problem, Colowyo cleaned a large amount of sediment from the pond during August and <br />September 2012, and it is anticipated that this will reduce TSS in the discharge to acceptable <br />values (there was no report of exceedances of limitations for the fourth quarter of 2012). If the <br />problem persists in year 2013, Colowyo is prepared to use an algaecide (approved by CDPHE) to <br />address the problem. <br />In recent years, other exceedances have been reported for Total Recoverable Iron and TSS, <br />however these were all affiliated with a rainstorm event or snowmelt runoff, and waivers were <br />granted by the Water Quality Control Division per Colowyo's CDPS permit. <br />Staff at CDPHE are currently reviewing Colowyo's CDPS permit and plan to issue a new permit <br />in 2013. <br />Surface drainage from all disturbed areas passes through sediment ponds with some exceptions. <br />The Division has granted Small Area Exemptions (SAEs) for some areas on the mine site. SAEs <br />include the area along the East Side Collection Ditch, the topsoil stockpiles along Haul Road A, <br />and the East Taylor Holding Pond and pump station (shown on Map 11 and Map 12). All <br />disturbed area surface drainage in the South Taylor area will drain through sediment ponds; no <br />SAEs are approved in the South Taylor area (4.05.2(3)(b)(i)). These sites are relatively small <br />and analysis indicates that standard treatment facilities (i.e., large sediment ponds) are not <br />necessary for the drainage to meet the effluent limitations of Rule 4.05.2 and the applicable State <br />and Federal water quality standards for receiving streams. Mixing of surface drainage with a <br />discharge from underground workings will not occur at these sites. <br />B. Diversions and Conveyance of Overland Flow - Rule 4.05.3 <br />The drainage and sediment control plan provides for temporary and permanent diversion of <br />surface drainages within the permit area. A system of ditches, as shown on the Hydrology - <br />South Map (Map 12) and the Hydrology - North Map (Map 11), convey runoff through disturbed <br />areas and divert runoff from disturbed areas to sediment ponds. <br />C. Stream Channel Diversions and Reconstruction - Rule 4.05.4 <br />Diversion of perennial streams around mined areas is not a regular practice at the Mine. <br />Reconstruction of channels is a very important aspect of Colowyo's reclamation practices. <br />Reconstructed channels are designed (and certified by a registered professional engineer) to <br />accommodate the 100 -year design storm (Rule 4.05.4(2)(a) and (b)). They are designed not to <br />increase flooding or otherwise endanger property or public safety and are designed to be stable <br />and not adversely impact the hydrologic balance. Reconstructed channels at the Mine have not <br />been designed with a lesser flow capacity than the unmodified stream channel immediately <br />above and below the diversion (Rule 4.05.4(2)(b)). These channels are shown on Map 41 and <br />Map 41A. <br />Proposed Decision and Findings of Compliance January 2012 <br />Permit Renewal 06 Page 132 <br />