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Seneca Coal Company has permitted permanent and temporary stock pond <br />impoundments in both the reclaimed drainage channels at the Seneca H-W Mine and <br />some existing culvert outlets. The stock ponds will slow the peak runoff of <br />precipitation events and help to minimize erosion in the drainage channels. They will <br />also act as additional alternate sediment control measures, minimizing the potential for <br />sediment from roads to be carried off the permit site. These small ponds will benefit <br />both livestock grazing and wildlife utilization of the reclamation. Required <br />information regarding stock pond construction, including stability analysis <br />documentation based on worst case embankment geometry assumptions, was <br />incorporated into the application by TR-48 and PR-4 amendments. Additional <br />information related to pre-construction design for individual stock ponds and <br />professional engineer certification of stock ponds following construction was <br />incorporated into the permit by PR-5. <br />Several of the stock ponds have been proposed as permanent impoundments, and the <br />impoundments would appear to be warranted to facilitate postmine livestock grazing <br />and wildlife use. However, documentation required by Rule 4.05.9(13) has not been <br />provided to allow for approval of any stock ponds as permanent impoundments. The <br />following commitment is included in Permit Tab 13, page 5, regarding permanent <br />impoundment demonstration of compliance: <br />Permanent impoundments will be reevaluated prior to bond release and remedial <br />construction performed to satisfy the appropriate sections of the regulations. <br />Prior to submittal of a bond release request, SCC will submit a complete <br />technical revision demonstrating that each permanent impoundment meets the <br />requirements of 4.05.9(13). <br />C. Sedimentation Ponds <br />Seneca Coal Company will primarily use .sediment ponds to prevent additional <br />contributions of sediment to streamflow or runoff outside the permit area due to <br />mining disturbance. Existing sediment ponds include 005, 006, 009, 015, 016, 016A <br />and 017. All sediment ponds that have been approved have been constructed. <br />Information regarding design of ponds and diversions is provided in Tab 13 of the <br />permit application. <br />Pond 005 was permitted as a permanent impoundment that treats runoff from 285.6 <br />disturbed acres which drain to Dry Creek. <br />Pond 006 was permitted as a permanent impoundment that is located in a watershed <br />that is tributary to Hubberson Gulch. The pond was constructed in five separate <br />phases as disturbance increased within the watershed. The final (Phase V) design <br />involved a 1.5 foot extension of the principal spillway riser, and elimination of a "pre- <br />Seneca II-W Findings Document 23 C1982057 <br />Permit Renewal No. 5 December 9, 2010