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<br />POND 016A <br />AS-BUILT REPORT <br />INTRODUCTION <br />in response to a new mine plan, which increased the disturbance area controlled by Pond 016, SCC <br />proposed and design a second pond to operate in series to effectively treat runoff from the mining <br />disturbance area. Sediment Pond 016A was constructed in the NE/4 SE/4, Section 27, TSN, R87W, <br />6`h P.M. just upstream from Pond 016. Construction was initiated in June 2003 and completed in <br />July 2003. This As-Built Report is intended to serve as the construction certification for Pond 016A <br />in accordance with Rule 4.05.6 and 4.05.9. <br />The back slope of the impoundment began to experience slumping during the fall of 2003 and is not <br />depicted on Exhibit 13-9C. The slumping does not currently affect the capacity or operating <br />capability of the pond. However, SCC is evaluating methods of stabilizing this back slope and wil[ <br />initiate corrective action in 2004. <br />EMBANKMENT AND EXCAVATION <br />The embankment is a homogeneous earth filled structure. The top width of the embankment is <br />approximately 15 feet with an upstream slope of 3H:1 V and a downstream slope of 3H:1 V. The <br />principal spillway is a 48-inch CMP riser pipe which drops into a 48-inch barrel CMP. The <br />emergency spillway is a trapezoidal riprapped channel 48-feet wide at the embankment crest and <br />25 feet wide along the outslope (see Exhibit 13-9C, Pond 016A As-Built). <br />Due to the silty nature of the alluvial subgrade material at the embankment location, a keyway was <br />constructed into impervious materials. The keyway for the embankment was constructed at a <br />minimum S feet deep and 10 feet wide. <br />A portion of the pond capacity is a result of excavating topsoil and subgrade material below natural <br />ground level. Suitable materials excavated from the pond area and associates side-slopes were used <br />in the embankment construction. <br />DESIGN ANALYSIS <br />Pond 016A was designed to meet or exceed the design and performance requirements of CDMG <br />while utilizing as much of the existing topography as possible. Sedimentation Pond 016A was <br />designed and constructed to adhere to the following specifications. <br />I. Provide storage and treatment for runoff from the 10-year, 24-hour storm event without <br />experiencing any discharge through the emergency spillway; <br />TR-56 13-SF-F. i Revised 09/06 <br />