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-7- <br />The designs must be of sufficient accuracy and detail to allow <br />volume calculations which verify the sizing numbers provided <br />elsewhere. This is not the case with the current submittal. For <br />example, the surface area is shown to be 0.61 acres (determined by <br />planimeter), with a depth which is shown to be two feet from the <br />primary dewatering device to the base of the pond. These factors <br />combined indicate a pond volume of 1.22 acre feet at the primary <br />dewatering device level and 2.75 acre feet at the 100 year, 24 hour <br />storm storage level. These values are far less than the required <br />volumes. The drawn pond designs do not corroborate the calculated <br />figures. <br />d. As drawn, the embankment dimensions do not comply with the <br />Cis requirements of Rule 4.05.6(8)(h). <br />e. The following information must be provided to ensure compliance <br />with Rule 2.05.3(4) and 4.05.6. <br />Detailed and accurate scale engineering specifications <br />including a plan view that contains contour information and <br />cross section(s) sufficient to determine pond stage/pond <br />area/pond volume relationships. <br />ii. The cross section must be keyed to the plan view. <br />iii. Specific elevations must be provided for the upstream and <br />downstream dam toes, maximum sediment elevation, the 10 year, <br />24 hour storage elevation, the 25 year, 24 hour or the 100 <br />~_ year, 24 hour storage elevation (depending on pond size as <br />/ specified in Rule 4.05.6). The primary spillway inlet <br />elevation, the emergency spillway crest elevation, and the <br />dam top elevation. <br />~~ iv. Primary dewatering device specifications must include the <br />~~ primary device diameter, pipe length, pipe slope, and <br />mannings n for the pipe. <br />v. The emergency spillway specifications must include spillway <br />channel bottom width, side slope gradients, crest and <br />outslope gradients, length of crest and outslopes, <br />anticipated peak flows and velocities, riprap calculations <br />if erosive velocities are expected, and the spillway riprap <br />safety factor. <br />vi. The calculations must include the anticipated detention time, <br />which must be greater than 24 hours, and the dewatering time <br />which should be less than 10 days. <br />vii. A scale embankment diagram with specific elevations as noted <br />above. <br />