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<br />Thus, the embankment will have to be raised about one <br />foot, to Elevation 99.0, in order to meet CMLRD requirements <br />for storage and freeboard.- <br />The pond now has an accumalation of sediment. Before <br />mining operation begins, the pond should be cleaned and the <br />bottom elevation set uniformly at E1. 93.50. Cleaning of the <br />pond on an annual basis will be done, consistent with the <br />assumptions made in the volume calculations. <br />The principal spillway as it now exists is not suitable <br />to meet CMLRD requirements. The spillway consists of a 12 <br />inch diameter standpipe covered with an open 25 gallon drum <br />which fits tightly around the CMP. The drum is open at the <br />top, and has a simple trashrack composed of reinforcing bars <br />within it (see Fig. 3.2). There are no outlets in the <br />existing principal spillway other than flow over the top of <br />the drum. In order to permit the pond to drain and still <br />meet the 24-36 hour retention requirement, it will be <br />necessary to drill two 1-inch diameter holes on either aide <br />of the standpipe at E1. 94.3 and two 2-inch diameter holes at <br />E1. 95.5 (see Fig. 3.4). The stage-discharge curves for both <br />the principal spillway and the emergency spillway are shown <br />in Figure 3.5. <br />The emergency spillway currently is at the correct <br />elevation. The riprap needs to be restored and extended as <br />shown on Figure 3.4 <br />The existing NPDES permit must be modified to include <br />this pond's discharge point. A copy of the letter requesting <br />this change from the Department of Health is attached. <br />