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'~ERm d r co-oa ~ -s 1 <br />The emergency spillway consists of a 12 foot wide rock-lined <br />length of the embankment. The elevation of the emergency <br />spillway is only 0.33 foot below the nominal elevation of the <br />crest of the embankment. This does not provide the necessary 1 <br />foot freeboard. <br />The pond can be made to meet current requirements by: <br />(1) To allow drainage of the pond so as to meet <br />detention time of 24-36 hrs for the 10-yr 24-hr <br />event, four 1 inch diameter holes need to be drilled <br />in the standpipe. Two would be set at elevation <br />94.60 and two at elevation 95.10. <br />(2) To provide the necessary freeboard, the water <br />surface elevation in the emergency spillway at the <br />design flow must be at least 1.0 foot below the <br />embankment. Therefore, crest of the spillway should <br />be lowered to elevation 96.8 and the sides and <br />bottom of the spillway riprapped as shown on the <br />attached drawings. <br />(3) The standpipe structure should be modified so that <br />the inlet to the CMP is set just above the level of <br />the water surface equivalent to the 10-yr 24-hr <br />storm volume. This would be elevation 95.8. <br />Approximately 1.25 ft would need to be cut off the <br />existing standpipe. <br />The NPDES permit must be modified to include this pond's <br />discharge point. A copy of the letter requesting this change <br />from the Department of Health is attached. <br />