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Memo to Kate Pickford <br />Storm Water Pond Proposal <br />October 31, 2003 <br />File No. M-1992-069 <br />flow velocities of about 3.5 feet per second can be anticipated through the spillway (see attached <br />worksheet). With these flow velocities armoring ofthe spillway must be provided to prevent erosion. <br />The Applicant must provide DMG with a design for construction of the spillway, including cross <br />section, armoring, and transition detail where the armored spillway enters the historic channel to the <br />river. Once these designs have been reviewed and approved by DMG, the hydraulic engineering <br />aspects of this permit modification will complete and acceptable for approval. <br />Finally, a qualitative review of the storm water quality that will be entering the east gravel pit under the <br />proposed plan was conducted. The existing Eagleview Pond up gradient of the east gravel pit was <br />designed and constructed to completely retain runoff from the 2-year storm, and runoff from the 5 and <br />10-year storms is routed into 3-ditch. As a result, only runoff from events in excess of the 10-yeaz <br />storm will report to the gravel pit pond. DMG concurs with the applicant that contamination carried by <br />the runoff will be greatly diluted by the magnitude of the water volume generated by these lazge-scale <br />storm events. <br />attachment(s) <br />cc: Cazl Mount, DMG (via email & w/o attachments) <br />c:~acsU.OANER MACHINEVvIy Documrnis\83idjoint venture.doc <br />