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Phil Belfiori <br />Kyle Axtell <br />February 20, 2015 <br />Page 2 <br /> <br /> <br />4. Improve pond safety. <br />5. Avoid impact to the high-pressure gas pipeline beneath the pond. <br />6. Draw down pond to NWL within 48 hours for the 1.1 inch event. <br />7. Stabilize shoreline around Mirror Pond and improve habitat of the pond and surrounding <br />area. <br /> <br />Proposed Improvements to Mirror Pond <br /> <br />The following Improvements are purposed for Mirror Pond: <br /> <br />1. Excavate two feet on average to remove unconsolidated nutrient rich soils from the pond. <br />This will reduce the internal nutrient loading in Mirror Pond and benefit Long Lake <br />downstream. <br />2. Stabilize shoreline areas and reduce erosion by providing a 3:1 slope along the shoreline. <br />Shoreline erosion can add significant contributions of nutrients to Mirror Pond. <br />3. Improve Safety and biological diversity with the construction of a 10:1 safety bench at <br />the NWL. This bench will provide safety and encourage plant diversity and biological <br />uptake of nutrients. <br />4. Restore disturbed upland areas with native vegetation. This native buffer area will <br />stabilize shore land area, provide plant diversity, and filter nutrients from existing <br />stormwater that runs off from the adjacent lawns. <br />5. Construct a berm on the west side of Mirror Pond to eliminate overland overflow of <br />Mirror Pond in the Atlas 14 – 100 year rainfall event (7.38 inch – 24 hour event). <br />6. Lower the NWL in Mirror Pond from 920.86 to 918.86 feet. Construct a new outlet <br />structure consisting of a: <br />a. 12-inch orifice at 918.86 feet – primary outlet <br />b. Internal weir at 921.3 feet – secondary outlet <br />c. 18-inch RCP pipe at 916.5 feet – control outlet <br /> <br />The Mirror Pond design shown in the attached documents allows for the redirection of Ramsey <br />County Road D (37th Avenue) drainage into Mirror Pond at a future date. The result of these <br />improvements are summarized in the attached table and grading plan. <br /> <br /> K:\01626 -790\Admin\Docs\Final\MEMO-Mirror Pond-022015.docx