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Updated Surface Water Management Plan (SWMP) <br />City of Ramsey, Minnesota <br />D. Design Requirements <br />The Ramsey SWMP has a dual purpose: 1) It will serve as a guide for the construction of <br />storm drainage facilities, and 2) It will provide a basis for a consistent approach to the <br />preservation of lakes, wetlands, streams, and the Mississippi and Rum Rivers. The <br />following issues have been incorporated into this plan: <br />1. Division of the City into major watersheds based on contour maps, grading plans <br />and natural topography <br />2. Determination of storm water runoff problems under current land use conditions <br />3. General layout and sizing of trunk storm sewers and open channels <br />4. Tributary areas, storage volumes, and high water levels of all existing ponding <br />areas <br />5. Recommendations to accommodate the ultimate land use conditions <br />6. Recommendations for the revision of the current development ordinances <br />7. Recommendations for standard Operations and Maintenance procedures <br />8. Recommendations for specific construction site erosion control practices <br />9. Estimated construction and implementation costs of the SWMP <br />10. Recommendations for education of City residents, staff, and development <br />community. <br />The primary function of an urban storm drainage system is to minimize economic loss <br />and inconvenience due to periodic flooding of streets and other low-lying areas. <br />Adequately designed storm drainage facilities provide flood control, minimize hazards <br />and inconvenience associated with flooding, and protect or enhance water quality. The <br />SWMP takes the entire drainage basin with future saturation development into <br />consideration. <br />Wet water quality ponds upstream of dry regional infiltration basins (where possible) will <br />help control the rate and the volume of storm water runoff. To provide flood protection <br />for adjacent property, the design storm interval for ponding areas is a 100-year storm as <br />compared to a 10-year storm for design of storm sewer piping. Any new residential, <br />commercial, industrial and other habitable structures shall be constructed with the <br />following low floor elevation: Elevation of the lowest opening of a structure shall be a <br />minimum of 1 foot above the Emergency Overflow, or 2 feet above the HWL of the <br />nearby pond or water body, whichever is higher. The area of a pond's HWL plus 1 foot <br />of freeboard shall be contained entirely within an outlot that is owned and maintained by <br />the City or within a drainage utility easement. <br />Section IV <br />March 20, 2015 Page 31 <br />