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Updated Storm Water Management Plan (SWMP) <br />City of Ramsey, Minnesota <br />Easement: A grant of one or more property rights by a property owner for use by the <br />public, a corporation, or another person or entity. <br />Emergency Overflow (EDF): A hydraulic channel, swale, weir, etc. that provides an <br />outlet from a pond or flooded area at an elevation below the point where property damage <br />can occur. <br />End of Pipe Control: Water quality control technologies suited for the control of <br />existing urban storm water at the point of storm sewer discharge to a receiving water. <br />Due to typical space constraints, these technologies are usually designed to provide water <br />quality control rather than quantity control. <br />Erosion: The wearing away of land surface and soil by the action of natural elements <br />(wind and/or water). <br />Eutrophication: Process by which overabundance of nutrients in a waterbody lead to <br />accelerated productivity and general decrease in water clarity and quality. <br />Exfiltration: The downward movement of runoff through the surface and into the <br />subsoil. <br />Existing Development: A property or parcel of land that has previously been subject to <br />development and no major changes are anticipated to the property in the near future. <br />Exotic Species or Invasive Species: Non-native plants or wild animals that can <br />naturalize, have high propagation potential, are highly competitive for limiting factors, <br />and cause displacement of, or otherwise threaten, native plants or native animals in their <br />natural communities. <br />Extended Detention: A storm water design feature that provides for the gradual release <br />of a volume of water (typically 0.25 to 1.0 inches per impervious acre) over a 12 to 48 <br />hour time period. With proper design, the extended detention period allows for an <br />increased settling of pollutants, and can protect channels from frequent flooding or scour. <br />Extended Detention (ED) Ponds: A conventional ED pond temporarily detains a <br />portion of storm water runoff for a period of 12 to 48 hours after a storm using a fixed <br />orifice. Such extended detention allows urban pollutants to settle out. ED ponds can be <br />designed to be "dry" between storm events and thus do not have any permanent standing <br />water or "wet" with a permanent pool of water. An enhanced ED pond is designed to <br />prevent clogging and resuspension and provides greater flexibility in achieving target <br />detention times. It may be equipped with plunge pools near the inlet, a micropool at the <br />outlet, and utilize an adjustable reverse -sloped pipe at the ED control device. See also <br />"wet pond" defmition for diagram. <br />Extended Detention Wetland: A storm water wetland design alternative in which the <br />total treatment volume is equally split between a shallow marsh and temporary detention <br />of runoff above the marsh. After a storm, the normal pool of the shallow marsh may rise <br />Section XI <br />February 20, 2015March 6, 2015 Page 75 <br />