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CMP Part 3A. Environmental Protection Plan <br /> c. Diversion of storm water to marshlands or swamps shall be encouraged <br /> for existing or planned surface drainage wherever marshes and swamps <br /> occur naturally and are feasible as receiving bodies. <br /> d. Marshlands and swamps receiving storm waters shall include provisions <br /> for water level control. <br /> e. Temporary storage areas or retention basins scattered throughout <br /> developed areas shall be encouraged where feasible to reduce peak flows, <br /> erosion damage, and possibly reduce the total cost to the community. <br /> £ Wide, shallow, grass waterways, where feasible, shall be used as <br /> overflow channels from the retention basins to form an above-ground <br /> drainage network. This waterway concept should be coordinated with the <br /> greenways and open-space plans of the municipalities. <br /> g. Natural vegeta�ion shall be used to reduce erosion in the waterways and <br /> act as a buffer between developed land and the retention basins. <br /> h. The practice of storing all storm water from natural units on that unit <br /> shall be encouraged. Many residential lots may be amenable to this <br /> concept and thus, ideally, whole subdivisions may be handled by this <br /> method. <br /> i. If marshland swamp disposal is not practical, some means to reduce the <br /> level of settleable and suspended solids shall be constructed. <br /> j. The drainage system components should be designed to maximize <br /> upstream storage. <br /> k. Facilities for temporary storage or for treatment of surface runoff shall be <br /> designed for the discharge from a 100-year storm. <br /> Orono's 1974 Surface Water Management Plan was a detailed quantitative <br /> analysis of Orono's entire surface water drainage system. All wetlands and <br /> marshes were individually reviewed as far as watershed, urbanization, runoff <br /> characteristics, nutrient assimilative capacity and ponding capacity. <br /> Pollution loads to the marshes and ponds were determined based on phosphorus <br /> as the limiting nutrient. These loads took into consideration tributary acreage and <br /> potential development on the tributary lands. The maximum phosphorus loading <br /> comes from high density residential development and is 3.46 lbs/acre/year. <br /> The assimilative capacity of the marshes was determined using two rates. <br /> Permanent standing water has an assimilative capacity of 4 lbs/acre/year. <br /> Permanent standing water was defined as areas of the marshes having cattails <br /> and other emergent vegetation. The dryer areas of the marsh, which have water <br /> City of Orono Community Management Plan 2008-2030 Page 3A-22 <br />