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1.If marshland swamp disposal is not practical, some means to reduce <br />the 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 <br />shall be designed for the discharge from a 100-year storm. <br />Finally*, Orono ’s 1974 Surface Water Management Plan is was a detailed <br />quantitative analysis of Orono's entire surface water drainage system. All wetlands <br />and marshes were individually reviewed as far as watershed, urbanization, runoft <br />characteristics, nutrient assimilative capacity and ponding capacity. <br />Pollution loads to the marshes and ponds were determined based on phosphorus as <br />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 Ibs/acre/year. <br />The assimilative capacity of the marshes was determined using two rates. Permanent <br />standing water has an assimilative capacity of 4 Ibs/acre/year. Permanent standing <br />water was defined as areas of the marshes having cattails and other emergent <br />vegetation. The drver areas of the marsh, which have water in them only <br />intermittently, absorb a greater amount of phosphorus and have an assimilative rate <br />of 20 Ibs/acre/year. <br />The study data was then compiled into one table listing all identified marshlands in <br />the Citv (as shown on Map hlo. 4 and as legally identified in Orono s Flood Plain <br />Management Ordinance No. 213) for purposes of determining minimum required <br />marsh areas necessaiy to properly detain the surface water runoff, thereby avoiding <br />Hooding and affecting nutrient assimilation. The data included in this table is <br />outlined as follows: <br />1. Names of watersheds and code names for sub-watersheds. <br />2.Acreage drained to the individual marshes, with totals for the <br />drainage areas where necessary . <br />3.The acreage of permanent water in the specified marshes and totals <br />when necessary. <br />4.The acreage of intermittently flooded wetland and totals when <br />necessary'. <br />CMP3A- 19 <br />I <br />I <br />I <br />1 <br />1 f <br />n <br />1 <br />I <br />•n <br />i <br />• I