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VII. RESULTS OF BEST MANAGEMENT PRACTICE EVALUATION As part of the development of this storm water management Capital Improvement Plan, an evaluation was undertaken into various best management practices that could be considered to address the storm water needs of the City and RCWD. Outlined below, please find a general discussion of the various practices that were identified to be available and a discussion of the City and/or RCWD perspectives regarding their applicability for use within the City of Hugo. Storm Water Retention Ponds Storm Water Retention Ponds are required to manage runoff rates from developing areas so that increases in storm water runoff rates or extended runoff volumes will not impact downstream lakes and streams. For the purpose of this description, these ponds will only be identified to provide this rate control function, to limit downstream rates, and also create floodplain storage to protect roads and other structures from flooding. NURP Treatment Ponds Ponds designed to NURP guidelines which generally anticipate creating dead pool storage to accommodate the runoff volume generated from the watershed tributary to the pond for a 2.5 inch rainfall event are anticipated to provide the following level of treatment: • Removal of sixty (60) percent of the total phosphorus loading directed to the pond from untreated storm water runoff. • Removal of ninety (90) percent of the total suspended solids loading from untreated runoff directed to the pond. Water Reuse/Irrigation/Infiltration This practice will generally involve the removal of one hundred (100) percent of the runoff volume and its corresponding pollutant load for water that is reused and not returned to the drainage system. Based on P8 models that were developed by the RCWD, we anticipate that for every acre foot of storm water runoff removed from the system, 1 pound of phosphorus will also be removed in this process. Flocculation Treatment This practice involves taking pretreated storm water runoff and treating it utilizing a flocculation process to achieve a significantly enhanced treatment. Storm water treated by this process will be anticipated to remove ninety (90) percent of the total phosphorus present in the storm water runoff, achieve a phosphorus concentration of less than fifty (50) micrograms per liter, and achieve total suspended solids concentrations of less than ten (10) milligrams per liter. CIP for Storm Water Projects Within the City of Hugo City of Hugo, MN WSB Project No. 1687-85 Page 19