FINAL ORDINANCE NO. 08-016 - Laserfiche WebLink

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impacts of the land activity by maintaining pre -development hydrological conditions in the following ways: i) Decrease runoff volume. ii) Decrease erosion and sedimentation. iii) Decrease flow frequency, duration, and peak runoff rates. iv) Increase infiltration (groundwater recharge). v) Maintain existing flow patterns. vi) Reduce time to peak flows by increasing the time of concentration to and through drainage ways and storm sewers. vii) Storage of storm water runoff on -site. viii)Avoid channel erosion. b) Rate Control Requirements i) The rate of storm water runoff discharging from a proposed site shall not be greater than the rate of storm water runoff discharging prior to the proposed site alteration for the 2-, 10-, and 100-year storm events. Stone water best management practices to meet this requirement shall be designed and constructed in accordance with the most current version of the City Engineering Design Standards. The analyses for the rate of storm water runoff shall be calculated using the Soil Conservation Service Type II time distribution for the 2-, 10, and 100-year 24-hour storm events. The rate of storm water runoff prior to the proposed development shall be calculated at the pre - settlement condition as defined in the State of Minnesota Stormwater Manual for a "meadow" condition based on the applicable Hydrologic Soil Group(s) for the development (see Table 1). c) Volume Control Requirements i) The volume of storm water runoff discharging from a proposed site shall not be greater than the volume of storm water runoff discharging prior to the proposed site alteration for the 2-, 10-, and 100-year storm events. Storm water best management practices to meet this requirement shall be designed and constructed in accordance with the most current version of the City Engineering Design Standards. The analyses for the volume of storm water runoff shall be calculated using the Soil Conservation Service Type II time distribution for the 2- , 10, and 100-year 24-hour storm events. The volume of storm water runoff prior to the proposed development shall be calculated at the pre - settlement condition as defined in the State of Minnesota Stormwater Manual for a "meadow" condition based on the applicable Hydrologic Soil Group(s) for the development (see Table 1).