The following section describes the criteria and policies which are to be followed for the analysis and design of storm water storage facilities associated with developments located within the town. The purpose of implementing storm water storage is to mitigate the impacts of increased flow peaks that occur as a result of watershed urbanization. The intent of storm water storage requirements is to maintain post-development peak flows to at or below of historic peak levels for the full range of storm events, from the 2-year through the 100-year event. Regardless of the calculation method utilized to analyze detention facilities, it is necessary to demonstrate that post-development peak flows are no more than the peak flows at "existing conditions" levels for the 2-, 10- and 100-year 24-hour storm events. The reason for this requirement is that the impact of development is normally far more pronounced for the frequent storms than it is for major storms, such as the 100-year event. For example, while the developed peak runoff for a 100-year event may be only 20% higher than the historic runoff, it is common that the 2-year peak runoff, under developed conditions, may be as much as two to six times larger than the undeveloped runoff. A facility designed to detain only the 100-year storm event may be practically ineffectual when functioning under the more frequent storm events. As a result, facilities must be designed with multi-frequency outlet structures in order to perform as intended.
(Res. 1637, passed 2-28-02; Am. Res. 2272, passed 5-17-07; Am. Ord. 714, passed 5-17-07; Am. Res. 2871, passed 9-17-15; Am. Ord. 872, passed 9-17-15)