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<br />. <br /> <br />. <br /> <br />. <br /> <br />seven days, and the stormdrain inlets must be protected with straw bale or other <br />appropriate filtering barriers. <br /> <br />8.7 <br /> <br />Storm water .mana~ement criteria for permanent facilities. <br /> <br />a) An applicant shall install or construct, on or for the proposed land disturbing or <br />development activity, all storm water management facilities necessary to manage <br />increased runoff so that the two-year, ten-year, and l00-year storm peak discharge rates <br />existing before the proposed development shall not be increased and accelerated <br />channel erosion will not occur as a result of the proposed land disturbing or <br />development activity. An applicant may also make an in-kind or monetary contribution <br />to the development and maintenance of community storm water management facilities <br />designed to serve multiple land disturbing and development activities undertaken by one <br />or more persons, including the applicant. <br /> <br />b) The applicant shall give consideration to reducing the need for storm water <br />management facilities by incorporating the use of natural topography and land cover <br />such as wetlands, ponds, natural swales and depressions as they exist before <br />development to the degree that they can accommodate the additional flow of water <br />without compromising the integrity or quality of the wetland or pond. <br /> <br />c) The following storm water management practices shall be investigated in developing a <br />storm water management plan in the following descending order of preference: <br /> <br />1) Infiltration of runoff on-site, if suitable soil conditions are available for use; <br /> <br />2) Flow attenuation by use of open vegetated swales and natural depressions; <br /> <br />3) Storm water retention facilities; and <br /> <br />4) Storm water detention facilities. <br /> <br />A combination of successive practices may be used to achieve the applicable minimum <br />control requirements specified in subsection (a) above. Justification shall be provided <br />by the applicant for the method selected. <br /> <br />8.8 Desilm standards. Storm water detention facilities constructed in the [City, Town, County] <br />of shall be designed according to the most current technology as reflected In the <br />MPCA publication .Protecting Water Quality in Urban Areas., and shall contain, at a <br />minimum, the following design factors: <br /> <br />d) <br /> <br />a) <br /> <br />A permanent pond surface area equal to two percent of the impervious area draining <br />to the pond or one percent of the entire area draining to the pond, whichever amount <br />is greater; <br /> <br />b) <br /> <br />An average permanent pool depth of four to ten feet; <br /> <br />[COMMENTARY: An alternative to subsections (a) and (b) would be to require that the <br />volume of the pennanenl pool be equal to or greater than the nmoff from a l.O-inch <br />rainfall for the fully developed site.) <br /> <br />c) <br /> <br />A permanent pool length-ta-width ratio of 3:1 or greater; <br /> <br />d) <br /> <br />A minimum protective shelf extending ten feet into the permanent pool with a slope <br />of 10:1, beyond which slopes should not exceed 3:1; <br /> <br />v <br />