PL PACKET 08181998 - Laserfiche WebLink

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Page 10 C) The following storm water management practices shall be investigated in developing a storm water management plan in the following descending order of preference: 1) Natural infiltration of precipitation on-site; 2) Flow attenuation by use of open vegetated swales and natural depressing; 3) Storm water retention facilities; and 4) Storm water detention facilities. d) A combination of successive practices may be used to achieve the applicable minimum control requirements specified in subsection a) above. Justification shall be provided by the applicant for the method selected. Subd. 8. Design standards. Storm water detention facilities constructed in the City of St. Anthony shall be designed according to the most current technology as reflected in the MPCA publication "Protecting Water Quality in Urban Areas", and shall contain, at a minimum, the following design factors: . a) A permanent pond surface area equal to two percent of the impervious area draining to the pond or one percent of the entire area draining to the pond, whichever amount is greater; b) An average permanent pool depth of four to ten feet; C) A permanent pool length-to-width ration of 3:1 or greater; d) A minimum protective shelf extending ten feet into the permanent pool with a slope of 10:1; beyond which slopes should not exceed 3:1; e) A protective buffer,strip of vegetation surrounding the permanent pool at a minimum width of one rod (16.5 feet); f) All storm water detention facilities shall have a device to keep oil, grease, and other floatable material from moving downstream as a result of normal operations; g) Storm water detention facilities for new development must be sufficient to limit peak flows in each subwatershed to those that existed before the development for the 10 year storm event. All calculations and hydrologic models/information