08-09-1993 Council Packet - Laserfiche WebLink

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c.storm water facilities; and d.Storm water detent ion facilities. 4 . A combination of successive practices may be used to achieve the applicable minimum control requirement specified in subsection 1 above. Justification shall be provided by the applicant for the method selected. H. Design Standards. Storm water detention facilities constructed in the City of Orono 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: 1. Permanent pond surface equal to 2 percent of the impervious area draining to the pond or 1 percent of the entire area draining to the pond, whichever amount .is greater; four to ten feet; 2. An average permanent pool depth of 3. As an alternative to items 1 and 2 above, the volume of the permanent pool shall be equal to or greater than the runoff from a 2.0 inch rainfall for the fully developed site. 4. A permanent pool length-to-width ratio of 3:1 or greater; 5. 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; 6. A protective buffer strip of vegetation surrounding the permanent pool at a minimum width of one rod (16.5 feet). 7. All storm water detention facilities shall have a device to keep oil, grease, and other floatable materials from moving downstream as a result of normal operations; 8. stormwater detention facilities for new development must be sufficient to limit peak flows in each subwatershed to those that existed before the development for the ten-year storm event. All calculations and hydrologic models/information used in determining peak flows shall be submitted along with the storm water management plan; A I