Agenda - Council - 07/11/2000 - Laserfiche WebLink

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I ,I I I I I I I I I I I I I I I I I I II. An additional fifteen percent (15%) credit will be given to parcels that limit peak outflow rate during a 100-year rainfall event to rates comparable to the rates from an unimproved vacant property of the same size. C. Wet ponding credit - An adjustment of up to twenty-five percent (25%) will be made to the storm water utility fee of a parcel for onsite measures which are owned and maintained by the applicant that effectively reduces the amount of sediments/nutrients that enter the system. No adjustments will be made to single family, duplex residential, and agricultural parcels. It is the responsibility of the applicant to prove that the wet pond in question meets the following design criteria. I. Permanent Pool Volume: The volume of the permanent pool ("dead storage") should be at least 1.3 and preferably up to 2.5 times greater than the runoff volume generated from a 0.34 inch rainfall event (average summer storm) over the pond tributary area. II. Permanent Pool Depth: To promote settling and provide space for sediment accumulation, the average depth (volume/area) of the permanent pool should be at least 4 feet with a maximum depth of 10 feet. II1. Pond Shape: The pond should be wedge shaped, narrowest at the inlet and widest at the outlet. A minimum length to width ratio of 3:1 should be used. The distance between storm sewer outfalls and the pond outlet should be maximized to prevent short-circuiting. IV. Detention Time: The pond should provide a detention time of at least 6 hours. V. Skimming: The pond should have some type of facility to retain oils and floatable debris. This facility will be maintained by the applicant. Skimming shall be considered adequate if a baffle structure extends at least 4 inches below the normal water surface and the velocity of water passing under the baffle does not exceed 0.5 feet per second for the one year rainfall event. VI. Emergency Overflow: An emergency overflow structure or stabilized spillway will be provided to accommodate discharges during a storm event greater than a 2.5 inch rainfall. VII. Side Slopes: For purposes of stability, the side slopes should not exceed three feet horizontal to one foot vertical. The motion for the adoption of the foregoing resolution as duly seconded by Councilmember , and upon vote being taken thereon, the following voted in favor thereof: Resolution #00-06- Page 2 of 3