2016-097 Ordinance - Laserfiche WebLink

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EXHIBIT A: EXISTING CHAPTER 928 66R-9 Post Construction Storm Water Management Regulations 928.06 (e) An additional volume equal to 20ercent of the WQV shall be incorporated into the BMP for sediment storage and/or reduced infiltration capacity. The BMPs will be designed according to the methodology included in the Ohio Rainwater and Land Development manual, ODOT Post -Construction storm water standards, or other manual that is acceptable to Ohio EPA. (f) The BMPs listed in Table 2 below shall be considered standard BMPs approved for general use. However, communities with a regulated MS4 may limit the use of some of these BMPs. BMPs shall be designed such that the drain time is long enough toprovide treatment, but short enough to provide storage available for successive rainfall events and avoid the creation of nuisance conditions. The outlet structure for the post -construction BMP must not discharge more than the first half of the WQv in less than one-third of the drain time. Table 2: Target Drain Times for Structural Post -Construction BMPs BMPs Suitable for Drainage Areas > 5 Acres BMPs Suitable for Drainage Areas < 5 Acres Best Management Practice Drain Time Best '.Management Practice Drain Time Dry Extended Detention Basin* 48 hours Infiltration Basins", 24-48 hours Wet Extended Detention Basin ** 24 hours Bioretention Cells 40 hours Constructed Wetlands + 24 hours Sand & Other Media Filters 40 hours * Infiltration Basins ^ 24-48 hours Enhanced Water Quality Swales 24 hours Pocket Wetlands# 24 hours Vegetated Filter Strips 24 hours Dry basins must include forebay and micropool each sized at 10% of the WQv * * Provide both a permanent pool and an EDv above the permanent pool, each sized at 0.75 WQv -i- Extended detention shall be provided for the full WQv above the permanent water pool. The WQv shall completely infiltrate within 48 hours so there is no standing water or residual water in the BMP. 9 Pocket wetlands must have a wet pool equal to the WQv, with 25% of the WQv in a pool and 75% in marshes. The EDv above the permanent pool must be equal to the WQv. (g) The owner may request approval from the City of north Olmsted Engineer to use alternative structural Post -Construction BMPs if the owner can demonstrate, in a way that is acceptable to Ohio EPA rules and regulations that the alternative BMPs are equivalent in effectiveness to those listed in Table 2 above. The use of alternative or vendor supplied Post Construction BMPs should be limited to redevelopment projects where justification is provided that the traditional BMPs in Table 2 are technically and economically infeasible.