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Part II.C.2.a.iii. iii. Overbank Flood Control Criteria (Qp): Requires storage to attenuate the post-development 10-year, 24-hour peak discharge rate (Qp) to predevelopment rates. The Qp requirement does not apply when: 1. the site directly discharges to tidal waters or fifth order or larger streams, or 2. A downstream analysis reveals that overbank control is not required. iv. Extreme Flood Control Criteria (Qf): Requires storage to attenuate the post-development 100-year, 24-hour peak discharge rate (Qf) to predevelopment rates. The Qf requirement does not apply when: 1. the site directly discharges to tidal waters or fifth order or larger streams, or 2. A downstream analysis reveals that overbank control is not required. b. Sizing Criteria for New Development in Enhanced Phosphorus Removal Watersheds i. Runoff Reduction Volume (RRv) and Water Quality Volume (WQv): 1. Reduce the WQv by application of RR techniques and standard SMPs with RRv capacity. The total WQv is the runoff volume from the 1-year, 24-hour design storm over the post-developed watershed and must be calculated in accordance with the criteria in Section 4.3 of the DM; or 2. Minimum RRv and Treatment of Remaining Total WQv: Construction activities that cannot meet the criteria in Part II.C.2.b.i.1. due to site limitations must direct runoff from all newly constructed impervious areas to a RR technique or standard SMP with RRv capacity unless infeasible. The specific site limitations that prevent the reduction of 100% of the WQv must be documented in the SWPPP. For each impervious area that is not directed to a RR technique or standard SMP with RRv capacity, the SWPPP must include 25 Page 731 of 849