ORD 15-10 - Laserfiche WebLink

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�- 1 a. New development. For new, nonlinear developments_.that create more than one acre of new m2pervious surface on sites without restrictions- stormwater runoff volumes will be controlled the post - construction runoff volume shall be retained on site for 1.1 inches of runoff from all impervious surfaces on the site. b. Redevelopment. Redevelopment projects (including linear projects). on sites without restrictions that create new impervious surfaces shall capture and retain on site 1.1 inches of runoff from the new impervious surface and show a net pollutant reduction for any reconstructed impervious surfaces. 6. Water QuQE a. Total suspendcdsohds. Treatment also must achieve an 80, percent removal of suspended solids. b. Phosphorus control. Stormwater shall be treated to remove 60 percent of the post - development phosphorus load on an annual basis before discharge to natural water bodies. The amount of total phosphorus removed should be modeled using the Minimal Impact DesiWi Standards (MUDS) calculator or an equivalent water quality, modeling program. Where water duality ponding is exclusively used to meet the phosphorus removal requirement, the ponds must be sized to store the site runoff from a two and one -half inch rainfall below the normal outlet elevation. 7_e:. Rate Control. For post - construction rate control modeling a minimum curve number of 84 shall be used on all disturbed /graded soil areas, due to soil compaction impacts, unless Soil Protection /Compaction Remediation specifications have been incorporated into the Proposal (Plan Set, Stormwater Management Plan, etc.) and are approved bby the City Engineer. Atlas 14 shall be used in all rate - control estimates. New ronstrzution._Projects shall have no increase in runoff from th , grease, T-rea"ent also most ftehie-ee a 60 per-eent r-emoval of suspended solids. both, a . predevelopment peak runoff rates for the twe2. 10, and 100 year; 24 hour storm everrtevents. PGge 16