§ 106-7. Stormwater management requirements.

(a)

For the purpose of this chapter, new development or redevelopment will be set to grades which will preclude flooding or any part or portion thereof due to excessive rainfall.

(b)

All runoff shall be first diverted to retention/detention facilities which shall meet the requirements as prescribed by the St. Johns River Water Management District.

(c)

All retention/detention facilities shall incorporate designs which will provide for percolation, recovery, and other pertinent factors, as required by the St. Johns River Water Management District.

(d)

In addition to meeting the retention/detention requirements as required by the St. Johns River Water Management District, the project shall have detention capacity sufficient to ensure that post-development runoff flow rates, quantities, peaks, and velocities shall be equal to or less than predevelopment runoff for the 25-year, 24-hour storm event, and quality of the runoff shall conform to the minimum standards set forth in the state water policy, F.A.C. ch. 17-40. Hydrograph analysis for this purpose shall be based on realistic and applicable methods for time of concentration of less than 15 minutes.

(e)

In all cases, outfall from retention/detention facilities must be connected by approved means to the city storm drainage system. Where the outfall cannot be connected to the city storm drainage system, stormwater management shall be designed according to the criteria established by the city engineer. In any event, no overflow through the city curbs and gutters or streets (overland) shall be permitted.

(f)

An exfiltration or porous pavement system may be designed in lieu of a retention/detention system. The design shall be based on the criteria set by the city engineer, who will take into account the size and type of the project, soil and water table conditions, impact on the surrounding areas, and other applicable conditions.

(g)

Final stormwater storage locations shall not impound water against roadway or building structural sections. The city engineer may, at his discretion, waive the requirement in certain situations provided he has the approval from the structural engineer of record that the structural design of the building is safe from hydrostatic, hydrodynamic, or any such effects.

(h)

Floodways and floodplains, level of flood flows or velocities of adjacent streams, impoundments, or other watercourses must not be altered so as to adversely impact the off-site storage or conveyance capacities of the water resources. Any proposed alteration of floodways or floodplains must be approved by all agencies which have jurisdiction over such activities.

(i)

Erosion and sediment control best management practices shall be used during construction to retain sediment on site. Land which has been cleared for development and upon which construction will not begin within 30 days shall be protected from erosion and sedimentation by adequate methods acceptable to the city. Wetlands and other water bodies shall not be used as sediment traps during or after development.

(j)

Water reuse and conservation shall, to the maximum extent practicable, be achieved by incorporating the stormwater management system into irrigation systems serving the development.

(k)

The design and construction of the proposed stormwater management system shall be certified as meeting the requirements of this chapter by a professional engineer, registered in the state.

(Code 1988, § 25-7)