G303.4 Water facilities.

All new or replacement water facilities shall be designed in accordance with the provisions of Chapter 7, ASCE 24, to minimize or eliminate infiltration of floodwaters into the systems.

G303.5 Storm drainage.

Storm drainage shall be designed to convey the flow of surface waters to minimize or eliminate damage to persons or property and shall meet the requirements of ASCE 24.

G303.6 Streets and sidewalks.

Streets and sidewalks shall be designed to minimize potential for increasing or aggravating flood levels and shall meet the requirements of Section G303.8.

G303.7 Retaining walls and driveways.

Retaining walls shall be designed in accordance with Section 1807. Retaining walls and driveways shall meet the requirements of Section G303.8.

G303.8 Grading and fill.

In flood hazard areas, grading and/or fill shall not be approved:

   1.   Unless such fill is placed, compacted and sloped to minimize shifting, slumping and erosion during the rise and fall of flood water and, as applicable, wave action, in accordance with ASCE 24 and Section 1804 of this code.

   2.   In floodways, unless it has been demonstrated through hydrologic and hydraulic analyses performed by an engineer in accordance with standard engineering practice that the proposed grading or fill, or both will not result in any increase in the flood levels during the occurrence of the design flood, in accordance with Section G103.5.

   3.   In coastal A-Zones and coastal high-hazard areas, unless such fill is conducted and or placed to avoid diversion of water and waves towards any building or structure.

Section BC G304: Post-FIRM Construction, Horizontal Enlargements and Substantial Improvements

G304.1 A-Zone construction standards.

In addition to the requirements of ASCE 24, the following standards shall apply to post-FIRM construction, horizontal enlargements and substantial improvements located within A-Zones, other than Coastal A-Zones.