Appendix 312. FLOOD HAZARDS

312.1

Flood Requirements

The subdivision shall conform to the flood requirements for both lots and subdivisions of the Zoning Ordinance.

312.2

Additional Flood Information Required

Where appropriate, the Floodway (Valley Zone) Borders (Floodway line and the 100 Year Flood line) shall be shown on the plat. Also, a note shall be added to the plat stating the base flood (100 Year Flood) elevation.

312.3

Minimum Street Elevations

The Planning Commission, City Manager, or City Engineer may require that all streets be at an elevation which is not lower than the base flood elevation (100 Year Flood elevation).

312.4

Setback and Elevation Requirements on Unmapped Watercourses

Due to the potential flood hazard on property adjacent to an unmapped watercourse draining 300 acres or more above the property under construction, the Planning Commission may require that each unmapped watercourse draining 300 or more acres be investigated by a professional engineer and the elevation of adjacent structures with setbacks from the centerline of the watercourse marked on the subdivision plat. The minimum elevation of the proposed structure shall be determined on the basis of a 100 year storm elevation water level. The engineer shall use an accepted national method of calculation. Example: USDA Technical Release No. 55 "Urban Hydrology for Small Watersheds"; ASCE Manual of Practice No. 37 "Design and Construction of Sanitary and Storm Sewers." The minimum setback shall be determined by an evaluation of the unmapped watercourse based on the erosion potential of the watercourse and lot elevation as determined by the engineer. All subdivisions adjacent to an unmapped watercourse draining 300 or more acres and for which 100 year storm elevation calculations were required shall have a certification by a professional engineer which reads as follows:

I ___________ have made a flood hazard study of the subdivision and the drainage area above it and all affected lots within this subdivision are marked with a minimum building elevation. A bench mark of public record for reference is noted on the plat, and established on the subdivision. Unmarked lots have been determined to not require a minimum building elevation due to their location and the existing drainage structure design.

SEAL

Name ___________ P.E. #_____