A. Grading Permit: All new developments, which require a grading permit, or exceed one acre in area, shall submit a drainage control plan and report prepared by a Utah registered professional engineer.
B. Building Requirements: Building floor levels shall be constructed a minimum of two feet above the 100-year FEMA, and non-FEMA flood level, unless otherwise approved by LaVerkin City as outlined in this title. Encroachment within the 100-year floodplain for FEMA and non-FEMA natural watercourses will not be permitted without HEC-2 hydraulic studies as directed by LaVerkin City. All natural drainages, washes, and waterways that convey a developed 100-year flow of one hundred (100) cfs or more shall be left open and undisturbed, unless otherwise approved by LaVerkin City. Any alteration of FEMA floodways is not permitted unless the proposed use can be shown to have no negative influence on flood conveyance.
C. Drainage Design: Because of potential negative impacts, design of drainage systems associated with new development cannot cause increases in existing flood peak discharges downstream for 10-year and 100-year floods. Drainage facilities shall be designed using currently accepted civil engineering standards of care, applicable safety standards, and public agency or other approved design specifications and shall be approved by the city engineer.
D. Capacity: The official level of flood protection is the 100-year recurrence interval for future land use conditions as defined by the flood control plan. Drainage collection system capacities shall be sized for a minimum of the 10-year flood, but no significant damage or risk of personal injury may occur in a 100-year flood. Major hydraulic structures (including bridges and open channels) shall be designed for the 100-year flood. (Ord. 2005-21, 5-4-2005)
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