(A) Base flood elevation. The appropriate base flood elevation(s) shall be determined by appropriate methods and utilized in the design and layout of the project by an engineer demonstrating the appropriate design and construction criteria herein are met. Regulated flood hazard areas that do not have computed and published base flood elevations in the adopted flood hazard study referenced in §§ 11-1-45
through 11-1-47
of this chapter, the base flood elevation must be computed as well, using appropriate engineering methods and analysis.
(B) Flood damage. Projects must be constructed by methods and practices that minimize flood damage and are reasonably safe from flooding.
(C) Materials. Structures are reasonably safe from flooding and constructed with materials resistant to flood damage.
(D) Structures or fill. Structures or fill must not be prohibited by any other statute, regulation, ordinance or resolution and must be compatible with subdivision, zoning and any other land use regulations, if any.
(E) Anchoring. All construction and substantial improvements shall be designed and adequately anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
(F) Certification. Certification by an engineer, architect or other qualified person must accompany the application as to an encroachment analysis where required, adequacy of structural elevations, determination of the base flood elevation, flood-proofing, wet-proofing, dry-proofing, design and construction to withstand the flood depths, hydrodynamic and hydrostatic pressures, velocities, impact, buoyancy and uplift forces associated with the base flood. A certification is not intended to constitute a warranty or guarantee of performance, expressed or implied.
(G) Access. Whether structures must have safe access during times of flooding up to the base flood for ordinary and emergency services; provided, there are no reasonable alternate locations for structures is subject to a higher regulatory standard.
(H) Encroachment limit. Allowable encroachment for developments in the regulated flood hazard area without a floodway must be supported by an encroachment analysis and cannot exceed one-half feet increase to the base flood elevation. An encroachment analysis is not required for any development in the flood fringe where an accompanying floodway has been designated within the regulated flood hazard area.
(I) Electrical systems.
(1) All incoming power service equipment including all metering equipment, control centers, transformers, distribution and lighting panels and all other stationary equipment must be located at least two feet above the base flood elevation.
(2) Portable and movable electrical equipment may be placed below the elevation of the base flood elevation; provided that, the equipment can be disconnected by a single plug and socket assembly of the submersible type.
(3) The main power service lines must have automatically operated electrical disconnect equipment or manually operated electrical disconnect equipment located at an accessible remote location outside the floodplain or two feet above the base flood elevation.
(4) All electrical wiring systems installed below the base flood elevation must be suitable for continuous submergence and may not contain fibrous components.
(J) Heating and cooling systems.
(1) Be installed with float operated automatic control valves so that fuel supply is automatically shut off when flood waters reach the floor level where located;
(2) Have manually operated gate valves installed in gas supply lines. The gate valves must be operable from a location above the base flood elevation;
(3) Be installed in accordance with the provisions of electrical systems flood-proofing; and
(4) Have furnaces and cooling units and ductwork installed at least two feet above the base flood elevation.
(K) Plumbing systems.
(1) Sewer lines, except those to be buried and sealed, must have check valves installed to prevent sewage backup into permitted structure.
(2) All toilets, stools, sinks, urinals, vaults and drains must be located so the lowest point of possible entry is at least two feet above the base flood elevation.
(L) Structural fill. Fill used to elevate structures, including, but not limited to, residential, commercial and industrial structures must be suitable and meet the following requirements:
(1) The filled area is at or above the base flood elevation and extends at least 15 feet beyond the structure in all directions;
(2) The fill is compacted to minimize settlement and compacted to 95% of the maximum density. Compaction of earthen fill must be certified by a registered professional engineer;
(3) No portion of the fill is within the floodway;
(4) The fill slope must not be steeper than one and one-half horizontal to one vertical unless substantiating data justifying a steeper slope is provided and adequate erosion protection is provided for fill slopes exposed to flood waters. The erosion protection for fill slopes exposed to velocities of four feet per second and less may consist of vegetative cover consisting of grasses or similar undergrowth as approved by the permit issuing authority. Slopes exposed to velocities greater than four feet per second shall be protected by armoring with stone or rock slope protection;
(5) The fill must be a minimum of 0.5 feet above the base flood elevation;
(6) No portion of the fill is in the estimated floodway if none has been designated; and
(7) Mitigation may be required for lost natural flood storage due to added fill.
(M) Water and sewage systems. All new construction or substantial improvements shall be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment and other services designed and located so as to prevent waters from entering or accumulating within the components during conditions of flooding or to prevent impairment or contamination during flooding.
(Ord. 2013-01, passed 1-30-2013)
Federal law reference:
Substantial improvements; permits, see 44 C.F.R. § 60.3(a)(3)
Utility requirements, see 44 C.F.R. § 60.3(a)(5) and (a)(6)
Statutory reference:
Flood-proofing for electrical and plumbing systems, see ARM 36.15.901, 36.15.902, 36.15.903
Flood-proofing for residential structures, see ARM 36.15.702
Uses allowed, see ARM 36.15.701