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All uses and the associated requirements allowed by permit in the floodway shall also be allowed by permit within the flood fringe or regulated flood hazard area with no floodway. Additionally, new construction, substantial improvements, alterations to structures (including, but not limited to, residential, commercial, agricultural and industrial) and suitable fill shall be allowed by permit subject to the minimum development requirements in § 11-1-76 of this chapter.
(Ord. 2013-01, passed 1-30-2013)
Statutory reference:
Allowed uses, see ARM 36.15.701(2)
(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
New construction, alterations and substantial improvements of residential dwellings, including manufactured homes and recreational vehicles on site for more than 180 consecutive days, must be constructed such that:
(A) The lowest floor elevation (including basement) including electrical, heating, duct work, ventilation, plumbing and air conditioning equipment and other services is two feet above the base flood elevation. Elevating may be by either suitable fill, stem walls, pilings or other acceptable means;
(B) Crawl spaces must be designed so that the crawl space floor is at or above the base flood elevation. Crawl spaces having an inside dimension of more than five feet from the ground to the living floor level must meet the requirements in this section for a basement;
(C) Where existing streets, utilities, lot dimensions or additions onto existing structures make strict compliance with these provisions impossible, a lesser amount of fill or alternative flood-proofing measures may be permitted only by variance approval; and
(D) All manufactured homes for residential use shall:
(1) Use methods and practices which minimize flood damage;
(2) Elevate the lowest floor two feet above the base flood elevation;
(3) Elevate on suitable fill or be raised on a permanent foundation;
(4) Have a foundation consisting of reinforced concrete, reinforced-mortared block, reinforced piers or other foundation elements of equal strength; and
(5) Secure the chassis, including additions by anchoring to the foundation system so that it will resist flotation, collapse or lateral movement. Anchoring may include, but are not limited to:
(a) Over-the-top ties to ground anchors be provided at each of the four corners of the mobile home, with two additional ties per side at intermediate locations for manufactured homes less than 50 feet long;
(b) Frame ties to ground anchors be provided at each corner of the home with five additional ties per side at intermediate points, for manufactured homes more than 50 feet long; and
(c) Components of the anchoring system capable of carrying a force of 4,800 pounds.
(6) Adequate surface drainage and access for a hauler.
(Ord. 2013-01, passed 1-30-2013)
Federal law reference:
Manufactured homes, see 44 C.F.R. § 60.3(c)(6) and (c)(12)
Statutory reference:
Flood-proofing for residential structures, see ARM 36.15.702(a)
(A) General. New construction, alterations and substantial improvements of commercial and industrial buildings must be constructed on suitable fill, stem walls, pilings or other suitable means such that the lowest floor elevation (including basement) is two feet above the base flood elevation or, if not, the building must be adequately dry or wet flood-proofed as follows. Manufactured homes proposed for use as commercial or industrial buildings cannot be wet- or dry-flood-proofed.
(B) Exemptions. Also, agricultural structures used solely for agricultural purposes and used exclusively in connection with the production, harvesting, storage, drying or raising agricultural commodities including raising of livestock, not be intended for human habitation, and having low flood damage potential are exempt from dry- or wet-flood-proofing, but shall:
(1) Be located on higher ground and as far from the channel as possible;
(2) Offer minimum obstruction to flood flows;
(3) Be adequately anchored to prevent flotation or collapse;
(4) Where electrical, heating and plumbing systems are installed, must meet flood-proofing requirements in this section; and
(5) Meet the elevation or dry-flood-proofing requirements if the structure is an animal confinement facility.
(C) Wet flood-proofing. Building designs to allow internal flooding of the lowest floor must:
(1) Limit uses to parking, loading areas and storage of equipment or materials not appreciably affected by flood waters;
(2) Use materials for walls and floors that are resistant to flooding to an elevation two feet or more above the base flood elevation;
(3) Equalize hydrostatic forces on walls by designing for entry and exit of flood waters that include screens, louvers, valves and other coverings or devices that:
(a) Automatically allow entry and exit of flood waters;
(b) Have two or more openings with a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding; and
(c) Have the bottom of all openings no higher than one foot above grade.
(D) Dry-flood-proofing. Buildings designs that do not allow internal flooding of the lowest floors must be:
(1) Used for a purpose other than parking, loading or storage of materials resistant to flooding shall be dry-flood-proofed;
(2) Flood-proofed to an elevation no lower than two feet above the BFE;
(3) Constructed of impermeable membranes or materials for floors and walls and water-tight enclosures for all windows, doors and other openings; and
(4) Designed to withstand the hydrostatic pressures and hydrodynamic forces resulting from the base flood.
(Ord. 2013-01, passed 1-30-2013)
Federal law reference:
Areas of special flood hazard, see 44 C.F.R. § 60.3(b)
Substantial improvements, see 44 C.F.R. § 60.3(c)
Statutory reference:
Allowed uses, see ARM 36.15.701
Flood-proofing for residential structures, see ARM 36.15.702
EMERGENCIES
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