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Larimer County Building Code - Flood Plain Amendment

Section 1.0 Title
Section 2.0 Interpretation and Application
Section 3.0 Regulations - Floodway District FW
Section 4.0 Regulations - Flood Fringe District FF
Section 5.0 Regulations - Flood Prone Areas
Section 6.0 Administration
Section 7.0 Definitions
Section 8.0 Enactment

SECTION 1.0 TITLE

1.1 Short Title. This resolution shall hereafter be referred to as the Larimer County Flood Plain Building Code.

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SECTION 2.0 INTERPRETATION AND APPLICATION

2.1 Whenever possible, the provisions of this supplementary building code shall be interpreted to apply together with an in conjunction with other Larimer County Building Codes. This Amendment is not to be interpreted as a repeal of prior building codes, but rather, regulations to apply in addition to other building codes.

2.2 Except as specifically provided in this Amendment, all other provisions of the Larimer County Building Code shall continue to be applied in addition to the requirements set forth herein.

2.3 This amendment to the Larimer County Building Code shall apply in those areas of the County zoned either FW-Floodway or FF-Flood fringe.

2.4 Zoning map. The boundaries and zoning classifications of the districts herein referenced are as shown on the official zoning maps for the areas within Larimer County as adopted or amended after public hearings by the Board of County Commissioners of Larimer County. Such maps and of this resolution.

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SECTION 3.0 REGULATIONS - FLOODWAY DISTRICT FW

3.1 Use of fill. Fill shall not be permitted in the FW District except when such fill, acting along or in combination with existing or future flood plain uses shall be shown to have no detrimental effect upon the hydraulic capacity of the floodway. In the event fill is permitted, it shall be protected against erosion where erosive velocities may occur by the use of riprap, bulkheading, or vegetative cover.

3.2 Structures. Where structures are allowed by the Larimer County Comprehensive Zoning Resolution, the following restrictions shall apply:

  1. Structures shall not be designed for human habitation.
  2. Structures shall be constructed so that the longitudinal axis of the structure is parallel to the direction of the flood flow.
  3. Whenever possible, placement of structure shall be upon the same flood-flow lines as those of adjoining structures.
  4. Structures shall be firmly anchored.
  5. All utility services in connection with structures shall whenever possible be placed above the flood protection elevation or where not practicable shall be adequately floodproofed in a manner approved by the County Building Department.

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SECTION 4.0 REGULATIONS - FLOOD FRINGE DISTRICT FF

4.1 Fill. The use of fill in the FF District shall be the minimum necessary to comply with the provisions of this regulation. When required by the provisions of the Larimer County Comprehensive Zoning Resolution, fill in the FF District shall be to a point no lower than the elevation at least fifteen feet beyond the extremities of any structure erected on such fill. No fill shall be used in such a manner as to restrict the flow capacity of any tributary or other drainway to the main stream.

4.2 Structures

  1. Any structure may be placed in the FF District only if the lowest floor level is at or above the regulatory flood protection elevation.
  2. If any structure or portions of any structure are not constructed upon fill, the portion not on fill shall be floodproofed in a manner consistent with requirements for placing a structure in the FW District to an elevation equal to the flood protection elevation.
  3. All utility services, furnaces, water heaters, and electrical wiring in connection with structure shall wherever possible be placed above the flood protection elevation or where elevation is not practicable shall be adequately flood proofed in a manner approved by the County Building Department.

4.3 Require that all manufactured homes to be placed or substantially improved within the flood plain on the Larimer County's FIRM be elevated on a permanent foundation such that the lowest floor of the manufactured home is at or above the base flood elevation; and be securely anchored to an adequately anchored foundation system and all manufactured homes shall be installed using methods and practices which minimize flood damage. For the purposes of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not to be limited to, use of over- the-top or frame ties to ground anchors. This requirement is in addition to other applicable State and local anchoring requirements for resisting wind forces.

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SECTION 5.0 REGULATIONS - FLOOD PRONE AREAS

5.1 If a proposed building site is in a flood-prone area, all new construction and substantial improvements including the placement of prefabricated buildings and manufactured homes shall (i) be designed (or modified) and adequately anchored to prevent flotation, collapse, or lateral movement of the structure, (ii) be constructed with materials and utility equipment resistant to flood damage, and (iii) be constructed by methods and practices that eliminate flood damage.

5.2 All manufactured homes to be placed within flood-prone areas shall be anchored to resist flotation, collapse, or lateral movement by providing over-the-top and frame ties to ground anchors. Specific requirements shall include (i) over-the-top ties at each of the four corners of homes less than 50 feet long as well as one additional tie per side at intermediate locations; (ii) frame ties at each corner of the home with five additional ties per side at the intermediate points and manufactured homes less than fifty feet long to have four additional ties per side. All components of the anchoring system shall be capable to carrying a force of 4,800 pounds; and any additions to the manufactured home shall be similarly anchored.

5.3 All manufactured homes or those to be substantially improved shall conform to the Larimer County Mobile Home Resolution and to the following requirements:

  1. Manufactured homes that are placed or substantially improved on a site (i) outside of manufactured home park or subdivision, (ii) in a new manufactured home park or subdivision, (iii) in an expansion to an existing manufactured home park or subdivision, or (iv) in an existing manufactured home park or subdivision on which a manufactured home has incurred "substantial damage" as the result of a flood, shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to or above the flood protection elevation and shall be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
  2. Manufactured homes to be placed or substantially improved on sites in existing manufactured home parks or subdivisions that are not subject to the provisions in (a) above shall be elevated so that either (i) the lowest floor of the manufactured home is at or above the flood protection elevation, or (ii) the manufactured home chassis is supported by reinforced piers or other foundation elements that are no less than 36 inches in height above grade and shall be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.

5.4 Recreational vehicles

  1. Recreational vehicles must either (i) be on the site for fewer than 180 consecutive days, (ii) be fully licensed and ready for highway use, or (iii) meet the building permit requirements for a manufactured home as referenced in Section 4.3 and elevation and anchoring requirements as set forth herein and in compliance with the Larimer County Mobile Home Resolution. As amended March 4, 1996

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SECTION 6.0 ADMINISTRATION

6.1 Application procedure. Applications for building permits in the FF and FW Zoning District shall be accompanied by surveys, plot plans, drawings, plans, and other materials as necessary showing compliance of the proposed construction with the provisions of this resolution and the flood plain supplementary zoning resolution. Such submittals may include the following as necessary and shall be prepared by a registered professional engineer or architect:

  1. Four sets of plans drawn to scale showing the nature, location, dimensions, and elevation of the lot, existing or proposed structures, fill storage of materials, floodproofing measures, and the relationships of the above to the location of the channel, floodway, and the flood-protection elevation.
  2. A typical valley cross section showing the channel of stream, elevation of land areas adjoining each side of the channel, cross sectional areas to be occupied by the proposed development, and high-water information.
  3. Plans (surface view) showing elevations or contours of the ground; pertinent structure, fill, or storage elevations; size, location, and spatial arrangement of all proposed and existing structures on the site; location and elevations of streets, water supply, sanitary facilities; photographs showing existing land uses and vegetation upstream and downstream, soil types, and other pertinent information.
  4. A profile showing the slope of the bottom of the channel or flow line of the stream.
  5. Specifications for building construction and materials, floodproofing, filling, dredging, grading, channel improvements, storage of materials, water supply, and sanitary facilities.
  6. An additional fee in the amount of one-fourth times normal permit fee.

6.2 Flood-proofing measures taken pursuant hereto, shall be designed consistent with the flood protection elevation for the particular area, flood velocities, duration's, rate of rise, hydrostatic and hydrodynamic forces, and other factors associated with the regulatory flood. The building department shall require that the applicant submit a plan or document certified by a registered professional engineer or architect that the flood-proofing measures are consistent with regulatory flood-protection elevation and associated flood factors for a particular area. The following flood- proofing measures may be required or taken in connection with specific construction. Such measures shall be undertaken in a manner consistent with requirements detailed by flood proofing regulations as published by the U.S. Army Corps of Engineers.

  1. Anchorage to resist flotation and lateral movement.
  2. Installation of watertight doors, bulkheads, and shutters, or similar methods of construction.
  3. Reinforcement of walls to resist water pressures.
  4. Use of paints, membranes, or mortars to reduce seepage of water through walls.
  5. Addition of mass or weight to structure to resist flotation.
  6. Installation of pumps to lower water level in structures.
  7. Construction of water supply and waste treatment systems so as to prevent the entrance of flood waters.
  8. Installation of pumping facilities or comparable practices for subsurface drainage systems for buildings to relieve external foundation wall and basement flood pressures.
  9. Construction to resist rupture or collapse cause by water pressure of floating debris.
  10. Installation of valves or controls on sanitary and storm drains sewage and storm waters into the buildings or structures.
  11. Location of all electrical appliances in a manner which will assure they are not subject to flooding.
  12. Construction of water, sewer, and natural gas lines to resist rupture or collapse cause by water pressure.
  13. Location of any structural storage facilities for chemical explosives, buoyant materials, flammable liquids or other toxic materials which could be hazardous to public health, safety, and welfare in a manner which will assure that the facilities are situated at elevations above the heights associated with the regulatory flood protection elevation or are adequately flood-proofed to prevent flotation of storage containers which could result in the escape of toxic materials into flood water.

6.3 Board of Review. There shall be a Board of Review appointed by the Board of County Commissioners consisting of three members and one alternate. Terms shall be for two years. Such Board of Review shall have the qualifications and powers designated in Colorado Revised Statutes, 1973, 30-28-206 as amended. In addition, all members of the Board of Review shall be trained and experienced in technical matters relative to flood control and protection specified herein. The alternate may vote only upon the absence of one of the regular members.

6.4 Appeals to the Board of Review may be taken by any person aggrieved by his inability to obtain a building permit in the FW or FF zones or by any officer, department, board, or bureau of the County. Upon review, the Board of Review shall have jurisdiction only over the following matters:

  1. To review the exact zoning district boundary of the FW and FF districts as it relates to any specific piece of property.

    As amended March 4,1996

  2. Determining the suitability and advisability of alternate methods of construction in the FW and FF zones which alternate methods withstand flood damage, and which alternate methods shall not restrict the flow capacity of the main channel or any drainage relative thereto.
  3. In appropriate cases, the Board of Review may issue a variance from the provisions of this regulation only after making a specific finding that the variance will not endanger health, welfare or prosperity and property of the applicant or any upstream or downstream owner or occupier of land.

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SECTION 7.0 DEFINITIONS

7.1 Appeal - A request for a review of the Flood Plain Administrator's interpretation of any provisions of this ordinance or a request for a variance.

7.2 Area of Special Flood Hazard - The land in the flood plain within a community subject to a one percent or greater change of flooding in any given year.

7.3 Base Flood - The flood having a one percent change of being equaled or exceeded in any given year.

7.4 Channel - A natural or artificial watercourse or drainway of perceptible extent with definite bed and banks to confine and conduct continuously or periodically flowing water.

7.5 Development - Any man-made change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations located within the area of special flood hazard.

7.6 Drainway - A natural or artificial land surface depression with or without perceptibly defined beds and banks to which surface runoff gravitates and collectively forms a flow of water continuously or intermittently in a definite direction.

7.7 Existing Manufactured Home Park or subdivision - A manufactured home park for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) are completed before the effective date of this ordinance.

7.8 Expansion to existing manufactured home park or subdivision- means the preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads.)

7.9 Fill - A deposit of materials or any kind placed by artificial means.

As amended March 4, 1996

7.10 Flood or Flooding - A general and temporary condition of partial or complete inundation or normally dry land areas from:

1. The overflow of inland or tidal waters and/or

2. The unusual and rapid accumulation or runoff of surface waters from any source.

7.11 Flood Insurance Rate Map (FIRM) - The official map on which the Federal Emergency Management Agency has delineated both the areas of special flood hazards and the risk premium zones applicable to the community.

7.12 Flood Insurance Study - The official report provided by the Federal Emergency Management Agency that includes flood profiles, the Flood Boundary-Floodway Map, and the water surface elevation of the base flood.

7.13 Floodproofing - A combination of structural provisions, changes or adjustments to properties and structures subject to flooding for the purpose of reduction and elimination of flood damages to properties, water and sanitation facilities, structures and contents of buildings in a flood hazard area.

7.14 Floodway - The channel of a river or other water course and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than 0.5 feet.

7.15 Flood Fringe - That portion of the flood plain inundated by the 100 year return frequency flood not within the floodway.

7.16 Flood Plain - The land adjacent to a body of water which has been or may hereafter be covered by floodwater.

7.17 Flood Profile - A graph or longitudinal profile showing the relationship of the water surface elevation of a flood event to location along a stream or river.

7.18 Flood Prone Areas - All areas in Larimer County indicated as being within Zone A on official maps issued by the U.S. Department of Housing and Urban Development

7.19 Lowest Floor - The lowest floor of the lowest enclosed area (including basement). An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access or storage, in an area other than a basement area, is not considered a building's lowest floor, provided that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of this ordinance.

7.20 Manufactured Home - A structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when connected to the required utilities. The definition does not include recreational vehicles.

As amended March 4, 1996

7.21 New Construction - Structures for which the "state of construction" commenced on or after the effective date of the resolution, and includes any subsequent improvements to such structures.

7.22 Obstruction - Any dam, wall, wharf, embankment, levee, dike, pile abutment, projection, excavation, channel rectification, bridge structure or matter in, along, across, or projecting into any channel, water course, or regulatory flood hazard area which may impede, retard or change the direction of water flow, either in itself or by catching or collecting debris carried by such water, or that is placed where the flow of water might carry the same downstream to the damage of life and property elsewhere.

7.23 Recreational vehicle - A vehicle which is (1) built on a single chassis; (2) 400 square feet or less when measured at the largest horizontal projections; (3) designed to be self propelled or permanently towable by a light duty truck; and (4) designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.

7.24 Regulatory Flood Datum - The reference elevation above mean sea level which represents the peak elevation of the 100 year return-frequency flood.

7.25 Regulatory Flood Protection Elevation - The elevation one and one-half feet above the regulatory flood datum.

7.26 Start of Construction - Includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, placement, or other improvement was within 180 days of the permit date. The actual start means the first placement for permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, or foundations. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include the excavation for a basement, footings, piers, or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure.

7.27 Structure- A walled and roofed building or manufactured home that is principally above ground.

7.28 Substantial Improvement - Any repair, reconstruction or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure:

  1. before the improvement or repair is started, or
  2. if the structure has been damaged and is being restored, before the damage occurred. For the purpose of this definition, "substantial improvement" is considered to occur when the first alteration of any wall, ceiling, floor, or other structural part of the building commences, whether or not that alteration affects the external dimensions of the structure.

    As amended March 4 , 1996

The term does not, however, include either:

  1. any project for improvement of a structure to comply with existing state or location health, sanitary, or safety code specifications which are solely necessary to assure safe living conditions, or
  2. any alteration or a structure listed on the National Register of Historic Places or a State Inventory of Historic Places.

7.29 Variances - A grant of relief from the requirements of this ordinance which permits construction in a manner that would otherwise be prohibited by this ordinance.

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SECTION 8.0 ENACTMENT

8.1 This supplemental regulation, as amended, shall take effect upon its approval and adoption.