7-20-40 Floodplain Hazards

• (b) Permit Procedures
  • Application for a Floodplain Development Permit shall be presented to the Floodplain Administrator on forms furnished by him/her and may include, but not be limited to, plans in duplicate drawn to scale showing the location, dimensions, and elevation of proposed landscape alterations, existing and proposed structures, including manufactured homes, and the location of the foregoing in relation to SFHA. Additionally, the following information is required:
    1. Elevation (in relation to mean sea level), of the lowest floor (including basement) of all new and substantially improved structures;
    2. Elevation (in relation to mean sea level) to which any nonresidential structure shall be flood proofed;
    3. A certificate from a registered Colorado Professional Engineer that the nonresidential flood proofed structure shall meet the flood proofing criteria of 7-20-40 (h) and by providing an Elevation Certificate with the proposed finished elevation of the lowest floor of the structure, including the basement in relation to mean sea level;
    4. Description of the extent to which any watercourse or natural drainage will be altered or relocated as a result of proposed development.
    5. Approval or denial of a Floodplain Development Permit by the Floodplain Administrator shall be based on all of the provisions of this section and the following relevant factors:
       • (a) The danger to life and property due to flooding or erosion damage;
       • (b) The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner;
       • (c) The danger that materials may be swept onto other lands to the injury of others;
       • (d) The compatibility of the proposed use with existing and anticipated development;
       • (e) The safety of access to the property in times of flood for ordinary and emergency vehicles;
       • (f) The costs of providing governmental services during and after flood conditions including maintenance and repair of streets and bridges, and public utilities and facilities such as sewer, gas, electrical and water systems;
       • (g) The expected heights, velocity, duration, rate of rise and sediment transport of the flood waters and the effects of wave action, if applicable, expected at the site;
       • (h) The necessity to the facility of a waterfront location, where applicable;
       • (i) The availability of alternative locations, not subject to flooding or erosion damage, for the proposed use;
       • (j) The relationship of the proposed use to the comprehensive plan for that area.

• (c) Duties and Responsibilities of the Floodplain Administrator
  • Duties and responsibilities of the Floodplain Administrator shall include, but not be limited to, the following:
    1. Maintain and hold open for public inspection all records pertaining to the provisions of this section, including the actual elevation (in relation to mean sea level) of the lowest floor (including basement) of all new or substantially improved structures and any flood proofing certificate required by the 7-20-40 (b) Permit Procedures.
    2. Review, approve, or deny all applications for Floodplain Development Permits required by this section.
    3. Review Floodplain Development Permit applications to determine whether a proposed building site, including the placement of manufactured homes, will be reasonably safe from flooding.
    4. Review permits for proposed development to confirm that all necessary permits have been obtained from those Federal, State or local governmental agencies (including Section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 U.S.C. 1334) from which prior approval is required.
    5. Inspect all development at appropriate times during the period of construction to ensure compliance with all provisions of this ordinance, including proper elevation of the structure.
    6. Where interpretation is needed as to the exact location of the boundaries of the Special Flood Hazard Area (for example, where there appears to be a conflict between a mapped boundary and actual field conditions) the Floodplain Administrator shall make the necessary interpretation.
    7. When Base Flood Elevation data has not been provided, the Floodplain Administrator shall obtain, review and reasonably utilize any Base Flood Elevation data and Floodway data available from a Federal, State, or other source, in order to administer the provisions of 7-20-40.
    8. For waterways with Base Flood Elevations for which a regulatory Floodway has not been designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within Zones A1-30 and AE on the community's Flood Insurance Rate Maps (FIRM), unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the Base Flood Elevation more than one half of one (1/2) foot.
    9. Notify, in riverine situations, adjacent communities and the State Coordinating Agency, which is the Colorado Water Conservation Board, prior to any alteration or relocation of a watercourse, and submit evidence of such notification to FEMA.
    10. Ensure that the flood carrying capacity within the altered or relocated portion of any watercourse is maintained.
    11. Before providing a Certificate of Occupancy for any structure within a Flood Hazard Area the Floodplain Administrator shall be provided an Elevation Certificate from a registered Colorado Professional Engineer that the built structure meets the requirements of 7-20-40 (g) or the flood proofed structure shall meet the flood proofing criteria of 7-20-40 (h) and shall be provided an Elevation Certificate with the finished recorded elevation of the lowest floor of the structure, including the basement in relation to mean sea level;

• (d) Warning and Disclaimer of Liability
  • The degree of flood protection required by this section is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. On rare occasions greater floods can and will occur and flood heights may be increased by man-made or natural causes. This section does not imply that land outside the areas of the floodplain or uses permitted within such areas will be free from flooding or flood damages. This section shall not create liability on the part of the community or any official or employee thereof for any flood damages that result from reliance on this ordinance such provisions or any administrative decision lawfully made thereunder.
• (e) Floodplain Maps
  1. The maps depicting the floodplain for the base flood in the report, Federal Emergency Management Agency (FEMA) Flood Insurance Study for Pitkin County, dated August 15, 2019, with accompanying Flood Insurance Rate Maps (FIRM) and any revisions thereto and hereby adopted by reference, shall be the maps used to locate the SFHA, together with all of the technical information contained in such report, The Floodplain Administrator shall keep a copy of this report on file and available for public inspection.
  2. Where a property owner believes that the mapped SFHA shown on the FEMA Flood Insurance Rate Map are inaccurate, the property owner may request that FEMA process an amendment to that map. Where the proposed development is within Zone A on the FIRM, the applicant may present alternative mapping to the County Floodplain Administrator, who may accept such mapping as an indication of the floodplain area only if the County Flood Plain Administrator believes the alternative mapping to be more accurate than the FEMA Flood Insurance Rate Map.
  3. When Base Flood Elevation (BFE) data has not been provided the applicant shall obtain, review, and reasonably utilize other BFE and floodway data as a basis for elevating residential structures to or above the Base Flood Elevation and for flood proofing or elevating non-residential structures to or above the Base Flood Elevation.
  4. For waterways with Base Flood Elevations for which a regulatory Floodway has not been designated no new and permitted development may increase the Base Flood Elevation more than one half of one (1/2) foot.
  5. Where the SFHA has not been established, a property owner may conduct a floodplain study to determine the boundaries of the SFHA. The applicant shall demonstrate that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the Base Flood Elevation more than one half of one (1/2) foot as any point within the community. The property owner should consult with the County Flood Plain Administrator to determine the appropriate methodology for the floodplain study.
  6. It shall be the burden of the applicant to demonstrate that the property seeking development approval is not within the SFHA.

• (f) General Standards
  • The following conditions apply to all new development and/or substantial improvements, including development in SFHA. All development plans shall:
    1. Be designed (or modified) and adequately anchored to prevent floatation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
    2. Include an Elevation Certificate which shall be prepared by a registered professional engineer, architect or land surveyor and shall submitted to the Floodplain Administrator both at permit application and with as-built conditions prior to Certificate of Occupancy;
    3. Be constructed with flood-resistant materials;
    4. Be constructed by methods and practices that minimize flood damage;
    5. Be constructed with electrical, heating, ventilation, plumbing, air conditioning equipment, and other service facilities designed and/or located to prevent water entry or accumulation within the components during conditions of flooding;
    6. All new and replacement water supply systems shall be designed to minimize of eliminate infiltration of flood waters into the system; and
    7. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system and discharge from the systems into flood waters.
    8. Within the SFHA, no use, fill, construction, excavation, embankment, or alteration on or over any portion of the SFHA shall be permitted that would result in any of the following:
       • (a) The storage or processing of materials that in times of flooding are buoyant, flammable, explosive, or otherwise potentially injurious to human, animal or plant life.
       • (b) The disposal of garbage or other solid waste materials.
       • (c) The human occupation of structures either fixed or mobile, permanent or temporary.
       • (d) Substantial solid debris being carried downstream by floodwaters.
       • (e) Any obstruction that would impair the flow or storage capacity of a SFHA so as to cause foreseeable damage to others either within or outside of SFHA boundaries.
       • (f) A substantial increase in sedimentation or erosion.
       • (g) The infiltration of floodwaters into on-site water supply and wastewater disposal systems that would impair their functioning or pollute the stream.
       • (h) Damage to or destruction of aquatic ecosystems, including but not limited to, wetlands and riparian habitat areas.

• (g) Residential Construction
  • New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one (1) foot or higher above the Base Flood Elevation. A registered professional engineer, architect or land surveyor shall submit an Elevation Certificate to the Floodplain Administrator citing that this standard has been met.
• (h) Nonresidential Construction
  • New construction and substantial improvements of any commercial, industrial or other nonresidential structure shall:
    1. Have the lowest floor (including the basement) shall be elevated to at least one (1) foot above, the level of the Base Flood Elevation; or
    2. All attendant utility and sanitary facilities, shall be flood proofed to an elevation one(1) foot above the Base Flood Elevation the structure shall watertight with walls substantially impermeable to the passage of water; and
    3. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
    4. A registered professional engineer or architect licensed in the State of Colorado shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design methods of construction are in accordance with accepted standards of practice.
• (i) Enclosures
  • New construction and substantial improvements, with fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. The design must be either certified by a registered professional engineer or architect or meet the following criteria:
    1. A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided.
    2. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.

• (j) Manufactured Homes
  • New placement and substantial improvements of all manufactured homes shall meet the following requirements:
    1. Homes within Zone A on the FIRM 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 limited to, use of over-the-top frame ties to ground anchors. This requirement is in addition to applicable State and local anchoring requirements for resisting wind forces.
    2. Homes within Zone A1-30, AH, and AE on the FIRM on sites (i) outside of a 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 a result of a flood, shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to at least one (1) foot above the Base Flood Elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.
    3. Homes on sites in an existing manufactured home park or subdivision within Zones A1-30, AH, and AE on the FIRM shall be elevated so that either:
       • (a) The lowest floor of the manufactured home is at least one (1) foot above the BFE, or
       • (b) The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade and is securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.
• (k) Recreational Vehicles
  • Recreational vehicles placed on sites within Zones A1-30, AH and AE on the FIRM shall be required to either:
    1. Be on the site for fewer than 180 consecutive days;
    2. Be fully licensed and ready for highway use (A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions.), or
    3. Meet the permit and anchoring requirements of Section 7-20-50.

• (l) Subdivision Proposals

The following shall apply to all subdivision proposals and other development, including manufactured home parks or subdivisions, to determine whether such proposals will be reasonably safe from flooding:

1. Such proposals shall minimize flood damage.
2. BFE data shall be generated for subdivision proposals and other proposed development which are greater than 50 lots or 5 acres, whichever is lesser, if not otherwise provided
3. Adequate drainage shall be provided to reduce exposure to flood hazards
4. Public utilities and facilities such as sewer, gas, electrical and water systems shall be located and constructed to minimize or eliminate flood damage.
• (m) Floodways

Floodways are an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles and erosion potential. The following provisions shall apply to floodways:

1. Encroachments are prohibited, including fill, new construction, substantial improvements and other development within the regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the 100 year flood.
2. Under the provisions of the NFIP a community may permit encroachments within the adopted regulatory floodway that would result in an increase in Base Flood Elevation, provided that the community first applies for and obtains a Conditional Letter of Map Revision and floodway revision through FEMA.
• (n) Properties Removed from the Floodplain by Fill

A Floodplain Development Permit shall not be issued for the construction of a new structure or addition to an existing structure on a property removed from the floodplain by the issuance of a FEMA Letter of Map Revision Based on Fill (LOMR-F), unless such new structure or addition complies with the following:

1. Residential Construction
   • The lowest floor (including basement), electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities (including ductwork), must be elevated to one foot above the Base Flood Elevation that existed prior to the placement of fill.
2. Nonresidential Construction
   • The lowest floor (including basement), electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities (including ductwork), must be elevated to one foot above the Base Flood Elevation that existed prior to the placement of fill, or together with attendant utility and sanitary facilities be designed so that the structure or addition is watertight to at least one foot above the base flood level that existed prior to the placement of fill with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads of effects of buoyancy.

• (o) Standards for Critical Facilities
  • A Critical Facility is a structure or related infrastructure, but not the land on which it is situated, as specified in Rule 6 of the Rules and Regulations for Regulatory Floodplains in Colorado, that if flooded may result in significant hazards to public health and safety or interrupt essential services and operations for the community at any time before, during and after a flood.
    1. Protection for Critical Facilities
       • All new and substantially improved Critical Facilities and new additions to Critical Facilities located within the SFHA shall be regulated to a higher standard than structures not determined to be Critical Facilities. For the purposes of this section, protection shall include one of the following:
         • (a) Location outside the SFHA; or
         • (b) Elevation of the lowest floor or flood proofing of the structure, together with attendant utility and sanitary facilities, to at least two feet above the Base Flood Elevation.
    2. Ingress and Egress for New Critical Facilities
       • New Critical Facilities shall, when practicable as determined by the Board of County Commissioners, have continuous non-inundated access (ingress and egress for evacuation and emergency services) during a100-year flood event.
• (p) Floodplain Hazards - Uses Permitted
  • The following uses shall be permitted in the SFHA area to the extent that they are not prohibited by any other regulation and they comply with the guidelines set forth in this Section 7-20-40.
    1. Agricultural uses such as general farming, grazing, forestry, sod farming and wild crop harvesting.
    2. Identified and approved public and private recreational uses are permitted in the SFHA only if the approved uses do not cause a concentration of people in such areas during high flood hazard probability. Any structures associated with such uses shall be subject to the provisions of this Section 7-20-40. Terrestrial and aquatic habitat restoration activities shall also be an allowed use in the SFHA, provided that the BOCC makes a finding that the restoration project has been designed for the purpose of restoring, or preventing further degradation of the natural, dynamic functions of the river, stream, or other body of water; the applicant shall be required to provide sufficient scientific information to establish both the existence of pre-restoration degradation and the scope and desirability of the post-restoration improvements. Acceptable scientific information may include, but is not limited to, information on channel hydrology, site geomorphology, streambed characteristics, macroinvertebrate populations, and fish populations. Applicant must also demonstrate that the scientific information provided has been generated by an individual(s) or legal entity (ies) qualified to render an assessment in all pertinent subject areas. This demonstration may be provided in the form of a curriculum vitae (CV) for an individual, a company resume of project experience, personnel certifications and licenses, etc., or any other manner reasonable under the circumstances.
    3. Bridges or other structures for irrigation, drainage, flood control, hydropower, or water diversion may be allowed upon approval of plans and specifications by the County Floodplain Administrator and Community Development Director, provided they are engineered to prevent blockage of drainage channels during peak water flows and their placement does not result in the loss of wetlands or riparian areas. All structures shall be required to clear span the waterway to the maximum extent practicable. Any structures associated with such uses shall be subject to the provisions of this Section 7-20-40.
    4. Bank stabilization, riparian restoration work and restoration of natural, dynamic riverine functions (in accordance with the requirements of Section 7-20-40 may also be permitted in the SFHA upon the BOCC finding that any adverse impacts will be adequately mitigated, as required by Section 7-20-80.
    5. Placement and maintenance of improvements for a micro hydroelectric facility may be permitted within the SFHA, upon finding that any adverse impacts will be adequately mitigated, as required by Section 7-20-80.
• (q) Redstone Townsite Floodplain Exemption Area
  • Because of the extensive historical development within the SFHA of the Redstone Townsite, the public interest in providing incentives for the preservation of the historic character of the Townsite, and the determination that the SFHA will not be unduly impacted, any property within the Redstone Townsite zoned Village Commercial or Village Residential shall be allowed to develop within the SFHA, subject to the conditions outlined in 7-20-40 (f) and (g), and the following development standards:
    1. No alternative Building Site:
       • If there is no alternative building site on the property, development may be approved subject to compliance with the minimum development standards set forth in Sec. 7-20-40 and 7-20-50.
    2. Building Site with Fewer Impacts:
       • If the building site proposed creates fewer impacts than if the development was limited exclusively to an area outside of the 100-year SFHA, development may be approved subject to compliance with the minimum development standards set forth in Sec. 7-20-40 and Sec. 7-20-50.
• (r) Lazy Glen Floodplain Exemption Area
  • Because of the existing mobile home park development within the SFHA of the Lazy Glen MHP Subdivision/PUD, any property within the Lazy Glen MHP Subdivision/PUD shall be allowed to develop within the SFHA, subject to Sec. 7-20-40(j) and the following development standards:
    1. Structures on all lots located within the 100-year SFHA shall be placed so that the lowest loor is at least 1-foot above the Base Flood Elevation.
    2. Structures on all lots located within the 100-year SFHA shall be firmly anchored to the ground so as not to float or drift during the catastrophic event.
    3. Water heater, furnaces, and other major appliances shall be placed on or above the lowest floor in structures on all lots located within the SFHA.
    4. Basements are prohibited. Crawl spaces shall be limited to a maximum depth of four feet below existing grade.