Grand Junction City Zoning Code
CHAPTER 21
06 Natural Resources and Environmentally Sensitive Lands
§ 21.06.010 Environmental and sensitive land regulations.
(a)
Purpose.
Environmental and sensitive lands (ESL) regulations shall apply to identified hazard areas and/or lands, which have or may have specific environmental conditions. The intent of this regulation is to:
(1)
Guide development and land use within these areas;
(2)
Protect the public from avoidable financial expenditures for hazard control projects, hazard relief measures and damages to public utilities, streets, and bridges;
(3)
Protect people and property and minimize damage from possible hazards; and
(4)
Provide a mechanism by which people owning/purchasing land can gain information about the land and whether the land is suitable for development.
(b)
Applicability.
The provisions of this section, in addition to any other applicable regulation(s), shall apply to a Planned Development Outline Development plan, Preliminary Subdivision Plat or Minor Subdivision for environmental and sensitive lands. This section shall not apply to the following:
(1)
Development of a single-unit detached dwelling on any lot or parcel in existence as of the Effective Date;
(2)
State, county or City highway personnel engaged in constructing or effecting repair of bridges and/or roads;
(3)
Colorado Division of Wildlife and/or U.S. Fish and Wildlife Service engaged in habitat improvement; and
(4)
Railroad personnel engaged in constructing or effecting repair of bridges and track.
(c)
General Requirements.
(1)
The Director shall administer this Code making any necessary interpretations of maps and other documents or information necessary or required, to determine among other things the boundaries of geologic and wildfire hazard areas.
(2)
Any development application involving a property with a known or suspected geologic hazard shall be submitted by the Director for review by the Colorado Geological Survey.
(3)
Any development application involving a property with a known or suspected wildfire hazard shall be submitted by the Director for review by the State Forestry Service.
(4)
Protection from or against hazard or loss by the application of this regulation is not guaranteed. The analysis and recommendations are based on engineering and scientific studies, which are reasonably believed to be accurate and complete. A review consistent with this regulation does not guarantee, either expressly or impliedly that areas outside of established hazard boundaries or uses permitted within hazard boundaries will be free from damage or that people will be free from death or injury caused by known or unknown hazards. Application of this regulation to any development shall not create any liability on the part of, or create a cause of action against, the City or any officer or employee thereof.
(d)
Wildfire Standards.
(1)
Defensible Space.
Any new residential development on or adjacent to land that is predominantly woods, brush or grasslands, shall be developed to minimize the potential for the buildings to be ignited by wildfire and for a building fire to ignite surrounding woods, brush or grasslands. In addition to all other applicable regulations woods, brush or grassland development shall be developed with the area surrounding each dwelling unit modified and managed using a two-area system as follows:
(i)
Area 1.
Area 1 shall consist of a thirty-foot area immediately surrounding the dwelling unit, not to extend beyond the property line. No dead trees or other dead vegetation may remain in Area 1 at the time of initial sale or initial construction, whichever is first. Area 1 shall be further subdivided into two segments:
(A)
Segment A shall consist of the five feet immediately surrounding all sides of the dwelling unit. All vegetation shall be removed from this area at the time of initial sale or construction, whichever is first. No new vegetation shall be planted in Segment A if the structure is sided with combustible materials such as wood or logs. If noncombustible siding is used, however, low-growing shrubs may remain or be installed. In no case shall shrubs be planted so as to be continuous with grass. No propane tanks may be installed in Segment A and no firewood or other combustible materials may be stored there.
(B)
Segment B shall consist of the 25 feet immediately beyond Segment A. At the time of initial sale or initial construction, whichever occurs first, all installed trees within Area 1 shall be located, and all existing vegetation shall be thinned, as follows to break up the horizontal and vertical continuity of fuels:
a.
Spacing between clumps of brush or trees, as measured between the crown of each clump, shall be no closer than two times the height of the taller clump. The maximum width of any clump of brush or trees shall be no greater than two times the height of the clump. Thinned material shall be removed from the site.
b.
All branches of trees or brush shall be pruned to a minimum height of 10 feet above the ground or one-half the total height of the tree or bush, whichever is less. Pruned material shall be removed from the site.
c.
Propane tanks and firewood may be located in Segment B, but in no case shall such tanks be located within 20 feet of the principal structure. Propane tanks shall be located on gravel pads and shall not be located immediately adjacent to grass-covered areas.
(ii)
Area 2.
Area 2 shall consist of the area immediately beyond Area 1 and extending to 75 feet from the principal structure, not to extend beyond the property line. Trees shall be initially thinned in this area to maintain a minimum of five feet between tree crowns at maturity. All dead trees must be removed from Area 2 prior to initial sale or initial construction, and subsequent dead trees shall be removed annually, except that two dead trees per acre may remain to serve as wildlife habitat.
(2)
Maintenance.
Persons owning, leasing or otherwise maintaining new dwelling units covered by provisions of this Code are responsible for proper maintenance of the defensible space. Maintenance of the defensible space shall include modifying or removing flammable vegetation and keeping leaves, needles, and other dead vegetative material from accumulating on roofs of structures.
(e)
Wildlife Habitat Protection.
(1)
Prior to development of a moderate, high, or very high potential for impact category parcel, as shown on the 1999 Wildlife Composite Map for the urban area or an amended map approved by the City, the developer shall consult with the Colorado Division of Wildlife to substantiate the basis for the potential impact and to address various specific measures to avoid, minimize, or mitigate negative impacts to wildlife and/or habitat.
(2)
New structures shall not be located within 100 feet of the floodways of the Colorado or Gunnison Rivers or as recommended by the Colorado Division of Wildlife. Roads, trails, recreation access sites, bridges, fences, irrigation and water diversion facilities, erosion and flood control devices, underground utilities, and similarly necessary structures may be located within this setback, if necessary. The installation of these structures shall comply with all other applicable federal, state, and local regulations.
(f)
Hillside Development.
(1)
Purpose.
The provisions in this section are designed to accomplish the following:
(i)
Prohibit development or uses which would likely result in a hazardous situation due to slope instability, rock falls, or stormwater runoff and excessive soil erosion;
(ii)
Minimize the threat and consequent damages resulting from hillside area fires by establishing fire protection measures and adequate emergency vehicle access;
(iii)
Preserve natural features, wildlife habitats, natural vegetation, trees, and other natural plant formations;
(iv)
Provide for safe vehicular circulation and access to recreation areas, natural drainage channels, paths, and trails;
(v)
Encourage the location, design, and development of building sites in a manner that will provide for greater aesthetic appeal, blend with the slopes and hillside terrain, minimize the scarring and erosion effects of cutting, filling and grading of hillsides and prohibit development of ridge lines as defined; and
(vi)
Encourage preservation of open space by encouraging clustering or other design techniques to preserve natural terrain, views, and vistas.
(2)
Applicability.
Hillside development standards are applicable to hillside development and excavation of hillside so that:
(3)
Hillside Development Standards.
In furtherance of the purposes set forth in this section, any hillside development shall comply with the tables below. Any portion of a development having a slope greater than 30% with an elevation change of 20 feet or greater shall not be included in calculation of the area of such parcel for the purposes of determining conformity with the minimum lot parcel size and density requirements below.
Table 21.06-1: Minimum Lot Size and Width for Hillside Development: Single-Family, Planned Development, and Cluster Development | ||
|---|---|---|
Average Slope of Development Area | Minimum Lot Size (square feet) [1] | Minimum Lot Width (feet) [2] |
0% to 10% | See existing zone | See existing zone |
10.01% to 20% | 10,000 | At least 100 at front setback line |
20.01% to 30% | 15,000 | At least 200 at front setback line |
30.01%+ | Development not permitted [3] | Development not permitted [3] |
Notes: | |
[1] | Minimum lot size as finally approved. |
[2] | Maximum setback for single-family dwelling structures - 150 feet from public or private street. |
[3] | Development on slopes of greater than 30% is not permitted unless, after review and recommendation by the Planning Commission and approval by the City Council, it is determined that: a) Appropriate engineering measures will be taken to minimize the impact of cuts, fills, erosion and stormwater runoff consistent with the purpose of this section; and b) The developer has taken reasonable steps to minimize the amount of hillside cuts and also has taken measures to mitigate the aesthetic impact of cuts through landscaping or other steps. |
Table 21.06-2: Minimum Width and Maximum Density for Hillside Development: Multiple Dwelling Units | ||
|---|---|---|
Average Slope of Development Area | Minimum Lot Width (feet) | Maximum Density |
0% to 10% | See existing zone | See existing zone |
10.01% to 20% | 100 | Maximum density of underlying zone x 0.80 unless clustered |
20.01% to 30% | 100 | Maximum density of underlying zone x 0.60 unless clustered |
30.01% + | Development not permitted [1] | Development not permitted [1] |
Notes: | |
[1] | Development on slopes of greater than 30% is not permitted unless, after review and recommendation by the Planning Commission and approval by the City Council, it is determined that: a) Appropriate engineering measures will be taken to minimize the impact of cuts, fills, erosion and stormwater runoff consistent with the purpose of this section; and b) The developer has taken reasonable steps to minimize the amount of hillside cuts and also has taken measures to mitigate the aesthetic impact of cuts through landscaping or other steps. |
(4)
Cluster Development.
Property with slopes in excess of 20% may be clustered on the portion of the site with slopes less than 20% per GJMC § 21.06.010(f)(4).
(5)
Determination of Slope and Slope Areas.
(i)
Slope shall be determined on a parcel-by-parcel basis if the slope is not generally uniform.
(ii)
The Director may allow some incursion hillside disturbance between slopes. Such incursions shall not exceed 20 feet unless, upon recommendation of the Planning Commission, the City Council finds that a greater incursion is consistent with the purposes of this section.
(iii)
All property with a slope greater than 30% shall be excluded from the calculation of development area for purposes of determining hillside disturbance and density/intensity limitations.
(iv)
Natural slope delineation for the purposes of this section shall be determined as follows:
(A)
Contour intervals, maps and calculations required to determine the natural slope shall be prepared by the applicant and shall be submitted with the development application.
(B)
Contour maps shall be prepared and certified by a licensed professional engineer or licensed surveyor showing contours at intervals no greater than two feet (the contour map).
(C)
A qualified professional shall prepare all reports, documents, maps, reports, and calculations. The basis of the information used/analyzed shall be conspicuously disclosed thereon. Each report shall include a current statement of the professionals' certifications, credentials, and qualifications to prepare the report.
(D)
The Director may require that the applicant perform a field survey to verify the accuracy of the contour lines shown on the contour map.
(E)
The contour map shall identify profile lines, which shall be used for performing the field survey. Profile lines shall be perpendicular to contour lines and in no case occur at intervals greater than 150 feet apart or 75 feet from a property line.
(6)
Determination of Slope Areas/Density Calculation.
Using the field survey, slopes shall be calculated in horizontal intervals no greater than 40 feet. Points identified as slopes, as listed above, shall be located on the contour map and connected by a continuous line. The area bounded by the lines and intersecting property lines shall be used for determining dwelling unit density.
(7)
Street Design.
TEDS (GJMC Title 29) shall apply to all hillside development, except that streets, roads, driveways, and other vehicular routes shall not traverse property that has a slope greater than 30%. The Planning Commission may recommend and the City Council may approve vehicular routes on slopes greater than 30% when:
(i)
Appropriate engineering measures will be taken to minimize the impact of cuts, fills, erosion, and stormwater runoff consistent with the purposes of this section; and
(ii)
The site design minimizes the amount of hillside cuts and includes measures to mitigate the aesthetic impact of cuts through the use of landscaping and other mitigation measures.
(A)
Existing vegetation, where streets are to be located, shall be preserved to the greatest extent possible. As much as possible street alignment should follow the natural terrain.
(B)
The Director may recommend and the Planning Commission may approve the waiver of sidewalk construction when sidewalk construction would result in excessive grading and/or cut/fill of slopes.
(C)
Vertical or drive-over, curb and gutter, as determined by the Director, shall be installed along all public streets.
(8)
Joint Development Applications.
Multiple owners of hillside property, whether or not such property is contiguous, may file a joint development application for all such property or the City Council may direct the Director to file such an application on behalf of the City.
(i)
For all purposes of this section, hillside property shall be treated as a single development parcel.
(ii)
Development permitted on hillside property, pursuant to this section, may be clustered on any one or more of the parcels under such joint application subject to the requirements and limitations of this section. The provisions of this section shall not allow variance in the use requirements of the underlying and existing zoning category for the receiving parcel and may not result in a violation of the purposes of these regulations.
(g)
Ridgeline Development.
(1)
Purpose.
The City recognizes the value of its visual resources and amenities. The purpose of the ridgeline development standards is to preserve the character of the identified ridgelines and to minimize soil and slope instability and erosion.
(2)
Ridgeline Setback.
(i)
For all lots platted within the mapped ridgeline protection area shown on Exhibits 7.2.C1, 7.2.C2 and 7.2.C3, buildings, fences and walls shall be set back a minimum of 200 feet from the ridgeline except as follows:
(A)
This section does not apply to existing structures or lots platted prior to the Effective Date or to fences constructed primarily of wire.
(B)
This setback can be reduced to a minimum of 30 feet if the applicant produces adequate visual representation that a proposed new structure will not be visible on the skyline from public view, or that mitigation will be provided. Mitigation techniques might include:
a.
Earth tone colors to blend with the surrounding area;
b.
The use of nonreflective materials;
c.
Vegetation to screen and soften the visual impact of the structure; and/or
d.
A reduction of building height or the "stepping" of the building height; or
e.
Other means that minimize the appearance from the road corridor.
(ii)
The required setback shall be measured to the building envelope, to be established at the time of platting.
(3)
Measurements.
(i)
View impact shall be measured by a straight line measuring the line of sight between any public view, public road, or public area and the ridgeline protection area.
(ii)
Ridgeline shall be determined on a site-specific basis and shall be that point at which the line of sight is tangent with the slope profile.
Exhibit 7.2.C1  |
 |
Exhibit 7.2.C3  |
(h)
Natural Resources.
(1)
Natural resources, especially mineral resources, shall be protected. In the event that development is proposed in an area of known mineral deposits, the applicant shall provide an estimate of the economic value of the on-site mineral resources.
(2)
This estimate shall be prepared by a registered engineer and submitted prior to approval of development.
(3)
The City Council shall make an evaluation of the value of both the resource and the cost of extraction prior to development of the property. The City Council may delay development approval until extraction has been accomplished or protection provided within the design of the development.
(i)
Geologic Hazard Maps.
(1)
The Colorado Geological Survey (CGS) has identified geologic hazard areas. The CGS maps, together with explanatory text, references and supporting and supplemental studies, results and findings delineating the boundaries of geologic hazard areas are incorporated into this Code by reference.
(2)
The CGS maps approximate the boundaries of hazard areas. The maps shall primarily provide notice to the Director, Planning Commission, City Council, and the applicant, that geologic hazards may exist and if so require consideration prior to and if approved, during development. Precise boundaries and determination of hazard require on-site evaluation by qualified professionals. The Director may require a detailed engineering analysis, study and/or report if a hazard is known or reasonably believed to exist. The engineering analysis, study and/or report, if required, may, as determined by the Director, be required to include a map of the extent of the hazard, a definition of its degree of severity, a determination of the frequency of occurrence/reoccurrence, an evaluation of the compatibility of the proposed land use and consideration of the means and methods of hazard mitigation.
(3)
Hazard mitigation is not intended to categorically preempt development but development may occur only if mitigation is appropriate and proportionate to the severity and frequency of the hazard.
(4)
Mitigation techniques, which may be acceptable, are:
(5)
Mitigation plans shall be prepared and stamped by a Colorado registered, professional engineer.
(j)
Environmental Audit.
A Phase I environmental audit shall be required for any property dedicated or deeded to the City. The City may require additional investigation.
(Ord. 5267, 7/16/2025; Ord. 5190, 12/20/2023)
§ 21.06.020 Flood damage protection.
(a)
Purpose.
Flood damage prevention regulations promote the public health, safety and general welfare and minimize public and private losses due to flooding. The regulations are designed to:
(1)
Protect human life and health;
(2)
Minimize expenditure of public money for costly flood control projects;
(3)
Minimize the need for rescue and relief efforts associated with flooding;
(4)
Minimize prolonged business interruptions;
(5)
Minimize damage to critical facilities, infrastructure and other public facilities and utilities such as water and gas mains, electric, telephone and sewer lines, streets, and bridges;
(6)
Help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard so as to minimize future flood blight areas;
(7)
Ensure that potential buyers are notified that property is in an area of special flood hazard; and
(8)
Ensure that those who occupy the areas of special flood hazard assume responsibility for their actions.
(b)
Methods and Provisions for Flood Damage Prevention.
In order to accomplish its purposes, this section includes methods and provisions for:
(1)
Restricting or prohibiting uses which are dangerous to health, safety and property because of water or erosion hazard;
(2)
Restricting or prohibiting uses which result in damaging increases in erosion or in flood heights or velocities;
(3)
Requiring that uses vulnerable to floods, including facilities which serve such uses, be protected against flood damage at the time of initial construction;
(4)
Controlling the alteration of natural floodplains, stream channels and natural protective barriers which help accommodate or channel flood waters;
(5)
Controlling filling, grading, dredging and other practices which may increase flood damage; and
(6)
Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or which may increase flood hazards in other areas.
 Figure 06.02-1 Areas of Special Flood Hazard |
(c)
General Provisions.
This section applies to all areas of special flood hazard and areas removed from the floodplain by the issuance of a Federal Emergency Management Agency (FEMA) Letter of Map Revision Based on Fill (LOMR-F) within the City.
(1)
Basis for Establishing the Areas of Special Flood Hazard.
FEMA has identified areas of special flood hazard in a scientific and engineering report entitled, "The Flood Insurance Study for Mesa County and Incorporated Areas," dated October 16, 2012. The study together with the Flood Insurance Rate Maps (FIRMs) are hereby adopted by reference and declared to be a part of this Code. The FIRMs may be superseded by local engineering studies approved by the Director, provided such studies fully describe and analyze, based on the FIRMs and generally accepted engineering practice, design floodwater build-out conditions.
(2)
Compliance.
No structure shall be constructed, located, extended, converted, or altered without full compliance with the terms of this section and other applicable regulations. No land shall be developed without full compliance with the terms of this section and other applicable regulations. For waterways with base flood elevations (BFEs) 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 City's FIRMs, 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 water surface elevation of the base flood more than one-half foot at any point within the City. Under the provisions of 44 CFR Chapter 1, Section 65.12, of the NFIP regulations, the City may approve certain development in Zones A1-30, AE, AH, on the City's FIRM which increases the water surface elevation of the base flood by more than one-half foot; provided, that a conditional FIRM revision through FEMA (Conditional Letter of Map Revision), fulfills the requirements for such revisions as established under the provisions of Section 65.12 and receives FEMA approval.
(3)
Relationship to Existing Restrictions.
This section does not and it is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. If this section and another ordinance, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions on use and development shall prevail and be applied.
(4)
Terms and Provisions.
All terms and provisions of this section shall be:
(5)
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. Larger floods can and will occur. Flood heights may be increased because of manmade or natural causes. This section does not imply that land outside the areas of special flood hazard 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 City, or any officer or employee thereof, or FEMA for any flood damage that results from reliance on this section or any administrative decision lawfully made hereunder.
(6)
Flood Carrying Capacity.
The flood carrying capacity within an altered or relocated portion of any watercourse shall be maintained.
(7)
Records.
The Director shall maintain records obtained as part of a Floodplain Development Permit, including but not limited to the lowest floor and floodproofing elevations for new and substantially improved construction.
(8)
Riverine.
In riverine situations, notice shall be given by the Director to an adjacent community(ies) prior to any alteration or relocation of a watercourse.
(d)
Provisions for Flood Hazard Reduction.
(1)
General Standards.
The following standards shall apply to all property located in special flood hazard areas:
(i)
Anchoring.
(A)
All new construction and substantial improvement shall be anchored to prevent flotation, collapse, or lateral movement of the structure and as anchored must be capable of resisting the hydrostatic and hydrodynamic loads.
(B)
All manufactured homes shall be elevated and anchored to resist flotation, collapse, or lateral movement and as anchored is capable of resisting the hydrostatic and hydrodynamic loads. Methods of anchoring may include, but are not limited to, over the top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces. Specific requirements may be:
a.
Over the top ties provided at each of the four corners of the manufactured home, with two additional ties per side at intermediate locations, with manufactured homes less than 50 feet long requiring one additional tie per side;
b.
Frame ties provided at each corner of the home with five additional ties per side at intermediate points, with manufactured homes less than 50 feet long requiring four additional ties per side;
c.
Each component of the anchoring system shall be capable of carrying a force of 4,800 pounds; and
d.
Any addition to the manufactured home shall be similarly anchored.
(ii)
Construction Materials and Methods.
(A)
All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
(B)
All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
(C)
All new construction and substantial improvements shall be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during flooding.
(iii)
Utilities.
(A)
All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system;
(B)
New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters; and
(C)
On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
(iv)
Subdivision Proposals.
(A)
All subdivision proposals shall be consistent with the need to minimize flood damage;
(B)
All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage;
(C)
All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and
(D)
BFE data shall be provided for subdivision proposals and other proposed development which contain at least 50 lots or five acres (whichever is less).
(2)
Specific Standards.
The following provisions, as determined from BFE data, are required for all special flood hazard areas:
(i)
New Construction and Substantial Improvements.
(A)
New construction and substantial improvement of any residential structure shall have the lowest floor (including basement) elevated at least one foot above the BFE.
(B)
New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall either have the lowest floor (including basement) elevated at least one foot above the level of the BFE; or, together with attendant utility and sanitary facilities, shall:
a.
Be flood-proofed so that below the BFE the structure is watertight with walls being substantially impermeable to the passage of water;
b.
Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
c.
Be certified by a Colorado registered professional engineer. The certification shall state that the design and methods of construction are in accordance with accepted standards of practice and meet the minimum provisions of this Code. Such certifications shall be provided to and reviewed by the Director.
(ii)
Openings in Enclosures Below the Lowest Floor.
For all new construction and substantial improvements, fully enclosed areas below the lowest floor that 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. Designs for meeting this requirement shall be certified by either a Colorado registered professional engineer or architect and must meet or exceed the following minimum criteria:
(A)
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;
(B)
The bottom of all openings shall be no higher than one foot above grade;
(C)
Openings may be equipped with screens, louvers, or other coverings or devices; provided that they permit the automatic entry and exit of floodwaters.
(iii)
Manufactured Homes.
(A)
All manufactured homes that are placed and/or substantially improved on a site:
a.
Outside of a manufactured home subdivision;
b.
In a new manufactured home park or manufactured home subdivision;
c.
In an expansion to an existing manufactured home park or manufactured home subdivision; or
d.
On an existing manufactured home park or manufactured home subdivision on which a manufactured home has incurred substantial damage as a result of a flood;
(B)
Shall be anchored and elevated on a permanent foundation such that the lowest floor of the manufactured home is at least one foot above the BFE;
(C)
The manufactured home shall be securely anchored to an anchored foundation system in order to resist flotation, collapse, and lateral movement; and
(D)
Manufactured homes that are placed or substantially improved on sites in existing manufactured home parks or manufactured home subdivisions that are not subject to the provisions of this subsection shall be elevated so that either:
a.
The lowest floor of the manufactured home is at least one foot above the BFE; or
b.
The manufactured home frame or chassis is supported by reinforced piers or other foundation elements that are no less than 36 inches in height above grade and securely anchored to an anchored foundation system in order to resist flotation, collapse, and lateral movement.
(iv)
Recreational Vehicles.
Recreational vehicles occupied as a temporary dwelling in a special flood hazard area shall meet all of the following requirements or meet permit requirements, elevation, and anchoring requirements for manufactured homes:
(3)
Specific Standards for Areas of Shallow Flooding.
Specific standards are required for special flood hazard areas associated with base flood depths of one to three feet where a clearly defined channel does not exist and where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow; therefore, the following provisions apply:
(i)
Residential Construction.
All new construction and substantial improvements of residential structures must have the lowest floor (including basement) elevated above the highest adjacent grade at least one foot above the depth number specified in feet on the City's FIRM (at least three feet if no depth number is specified). Upon completion of the structure, the elevation of the lowest floor, including basement, shall be certified by a registered Colorado professional engineer.
(ii)
Nonresidential Construction.
(A)
With the exception of critical facilities, all new construction and substantial improvements of nonresidential structures must have the lowest floor (including basement) elevated above the highest adjacent grade at least one foot above the depth number specified in feet on the City's FIRM (at least three feet if no depth number is specified), or together with attendant utility and sanitary facilities be designed so that the structure is watertight to at least one foot above the base flood level 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. A registered Colorado professional engineer or architect shall submit a certification which shall state that the design and methods of construction are in accordance with accepted standards of practice and meet the minimum provisions of this Code.
(B)
Within Zones AH or AO, adequate drainage paths around structures on slopes are required to guide floodwaters around and away from proposed structures.
(4)
Specific Standards for Floodways.
A floodway is an area within a special flood hazard area. The floodway is extremely hazardous due to the velocity of floodwaters, debris, and erosion potential. To mitigate those hazards the following provisions apply:
(i)
Encroachments, including fill, new construction, substantial improvements, and other development are prohibited unless a Colorado registered professional engineer certifies in writing with a no-rise certificate that encroachments will not result in any increase in flood levels during the occurrence of the base flood discharge. The supporting technical date for the no-rise certificate shall be based on the standard step-backwater computer model used to develop the 100-year floodway shown on the FIRM or Flood Boundary and Floodway Map (FBFM), unless otherwise approved by the Director.
(ii)
All new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section.
(5)
Specific Standards for Alteration of a Watercourse.
For all proposed developments that alter a watercourse within a special flood hazard area, the following standards apply:
(i)
Channelization and flow diversion projects shall appropriately consider issues of sediment transport, erosion, deposition, and channel migration and properly mitigate potential problems through the project as well as upstream and downstream of any improvement activity. A detailed analysis of sediment transport and overall channel stability should be considered, when appropriate, to assist in determining the most appropriate design.
(ii)
Channelization and flow diversion projects shall evaluate the residual 100-year floodplain.
(iii)
Any channelization or other stream alteration activity proposed by a project proponent must be evaluated for its impact on the regulatory floodplain and be in compliance with all applicable federal, state and local floodplain rules, regulations and ordinances.
(iv)
Any stream alteration activity shall be designed and sealed by a registered Colorado professional engineer or certified professional hydrologist.
(v)
All activities within the regulatory floodplain shall meet all applicable federal, state, and City floodplain requirements and regulations.
(vi)
Within the regulatory floodway, stream alteration activities shall not be constructed unless the project proponent demonstrates through a floodway analysis and report, sealed by a registered Colorado professional engineer, that there is not more than a 0.00-foot rise in the proposed conditions compared to existing conditions floodway resulting from the project, otherwise known as a no-rise certification.
(vii)
Maintenance shall be required for any altered or relocated portions of watercourses so that the flood-carrying capacity is not diminished.
(6)
Specific Standards for 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), with a lowest floor elevation placed below the base flood elevation with one foot of freeboard that existed prior to the placement of fill.
(7)
Specific Standards for Critical Facilities.
A critical facility is a structure or related infrastructure, but not the land on which it is situated, as classified below, that if flooded may result in significant hazards to public health and safety or interrupt essential services and operations for the City at any time before, during and after a flood.
(i)
Classification of Critical Facilities.
Critical facilities are classified under the following categories: a) essential services; b) hazardous materials; c) at-risk populations; and d) vital to restoring normal services.
(A)
Essential services facilities include public safety, emergency response, emergency medical, designated emergency shelters, communications, public utility plant facilities, and transportation lifelines.
a.
These facilities consist of:
1.
Public safety (police stations, fire and rescue stations, emergency vehicle and equipment storage, and emergency operation centers);
2.
Emergency medical (hospitals, ambulance service centers, urgent care centers having emergency treatment functions, and non-ambulatory surgical structures but excluding clinics, medical offices, and nonurgent care medical structures that do not provide these functions);
3.
Designated emergency shelters;
4.
Communications (main hubs for telephone, broadcasting equipment for cable systems, satellite dish systems, cellular systems, television, radio, and other emergency warning systems, but excluding towers, poles, lines, cables, and conduits);
5.
Public utility plant facilities for generation and distribution (hubs, treatment plants, substations, and pumping stations for water, power, and gas, but not including towers, poles, power lines, buried pipelines, transmission lines, distribution lines, and service lines); and
6.
Air transportation lifelines [airports (municipal and larger)], helicopter pads and structures serving emergency functions, and associated infrastructure (aviation control towers, air traffic control centers, and emergency equipment aircraft hangars).
b.
Specific exemptions to this category include wastewater treatment plants (WWTP), non-potable water treatment and distribution systems, and hydroelectric power generating plants and related appurtenances.
c.
Public utility plant facilities may be exempted if it is demonstrated to the satisfaction of the Director that the facility is an element of a redundant system for which service will not be interrupted during a flood. At a minimum, it shall be demonstrated that redundant facilities are available (either owned by the same utility or available through an intergovernmental agreement or other contract) and connected, the alternative facilities are either located outside of the 100-year floodplain or are otherwise compliant with all floodplain regulations, and an operations plan is in effect that states how redundant systems will provide service to the affected area in the event of a flood. A development approval includes the condition that evidence of ongoing redundancy be provided to the Director upon the Director's request.
(B)
Hazardous materials facilities include facilities that produce or store highly volatile, flammable, explosive, toxic and/or water-reactive materials.
These facilities include:
a.
Chemical and pharmaceutical plants (chemical plant, pharmaceutical manufacturing);
b.
Laboratories containing highly volatile, flammable, explosive, toxic and/or water-reactive materials;
c.
Refineries;
d.
Hazardous waste storage and disposal sites; and
e.
Above ground gasoline or propane storage or sales centers.
(C)
At-risk population facilities include medical care, congregate care, and schools. These facilities consist of:
(D)
Facilities vital to restoring normal services including government operations.
a.
These facilities consist of:
b.
These facilities may be exempted if it is demonstrated to the Director that the facility is an element of a redundant system for which service will not be interrupted during a flood. At a minimum, it shall be demonstrated that redundant facilities are available (either owned by the same entity or available through an intergovernmental agreement or other contract), the alternative facilities are either located outside of the 100-year floodplain or are otherwise compliant with all floodplain regulations and an operations plan is in effect that states how redundant facilities will provide service to the affected area in the event of a flood. Evidence of ongoing redundancy shall be provided to the Director on an as-needed basis as determined by the Director upon request.
(ii)
Protection for Critical Facilities.
All new and substantially improved critical facilities and new additions to critical facilities located within the special flood hazard area shall be regulated to a higher standard than structures not determined to be critical facilities. For the purposes of critical facilities, protection shall include one of the following:
(iii)
Ingress and Egress for New Critical Facilities.
New critical facilities shall, when practicable as determined by the Director, have continuous non inundated access (ingress and egress for evacuation and emergency services) during a 100-year flood event.
(e)
Data, Information, and Interpretation.
(1)
The Director shall obtain and maintain the following information:
(i)
The actual elevation, relative to mean sea level, of the lowest floor, including basement, of each structure;
(ii)
For each new or substantially improved floodproofed structure, the actual elevation, relative to mean sea level, to which the structure has been floodproofed and the required floodproofing certifications;
(iii)
Proof that an applicant has, prior to altering or relocating any watercourse or part thereof, notified adjacent communities and the Colorado Water Conservation Board of such alteration and demonstrated that there is adequate maintenance within the altered or relocated portion of the watercourse so that the flood-carrying capacity is not diminished. The Director shall also submit evidence of such notification to the Federal Emergency Management Agency.
(2)
The Director shall interpret the Flood Insurance Rate Maps (FIRM) to decide location of the boundaries of the areas of special flood hazard.
(Ord. 5190, 12/20/2023)