Special Districts provide for base districts that allow multiple land uses and flexible development, with the requirement that a specific plan for the area be submitted by applicants. Overlay Districts are used in combination with base districts to modify or expand base district regulations. Overlay Districts are adapted to special needs of different parts of the City of Mount Vernon. The Overlay Districts are designed to achieve the following objectives:

1.   Overlay Districts are intended to help the city manage development in areas that exhibit special characteristics or features that warrant a greater differentiation of standards. These districts may be applied to a parcel in combination with a Base Zoning District.

2.   To recognize special conditions in specific parts of the City which require specific regulation.

3.   To provide flexibility in development and to encourage innovative design through comprehensively planned projects.

The following overlay districts are herewith established:

1.   MU      Mixed Use

   PUD      Planned Unit Development

   ED      Environmental Resources

   HD      Historic

   P      Public

   FP / FW   Floodplain / Floodway

The MU Mixed Use District is intended to accommodate projects which combine several compatible land uses into an integrated development. The MU District may also be used to pre-designate parts of the city which are appropriate for a mixture of residential, commercial, office, and accessory uses. The District permits mixing residential areas with workplaces and services. Development in the MU District must accommodate transportation systems, pedestrian and bicycle movement, and surrounding environments.

1.   Permitted Uses and Minimum Area. Each ordinance establishing an MU District establishes the use types permitted within its boundaries. The minimum area of any MU District is one acre.

2.   Issuance of Permits. Prior to the issuance of any building permits or other authorization, all projects in the MU District shall receive approval by the City Council, following a recommendation by the Planning and Zoning Commission. This approval may be granted for a specific plan for the development of an MU District in lieu of a plan for individual projects, provided that any subsequent developments are consistent with the specific plan.

3.   Applications for Approval. All applications must contain at a minimum the following information:

   A.   A detailed site map, including:

      (a)   A boundary survey

      (b)   Site dimensions

      (c)   Contour lines at no greater than five foot intervals

      (d)   Adjacent public rights of way, transportation routes, and pedestrian or bicycle systems

      (e)   Description of adjacent land uses

      (f)   Utility service to the site and easements through the site

      (g)   Description of other site features, including drainage, soils, or other considerations that may affect development.

   B.   A development plan, including:

      (a)   A site layout, including the location of proposed buildings, parking, open space, and other facilities

      (b)   Location, capacity, and conceptual design of parking facilities

      (c)   Description of the use of individual buildings

      (d)   Description of all use types to be included in the project or area, and maximum floor area devoted to each general use

      (e)   Maximum height of buildings

      (f)   Schematic location and design of open space on the site, including a landscaping plan

      (g)   Vehicular and pedestrian circulation plan, including relationship to external transportation systems

      (h)   Schematic building elevations and sections if required to describe the project

      (i)   Grading plans

      (j)   Proposed sewer and utility improvements

      (k)   Location, sizes, and types of all proposed signage.

   C.   Specific proposed development regulations for the project, including:

      (a)   The specific use types permitted within the proposed district

      (b)   Maximum floor area ratios

      (c)   Front, side, and rear yard setbacks

      (d)   Maximum height

      (e)   Maximum building and impervious coverage

      (f)   Design standards applicable to the project.

   D.   A traffic impact analysis, if required by the City.

4.   Adoption of District. The Planning and Zoning Commission and City Council shall review and evaluate each Mixed Use District application. The City may impose reasonable conditions, as deemed necessary, to ensure that a Mixed Use District (MUD) shall be compatible with adjacent land uses, will not overburden public services and facilities and will not be detrimental to public health, safety and welfare.

   A.   The Planning and Zoning Commission, after proper notice, shall hold a public hearing and act upon each application.

   B.   The Planning and Zoning Commission may recommend amendments to MU district applications.

   C.   The recommendation of the Planning and Zoning Commission shall be transmitted to the City Council for final action.

   D.   The City Council, after proper notice, shall hold a public hearing and act upon any Ordinance establishing a MU Mixed Use District. Proper notice shall mean the same notice established for any other zoning amendment.

   E.   An Ordinance adopting a Mixed Use District shall require a favorable simple majority of the City Council for approval.

   F.   Upon approval by the City Council, the Development Plan shall become a part of the Ordinance creating or amending the Mixed Use District. All approved plans shall be filed with the City Clerk.

5.   Amendments. The Zoning Administrator is authorized at his/her discretion to approve amendments to an approved development plan, provided that:

   A.   A written request is filed with the Zoning Administrator, along with information specifying the exact nature of the proposed amendment.

   B.   The amendment is consistent with the provisions of this section.

   C.   The amendment does not alter the approved site regulations of the development plan and does not materially alter other aspects of the plan, including traffic circulation, mixture of use types, and physical design.

   D.   Any amendment not conforming to these provisions shall be submitted to the Planning and Zoning Commission and City Council for action.

The PUD Planned Unit Development Overlay District is intended to provide flexibility in the design of planned projects; to permit innovation in project design that incorporates open space and other amenities; and to insure compatibility of developments with the surrounding urban environment. The PUD District may be used in combination with any base district specified in this Ordinance. The PUD District, which is adopted by the City Council with the recommendation of the Planning and Zoning Commission, assures specific development standards for each designated project.

1.   Permitted Uses. Uses permitted in a PUD Overlay District are those permitted in the underlying base district. A PUD also may be combined with an MU Mixed Use District to allow a combination of use types not anticipated by conventional base districts.

2.   Site Development Regulations. Site Development Regulations are developed individually for each Planned Unit Development District, but must comply with the minimum or maximum standards established for the base district, with the following exceptions:

   A.   Lot area and lot width are not restricted, provided that the maximum density allowed for each base district is not exceeded.

   B.   Maximum building coverage shall be the smaller of the allowed building coverage in the base district, or 60 percent.

   C.   Setback requirements may be varied according to the specific Planned Unit Development plan.

3.   Access to Public Streets. Each PUD District must abut a public street for at least 100 feet and gain access from that street.

4.   Application Process. The application for a Planned Unit Development District shall include a Development Plan containing the following information:

   A.   A tract map, showing site boundaries, street lines, lot lines, easements, and proposed dedications or vacations.

   B.   A land use plan designating specific uses for the site and establishing site development regulations, including setback, height, building coverage, impervious coverage, density, and floor area ratio requirements.

   C.   A site development and landscaping plan, showing building locations, or building coverage; site improvements; public or common open spaces; community facilities; significant visual features; and typical landscape plans.

   D.   A circulation plan, including location of existing and proposed vehicular and pedestrian, facilities and location and general design of parking and loading facilities.

   E.   Schematic architectural plans and elevations sufficient to indicate a building height, bulk, materials, and general architectural design.

   F.   A statistical summary of the project, including gross site area, net site area, number of housing units by type, gross floor area of other uses, total amount of parking, and building and impervious surface percentages.

5.   Adoption of District. The Planning and Zoning Commission and City Council shall review and evaluate each Planned Unit Development application. The City may impose reasonable conditions, as deemed necessary to ensure that a PUD shall be compatible with adjacent land uses, will not overburden public services and facilities and will not be detrimental to public health, safety and welfare.

   A.   The Planning and Zoning Commission, after proper notice, shall hold a public hearing and act upon each application.

   B.   The Planning and Zoning Commission may recommend amendments to PUD district applications.

   C.   The recommendation of the Planning and Zoning Commission shall be transmitted to the City Council for final action.

   D.   The City Council, after proper notice, shall hold a public hearing and act upon any Ordinance establishing a Planned Unit Development Overlay District. Proper notice shall mean the same notice established for any other zoning amendment.

   E.   An Ordinance adopting a Planned Unit Development Overlay District shall require a favorable simple majority of the City Council for approval.

   F.   Upon approval by the City Council, the Development Plan shall become a part of the Ordinance creating or amending the PUD District. All approved plans shall be filed with the City Clerk.

6.   Amendment Procedure. Major amendments to the Development Plan must be approved according to the same procedure set forth herewith.

7.   Building Permits. The City shall not issue a building permit, certificate of occupancy, or other permit for a building, structure, or use within a PUD District unless it is in compliance with the approved Development Plan or any approved amendments.

8.   Termination of PUD District. If no substantial development has taken place in a Planned Unit Development District for three years following approval of the District, the Planning Board shall reconsider the zoning of the property and may, on its own motion, initiate an application for rezoning the property.

The ED Environmental Resources Overlay District enables the adoption of special performance standards in combination with site development regulations of a base district for areas of special environmental significance or sensitivity. These areas include hill environments; wetlands; forested areas; areas with unique soil or drainage characteristics; lake, river, or creek districts; and other areas with special environmental characteristics.

1.   Procedure for Adoption. The creation of an ED Environmental Resources Overlay District may be initiated by the Planning and Zoning Commission or the City Council.

2.   Requirements for Application. An application for the creation of an ED Overlay District must include:

   A.   A statement describing the proposed district's special environmental characteristics and stating the reasons for proposal of the district.

   B.   A map indicating the boundaries of the proposed ED Overlay District, specifying the base district(s) included within these boundaries.

   C.   Supplemental site development regulations and performance standards that apply to the proposed district.

3.   Adoption of District. The Planning and Zoning Commission and City Council shall review and evaluate each ED Overlay District application.

   A.   The Planning and Zoning Commission, after proper notice, shall hold a public hearing and act upon each application.

   B.   The Planning and Zoning Commission may recommend amendments to ED district applications. The recommendation of the Planning and Zoning Commission shall be transmitted to the City Council for final action.

   C.   The City Council, after proper notice, shall hold a public hearing and act upon any Ordinance establishing an ED Environmental Resources Overlay District.

   D.   The Ordinance adopting the ED District shall include a statement of purpose, a description of district boundaries, and a list of supplemental site development regulations and performance standards.

   E.   An Ordinance adopting an ED Overlay District shall require a favorable vote of a simple majority of the City Council for approval. Upon approval by the City Council, each ED Overlay District shall be shown on the Zoning Map, identified sequentially by order of enactment and referenced to the enacting Ordinance.

   G.   Any protest against an ED Overlay District shall be made and filed as provided by Iowa state statutes, and amendments thereto.

4.   Building Permits. Building or other development permits issued by the City in an ED District shall be consistent with the adopted ED District Ordinance.

The HD Historic Overlay District enables the adoption of special performance and development standards in combination with site development regulations of a base district for areas of special historical or architectural significance within the City of Mount Vernon. The District recognizes the importance of historically and architecturally significant districts to the character of Mount Vernon and provides for their conservation.

1.   Public Policy and Purpose. The City recognizes as a matter of public policy that the preservation, protection, perpetuation, and use of structures, sites, places, and objects having a special historical, architectural, archaeological or aesthetic interest or value, are public necessities, and are required in the interest of the health, prosperity, safety, and welfare of the people. The purpose of this district is to:

   A.   Promote the educational, cultural, economic and general welfare of the public through the preservation, protection, and perpetuation, and use of structures, sites, places, and objects which reflect elements of the City's cultural, social, economic, political, or architectural history;

   B.   Protect and enhance the City's attractions to residents, tourists, and visitors, and serve as a support and stimulus to economic development;

   C.    Enhance the visual and aesthetic character, diversity, and interest of the City;

   D.   Foster civic pride in the legacy of beauty and notable achievements of the past;

   E.   Stabilize and improve property values;

   F.   Promote the preservation and use of historic structures, sites, and districts for the education and general welfare of the people of the City.

2.   Procedure for Adoption. The creation of an HD Historic Overlay District may be initiated by the Historic Preservation Commission, the City Council, or by petition from residents of the City.

3.   Requirements for Application. An application for the creation of an HD Overlay District must include:

   A.   A statement describing the proposed district's special historical or architectural characteristics and stating the reasons and criteria for proposal of the district.

   B.   A map indicating the boundaries of the proposed HD Overlay District, specifying the base district(s) included within these boundaries.

   C.   An inventory of the structures or historically important sites located within the boundaries of the proposed district.

   D.   Supplemental city-required site development regulations, design criteria, and performance standards that apply to the proposed district.

4.   Adoption of District. The Historic Preservation Commission, Planning and Zoning Commission, City Council and the State shall review and evaluate each HD Overlay District application in accordance with Iowa State Code 303.34.1.

   A.   The Historic Preservation Commission and the Planning and Zoning Commission, after proper notice, shall hold a public hearing and act upon each application.

   B.   The Historic Preservation Commission, the Planning and Zoning Commission and the State may recommend amendments to HD district applications.

   C.   The recommendation of the Historic Preservation Commission and the Planning and Zoning Commission shall be transmitted to the City Council for final action.

   D.   The City will furnish the State with a copy of the Ordinance for review and comment prior to the public hearing and final approval in accordance with Iowa State Code 303.34.4. The City Council, after proper notice, shall hold a public hearing and act upon any Ordinance establishing an HD Historic Overlay District.

   E.   The Ordinance adopting the HD District shall include a statement of propose, a description of district boundaries, and a list of city-required supplemental site development regulations and performance standards.

   F.   An Ordinance adopting an HD Overlay District shall require a favorable vote of a simple majority of the City Council for approval.

   G.   Upon approval by the City Council each HD Overlay District shall be shown on the Zoning Map, identified sequentially by order of enactment and referenced to the enacting Ordinance.

5.   Building Permits. Building or other development permits issued by the City in an HD District shall be consistent with the adopted HD District Ordinance and shall follow all procedures for review that are established by the City.

The P Public Use District is designed to accommodate major public or civic facilities in the city. The district can be used in combination with one or more base districts. The district recognizes that development regulations that adapt to private development may not be appropriate for major public uses, including campus developments.

1.   Permitted Uses. Uses permitted in a Public Use Overlay District are those permitted in the underlying base district. A “P” Overlay District also may be combined with an MU Mixed Use District to allow a combination of use types not anticipated by conventional base districts.

2.   Site Development Regulations. Site Development Regulations may be developed individually for each Public Use District, but must comply with the following minimum or maximum standards established for the base district:

   A.   Maximum Building Coverage

   B.   Maximum Impervious Coverage

   C.   Floor Area Ratio

3.   Procedure for Adoption. The creation of a P Public Use Overlay District may be initiated by the Planning and Zoning Commission or the City Council.

4.   Requirements for Application. An application for the creation of an P Public Use Overlay District must include a map indicating the boundaries of the proposed P Overlay District, specifying the base district(s) included within these boundaries.

5.   Adoption of District. The Planning and Zoning Commission and City Council shall review and evaluate each P Overlay District application.

   A.   The Planning and Zoning Commission, after proper notice, shall hold a public hearing and act upon each application.

   B.   The Planning and Zoning Commission may recommend amendments to P district applications. The recommendation of the Planning and Zoning Commission shall be transmitted to the City Council for final action.

   D.   The City Council, after proper notice, shall hold a public hearing and act upon any Ordinance establishing a P Overlay District. An Ordinance adopting an P Public Use Overlay District shall require a favorable vote of a simple majority of the City Council for approval.

   E.   The Ordinance adopting the P Public Use Overlay District shall include a statement of purpose, a description of district boundaries, and a list of supplemental site development regulations and performance standards.

   F.   Upon approval by the City Council, each P Public Use Overlay District shall be shown on the Zoning Map, identified sequentially by order of enactment and referenced to the enacting Ordinance.

1.   Statutory Authority, Findings of Fact and Purpose. The Legislature of the State of Iowa has in Chapter 414, Code of Iowa, as amended, delegated the power to cities to enact zoning regulations to secure safety from flood and to promote health and the general welfare.

2.   Findings of Fact.

   A.   The flood hazard areas of the City of Mount Vernon are subject to periodic inundation which can result in loss of life and property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood protection and relief, and impairment of the tax base all of which adversely affect the public health, safety and general welfare of the community.

   B.   These flood losses, hazards, and related adverse effects are caused by: (i) The occupancy of flood hazard areas by uses vulnerable to flood damages which create hazardous conditions as a result of being inadequately elevated or otherwise protected from flooding and (ii) the cumulative effect of obstructions on the floodplain causing increases in flood heights and velocities.

3.   Statement of Purpose. It is the purpose of this Ordinance to protect and preserve the rights, privileges and property of the City of Mount Vernon and its residents and to preserve and improve the peace, safety, health, welfare, and comfort and convenience of its residents by minimizing flood losses with provisions designed to:

   A.    Restrict or prohibit uses which are dangerous to health, safety or property in times of flood or which cause excessive increases in flood heights or velocities.

   B.    Require that uses vulnerable to floods, including public facilities which serve such uses, be protected against flood damage at the time of initial construction or substantial improvement.

   C.    Protect individuals from buying lands which may not be suited for intended purposes because of flood hazard.

   D.    Assure that eligibility is maintained for property owners in the community to purchase flood insurance through the National Flood Insurance Program.

4.   General Provisions. The provisions of this Ordinance shall apply to all lands within the jurisdiction of the City of Mount Vernon which are located within the boundaries of the Floodplain Overlay District as established in Article 5.

5.    Rules for Interpretation of Floodplain Overlay District. The boundaries of the Floodplain Overlay District areas shall be determined by scaling distances on the official Flood Insurance Rate Map. When an interpretation is needed as to the exact location of a boundary, the Zoning Administrator shall make the necessary interpretation. The Board of Adjustment shall hear and decide appeals when it is alleged that there is an error in any requirement, decision, or determination made by the Zoning Administrator in the enforcement or administration of this Ordinance.

6.    Compliance. No structure or land shall hereafter be used and no structure shall be located, extended, converted or structurally altered without full compliance with the terms of this Ordinance and other applicable regulations which apply to uses within the jurisdiction of this Ordinance.

7.    Abrogation and Greater Restrictions. It is not intended by this Ordinance to repeal, abrogate or impair any existing easements, covenants, or deed restrictions. However, where this Ordinance imposes greater restrictions, the provision of this Ordinance shall prevail. All other ordinances inconsistent with this Ordinance are hereby repealed to the extent of the inconsistency only.

8.    Interpretation. In their interpretation and application, the provisions of this Ordinance shall be held to be minimum requirements and shall be liberally construed in favor of the governing body and shall not be deemed a limitation or repeal of any other powers granted by State statutes.

9.    Warning and Disclaimer of Liability. The standards required by this Ordinance are considered reasonable for regulatory purposes. This Ordinance does not imply that areas outside the designated Floodplain Overlay District areas will be free from flooding or flood damages. This Ordinance shall not create liability on the part of the City of Mount Vernon or any officer or employee thereof for any flood damages that result from reliance on this Ordinance or any administrative decision lawfully made thereunder.

10.    Severability. If any section, clause, provision or portion of this Ordinance is adjudged unconstitutional or invalid by a court of competent jurisdiction, the remainder of this Ordinance shall not be affected thereby.

11.   Establishment of Official Floodplain Zoning Map. The Flood Insurance Rate Map (FIRM) for Linn County and Incorporated Areas, City of Mount Vernon, Panels 19113C0465E, 0470E, dated July 20, 2021, which were prepared as part of the Flood Insurance Study for Linn County, is (are) hereby adopted by reference and declared to be the Official Floodplain Zoning Map. The Linn County Flood Insurance Study is hereby adopted by reference and is made a part of this ordinance for the purpose of administering floodplain management regulations.

12.   Standards of Floodplain Overlay District. All development must be consistent with the need to minimize flood damage and meet the following applicable performance standards. Where base flood elevations and floodway data have not been provided in the Flood Insurance Study, the Iowa Department of Natural Resources shall be contacted to compute such data. The applicant will be responsible for providing the Department of Natural Resources with sufficient technical information to make such determination. All development within the Floodplain Overlay District shall:

   A.    Be designed and adequately anchored to prevent flotation, collapse or lateral movement.

   B.    Use construction methods and practices that will minimize flood damage.

   C.    Use construction materials and utility equipment that are resistant to flood damage.

   D.    Obtain all other necessary permits from federal, state and local governmental agencies including approval when required from the Iowa Department of Natural Resources.

13.    Residential Structures. All new or substantially improved residential structures shall have the lowest floor, including basement, elevated a minimum of one (1) foot above the Base Flood Elevation. Construction shall be upon compacted fill which shall, at all points, be no lower than 1.0 ft. above the Base Flood Elevation and extend at such elevation at least 18 feet beyond the limits of any structure erected thereon. Alternate methods of elevating (such as piers) may be allowed subject to favorable consideration by the Board of Adjustment, where existing topography, street grades, or other factors preclude elevating by fill. In such cases, the methods used must be adequate to support the structure as well as withstand the various forces and hazards associated with flooding. All new residential structures shall be provided with a means of access which will be passable by wheeled vehicles during the Base Flood. All new residential structures shall be provided with a means of access which will be passable by wheeled vehicles during the 100-year flood.

14.   Non-residential Buildings. All new or substantially improved non-residential buildings shall have the lowest floor (including basement) elevated a minimum of one (1) foot above the 100-year flood level, or together with attendant utility and sanitary systems, be floodproofed to such a level. When floodproofing is utilized, a professional engineer registered in the State of Iowa shall certify that the floodproofing methods used are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the 100-year flood; and that the structure, below the 100-year flood level is watertight with walls substantially impermeable to the passage of water. A record of the certification indicating the specific elevation (in relation to North AmericanVertical Datum, 1988) to which any structures are floodproofed shall be maintained by the Administrator.

15.    New and Substantially Improved Structures.

   A.    Fully enclosed areas below the "lowest floor" (not including basements) 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 must either be certified by a registered professional engineer or meet or exceed the following minimum criteria:

      1)    A minimum of two (2) 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.

      3)    Openings may be equipped with screens, louvers, valves, or other coverings or devices provided they permit the automatic entry and exit of floodwaters.

      4)    Such areas shall be used solely for parking of vehicles, building access and low damage potential storage.

   B. New and substantially improved structures must be designed (or modified) and adequately anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.

   C. New and substantially improved structures shall be constructed with electric meter, electrical service panel box, hot water heater, heating, air conditioning, ventilation equipment (including ductwork), and other similar machinery and equipment elevated (or in the case of non-residential structures, optionally floodproofed to) a minimum of one (1) foot base flood elevation.

   D. New and substantially improved structures must be constructed with plumbing, gas lines, water/gas meters and other similar service utilities either elevated (or in the case of non­ residential structures, optionally floodproofed to) a minimum of one (1) foot base flood elevation or designed to be watertight and withstand inundation to such a level.

16.   Factory-Built Homes.

   A.    All new and substantially improved factory-built homes, including those placed in existing factory-built home parks or subdivisions, shall be elevated on a permanent foundation such that the lowest floor of the structure is a minimum of one (1) foot above the Base Flood Elevation.

   B.    All new and substantially improved factory-built homes, including those placed in existing factory-built home parks or subdivisions, shall be anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors.

   C.    Recreational vehicles are exempt from the requirements of SECTION 508-16 of this Ordinance regarding anchoring and elevation of factory-built homes when the following criteria are satisfied.

      i.   The recreational vehicle shall be located on the site for less than 180 consecutive days; and, the recreational vehicle must 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 and is attached to the site only by quick disconnect type utilities and security devices and has no permanently attached additions.

      ii.   Recreational vehicles that are located on the site for more than 180 consecutive days or are not ready for highway use must satisfy requirements of SECTION 508-16 of this Ordinance regarding anchoring and elevation of factory-built homes.

17.   Utility and Sanitary Systems. 

   A.    On-site waste disposal and water supply shall be located or designed to avoid impairment to the system or contamination from the system during flooding.

   B.    All new and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system as well as the discharge of effluent into flood waters. Wastewater treatment facilities (other than on-site systems shall be provided with a level of flood protection equal to or greater than one (1) foot above the base flood elevation.

   C.    New or replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system. Water supply treatment facilities (other than on-site systems) shall be provide with a level of protection equal to or greater than one (1) foot above the base flood elevation.

   D.    Utilities such as gas or electrical systems shall be located and constructed minimize or eliminate flood damage to the system and the risk associated with such flood damaged or impaired systems.

18.    Storage of Materials. Storage of materials and equipment that are flammable, explosive or injurious to human, animal or plant life is prohibited unless elevated a minimum of one (l) foot above the Base Flood Elevation. Other material and equipment must either be similarly elevated or (i) not be subject to major flood damage and be anchored to prevent movement due to flood waters or (ii) be readily removable from the area within the time available after flood warning.

19.     Flood Control. Flood control structural works such as levees, flood walls, etc. shall provide, at a minimum, protection from a Base Flood with a minimum of 3 ft. of design freeboard and shall provide for adequate interior drainage. In addition, structural flood control works shall be approved by the Department of Natural Resources.

20.    Watercourse Alterations. Watercourse alterations or relocations must be designed to maintain the flood carrying capacity within the altered or relocated portion. In addition, such alterations or relocations must be approved by the Department of Natural Resources.

21.    Subdivision Regulations. Subdivisions (including factory-built home parks and subdivisions) shall be consistent with the need to minimize flood damages and shall have adequate drainage provided to reduce exposure to flood damage. Development associated with subdivision proposals (including the installation of public utilities) shall meet the applicable performance standards of this Ordinance. Subdivision proposals intended for residential use shall provide all lots with a means of access which will be passable by wheeled vehicles during the Base Flood. Proposals for subdivisions greater than five (5) acres or fifty (50) lots (whichever is less) shall include Base Flood Elevation data for those areas located within the Floodplain Overlay District.

22.    Accessory Structures. Detached garages, sheds, and similar structures that are incidental to a residential use are exempt from the base flood elevation requirements where the following criteria are satisfied.

   A.   The structure shall be designed to have low flood damage potential. Its size shall not exceed 600 sq. ft. in size. Those portions of the structure located less than 1 foot above the base flood elevation must be constructed of flood-resistant materials.

   B.   The structure shall be used solely for low flood damage potential purposes such as vehicle parking and limited storage. The structure shall not be used for human habitation.

   C.    The structure shall be constructed and placed on the building site so as to offer minimum resistance to the flow of floodwaters.

   D.    The structure shall be firmly anchored to prevent flotation, collapse, and lateral movement which may result in damage to other structures.

   E.    The structure's service facilities such as electrical and heating equipment shall be elevated or floodproofed to at least one foot above the 100-year flood level.

   F.     The structure's walls shall include openings that satisfy the provisions of SECTION 508-15-A of this Ordinance.

   G.    Exemption from the base flood elevation requirements for such a structure may result in increased premium rates for flood insurance coverage of the structure and its contents.

23.    Pipeline Crossings. Pipeline river and stream crossings shall be buried in the streambed and banks, or otherwise sufficiently protected to prevent rupture due to channel degradation and meandering.

24.    Maximum Damage Potential Development. All new or substantially improved maximum damage potential development shall have the lowest floor (including basement) elevated a minimum of one (1) foot above the elevation of the 500-year flood, or together with attendant utility and sanitary systems, be floodproofed to such a level. When floodproofing is utilized, a professional engineer registered in the State of Iowa shall certify that the floodproofing methods used are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the 0.2% annual chance flood; and that the structure, below the 0.2% annual chance flood elevation is watertight with walls substantially impermeable to the passage of water. A record of the certification indicating the specific elevation (in relation to North American Vertical Datum 1988) to which any structures are floodproofed shall be maintained by the Administrator. Where 0.2% chance flood elevation data has not been provided in the Flood Insurance Study, the Iowa Department of Natural Resources shall be contacted to compute such data. The applicant will be responsible for providing the Department of Natural Resources with sufficient technical information to make such determinations.

25.   Administration. Appointment, Duties and Responsibilities of Zoning Administrator:

   A.    The Zoning Administrator is hereby appointed to implement and administer the provisions of this Ordinance and will herein be referred to as the Administrator.

   B.    Duties of the Administrator shall include, but not necessarily be limited to the following:

      (a)    Review all floodplain development permit applications to assure that the provisions of this Ordinance will be satisfied.

      (b)    Review floodplain development applications to assure that all necessary permits have been obtained from federal, state and local governmental agencies including approval when required from the Department of Natural Resources for floodplain construction.

      (c)    Record and maintain a record of the elevation (in relation to North American Vertical Datum, 1988) of the lowest floor (including basement) of all new or substantially improved structures in the Floodplain Overlay District.

      (d)    Record and maintain a record of the elevation (in relation to North American Vertical Datum, 1988) to which all new or substantially improved structures have been floodproofed.

      (e)    Notify adjacent communities/counties and the Department of Natural Resources prior to any proposed alteration or relocation of a watercourse and submit evidence of such notifications to the Federal Emergency Management Agency.

      (f)    Keep a record of all permits, appeals and such other transactions and correspondence pertaining to the administration of this Ordinance.

      (g)    Notify the Federal Insurance Administrator of any annexations or modifications to the community's boundaries.

      (h)    Maintain the accuracy of the community's Flood Insurance Rate Maps when;

         i.   Development placed within the Floodway (Overlay) District results in any of the following:

            (i)   An increase in the Base Flood Elevations, or

            (ii)   Alteration to the floodway boundary

         ii.   Development placed in Zones A, AE, AH, and Al-30 that does not include a designated floodway that will cause a rise of more than one foot in the base elevation; or

         iii.   Development relocates or alters the channel.

      Within 6 months of the completion of the development, the applicant shall submit to FEMA all scientific and technical data necessary for a Letter of Map Revision.

26.    Floodplain Development Permit Required. A Floodplain Development Permit issued by the Administrator shall be secured prior to any floodplain development (any approved change to improved and unimproved real estate, including but not limited to buildings or other structures, mining, filling, grading, paving, excavation or drilling operations), including the placement of factory-built homes.

   A.    Application for Permit - Application shall be made on forms furnished by the Administrator and shall include the following:

      (a)    Description of the work to be covered by the permit for which application is to be made.

      (b)   Description of the land on which the proposed work is to be done (i.e., lot, block, track, street address or similar description) that will readily identify and locate the work to be done.

      (c)    Indication of the use or occupancy for which the proposed work is intended.

      (d)    Elevation of the Base Flood

      (e)    Elevation (in relation to North American Vertical Datum, 1988) of the lowest floor (including basement) of structures or of the level to which a building is to be floodproofed.

      (f)    For structures being improved or rebuilt, the estimated cost of improvements and market value of the building prior to the improvements.

      (g)    Such other information as the Administrator deems reasonably necessary (e.g., drawings or a site plan) for the purpose of this Ordinance.

   B.    Action on Permit Application - The Administrator shall, within a reasonable time, make a determination as to whether the proposed floodplain development meets the applicable standards of this Ordinance and shall approve or disapprove the application. For disapprovals, the applicant shall be informed, in writing, of the specific reasons therefore. The Administrator shall not issue permits for variances except as directed by the City Board of Adjustment.

   C.    Construction and Use to be as Provided in Application and Plans - Floodplain Development Permits based on the basis of approved plans and applications authorize only the use, arrangement, and construction set forth in such approved plans and applications and no other use, arrangement or construction. Any use, arrangement, or construction at variance with that authorized shall be deemed a violation of this Ordinance. The applicant shall be required to submit certification by a professional engineer or land surveyor, as appropriate, registered in the State of Iowa, that the finished fill, building floor elevations, floodproofing, or other flood protection measures were accomplished in compliance with the provisions of this Ordinance, prior to the use or occupancy of any structure.

27.    Variance. The Board of Adjustment may authorize upon request in specific cases such variances from the terms of this Ordinance that will not be contrary to the public interest where, owing to special conditions, a literal enforcement of the provisions of this Ordinance will result in unnecessary hardship. Variances granted must meet the following applicable standards:

   A.    Variances shall only be granted upon:

      (a)    A showing of good and sufficient cause,

      (b)    A determination that failure to grant the variance would result in unnecessary hardship to the applicant, and

      (c)    A determination that the granting of the variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public or conflict with existing local codes or ordinances.

   B.    Variances shall only be granted upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.

   C.   In cases where the variance involves a lower level of flood protection for structures than what is ordinarily required by this Ordinance, the applicant shall be notified in writing over the signature of the Administrator that:

      (a)    the issuance of a variance will result in increased premium rates for flood insurance up to amounts as high as $25 for $100 of insurance coverage, and

      (b)    such construction increases risks to life and property.

   D.    Factors Upon Which the Decision of the Board of Adjustment Shall be Based - In passing upon applications for Variances, the Board shall consider all relevant factors specified in other sections of this Ordinance and:

      (a)    The danger to life and property due to increased flood heights or velocities caused by encroachments.

      (b)    The danger that materials may be swept on to other land or downstream to the injury of others.

      (c)    The proposed water supply and sanitation systems and the ability of these systems to prevent disease, contamination and unsanitary conditions.

      (d)    The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner.

      (e)    The importance of the services provided by the proposed facility to the City.

      (f)    The requirements of the facility for a floodplain location.

      (g)    The availability of alternative locations not subject to flooding for the proposed use.

      (h)    The compatibility of the proposed use with existing development and development anticipated in the foreseeable future.

      (i)    The relationship of the proposed use to the comprehensive plan and floodplain management program for the area.

      (j)    The safety of access to the property in times of flood for ordinary and emergency vehicles.

      (k)    The expected heights, velocity, duration, rate of rise and sediment transport of the flood water expected at the site.

      (l)    The cost of providing governmental services during and after flood conditions, including maintenance and repair of public utilities (sewer, gas, electrical and water systems), facilities, streets and bridges.

      (m)     Such other factors which are relevant to the purpose of this Ordinance.

   E.    Conditions Attached to Variances - Upon consideration of the factors listed above, the Board of Adjustment may attach such conditions to the granting of variances as it deems necessary to further the purpose of this Ordinance. Such conditions may include, but not necessarily be limited to:

      (a)    Modification of waste disposal and water supply facilities.

      (b)    Limitation of periods of use and operation.

      (c)    Imposition of operational controls, sureties, and deed restrictions.

      (d)    Requirements for construction of channel modifications, dikes, levees. and other protective measures, provided such are approved by the Department of Natural Resources and are deemed the only practical alternative to achieving the purpose of this Ordinance.

      (e)    Floodproofing measures.

28.   Nonconforming Uses. A structure or the use of a structure or premises which was lawful before the passage or amendment of this Ordinance, but which is not in conformity with the provisions of this Ordinance, may be continued subject to the following conditions:

   a.    If such use is discontinued for six (6) consecutive months, any future use of the building premises shall conform to this Ordinance.

   b.    Uses or adjuncts thereof that are or become nuisances shall not be entitled to continue as nonconforming uses.

   c.    If any nonconforming use or structure is destroyed by any means, including flood, it shall not be reconstructed if the cost is more than fifty (50) percent of the market value of the structure before the damage occurred, unless it is reconstructed in conformity with the provisions of this Ordinance. This limitation does not include the cost of any alteration to comply with existing state or local health, sanitary, building or safety codes or regulations or the cost of any alteration of a structure listed on the National Register of Historic Places, provided that the alteration shall not preclude its continued designation.

29.   Penalties for Violations. Violations of the provisions of this Ordinance or failure to comply with any of the requirements shall constitute a misdemeanor. Any person who violates this Ordinance or fails to comply with any of its requirements shall upon conviction thereof be fined not more than $500.00 (five hundred) or imprisoned for not more than 30 (thirty) days. Nothing herein contained prevent the City of Mount Vernon from taking such other lawful action as is necessary to prevent or remedy violation.

30.   Amendments. The regulations and standards set forth in this Ordinance may from time to time be amended, supplemented, changed, or repealed. No amendment, supplement, change, or modification shall be undertaken without prior approval of the Department of Natural Resources.

31.   Definitions. Unless specifically defined below, words or phrases used in this Ordinance shall be interpreted so as to give them the meaning they have in common usage and to give this Ordinance its most reasonable application.

APPURTENANT STRUCTURES - A structure which is on the same parcel of the property as the principal structure to be insured and the use of which is incidental to the use of the principal structure.

BASE FLOOD - The flood having one (1) percent chance of being equaled or exceeded in any given year. (See 100-year flood).

BASE FLOOD ELEVATION - The elevation floodwaters would reach at a particular site during the occurrence of a base flood event.

BASEMENT - Any enclosed area of a building which has its floor or lowest level below ground level (subgrade) on all sides. Also see "lowest floor."

DEVELOPMENT - Any approved change to improved or unimproved real estate, including but not limited to building or other structures, mining, dredging, filling, grading, paving, excavation, drilling operations or storage of equipment or materials. "Development" does not include "minor projects" or "routine maintenance of existing buildings and facilities" as defined in this section. It also does not include gardening, plowing, and similar practices that do not involve filling, grading.

EXISTING CONSTRUCTION - Any structure for which the "start of construction" commenced before the effective date of the first floodplain management regulations adopted by the community.

EXISTING FACTORY-BUILT HOME PARK OR SUBDIVISION - A factory-built home park or subdivision for which the construction of facilities for servicing the lots on which the factory­ built 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) is completed before the effective date of the first floodplain management regulations adopted by the community.

EXPANSION OF EXISTING FACTORY-BUILT HOME PARK OR SUBDIVISION - The preparation of additional sites by the construction of facilities for servicing the lots on which the factory-built 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).

FACTORY-BUILT HOME - Any structure, designed for residential use; which is wholly or in substantial part, made, fabricated, formed or assembled in manufacturing facilities for installation or assembly and installation, on a building site. For the purpose of this Ordinance factory-built homes include mobile homes, manufactured homes and modular homes which are placed on a site for greater than 180 consecutive days and not fully licensed for and ready for highway use.

FACTORY-BUILT HOME PARK - A parcel or contiguous parcels of land divided into two or more factory-built home lots for sale or lease.

FIVE HUNDRED (500) YEAR FLOOD - A flood, the magnitude of which has a two-tenths (0.2) percent chance of being equaled or exceeded in any given year or which, on average, will be equaled or exceeded at least once every five hundred (500) years.

FLOOD - A general and temporary condition of partial or complete inundation of normally dry land areas resulting from the overflow of streams or rivers or from the unusual and rapid runoff of surface waters from any source.

FLOOD INSURANCE RATE MAP (FIRM) - The official map prepared as part of (but published separately from) the Flood Insurance Study which delineates both the flood hazard areas and the risk premium zones applicable to the community.

FLOOD INSURANCE STUDY (FIS) - A report published by FEMA for a community issued along with the community's Flood Insurance Rate Maps(s). The study contains such background data as the base flood discharge and water surface elevations that were used to prepare the FIRM.

FLOODPLAIN -Any land area susceptible to being inundated by water as a result of a flood.

FLOODPLAIN MANAGEMENT - An overall program of corrective and preventive measures for reducing flood damages and promoting the wise use of floodplains, including but not limited to emergency preparedness plans, flood control works, floodproofing and floodplain management regulations.

FLOODPROOFING -Any combination of structural and nonstructural additions, changes, or adjustments to structures, including utility and sanitary facilities, which will reduce or eliminate flood damage to such structures.

FLOODWAY -The channel of a river or stream and those portions of the floodplains adjoining the channel, which are reasonably required to carry and discharge flood waters or flood flows so that confinement of flood flows to the floodway area will not cumulatively increase the water surface elevation of the base flood by more than one (1) foot.

FLOODWAY FRINGE - Those portions of the Special Flood Hazard Area outside the floodway.

HIGHEST ADJACENT GRADE - The highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.

HISTORIC STRUCTURE - Any structure that is:

Listed individually in the National Register of Historic Places, maintained by the Department of Interior, or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing of the National Register;

Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;

Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or,

Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified by either (i) an approved state programs determined by the Secretary of the Interior or (ii) directly by the Secretary of the Interior in states without approved programs.

LOWEST FLOOR - The floor of the lowest enclosed area in a building including a basement except when all the following criteria are met:

The enclosed area is designed to flood to equalize hydrostatic pressure during floods with walls or openings that satisfy the provisions of Section 508-15-A of this Ordinance, and

The enclosed area is unfinished (not carpeted, dry-walled, etc.) and used solely for low damage potential uses such as building access, parking or storage, and

Machinery and service facilities (e.g., hot water heater, furnace, electrical service) contained in the enclosed area are located at least one (1) foot above the 100-year flood level, and

The enclosed area is not a "basement" as defined in this section. In cases where the lowest enclosed area satisfies criteria 1, 2, and 3 above, the lowest floor is the floor of the next highest enclosed area that does not satisfy the criteria above.

MAXIMUM DAMAGE POTENTIAL DEVELOPMENT - Hospitals and like institutions; buildings or building complexes containing documents, data, or instruments of great public value; buildings or building complexes containing materials dangerous to the public or fuel storage facilities; power installations needed in emergency or other buildings or building complexes similar in nature or use.

MINOR PROJECTS - Small development activities (except for filling, grading and excavating) valued at less than $500.

NEW CONSTRUCTION - (new buildings, factory-built home parks)-Those structures or development for which the start of construction commenced on or after the effective date of the first floodplain management regulations adopted by the community.

NEW FACTORY-BUILT HOME PARK OR SUBDIVISION -A factory-built home park or subdivision for which the construction of facilities for servicing the lots on which the factory­ built 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) is completed on or after the effective date of the floodplain management regulations adopted by the community.

RECREATIONAL VEHICLE-A vehicle which is:

Built on a single chassis:

Four hundred (400) square feet or less when measured at the largest horizontal projection; Designed to be self-propelled or permanently towable by a light duty truck; and

Designed primarily not for use as a permanent dwelling but a s temporary living quarters or recreational, camping, travel or seasonal use.

ROUTINE MAINTENANCE OF EXISTING BUILDINGS AND FACILITIES - Repairs necessary to keep a structure in a safe and habitable condition that do not trigger a building permit, provided they are not associated with a general improvement of the structure or repair of a damaged structure. Such repairs include:

Normal maintenance of structures such as re-roofing, replacing roofing tiles and replacing siding;

Exterior and interior painting, papering, tiling, carpeting, cabinets, counter tops and similar finish work;

Basement sealing;

Repairing or replacing damaged or broken window panes;

Repairing plumbing systems, electrical systems, heating or air conditioning systems and repairing wells or septic systems.

SPECIAL FLOOD HAZARD AREA - The land within a community subject to the "base flood". This land is identified on the community's Flood Insurance Rate Map as Zone A, Al-30, AB, AH, AO, AR, and/or A99.

START OF CONSTRUCTION - Includes substantial improvement, and means the date the development permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement, or other improvement, was within 180 days of the permit date. The actual start means either the first placement or permanent construction of a structure on a site, such as pouring of a slab or footings, the installation of pile, the construction of columns, or any work beyond the stage of excavation; or the placement of a factory-built home on a foundation. 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 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. For a substantial improvement, the actual start of construction means the first alteration of any wall, ceiling, floor, or other structural part of the building, whether or not that alteration affects the external dimensions of the building.

STRUCTURE-Anything constructed or erected on the ground or attached to the ground, including, but not limited to, buildings, factories, sheds, cabins, factory-built homes, storage tanks, grain storage facilities and/or other similar uses.

SUBSTANTIAL DAMAGE-Damage of any origin sustained by a structure whereby the cost of restoring the structure to its before-damage condition would equal or exceed fifty (50) percent of the market value of the structure before the damage occurred. Substantial damage also means flood-related damages sustained by a structure on two separate occasions during a 10-year period for which the cost of repairs at the time of such flood event, on the average, equals or exceeds 25 percent of the market value of the structure before the damage occurred.

SUBSTANTIAL IMPROVEMENT - Any improvement to a structure which satisfies either of the following criteria:

Any repair, reconstruction, or improvement of a structure, the cost of which equals or exceeds fifty (50) percent of the market value of the structure either (i) before the "start of construction" of the improvement, or (ii) if the structure has been "substantially damaged" and is being restored, before the damage occurred.

The term does not, however, include any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions. The term also does not include any alteration of an "historic structure", provided the alteration will not preclude the structure's designation as an "historic structure".

Any addition which increases the original floor area of a building by 25 percent or more. All additions constructed after the first floodplain management regulations adopted by the community shall be added to any proposed addition in determining whether the total increase in original floor space would exceed 25 percent.

VARIANCE - A grant of relief by a community from the terms of the floodplain management regulations.

VIOLATION - The failure of a structure or other development to be fully compliant with the community's floodplain management regulations.

The US Highway 30 Overlay District (US30 Overlay District) is intended to provide building and site design guidelines within the overlay district boundary. The intent of this overlay district is to promote growth while protecting the general welfare and values of the community through established architectural standards, site design guidelines, and permitted uses. When a standard or code requirement is not addressed within the US Highway 30 Master Plan, the regulations as contained elsewhere within the City's code for the underlying zoning district in which the property is zoned shall apply. Should a conflict arise between the City Code and standards contained within the Master Plan, the more restrictive requirement, as determined by the Zoning Administrator, shall prevail.

Prior to the development or redevelopment of any parcel located within the US30 Overlay District, the property should be zoned or rezoned, as may be necessary, to be consistent with the land use designation as shown in the US Highway 30 Master Plan Future Land Use Plan and per the US Highway 30 Master Plan Zoning and Overlay Land Use Compatibility Table.

   1.   Permitted Uses. Uses permitted or permitted by approval of a Conditional Use Permit are those uses as listed in the US Highway 30 Master Plan Permitted Uses Table for the underlying Overlay Land Use Category identified for the property. Uses not listed in the table as permitted or permitted conditionally within the corresponding Land Use Category are prohibited even if listed as permitted or permitted conditionally within the underlying zoning of the property.

   2.   Application for Approval. An application is required for the development of a property, the construction of a new building or improvement, the redevelopment of an existing property (including a significant change in use), or an amendment or change to a previously approved site plan located within the US30 Overlay District. An application form, site plan (including required site plan details and number of copies), building elevations, and any additional information, details, and studies, as specified and required by the Zoning Administrator as necessary to determine compliance with all applicable codes and requirements shall be submitted to the Zoning Administrator along with the application fee as established by resolution of the City Council.