(A) Alteration or relocation of a watercourse.
(1) A watercourse or drainway shall not be altered or relocated in any way that in the event of a base flood or more frequent flood will alter the flood carrying characteristics of the watercourse or drainway to the detriment of upstream, downstream or adjacent locations.
(2) No alteration or relocation shall be made until all adjacent communities that may be affected by such action and the state’s Department of Natural Resources have been notified and all applicable permits obtained. Evidence of such notification shall be submitted to the Federal Emergency Management Agency.
(B) Encroachments.
(1) When proposing to permit any of the following encroachments, the standards in § 151.065 shall apply:
(a) Any development that will cause a rise in the base flood elevations within the floodway;
(b) Any development in Zones A, A1-30 and Zone AE without a designated floodway that will cause a rise of more than one foot in the base flood elevation; or
(c) Alteration or relocation of a stream.
(2) Then, the applicant shall:
(a) Apply to FEMA for conditional approval of such action via the conditional letter of map revision process (as per 44 C.F.R. ch. 1, pt. 65.12) prior to the permit for the encroachments; and
(b) Supply the fully approved package to the Floodplain Administrator, including any required notifications to potentially affected property owners.
(3) (a) Standards for the Floodway Overlay District are as follows.
1. New structures for human habitation are prohibited.
2. All encroachments, including fill, new construction, substantial improvements and other development must be prohibited unless certification by a registered professional engineer or architect is provided demonstrating that the development shall not result in any increase in water surface elevations along the floodway profile during the occurrence of the base flood discharge. These developments are also subject to all the standards of Section 5.
3. In Zone A areas, obtain, review and reasonably utilize any flood elevation and floodway data available through federal, state or other sources, including studies done under Section 5-1, in meeting the standards of this section.
(b) Only uses having a low flood damage potential and not obstructing flood flows shall be allowed within the Floodway Overlay District to the extent that they are not prohibited by any other ordinance. The following are recommended uses for the Floodway Overlay District:
1. Agricultural uses such as general farming, pasture, nurseries and forestry;
2. Residential uses such as lawns, gardens, parking and play areas;
3. Non-residential uses such as loading areas, parking and airport landing strips; and
4. Public and private recreational uses such as golf courses, archery ranges, picnic grounds, parks and wildlife and nature preserves.
(4) Elevation and flood-proofing requirements are as follows for residential structures.
(a) In Zones A, AE, A1-30 and AH, all new construction and substantial improvements shall have the lowest floor, including basement, elevated to or above one foot above the base flood elevation.
(b) In Zone AO, all new construction and substantial improvements shall have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as one foot above the depth number specified in feet on the FIRM or, if no depth number is specified on the FIRM, at least as high as three feet.
(c) In the floodway, new structures for human habitation are prohibited.
(5) Regulations for non-residential structures are as follows.
(a) In Zones A, AE, A1-30 and AH, all new construction and substantial improvements shall have the lowest floor, including basement, elevated to or above one foot above the base flood elevation or, together with attendant utility and sanitary facilities, flood-proofed so that below one foot above the base flood elevation:
1. The structure is watertight with walls substantially impermeable to the passage of water;
2. The structure has structural components with the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
3. A registered professional engineer or architect shall certify that the standards of this section are satisfied. A flood-proofing certificate shall be provided to the Floodplain Administrator as set forth in § 151.045 through 151.052.
(b) In Zone AO, all new construction and substantial improvements shall have the lowest floor elevated above the highest adjacent grade at least as high as one foot above the depth number specified in feet on the FIRM or, if no depth number is specified on the FIRM, at least as high as three feet; or, together with attendant utility and sanitary facilities, flood-proofed so that below one foot above the base flood elevation:
1. The structure is watertight with walls substantially impermeable to the passage of water; and
2. The structure has structural components with the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
(c) A registered professional engineer or architect shall certify that the standards of this section are satisfied. A flood-proofing certificate shall be provided to the Floodplain Administrator as set forth in § 151.045 through 151.052.
(6) Regulations for the space below lowest floor are as follows.
(a) Fully enclosed areas below the lowest floor (excluding basements) and below the base flood elevation shall be used solely for the parking of vehicles, building access or limited storage of readily removable items.
(b) Fully enclosed areas below the lowest floor (excluding basements) and below the base flood elevation 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 architect or meet or exceed the following minimum criteria:
1. A minimum or two openings having a net total area of not less than one square inch for every one square foot of enclosed space;
2. The bottom of all openings shall not be higher than one foot above grade; and
3. Openings may be equipped with screens, louvers, valves or other coverings or devices provided that they allow the automatic entry and exit of floodwaters.
(7) Structures accessory to a principal building may have the lowest floor below one foot above base flood elevation provided that the structure complies with the following requirements:
(a) The structure shall not be used for human habitation;
(b) The use of the structure must be limited to parking of vehicles or storage of items readily removable in the event of a flood warning;
(c) The floor area shall not exceed 400 square feet;
(d) The structure shall have a low damage potential;
(e) The structure must be adequately anchored to prevent flotation, collapse or other lateral movement;
(f) The structure shall be designed to automatically provide for the entry and exit of floodwaters for the purpose of equalizing hydrostatic forces. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:
1. A minimum of two openings having a net area of not less than one square inch for every one square foot of enclosed space;
2. The bottom of all openings shall not be higher than one foot above grade; and
3. Openings may be equipped with screens, louvers, valves or other coverings or devices provided that they allow the automatic entry and exit of floodwaters.
(g) No utilities shall be installed in the structure, except electrical fixtures which must be elevated or flood-proofed to one foot above base flood elevation;
(h) The structure shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters; and
(i) If the structure is converted to another use, it must be brought into full compliance with the minimum standards governing such use.
(8) Manufactured homes shall adhere to the following standards.
(a) All manufactured homes are required to be placed or substantially improved within floodplains on sites:
1. Outside of a manufactured home park or subdivision;
2. In a new manufactured home park or subdivision;
3. In an expansion to an existing manufactured home park or subdivision;
4. In an existing manufactured home park or subdivision on which a manufactured home as incurred substantial damage as the result of a flood; and
5. Be elevated on a permanent foundation such that the lowest floor of the manufactured home is at or above one foot above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of this section.
(b) Manufactured homes are required to be placed or substantially improved on sites in an existing manufactured home park or subdivision within special flood hazard areas that are not subject to the provisions of Section 5-2 be elevated so that either:
1. The lowest floor of the manufactured home is at or above one foot above the base flood elevation; or
2. The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade; and be securely anchored to an adequately anchored foundation system in accordance with the provisions of Section 5.2(F)(iv).
(c) New manufactured home parks of five acres or 50 lots, whichever is less, shall follow the standards of Section 5.3(H), “Subdivisions.”
(d) All manufactured homes shall be anchored to resist flotation, collapse or lateral movement. Manufactured homes must be anchored in accordance with local building codes or FEMA guidelines. In the event that over-the-top ties to ground anchors are used, the following specific requirements (or their equivalent) shall be met:
1. Over-the-top ties be provided at each of the four corners of the manufactured home, with two additional ties per side at intermediate locations and manufactured homes less than 50 feet long requiring one additional tie per side;
2. Frame ties be provided at each corner of the manufactured home with five additional ties per side at intermediate points and manufactured homes less than 50 feet long requiring four additional ties per side; and
3. Any additions to the manufactured home be similarly anchored.
(9) Existing structures shall adhere to the following rules.
(a) The provisions of this chapter do not require any changes or improvements to be made to lawfully existing structures. However, when an improvement is made to a structure in the floodplain, a floodplain development permit is required and the provisions of 5.2(G)(ii-iv) shall apply.
(b) Any addition, alteration, reconstruction or improvement of any kind to an existing structure where the costs of which would equal or exceed 50% of the pre-improvement market value shall constitute a substantial improvement and shall fully comply with the provisions of this chapter.
(c) Any addition, alteration, reconstruction or improvement of any kind to an existing structure in the floodway shall comply with the provisions of Section 5-1.
(d) Any addition, alteration, reconstruction or improvement of any kind to an existing structure that will change the compliance requirements of the building shall require applicable documentation including an elevation certificate, flood-proofing certificate or no rise certification.
(10) Design and construction standards are as follows.
(a) All buildings or structures shall be firmly anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
(b) All buildings or structures shall be constructed with materials and utility equipment resistant to flood damage. All buildings or structures shall also be constructed by methods and practices that minimize flood and flood-related damages.
(c) All buildings or structures shall be constructed with electrical, heating, ventilation, plumbing, 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 conditions of flooding.
(11) Within Zones AO and AH, adequate drainage paths around structures on slopes shall be required in order to guide floodwaters around and away from proposed structures.
(12) Provisions for water supply and sanitary sewer systems are as follows.
(a) All new or replacement water supply and sanitary sewer systems shall be located, designed and constructed to minimize or eliminate flood damages to such systems and the infiltration of floodwaters into the systems.
(b) All new or replacement sanitary sewage systems shall be designed to minimize or eliminate discharge from the system into floodwaters.
(c) On-site waste disposal systems shall be located and designed to avoid impairment to them or contamination from them during flooding.
(13) All other utilities such as gas lines, electrical, telephone and other utilities shall be located and constructed to minimize or eliminate flood damage to such utilities and facilities.
(a) The storage or processing of materials that are in time of flooding buoyant, flammable, explosive or could be injurious to human, animal or plant life is prohibited.
(b) The storage of other material or equipment may be allowed if not subject to major damage by floods and firmly anchored to prevent flotation or if readily removable from the area within the time available after flood warning.
(c) Within any floodway, recreational vehicles and recreational vehicle parks shall be prohibited.
(d) Recreational vehicles to be placed on sites within the floodplain shall:
1. Be on site for fewer than 180 consecutive days;
2. Be fully licensed and ready for highway use, which shall mean it is on its wheels or jacking system, is attached to the site by only quick-disconnect type utilities and security devices, and no permanently attached additions; or
3. Meet the permit requirements and the elevation and anchoring requirements for manufactured homes of this chapter.
(14) Subdivision proposals and other proposed new development, including manufactured home parks or subdivisions, shall require assurance that:
(a) All such proposals are consistent with the need to minimize flood damage;
(b) All public utilities and facilities such as sewer, gas, electrical and water systems are located, elevated and constructed to minimize or eliminate flood damage;
(c) Adequate drainage is provided so as to reduce exposure to flood hazards; and
(d) 1. Proposals for development (including proposals for manufactured home parks and subdivisions) of five acres or 50 lots, whichever is less, where base flood elevation data are not available, shall be supported by hydrologic and hydraulic analyses that determine base flood elevations and floodway information.
2. The analyses shall be prepared by a licensed professional engineer in a format required by FEMA for conditional letters of map revision and a letters of map revision.
(Ord. 23-09, passed 8-21-2023) Penalty, see § 151.999