In addition to the requirements found in Sections 15.68.050, 15.68.060 and 15.68.070 of this chapter for development in flood fringes, regulatory floodways, and SFHA or floodplains where no floodways have been identified (Zones AO, AH, AE, A1--A30, A99, VO, V1-V30, VE, V, M, E or X), § 601 and § 602 of the WMO and the following requirements shall be met:
A. Public Health Standards. No developments in the SFHA shall include locating or storing chemicals, explosives, buoyant materials, animals' wastes, fertilizers, flammable liquids, pollutants, or other hazardous or toxic materials below the FPE unless such materials are stored in a floodproofed and anchored storage tank and certified by a P.E. or floodproofed building constructed according to the requirements of Section 15.68.080 D.3 of this chapter.
B. Water and Sewer Lines. New and replacement water supply systems, wells, sanitary sewer lines and on-site disposal systems may be permitted providing all manholes or other above ground openings located below the FPE are watertight and shall meet the requirements of § 602.15-17 of the WMO. New and replacement on-site sanitary sewer lines or waste disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding.
C. Carrying Capacity and Notification. For all projects involving channel modification, fill or stream maintenance (including levees), the flood carrying capacity of the watercourse shall be maintained and the project shall meet the requirements of § 606 and § 607 of the WMO. In addition, the Village shall notify adjacent communities in writing thirty (30) days prior to the issuance of a permit for the alteration or relocation of the watercourse.
D. Public utilities and facilities such as telecommunication, gas and electric shall be located and constructed to minimize or eliminate flood damage.
E. All other activities, defined as development, such as pools, fences, filling, paving, etc., shall be designed so as not to alter flood flows or increase potential flood damages.
F. Protecting Buildings. All buildings located within the SFHA, shall be protected from flood damage below the FPE. However, existing buildings located within a regulatory floodway shall also meet the more restrictive appropriate use standards included in Section 15.68.060 of this chapter. These building protection criteria apply to the following situations:
1. New construction or placement of a new building.
2. A substantial improvement to an existing building.
3. Installing a manufactured home on a new site or a new manufactured home on an existing site.
4. A substantially damaged building under repair, the entire building must meet the flood protection standards of this section. Substantial damage shall be figured cumulatively during a 10-year period by comparing the cost to repair the building to its pre-damage condition with the market value of the building immediately prior to the damage, for each event in which the building sustains damage, and adding the percentages of damage for each event.
5. Installing a travel trailer or recreational vehicle on a site for more than 180 consecutive days.
G. Building Protection Methods. Building protection requirements may be met by one of the following methods.
1. Residential Buildings: In zones A, AO, AH, and AE, the lowest floor, including basement, of new construction of residential buildings, and substantially improved residential buildings, must be elevated to the FPE, and are subject to the more specific additional requirements below:
a. If fill, including grading to redistribute onsite material to alter existing topography, is used as a means of elevation:
i. The fill shall be placed in layers no greater than one foot deep before compaction, must extend at least 20 feet beyond the foundation before sloping below the FPE in lieu of a geotechnical report, and shall meet the requirements of § 602 of the WMO. The fill shall be protected against erosion and scour and shall be composed of clean rock or soil and not include debris or refuse material. The fill shall not adversely affect the flow or surface drainage from or onto neighboring properties.
ii. In order to construct a home with or without a basement, on a permanent landfill, the following equation must be satisfied:
Minimum Average Lot Grade = (FPE-2') - [(Total Required Side Yard-12') x 0.0833].
Therefore, if the average lot grade elevation on a site is above the elevation as defined by this equation, then a structure with its lowest floor below the BFE may be constructed. Otherwise, the structure must be protected in accordance with Section 15.68.080.E.2 of this Code.
b. If the building's lowest floor is elevated above ground level with an enclosed or unenclosed area below the lowest floor:
i. The building shall be elevated on piles, walls, columns, or other foundation that is permanently open to floodwaters.
ii. All enclosed areas below the FPE shall provide for equalization of hydrostatic pressures by allowing the automatic entry and exit of floodwaters. A minimum of two (2) permanent openings shall be provided on at least two walls located below the BFE and no more than one (1) foot above finished grade. The openings shall provide a total net area of not less than one (1) square inch for every one (1) square foot of enclosed area subject to flooding, or the design must be certified by a Registered P.E, as providing the equivalent performance in accordance with accepted standards of practice. Refer to FEMA TB1, Openings in Foundation Walls and Walls of Enclosures, for additional guidance.
iii. All electrical lines, switches, receptacles, and fixtures must be located above the FPE except to the minimum extent required by applicable building or life-safety codes. Any switches, receptacles, and/or fixtures required by applicable building or life-safety codes to extend below the FPE shall be rated, or located in enclosures rated, for prolonged submersion.
iv. The building, foundation, and supporting members shall be adequately anchored to prevent flotation, collapse, or lateral movement of the building resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy, and be designed so as to minimize exposure to current, waves, ice, and floating debris.
v. All building components below the FPE shall be constructed of materials resistant to flood damage.
vi. Water and sewer pipes, electrical and telephone lines, submersible pumps, and other service facilities may be located below the FPE provided they are waterproofed.
vii. The area below the FPE shall be used solely for parking, storage, or building access and not later modified or occupied as habitable space.
2. Nonresidential Buildings: In zones A, AO, AH, and AE, the lowest floor (including basement) of new construction of nonresidential buildings, and substantial improvement of nonresidential buildings, must either (1) be elevated to or above the FPE, subject to the more specific additional requirements of Sections 15.68.080.G.1.a through 15.68.080.G.1.b above; or (2) be structurally dry-floodproofed, provided a Registered P.E. or architect has developed and/or reviewed the structural design, specifications, and plans for construction, and the Registered P.E. or architect submits a FEMA Floodproofing Certificate, certifying that the design and methods of construction are in accordance with accepted standards of practice for meeting the requirements of ASCE 24-14, and the following conditions:
a. Below the FPE, the building and attendant utility and sanitary facilities shall be watertight with walls substantially impermeable to the passage of water and structural components capable of resisting hydrostatic and hydraulic loads and the effects of buoyancy.
b. The building design shall take into account flood velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the effects of buoyancy and impacts from debris or ice.
c. Floodproofing measures shall be incorporated into the building design and shall be operable without human intervention and without an outside source of electricity.
d. The building, utility, and sanitary facilities' design and construction will prevent the effect of sewer backup into the building.
e. For purposes of this subsection, levees, berms, floodwalls and similar works are not considered floodproofing.
3. In a coastal high hazard area (zone VE) and in any area of zone AE designated as a moderate wave action area, the building protection requirements of this Section 15.68.080E. must be met according to the following criteria:
a. All new construction and substantial improvements shall be elevated on pilings or columns so that the bottom of the lowest horizontal structural member of the lowest floor (excluding the pilings or columns) is elevated to or above the FPE, and the pile or column foundation and structure attached thereto is anchored to resist flotation, collapse, and lateral movement due to the effects of wind and water loads acting simultaneously on all building components.
i. Water loading values used shall be those associated with the base flood.
ii. Wind loading values shall be those defined according to American Society of Civil Engineers 7-16 Minimum design loads and associated criteria for buildings and other structures, or other equivalent standard.
b. A registered professional engineer or architect shall develop or review the structural design, specifications and plans for the construction, and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of Section 15.68.080.E.4.a.
c. All new construction and substantial improvements shall have the space below the lowest floor either free of obstruction or constructed with non-supporting breakaway walls, open wood lattice-work, or insect screening intended to collapse without causing collapse, displacement, or other structural damage to the elevated portion of the building or supporting foundation system.
i. A breakaway wall shall have a design safe loading resistance of not less than 10 and no more than 20 pounds per square foot.
ii. Use of breakaway walls which exceed a design safe loading resistance of 20 pounds per square foot (either by design or where so required by local or state codes) may be permitted only if a registered professional engineer or architect certifies that the designs proposed meet all of the following conditions:
a) Breakaway wall collapse shall result from a water load less than that which would occur during the base flood; and
b) The elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement, or other structural damage due to the effects of wind and water loads acting simultaneously on all building components (structural and non-structural). Water loading values shall be those associated with the base flood. Wind loading values shall be those defined according to American Society of Civil Engineers 7-16 Minimum design loads and associated criteria for buildings and other structures, or equivalent standard.
c) All space enclosed by breakaway walls, open wood lattice-work, or insect screening below the lowest floor shall be used solely for parking of vehicles, building access, or storage.
4. In Zones A, AO, AH and AE, detached accessory structures and detached garages may be constructed with the lowest floor below the FPE in accordance with the following:
a. The building shall not be used for human habitation, must not include areas intended or used for cooking, and must not include bathrooms, toilet rooms, or shower rooms.
b. All areas below the BFE shall be constructed with flood resistant materials.
c. The structure must have at least two permanent openings on at least two walls not more than one foot above grade and below the BFE, with one square inch of opening for every one square foot of floor area.
d. The building shall be located outside of the regulatory floodway unless the building can be constructed and placed on a building site so as not to block flood flows nor reduce floodway storage, can meet the appropriate use criteria of Section 15.68.060, and all other requirements of Sections 15.68.050, 15.68.060 and 15.68.070.
e. The structure shall be anchored to prevent flotation and overturning.
f. All electrical lines, switches, receptacles, and fixtures must be located above the FPE except to the minimum extent required by applicable building or life-safety codes. Any switches, receptacles, and/or fixtures required by applicable building or life-safety codes to extend below the FPE shall be rated, or located in enclosures rated, for prolonged submersion.
g. The building shall be valued at less than $25,000.00 as substantiated by a signed contract be no more than one-story in height, and shall have a roofed lot coverage of less than five hundred 500 square feet.
h. The building shall be used only for the storage of vehicles or tools and may not contain other rooms, greenhouses or similar uses. (Ord. MC-181-97 § 2, 1997; prior code § 28.08). All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, etc.) shall be stored above the FPE.
i. The lowest floor elevation should be documented, and the owner advised of the flood insurance implications of building with the lowest floor below the BFE.
5. Nonconforming structures located in a regulatory floodway may remain in use, but may not be enlarged, replaced or structurally altered, except to the extent such enlargement, replacement or alteration is permitted by Section 15.68.060 of this chapter. A nonconforming structure damaged by flood, fire, wind or other natural or man-made disaster may be restored provided the value of the damage is less than fifty (50) percent of the structure's market value before it was damaged, and provided that the restoration conforms to all applicable provisions of this chapter.
H. Retaining Walls and Grading Requirements.
1. When retaining walls are used either to bridge the grade differential between the FPE of the clay building pad for a new structure and the existing average lot grade on the site, or to create a vertical surface for any portion of a side of a compensatory storage area, the cumulative height of the retaining walls in the front and side yards shall not exceed 24 inches.
2. When slopes are used to provide a transition between the existing grade and the proposed grade for the top of the permanent fill, or for the construction of a compensatory storage basin, those slopes will be limited to a maximum of 1:6, or 1 foot of vertical rise for every six feet of horizontal run.
3. If a proposed construction or development project cannot meet the requirements of this Subsection F, then the use of permanent fill to elevate the structure out of the SFHA shall be prohibited and the structure shall be protected in accordance with Section 15.68.080.E.2 of this Code.
4. In floodplain zones AO and AH, drainage paths shall be provided to guide water around and away from the buildings.
5. Within a coastal high hazard area or within a moderate wave action area, bulkheads, seawalls, revetments, and other erosion control structures shall not be connected to the foundation or superstructure of a building, and shall be designed and constructed so as not to direct floodwaters or increase flood forces or erosion impacts on the foundation or superstructure of any building.
6. Man-made alterations of sand dunes within a coastal high hazard area (zone V, V1-30, or VE) or within a moderate wave action area are prohibited unless an engineering report documents that the alterations will not increase potential flood damage by reducing the wave and flow dissipation characteristics of the sand dunes.
7. Non-structural fill within a coastal high hazard area (zone V, V1-30, or VE) or within a moderate wave action area shall be permitted only if an engineering report demonstrates that the fill will not cause wave runup, ramping, or deflection of floodwaters that cause damage to buildings.
8. The use of fill for structural support of buildings within a coastal high hazard area (zone V, V1-30, or VE) or within a moderate wave action area is prohibited. (Prior code § 28.08)
(MC-4-2021, § 2, Amended 8/3/2021; Ord MC-5-2018, Amended, 08/07/2018: MC-5-2014 § 23, 04/17/2014; Ord. MC-2-2008, Amends, 05/06/2008; MC-4-2006, Amended, 07/18/2006; MC-5-2001, Amended, 08/21/2001; MC-3-2000, Amended, 09/05/2000, Reflects new FEMA maps; Ord. MC-181-97 § 2, 1997)