In addition to the requirements found in Sections 4-12-5, 4-12-6 and 4-12-7 for Development in Flood Fringes, Designated Floodways, and Floodplains where no Floodways have been identified, the following requirements shall be met. Where an existing or proposed Building or other Development is affected by multiple flood zones, by multiple BFEs, or both, the Development activity must comply with the provisions of the Ordinance applicable to the most restrictive flood zone and the highest base flood elevation affecting any part of the existing or proposed Building, or for other developments, affecting any part of the Development area.
A. Public Health and Other Standards
1. No Developments in the Floodplain shall include locating or storing chemicals, explosives, buoyant materials, animal 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 4-12-8 of this Chapter.
2. Public utilities and facilities such as sewer, gas and electric shall be located and constructed to minimize or eliminate Flood damage.
3. Public sanitary sewer systems and water supply systems shall be located and constructed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters.
4. New and replacement water supply systems, wells, sanitary sewer lines and on-site waste disposal systems may be permitted providing all manholes or other above ground openings located below the FPE are watertight. 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.
5. 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.
B. Carrying Capacity and Notification of Adjacent Communities
1. For all projects involving Channel Modification, fill, or stream maintenance (including levees), the Flood carrying capacity of the watercourse shall be maintained.
2. 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.
C. Protecting Buildings:
1. In addition to the damage prevention requirements in this Chapter, all Buildings located within a Floodplain, shall be protected from Flood damage below the FPE. This Building protection criteria applies to the following situations:
a. New Construction or placement of a new Building or alteration or addition to an existing Building.
b. Substantial Improvements, made to any existing Building. If substantially improved, both the existing Building and any addition must meet the Flood protection standards of this Section.
c. Substantially Damaged Building under repair. Substantial Damage shall be figured cumulatively during a ten (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. If Substantially Damaged, the entire Building must meet the Flood Protection standards of this Section.
d. Installing a Manufactured Home on a new site or a Manufactured Home on an existing site.
e. Installing a travel trailer or Recreational Vehicle on a site for more than one hundred and eighty (180) consecutive days; and
f. Repetitive Loss to an existing Building.
2. 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:
(1) The fill shall be placed in layers no greater than six inches before compaction and must extend at least twenty (20) feet beyond the foundation before sloping below the FPE in lieu of a geotechnical report.
(2) The fill shall be protected against erosion and scour during flooding by vegetative cover, riprap, or other structural measure.
(3) The fill shall be composed of clean rock or soil and not include debris or refuse material.
(4) The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties.
b. If the Building's lowest floor is elevated above ground level with an enclosed or unenclosed area below the lowest floor:
(1) The Building shall be elevated on piles, walls, columns, or other foundation that is permanently open to floodwaters.
(2) 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.
(3) All electrical lines, switches, receptacles, and fixtures must be located above the FPE except to the minimum extent required by applicable building or lifesafety 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.
(4) 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.
(5) All Building components below the FPE shall be constructed of materials resistant to Flood damage.
(6) Water and sewer pipes, electrical and telephone lines, submersible pumps, and other service facilities may be located below the FPE provided they are waterproofed.
(7) The area below the FPE shall be used solely for parking, storage, or building access and not later modified or occupied as habitable space.
3. 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:
a. Be elevated to or above the FPE, subject to the more specific additional requirements of Sections 4-12-8(C) above; or
b. 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:
(1) 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.
(2) The Building design accounts for Flood velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the effects of buoyancy, and impact from debris and ice.
(3) Floodproofing measures will be incorporated into the Building design and operable without human intervention and without an outside source of electricity.
(4) The Building, utility, and sanitary facilities' design and construction will prevent the effect of sewer backup into the building.
(5) Levees, berms, floodwalls, and similar works are not considered Floodproofing for the purpose of this Chapter.
4. In zones A, AO, AH, and AE, all placement or substantial improvement of Manufactured Homes and permanent installation of travel trailers on site for more than one hundred and eighty (180) consecutive days, shall be:
a. Elevated with the Lowest Floor at or above the FPE using a support and anchoring system, designed by a P.E. pursuant to 77 Ill. Adm. Code § 870.110.
b. Anchored to resist flotation, collapse, or lateral movement by being tied down in accordance with the rules and regulations for the Illinois Mobile Home Tie-Down Act issued pursuant to 77 Ill. Adm. Code § 870.220
5. In zones A, AO, AH, and AE, travel trailers and Recreational Vehicles, on site for more than one hundred and eighty (180) consecutive days, shall meet the elevation requirement and anchoring requirements of Section 4-12-8(C)(4) unless the following conditions are met:
a. The vehicle must be either self-propelled or towable by a light duty truck.
b. The vehicle must not be attached to any permanent additions or external Structures, such as decks and porches.
c. The vehicle must be designed solely for recreation, camping, travel, or seasonal use rather than as a permanent dwelling.
d. The vehicles having a total area not exceeding four hundred (400) square feet when measured at the largest horizontal projection.
e. The vehicle's wheels must remain on axles and have inflated tires.
f. Any air conditioning units must be attached to the frame so as to be safe for movement out of the Floodplain.
g. The vehicle must be attached to a site only by quick disconnect type utilities and security devices. Utility connections include, but are not limited to, propane tanks, electrical and sewage.
h. The vehicle must be licensed and titled as a Recreational Vehicle or park model, be entirely supported by jacks, or have a hitch jack permanently mounted, have the tires touching the ground and be supported by block in a manner that will allow the block to be easily removed by use of the jacks/hitch jack.
6. In zones A, AO, AH, and AE, detached Accessory Structures may be constructed with the Lowest Floor below the FPE provided the following conditions are met:
a. The Building must be non-habitable, 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 Floodresistant materials.
c. The Building must be used only for the storage and parking and cannot be modified later into another use.
d. The Building shall be located outside of the Designated 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 also meet the Appropriate Use criteria of Section 4-12-6(B), and all other applicable requirements of this Chapter.
e. 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.
f. No plumbing, heating, or air conditioning shall be permitted in Accessory Structures allowed under this Subsection to be wet floodproofed in lieu of elevation.
g. The structure must have at least two (2) permanent openings on at least two walls not more than one (1) foot above grade and below the BFE, with one (1) square inch of opening for every one (1) square foot of floor area.
h. The structure must be no more than one story in height and no more than six hundred (600) square feet in size.
i. The Building shall be anchored to resist floatation and overturning.
j. All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, etc.) shall be stored above the FPE.
k. 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.
7. In Floodplain zones AO and AH, drainage paths shall be provided to guide water around and away from the Buildings.
8. The repair, remodeling, or maintenance of existing Buildings located within a Designated Floodway, built before November 18, 1987, are exempt from 17 Ill. Adm. Code Part 3708, including the more restrictive Appropriate Use standards. Such Buildings are not exempt from Section 4-12-8(C)(1), including Substantial Damage and Substantial Improvement requirements, and if enlarged, replaced, or structurally altered must meet the requirements of 17 Ill. Adm. Code Part 3708.
9. New Construction or Substantial Improvement of Critical Facilities within the floodplain or the 0.2 percent annual chance flood elevation when defined, shall have the lowest floor (including basement) elevated or structurally dry floodproofed to the 0.2 percent annual chance flood elevation or three feet above the BFE, whichever is greater. Adequate parking shall be provided for staffing of the critical facilities at or above the BFE or 0.2 percent chance flood, when defined. Access routes to all critical facilities should be reviewed and considered when permitting. Access routes should be elevated to or above the level of the BFE.
Floodproofing and sealing measures may also be used to provide protection, as described in Section 4-12-6, and must be taken to ensure that toxic substances will not be displaced by or released into floodwaters.
Critical Facilities include emergency services facilities (such as fire and police stations), schools, hospitals, retirement homes, and senior care facilities.
10. When construction of a building following a LOMR Based on Fill is requested, the condition where a site in the floodplain is removed due to the use of fill to elevate the site above the BFE, the applicant may not apply for a permit from the Village to construct the lowest floor of a building below the BFE in the floodplain.
D. Compensatory Storage.
1. Whenever any portion of a riverine Floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or Structure below the BFE shall be compensated for and balanced by a hydraulically equivalent volume of excavation taken from below the BFE.
2. The excavation volume shall be at least equal to 1.1 times the volume of storage lost due to the fill or Structure.
3. In the case of streams and watercourses, such excavation shall be made opposite or adjacent to the areas so filled or occupied.
4. All Floodplain storage lost below the existing ten percent (10%) annual chance Flood elevation shall be replaced below the proposed ten percent (10%) annual chance Flood elevation. All Floodplain storage lost above the existing one percent (1%) annual chance Flood elevation shall be replaced above the proposed one percent (1%) annual chance Flood elevation. All such excavations shall be constructed to drain freely and openly to the watercourse. (Ord. 3852, 1-10-2022)