In addition to the requirements found in sections 14-1-6, 14-1-7 and 14-1-8 of this chapter for development in flood fringes, designated floodways and SFHA or floodplains where no floodways have been identified (zones A, AO, AH, AE, A1-A30, A99, VO, V1-30, VE, V, M or E), the following requirements shall be met:
A. Public Health Standards:
1. No developments in the SFHA shall include locating or storing chemicals, explosives, buoyant materials, animal wastes, fertilizers, flammable liquids, pollutants, or other hazardous or toxic materials below the FPE, or anywhere within this floodway, floodplain or flood fringe.
2. New and replacement water supply systems, wells, sanitary sewer lines and on site waste disposal systems may be permitted, providing all manholes or other aboveground openings located below the FPE are watertight. The city does not support wells, new sanitary sewer lines (except interceptor sewers) or on site waste disposal systems in the floodway.
B. 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. In addition, the city 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: All buildings located within a 100-year floodplain, also known as an SFHA, shall be protected from flood damage below the flood protection elevation. This building protection criteria applies to the following situations:
Improvements, structural alterations including replacements or reconstructions made to an existing building that increase the floor area by more than twenty percent (20%) or substantial improvements to existing structures. In these cases, the existing structure and the addition must meet the flood protection standards of this section, which includes, but is not limited to, elevating the finished floor at two feet (2') above the BFE;
Repairs made to a substantially damaged building. If a building is determined to be substantially damaged, the entire structure must meet the flood protection standards of this section, which includes, but is not limited to, elevating the finished floor two feet (2') above the BFE;
Installing a manufactured home on a new site or a new manufactured home on an existing site. This building protection requirement does not apply to returning a mobile home to the same site it lawfully occupied before it was removed to avoid flood damage;
Installing a travel trailer on a site for more than one hundred eighty (180) days; and
"Repetitive loss" to an existing building as defined in section 14-1-2 of this chapter. This building protection requirement may be met by one of the following methods:
1. A residential or nonresidential building, when allowed, may be constructed on permanent landfill in accordance with the following:
a. The lowest floor (including basement) shall be at two feet (2') above the base flood elevation.
b. The fill shall be placed in layers no greater than one foot (1') deep before compaction and should extend at least ten feet (10') beyond the foundation of the building before sloping below the flood protection elevation. The top of the fill shall be above the flood protection elevation. However, the ten foot (10') minimum may be waived if a structural engineer certifies an alternative method to protect the building from damages due to hydrostatic pressures. The fill shall be protected against erosion and scour. The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties.
2. A residential or nonresidential building may be elevated in accordance with the following:
a. The building or improvement shall be elevated on crawl space, stilts, piles, walls or other foundation that is permanently open to floodwaters and not subject to damage by hydrostatic pressures of the base flood or 100-year frequency flood. The permanent openings shall be no more than one foot (1') above grade, and consist of a minimum of two (2) openings. The openings must have a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding below the base flood elevation.
b. The foundation and supporting members shall be anchored and aligned in relation to flood flows and adjoining structures so as to minimize exposure to known hydrodynamic forces such as current, waves, ice and floating debris.
c. All areas below the flood protection elevation shall be constructed of materials resistant to flood damage. The lowest floor (including basement) and all electrical, heating, ventilating, plumbing and air conditioning equipment, utility meters, and other service facilities (including ductwork) shall be located or waterproofed to the flood protection elevation. Water and sewer pipes, electrical and telephone lines, submersible pumps and other waterproofed service facilities may be located below the flood protection elevation.
d. No area below the flood protection elevation shall be used for storage of items or materials.
e. When the building wall encloses open space that is below the base flood elevation, gravity, storm and sanitary sewer connections are specifically prohibited and overhead sewers are required for the sanitary connections and sumps for the storm sewer connection.
f. Manufactured homes and travel trailers, to be installed on a site for more than one hundred eighty (180) days, shall be elevated to or above the flood protection elevation; and shall be anchored to resist flotation, collapse or lateral movement by being tied down in accordance with the rules and regulations for the Illinois mobile home tiedown act issued pursuant to 77 Illinois administrative code 870.
3. Only an existing nonresidential building may be structurally dry floodproofed (in lieu of elevation); provided, that a registered professional engineer shall certify that the building has been structurally dry floodproofed below the flood protection elevation, the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood or 100-year frequency flood. 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. Floodproofing measures shall be operable without human intervention and without an outside source of electricity (levees, berms, floodwalls and similar works are not considered floodproofing for the purpose of this subsection).
4. A building may be constructed with a crawl space located below the flood protection elevation provided that the following conditions are met:
a. The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy; and
b. Any enclosed area below the flood protection elevation shall have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. A minimum of one opening on each wall having a total net area of not less than one square inch per one square foot of enclosed area. The openings shall be no more than one foot (1') above grade; and
c. The interior grade of the crawl space below the flood protection elevation must not be more than two feet (2') below the lowest adjacent exterior grade; and
d. The interior height of the crawl space measured from the interior grade of the crawl space to the top of the foundation wall must not exceed four feet (4') at any point; and
e. An adequate drainage system must be installed to remove floodwaters from the interior area of the crawl space within a reasonable period of time after a flood event; and
f. Portions of the building below the flood protection elevation must be constructed with materials resistant to flood damage; and
g. Utility systems within the crawl space must be elevated above the flood protection elevation.
5. Construction of new or substantially improved critical facilities shall be located outside the limits of the floodplain. Construction of new critical facilities shall be permissible within the floodplain if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor (including basement) elevated or structurally dry floodproofed to the 500-year flood frequency elevation or three feet (3') above the level of the 100-year flood frequency elevation whichever is greater. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters. Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities.
D. Inspection: In order to make a damage determination, the director of public works and engineering, or his designee, shall have the authority to conduct an internal inspection of all buildings located within the SFHA that, based on external observation, have been contacted by floodwaters at the foundation level or above within the past one hundred eighty (180) days. The purpose of this inspection will be to:
1. Determine whether damage has occurred to the building as a result of flooding which will require permitted repair work to be conducted and whether the damage qualifies as substantially damaged as defined in this title; and
2. Inform the owner/occupant of the damaged building of the city's flood control regulations.
If an owner/occupant of a property refuses to grant the director of public works and engineering, or his designee, access to inspect a building for the purpose of making a damage determination, the property and the owner/occupant will be declared in violation of this title, and the director of engineering shall be authorized to seek an administrative search warrant for the property from the circuit court of Cook County strictly for the purpose of conducting the inspection authorized by this subsection D. (Ord. M-15-16, 6-6-2016)