Section 15.68.080   Permitting requirements applicable to all floodplain areas.
   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.
   B.    Water and Sewer Lines. New and replacement water supply systems, wells, sanitary sewer lines and on-site disposal systems shall meet the requirements of § 602.17-20 of the WMO.
   C.   Carrying Capacity and Notification. For all projects involving channel modification, fill or stream maintenance (including levees), 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.   Protecting Buildings. All buildings located within a one hundred (100) year floodplain also known as an SFHA, shall be protected from flood damage below the flood protection elevation in accordance with this Section. 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 structural alteration to an existing building, if the cost of the alteration equals or exceeds fifty (50) percent of the pre-alteration market value of the building.
      3.   Installing a manufactured home on a new site or a new manufactured home on an existing site.
   E.   Building Protection Methods. Building protection requirements may be met by one of the following methods.
      1.   A residential or nonresidential building, when allowed, may be constructed on permanent land fill in accordance with the following:
         a.   The lowest floor (including basement) shall be at or above the FPE.
         b.   The fill shall be placed in layers no greater than one foot deep before compaction and shall meet the requirements of § 602.11 of the WMO. The fill shall be protected against erosion and scour. The fill shall not adversely affect the flow or surface drainage from or onto neighboring properties.
         c.   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.
      2.   A residential or nonresidential building may be elevated in accordance with the following:
         a.   The building or improvements 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 one hundred (100) year frequency flood. The permanent openings shall be no more than one foot above grade, and consist of a minimum of two openings that allow an automatic entry and exit of floodwaters (without human intervention and without an outside source of electricity). 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 BFE.
         b.   The foundation and supporting members shall be anchored and aligned in relation to the 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 FPE shall be constructed of materials resistant to flood damage. The lowest floor (including basement) and all electrical, heating, ventilating, plumbing, and air conditioning equipment and utility meters shall be located at or above the FPE. 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 FPE shall be used for storage of items or materials.
         e.   When the building wall encloses open space that is below the BFE, gravity storm and sanitary sewer connections are specifically prohibited and overhead sewers are required for the sanitary connections and sumps for the storm sewer connections.
      3.   Only a nonresidential building may be structurally dry floodproofed instead of being elevated, provided that:
         a.   An Illinois Registered Professional Engineer, retained by the applicant, shall certify that the building has been structurally dry floodproofed below the FPE, and that the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood or one hundred (100) year frequency flood.
         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 operable without human intervention and without an outside source of electricity.
         d.   For purposes of this subsection, levees, berms, floodwalls and similar works are not considered floodproofing.
      4.   Detached tool sheds and detached garages on an existing single-family lot of record 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.
         b.   All areas below the base flood or one hundred (100) year frequency flood elevation shall be constructed with waterproof materials.
         c.   All structures located in a regulatory floodway shall be constructed and placed on a building site so as not to block the flow of floodwaters and shall also 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.
         d.   The structure shall be anchored to prevent flotation.
         e.   Service facilities such as electrical and heating equipment shall be elevated or floodproofed to the FPE.
         f.   The building shall be valued at less than twenty-five thousand dollars ($25,000.00) as substantiated by a signed contract, and shall have a roofed lot coverage of less than five hundred (500) square feet.
         g.   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)
         h.   Any structure with a roofed lot coverage of more than seventy-five (75) square feet shall meet the permanent opening criteria of Section 15.68.080.E.2.a.
      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.
(Ord. MC-2-2008, Amends, 05/06/2008; Ord. MC-181-97 § 2, 1997; prior code § 28.08)
   F.   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 twenty-four inches (24").
      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 6 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 100-year flood plain shall be prohibited and the structure shall be protected in accordance with Section 15.68.080.E.2 of this Code.
(MC-5-2018, Amended, 08/07/2018: MC-5-2014 §23, 04/17/2014; 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)