The standards of this section apply to all regulatory floodplain development except when superseded by more stringent requirements.
(A) Modification and disturbance. Modification and disturbance of natural riverine regulatory floodplains shall be avoided to protect existing hydrologic and environmental functions. The disturbances shall be minimized and all negative impacts mitigated as described in a mitigation plan.
(B) Prohibited development. No development shall be allowed in the regulatory floodplain that, singularly or cumulatively, creates a damaging or potentially damaging increase in flood heights or velocity, or threat to public health, safety, and welfare, or impairs the natural hydrologic functions of the regulatory floodplain and linear/nonlinear water bodies.
(C) Maintenance of flood carrying capacity. For all projects involving linear water body modification or maintenance, fill, or levees, the flood-carrying capacity of the regulatory floodplain shall be maintained.
(D) Public flood control projects. For public flood control projects, the permitting requirements of this section will be considered met if the applicant can demonstrate to the Illinois Department of Natural Resources, Office of Water Resources through hydraulic and hydrologic calculations that the proposed project will not, singularly or cumulatively, result in increased flood heights outside the project right-of-way or in easements for all flood events up to and including the base flood event.
(E) Compensatory storage capacity. When compensatory storage is required for storage lost or displaced in a regulatory floodplain the following standards shall apply.
(1) Hydraulically equivalent compensatory storage requirements for development activity in a riverine regulatory floodplain shall be at least equal to 1.2 times the volume of regulatory floodplain storage lost or displaced. The compensation areas shall be designed to drain freely and openly to the channel and located opposite or adjacent to fill areas. A restrictive covenant or deed or plat restriction running with the land shall be recorded to prohibit any future modification to the compensation area.
(2) (a) Hydraulically equivalent com-pensatory storage requirements for development activity in a non-riverine regulatory floodplain shall be at least equal to one times the volume of regulatory floodplain storage lost or displaced. Compensation areas shall be designed to access the required volume. A restrictive covenant or deed or plat restriction is required to prohibit any modification to the compensation area. Upon approval of the Planning, Building and Development Director, hydraulic equivalency for non-riverine compensatory storage may be altered, provided that the storage is replaced at or below the existing elevation at which storage is lost or displaced but not below the proposed normal water level.
(b) Hydraulically equivalent com-pensatory storage requirements for development activity in a non-riverine regulatory floodplain, that is located partially on-site, with more than 10% of the BFE surface located on-site, shall be at least equal to 1.2 times the volume of regulatory floodplain storage lost or displaced. Such compensation areas shall be designed to access the required volume. A restrictive covenant or deed or plat restriction is required to prohibit any modification to the compensation area. Upon approval of the Planning. Building and Development Director, hydraulic equivalency for non-riverine compensatory storage may be altered, provided that the storage is replaced at or below the existing elevation at which storage is lost or displaced but not below the proposed normal water level.
(3) Upon approval of the Planning, Building and Development Director, shorelines or streambanks that have experienced erosion may be restored to their condition as of the current effective date of the first Flood Insurance Rate Map in that community without the need to provide compensatory storage or pay fee-in-lieu-of for the fill used to restore the eroded area according to the following criteria.
(a) The restoration fill shall meet existing grades and within riverine areas the current effective regulatory floodplain base flood elevation shall not be increased and the regulatory floodway conveyance shall be maintained.
(b) The amount of eroded property being restored shall be documented and submitted by the applicant as part of the permit process. Proper documentation shall be either field survey information or photo documentation of the erosion that has occurred for the property being restored.
(c) For rivers, lakes, and streams where no floodway has been designated, no documentation of past shoreline erosion is required if the applicant does not exceed one cubic yard of fill per lineal foot for a maximum of 200 feet. In this case the placing of the fill shall not significantly alter the alignment of the shoreline with adjoining properties as determined by the Enforcement Officer. Non-documentable fills are a one-time allowance on a per property basis and all fills exceeding 200 cubic yards shall be regulated as specified in subsection (E).
(d) Shoreline protection measures (e.g., sea wall, rip-rap, deep-rooted vegetation) shall be implemented in conjunction with all shoreline filling conducted under this provision.
(4) An above-ground swimming pool shall not be required to provide compensatory storage for the volume displaced within the regulatory floodplain. The pool shall be anchored to resist flotation. No backfilling of the pool walls will be allowed and any material excavated for the installation shall be removed from floodplain limits.
(5) Compensatory storage is not required in Coastal High Hazard Areas.
(F) Public health protection standards.
(1) For property located within the regulatory floodplain, no chemicals, explosives, buoyant materials, animal waste, fertilizers, flammable liquids, pollutants, or other hazardous or toxic materials shall be placed or stored below the flood protection elevation.
(2) New and replacement water supply systems, wells, and sanitary sewer lines may be permitted, providing all manholes or other above-ground openings located below the flood protection elevation are watertight.
(3) On-site individual sewage disposal systems shall be designed to avoid inundation by the base flood.
(4) If required to repair an existing individual sewage disposal system serving an existing
structure, either shallow or deep filling shall be permitted as a matter of right to the minimum extent necessary to comply with Lake County Health Department requirements for the repair. Compensatory storage shall be provided to the greatest extent possible.
(G) Filling.
(1) Four types of filling of the regulatory floodplain are regulated by this section: shallow filling, deep filling, topdressing erosion, and topdressing subsidence.
(a) Shallow filling is filling to realign contours, protect seawalls, or make yards or lands more useful which does not raise the land surface elevation above the base flood elevation. The placement of fill material so as to constitute shallow filling is permitted by right.
(b) Deep filling is filling which raises the land surface elevation above that of the base flood elevation. The placement of fill material within any regulatory floodplain so as to constitute deep filling shall be permitted only pursuant to § 151.148(B). For the following deep filling activities, all other standards of § 151.149 shall apply.
1. Deep filling required for the construction of a stormwater basin is subject to the standards contained § 151.146(E).
2. Driveway construction to allow access to an attached or detached garage. Maximum allowable are to be deep-filled shall not exceed 1,000 square feet.
3. Fill placed in the floodplain to elevate existing floodtable land where a new structure is being built. Compensatory storage shall be provided. The fill shall not be placed more than ten feet from the foundation of the building.
(c) Topdressing is the placement of not more than four inches of topsoil within the regulatory floodplain for the purposes of stabilizing an existing erosion control problem and establishing vegetative cover. Topdressing shall be allowed by permit on a per-parcel, one-time only allowance, and not damage or alter adjoining property drainage patterns. Upon approval of the Planning, Building and Development Director, floodplain compensatory storage shall not be required. Topdressing fill shall comply with the soil erosion and sediment control standards and wetlands provisions of this chapter (§§ 151.145 through 151.154). This provision shall not be applicable to the design process for new development.
(d) Topdressing is the placement of not more than four inches of topsoil within the regulatory floodplain. For the purposes of restoring pre-subsidence grade to an area that primarily experiences subsidence due to a documented flood event, topdressing shall be allowed by permit on a per-parcel basis and not damage or alter adjoining property drainage patterns. Upon approval of the Planning, Building and Development Director, floodplain compensatory storage shall not be required. Topdressing fill shall comply with the soil erosion and sediment control standards and wetlands provisions of this chapter (§§ 151.145 through 151.154). This provision shall not be applicable to the design process for new development. A one time allowance of this provision shall be in accordance with (1) through (3) of the following criteria and repeat allowances shall be in accordance with (1) through (4) of the following criteria.
1. The restoration fill shall meet pre-subsidence elevations, and within riverine areas, the pre-subsidence effective Regulatory Floodplain and Regulatory Floodway conveyance shall be maintained.
2. The property being considered for top dressing shall be documented and submitted by the applicant as part of the permit process. Proper documentation shall be either topographic information or photographic documentation of the flooding and subsidence that has occurred on the property.
3. Upon completion of top dressing, the applicant shall provide topographic or photographic documentation of completed work.
4. Repeat top dressing applications are limited to documented flood events with topographic or photographic evidence of subsidence.
(e) Impervious surface rehabilitative maintenance is the placement of not more than four inches of pavement or any other impervious material within the regulatory floodplain. For the purposes of restoring pre-subsidence grades to an area that has experienced subsidence, rehabilitative maintenance of such areas shall be allowed by permit on a per-project basis and not damage or alter adjoining property drainage patterns. Upon approval of the Planning, Building and Development Director, floodplain compensatory storage shall not be required. Rehabilitative maintenance fill shall comply with the Soil Erosion and Sediment Control standards and Wetlands Provisions of this chapter (§ 151.146(J) and (M)). This provision shall not be applicable to the design process for new development. A one-time allowance of this provision shall be in accordance with subsections (G)(1)(e)1. through (G)(1)(e)3. of the following criteria and repeat allowances shall be in accordance with subsections (G)(1)(e)1. through (G)(1)(e)4. of the following criteria:
1. The restoration fill shall meet pre-subsidence elevations, and within riverine areas, the pre-subsidence effective regulatory floodplain and regulatory floodway conveyance shall be maintained,
2. The project being considered for rehabilitative maintenance shall be documented and submitted by the applicant as part of the permit process. Proper documentation shall be either topographic information or photographic documentation of the subsidence that has occurred on the project.
3. Upon completion of rehabilitative maintenance, the applicant shall provide topographic or photographic documentation of completed work.
4. Repeat rehabilitative main-tenance applications are limited to documented topographic or photographic evidence of subsidence.
(2) The placement of fill material within any regulatory floodplain so as to constitute either shallow or deep filling shall be subject to the following standards.
(a) Compensatory storage is required for all storage volume lost or displaced due to either shallow or deep filling.
(b) Fill shall be of a material deemed stable enough to remain firm and in place during periods of flooding. Fill shall consist only of soil, rock, or concrete without rebar. Further, all fill areas shall be stabilized with material which will ensure and protect against erosion hazards, undercutting, and undermining. Asphalt shall not be used as a stabilizing material. Runoff and drainage protection shall be provided to adjacent property owners.
(c) All changes in velocity, depth of flood elevation, or storage shall be limited to the property of the owner doing the filling or those property owners who have granted flood or flow easements, provided that in no event shall an increase in flood elevation be permitted if it would affect any existing building or bring any building to within two vertical feet of the flood elevation.
(H) Building protection requirements for Regulatory Floodplains not within Coastal High Hazard Area. No principal or accessory structure shall be located in the regulatory floodplain, below the base flood elevation, with the exception of a road, detached garage, storage shed, swimming pool, boathouse, pump station, lift station, boat launching ramps, boat docks, piers, bridge and bridge approaches, picnic shelters having no permanent walls, and stormwater detention basins. All buildings and structures established in the regulatory floodplain shall conform to the following standards.
(1) Compensatory storage is required for all storage volume lost or displaced due to the placement of any building or structure in the regulatory floodplain.
(2) Building protection requirements for residential structures shall follow applicable FEMA regulations and include the following:
(a) The lowest floor including basements of all new residential structures, including additions, shall be elevated up to at least the Flood Protection Elevation (FPE). The floor of an attached garage for a new structure must be elevated up to at least one-half of one foot above the base flood elevation (BFE).
1. If placed on compacted fill, the top of the fill for a residential structure shall be above the FPE. The top of fill for an attached garage shall be one-half of one foot above the BFE. The fill pad shall be placed at the appropriate elevation and designed to extend a minimum of ten feet out from the building’s designed footprint unless the building is certified by a Licensed Structural Engineer to be protected from damages due to hydrostatic pressures. Additionally, the fill pad shall meet 95% of Standard Proctor Density in order to be demonstrated not to settle below the FPE for the residential structure and not below one-half of one foot above the BFE for an attached garage, and to be adequately protected against erosion, scour, and differential settlement. Foundation excavations shall not extend more than five feet beyond the foundation footprint. Backfill for the over excavated area does not need to meet the compaction requirements.
2. If elevated by means of walls, pilings, or other foundation, the building’s supporting structure must be permanently open to flood waters and not subject to damage by hydrostatic pressures of the base flood. The bottom of the permanent openings shall be no more than one foot above the lowest adjacent grade. The total net area shall be provided below the BFE and consist of a minimum of two openings for each enclosed area with each opening of an enclosed area on a different exterior wall. 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. Any louvers, screens, or other opening covers must not block or impede the automatic flow of floodwaters into and out of the enclosed area. 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, All areas below the FPE shall be constructed with materials resistant to flood damage. The lowest floor (including basement) for the residential structure and all electrical, heating, ventilation, plumbing, air conditioning equipment, and utility meters shall be located at or above the FPE. Waterproofed service facilities, including, but not limited to, water and sewer pipes, electrical and telephone lines, and submersible pumps, may be located below the FPE. No area less than one foot above the BFE shall be used for storage of items or materials.
(b) The lowest floor, including basements, of an existing residential structure with a substantial improvement shall be elevated to at least one foot above the BFE.
1. If placed on compacted fill, the top of the fill for a substantially improved residential structure shall be at least one foot above the BFE. The fill pad shall be placed at the appropriate elevation and designed to extend a minimum of 10 feet out from the building’s designed footprint unless the building is certified by a Licensed Structural Engineer to be protected from damages due to hydrostatic pressures. Additionally, the fill pad shall meet 95% of Standard Proctor Density in order to be demonstrated not to settle below one foot above the BFE for the substantially improved residential structure, and to be adequately protected against erosion, scour, and differential settlement. Foundation excavations shall not extend more than five feet beyond the foundation footprint. Backfill for the over excavated area does not need to meet the compaction requirements.
2. If elevated by means of walls, pilings, or other foundation, the building’s supporting structure must be permanently open to flood waters and not subject to damage by hydrostatic pressures of the base flood. The bottom of the permanent openings shall be no more than one foot above the lowest adjacent grade. The total net area shall be provided below the BFE, and consist of a minimum of two openings for each enclosed area with each opening of an enclosed area on a different exterior wall. 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. Any louvers, screens, or other opening covers must not block or impede the automatic flow of floodwaters into and out of the enclosed area. 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. All areas lower than one foot above the BFE shall be constructed with materials resistant to flood damage. The lowest floor (including basement) for the substantially improved residential structure and all electrical, heating, ventilation, plumbing, air conditioning equipment, and utility meters shall be elevated to at least one foot above the BFE. Waterproofed service facilities, including, but not limited to, water and sewer pipes, electrical and telephone lines, and submersible pumps, may be located below the BFE-plus-one-foot elevation.
(3) Building protection requirements for non-residential structures shall follow applicable Federal Emergency Management Agency regulations and include the following:
(a) The lowest floor, including basements, of all new non-residential buildings, including additions, shall be elevated at least to the FPE or be structurally dry flood-proofed to at least the FPE. A non-residential building may be structurally dry flood-proofed (in lieu of elevation) provided that a Licensed Professional Engineer, Licensed Structural Engineer, or Licensed Architect shall certify that the building has been structurally dry flood-proofed up to the FPE and the structure and attendant utility facilities are watertight and capable of resisting the effects of the base 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. Flood-proofing measures shall be operable without human intervention and without an outside source of electricity. (Levees, berms, floodwalls, and similar works are not considered flood-proofing for the purpose of this subsection.)
1. If a non-residential structure is not dry flood-proofed and is placed on compacted fill, the top of the fill shall be above the FPE. The fill pad shall be placed at the appropriate elevation and designed to extend a minimum of ten feet out from the building’s designed footprint unless the building is certified by a Licensed Structural Engineer to be protected from damages due to hydrostatic pressures. Additionally, the fill pad shall meet 95% of Standard Proctor Density in order to be demonstrated not to settle below the FPE and to be adequately protected against erosion, scour, and differential settlement. Foundation excavations shall not extend more than five feet beyond the foundation footprint. Backfill for the over excavated area does not need to meet the compaction requirements.
2. If a non-residential structure is not dry flood-proofed and is elevated by means of walls, pilings, or other foundation, the building’s supporting structure must be permanently open to flood waters and not subject to damage by hydrostatic pressures of the base flood. The bottom of the permanent openings shall be no more than one foot above the lowest adjacent grade. The total net area shall be provided below the BFE, and consist of a minimum of two openings for each enclosed area with each opening of an enclosed area on a different exterior wall. 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. Any louvers, screens, or other opening covers must not block or impede the automatic flow of floodwaters into and out of the enclosed area. 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. All areas below the FPE shall be constructed with materials resistant to flood damage. The lowest floor (including basement) for the non-residential structure and all electrical, heating, ventilation, plumbing, air conditioning equipment, and utility meters shall be located at or above the FPE. Waterproofed service facilities, including, but not limited to, water and sewer pipes, electrical and telephone lines, and submersible pumps, may be located below the FPE. No area less than one foot above the BFE shall be used for storage of items or materials.
(b) The lowest floor including basements of all substantially improved non-residential buildings and attendant utility facilities shall be elevated or structurally dry floodproofed to a minimum of one foot above the BFE. A substantially improved, nonresidential building may be structurally dry flood-proofed (in lieu of elevation) provided that a Licensed Professional Engineer, Licensed Structural Engineer, or Licensed Architect shall certify that the building has been structurally dry floodproofed up to a minimum of one foot above the BFE and the structure and attendant utility facilities are watertight and capable of resisting the effects of the base 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. Flood-proofing measures shall be operable without human intervention and without an outside source of electricity. (Levees, berms, floodwalls, and similar works are not considered flood-proofing for the purpose of this subsection.)
1. If a substantially improved non-residential structure is not dry floodproofed and is placed on compacted fill, the top of the fill for a nonresidential structure substantial improvement shall be at least one foot above the BFE. The fill pad shall be placed at the appropriate elevation and designed to extend a minimum of ten feet out from the building’s designed footprint unless the building is certified by a Licensed Structural Engineer to be protected from damages due to hydrostatic pressures. Additionally, the fill pad shall meet 95% of Standard Proctor Density in order to be demonstrated not to settle below one foot above the BFE for the residential structure, and to be adequately protected against erosion, scour, and differential settlement. Foundation excavations shall not extend more than five feet beyond the foundation footprint. Backfill for the over excavated area does not need to meet the compaction requirements.
2. If a substantially improved non-residential structure is not dry floodproofed and is elevated by means of walls, pilings, or other foundation, the building’s supporting structure must be permanently open to flood waters and not subject to damage by hydrostatic pressures of the base flood. The bottom of the permanent openings shall be no more than one foot above the lowest adjacent grade. The total net area shall be provided below the BFE, and consist of a minimum of two openings for each enclosed area with each opening of an enclosed area on a different exterior wall. 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. Any louvers, screens, or other opening covers must not block or impede the automatic flow of floodwaters into and out of the enclosed area. 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. All areas lower than one foot above the BFE shall be constructed with materials resistant to flood damage. The lowest floor (including basement) for the substantially improved non-residential structure and all electrical, heating, ventilation, plumbing, air conditioning equipment, and utility meters shall be elevated to at least one foot above the BFE. Waterproofed service facilities, including, but not limited to, water and sewer pipes, electrical and telephone lines, and submersible pumps, may be located below the BFE-plus-one-foot elevation.
COMMENTARY See § 151.145(F)(2)(l)1. and (F)(2)(l)2. for substantial improvement submittal requirements. |
(5) Mobile homes and recreational vehicles which are not road-ready and cannot be disconnected from utilities in a timely manner and installed on-site for more than 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 Tie-Down Act issued pursuant to 77 Ill. Adm. Code 870. The requirements in § 151.149(H)(2) shall apply to this section. Mobile homes and recreational vehicles that are not elevated above the flood protection elevation shall be moved to higher ground within 24 hours when the water level reaches a recreational vehicle site.
(6) Storage sheds, detached garages, and attached garages which are not substantial improvements on an existing single-family platted lot, may be constructed with the lowest floor below one-half (0.5) foot above the BFE in accordance with the following:
(a) The building shall not be used for human habitation.
(b) All areas below the FPE shall be constructed with materials resistant to flood damage. Structures located in a regulatory floodway shall be constructed and placed on a development site so as not to block the flow of flood waters and shall also meet the appropriate use criteria of § 151.150. In addition, all other requirements of this chapter must be met.
(c) The structure shall be anchored to prevent flotation.
(d) Service facilities such as electrical and heating equipment shall be elevated or floodproofed to the FPE.
(e) The building shall be used only for the storage of vehicles or tools and may not contain other rooms, workshops, greenhouses, or similar uses.
(f) If a residence is elevated appropriately, then the area below the residence can be used as a garage, as long as the garage conforms to (a) through (e) above and include permanent flow through openings as described in § 151.149(H)(2)(a)2.
(g) The building shall be valued at less than $24,550 (Feb. 2023 costs) and be no greater than 600 square feet in floor size.
(h) If elevated by means of walls or other foundation, the building’s supporting structure must be permanently open to flood waters on at least two walls and not subject to damage by hydrostatic pressures of the base flood. The permanent openings shall be at grade level and below the base flood elevation, and consist of a minimum of two openings. The openings shall have a total net area of at least one square inch for every one square foot of enclosed area subject to flooding below the base flood elevation. The requirement for permanent openings may be waived by the Planning, Building and Development Director if a Licensed Professional Engineer or Structural Engineer certifies that the building is not water tight, inside and outside hydrostatic pressures will be equal and that the rate at which the water rises will allow for pressures to equalize. 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.
(7) Boathouses may be constructed with the lowest floor below the flood protection elevation in accordance with all of the following:
(a) The boathouse shall be built on an earthen floor or over a water slip;
(b) The boathouse shall not be used for human habitation;
(c) All areas below the base flood elevation shall be constructed with waterproof material;
(d) The boathouse shall be anchored to prevent flotation;
(e) Service facilities such as electrical and heating equipment shall be elevated or flood-proofed to the flood protection elevation (a flood-proofing certificate shall be required); and
(f) The boathouse shall be used only for the storage of boats or tools and may not contain other rooms, workshops, greenhouses, or similar uses.
(8) If the proposed development would result in a change in the base flood elevation of a SFHA, the applicant shall submit sufficient data to Federal Emergency Management Agency or the Lake County Stormwater Management Commission to obtain a Letter of Map Amendment or Letter of Map Revision. Proposed changes to regulatory floodplain and regulatory floodway delineations and the base flood elevation shall be submitted to the Lake County Stormwater Management Commission. The Illinois Department of Natural Resources, Office of Water Resources concurrence is required for changes to the base flood elevation and floodway delineation.
(9) If the proposed development is located in a public body of water, as defined by the Illinois Department of Natural Resources, Office of Water Resources, a permit from the Illinois Department of Natural Resources, Office of Water Resources must be received.
(10) If the proposed development involves the construction, modification, or removal of a dam or an on-stream structure to impound water, an Illinois Department of Natural Resources, Office of Water Resources dam safety permit or letter indicating a permit is not required shall be received prior to the start of development activity.
(11) If flood-proofing construction is required beyond the outside dimensions of an existing habitable, residential, or commercial building, the outside perimeter of the flood-proofing construction shall be placed no further than ten feet from the outside of the building. Compensation of lost storage and conveyance will not be required for flood-proofing activities.
(I) Building Protection Requirement for CHHA. The building protection requirements of this section apply to development, including new construction and substantial improvements in, or partly in, a Coastal High Hazard Area according to the FIRM.
(1) 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 BFE-plus-one-foot elevation, 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.
(a) Water loading values used shall be those associated with the base flood.
(b) Wind loading values shall be those required by the applicable state or local building standards. If no state or local building standards required the application of wind loading values to structural design, then 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.
(2) A licensed professional structural 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 § 151.149(I)(2).
(3) 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.
(a) For the purpose of this section, a breakaway wall shall have a design safe loading resistance of not less than ten and no more than 20 pounds per square foot.
(b) 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 licensed professional structural engineer or architect certifies that the designs proposed meet all of the following conditions:
1. Breakaway wall collapse shall result from a water load less than that which would occur during the base flood; and
2. 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 required by the applicable state or local building standards. If no state or local building standards required the application of wind loading values to structural design, then 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 standards.
(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.
(5) Recreational vehicles, including park models, must either:
(a) Be on site for fewer than 180 consecutive days; or
(b) Be fully licensed and ready for highway use; or
(6) The use of fill for structural support of buildings within a Coastal High Hazard Area is prohibited.
(a) Non-structural fill within a Coastal High Hazard 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.
(7) Man-made alterations of sand dunes within a Coastal High Hazard 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.
(8) Within a Coastal High Hazard 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.
(Ord., § 8.5, passed 10-13-2009; Ord. passed 10-9-2012; Ord. 23-1056, passed 8-8-2023)