TITLE 14
FLOOD CONTROL
CHAPTER 1
FLOOD CONTROL REGULATIONS
SECTION:
14-1-1: Purpose
14-1-2: Definitions
14-1-3: How To Use This Chapter
14-1-4: Duties Of Enforcement Officials
14-1-5: Base Flood Elevation
14-1-6: Occupation And Use Of Flood Fringe Areas
14-1-7: Occupation And Use Of Identified Floodways
14-1-8: Occupation And Use Of Special Flood Hazard Areas Where Floodways Are Not Identified
14-1-9: Permitting Requirements Applicable To All Floodplain Areas And Protection Of Buildings
14-1-10: Other Development Requirements
14-1-11: Variances
14-1-12: Disclaimer Of Liability
14-1-13: Penalty
14-1-14: Abrogation And Greater Restrictions
14-1-1: PURPOSE:
This chapter is enacted pursuant to the police powers granted to this city by 65 Illinois Compiled Statutes 5/1-2-1, 5/11-12-12, 5/11-30-2, 5/11-30-8, and 5/11-31-2 by the Illinois constitution for the public health, safety and welfare of its citizens.
The purpose of this chapter is to maintain this city's eligibility in the national flood insurance program; to minimize potential losses due to periodic flooding including loss of life, loss of property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood protection and relief, and impairment of the tax base, all of which adversely affect the public health, safety and general welfare; and to preserve and enhance the quality of surface waters, conserve economic and natural values and provide for the wise utilization of water and related land resources. This chapter is adopted to accomplish the following specific purposes:
   A.   To meet the requirements of 615 Illinois Compiled Statutes 5/18g, the rivers, lakes and streams act.
   B.   To assure that new development does not increase the flood or drainage hazards to others, or create unstable conditions susceptible to erosion.
   C.   To protect new buildings and major improvements to buildings from flood damage.
   D.   To protect human life and health from the hazards of flooding.
   E.   To lessen the burden on the taxpayer for flood control projects, repairs to flood damaged public facilities and utilities and flood rescue and relief operations.
   F.   To make federally subsidized insurance available for property in the city by fulfilling the requirements of the national flood insurance program.
   G.   To comply with the rules and regulations of the national flood insurance program codified as 44 CFR 59 - 79, as amended.
   H.   To protect, conserve and promote the orderly development of land and water resources.
   I.   To preserve the natural characteristics of watercourses and floodplains in order to moderate flood and storm water impacts, improve water quality, reduce soil erosion, protect aquatic and riparian habitat, provide recreational opportunities, provide aesthetic benefits and enhance community and economic development. (Ord. M-15-16, 6-6-2016)
14-1-2: DEFINITIONS:
For the purpose of this chapter, the following definitions are adopted:
ACCESSORY STRUCTURE: A nonhabitable structure which is on the same parcel of property as the principal structure to be insured and the use of which is incidental to the use of the principal structure.
ACT: An act in relation to the regulation of the rivers, lakes and streams of the state of Illinois, 615 Illinois Compiled Statutes 5/5 et seq.
APPLICANT: Any person, firm, corporation or agency which submits an application.
APPROPRIATE USE: Only uses of the designated floodway are permissible and will be considered for permit issuance. The only uses that will be allowed are as specified in subsection 14-1-7B of this chapter.
BASE FLOOD: The flood having a one percent (1%) probability of being equaled or exceeded in any given year. The base flood is also known as the 100-year frequency flood event. Application of the base flood elevation at any location is defined in section 14-1-5 of this chapter.
BASE FLOOD ELEVATION (BFE): The elevation in relation to mean sea level of the crest of the base flood.
BASEMENT: That portion of the building having its floor subgrade (below ground level) on all sides.
BUILDING: A structure that is principally aboveground and is enclosed by walls and a roof. This term includes a gas or liquid storage tank, a manufactured home, mobile home or a prefabricated building. This term also includes recreational vehicles and travel trailers to be installed on a site for more than one hundred eighty (180) days.
CHANNEL: Any river, stream, creek, brook, branch, natural or artificial depression, ponded area, flowage, slough, ditch, conduit, culvert, gully, ravine, wash or natural or manmade drainageway, which has a definite bed and banks or shoreline, in or into which surface or ground water flows, either perennially or intermittently.
CHANNEL MODIFICATION: Alteration of a channel by changing the physical dimensions or materials of its bed or banks. Channel modification includes damming, riprapping (or other armoring), widening, deepening, straightening, relocating, lining and significant removal of bottom or woody vegetation. Channel modification does not include the clearing of dead or dying vegetation, debris or trash from the channel. Channelization is a severe form of channel modification typically involving relocation of the existing channel (e.g., straightening).
COMPENSATORY STORAGE: An artificially excavated, hydraulically equivalent volume of storage within the SFHA used to balance the loss of natural flood storage capacity when artificial fill or structures are placed within the floodplain. The uncompensated loss of natural floodplain storage can increase off site floodwater elevations and flows.
CONDITIONAL APPROVAL OF A DESIGNATED FLOODWAY MAP CHANGE: Preconstruction approval by IDNR/OWR and FEMA of a proposed change to the floodway map. This preconstruction approval, pursuant to this chapter, gives assurances to the property owner that once an appropriate use is constructed according to permitted plans, the floodway map can be changed, as previously agreed, upon review and acceptance of as built plans.
CONDITIONAL LETTER OF MAP REVISION (CLOMR): A letter which indicates that FEMA will revise base flood elevations, flood insurance rate zones, flood boundaries or floodway as shown on an effective flood hazard boundary map or flood insurance rate map, once the as built plans are submitted and approved.
CONTROL STRUCTURE: A structure designed to control the rate of flow that passes through the structure, given a specific upstream and downstream water surface elevation.
CRITICAL FACILITY: Any facility which is critical to the health and welfare of the population and, if flooded, would create an added dimension to the disaster. Damage to these critical facilities can impact the delivery of vital services, can cause greater damage to other sectors of the community, or can put special populations at risk. Examples of critical facilities where flood protection should be required include emergency services facilities (such as fire and police stations), schools, hospitals, retirement homes and senior care facilities, major roads and bridges, critical utility sites (telephone switching stations or electrical transformers), and hazardous material storage facilities (chemicals, petrochemicals, hazardous or toxic substances). Examples of critical facilities where flood protection is recommended include sewage treatment plants, water treatment plants, and pumping stations.
DAM: All obstructions, wall embankments or barriers, together with their abutments and appurtenant works, if any, constructed for the purpose of storing or diverting water or creating a pool. Dams may also include weirs, restrictive culverts or impoundment structures. Underground water storage tanks are not included.
DESIGNATED FLOODWAY: The channel, including on stream lakes, and that portion of the floodplain adjacent to a stream or watercourse, generally depicted on the FEMA FIRM map, which is needed to store and convey the existing 100-year frequency flood discharge with no more than a 0.1 foot increase in stage due to the loss of flood conveyance or storage, and no more than a ten percent (10%) increase in velocities.
   A.   The floodways are designated for on the countywide flood insurance rate map of Cook County prepared by FEMA and dated August 19, 2008. When two (2) floodway maps exist for a waterway, the more restrictive floodway limit shall prevail.
   B.   The floodways for those parts of unincorporated Cook County that are within the extraterritorial jurisdiction of the city of Des Plaines that may be annexed into the city of Des Plaines are designated for the Des Plaines River, Prairie Creek, Farmers Creek, Willow Creek, Weller Creek, and Feehanville Ditch on the countywide flood insurance rate map prepared by FEMA and dated August 19, 2008.
   C.   To locate the designated floodway boundary on any site, the designated floodway boundary should be scaled off the designated floodway map and located on a site plan, using reference marks common to both maps. Where interpretation is needed to determine the exact location of the designated floodway boundary, IDNR/OWR should be contacted for the interpretation.
DETACHED SINGLE-FAMILY GARAGE AND SHED: A structure or structures used for the storage of motor vehicles or other storage incidental to the principal use and which is independent, freestanding and not structurally attached to the principal structure.
DEVELOPMENT: Any manmade change to real estate, including:
   A.   Construction, reconstruction, repair, or placement of a building or any addition to a building;
   B.   Installing a manufactured home on a site, preparing a site for a manufactured home, or installing a travel trailer or recreational vehicle on a site for more than one hundred eighty (180) days. If the travel trailer or recreational vehicle is on site for more than one hundred eighty (180) days, it must be fully licensed and ready for highway use;
   C.   Drilling, mining, installing utilities, construction of roads, bridges, or similar projects;
   D.   Demolition of a structure or redevelopment of a site;
   E.   Clearing of land as an adjunct of construction;
   F.   Construction or erection of levees, walls, fences, dams, or culverts; channel modification; filling, dredging, grading, excavating, paving, or other nonagricultural alterations of the ground surface; storage of materials; deposit of solid or liquid waste;
   G.   Any other activity of man that might change the direction, height, or velocity of flood or surface water, including extensive vegetation removal;
   H.   Substantial improvement of an existing building;
   I.   Development does not include routine maintenance of existing buildings and facilities such as reroofing or resurfacing of roads or driveway replacement when there is no increase in elevation, or gardening, plowing, and similar agricultural practices that do not involve filling, grading, or construction of levees.
ELEVATION CERTIFICATES: A form published by FEMA that is used to certify the elevation to which a building has been elevated. Required with any development within the 100-year floodplain that requires the issuance of a building permit by the city or as directed by the director of public works and engineering.
EROSION: The general process whereby soils are moved by flowing water or wave action.
EXEMPT ORGANIZATIONS: Organizations which are exempt from this chapter per Illinois Compiled Statutes including state, federal or local units of government.
EXISTING MANUFACTURED HOME PARK OR SUBDIVISION: A manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) has been completed before April 1, 1990.
EXPANSION TO AN EXISTING MANUFACTURED HOME PARK OR SUBDIVISION: The preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads).
FEMA: Federal emergency management agency and its regulations at 44 CFR 59 - 79, as amended.
FLOOD: A general and temporary condition of partial or complete inundation of normally dry land areas from overflow of inland or tidal waves, or the unusual and rapid accumulation or runoff of surface waters from any source.
FLOOD FREQUENCY: A period of years, based on a statistical analysis, during which a flood of a stated magnitude may be expected to be equaled or exceeded.
FLOOD FRINGE: That portion of the floodplain outside of the regulatory floodway.
FLOOD INSURANCE RATE MAP (FIRM): A map prepared by FEMA that depicts the special flood hazard area (SFHA) within a community. This map includes insurance rate zones and floodplains and may or may not depict floodways.
FLOOD INSURANCE STUDY (FIS): An examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations.
FLOOD PROTECTION ELEVATION (FPE): The elevation of the base flood or 100-year frequency floods plus two feet (2') of freeboard at any given location in the SFHA.
FLOODPLAIN: That land typically adjacent to a body of water with ground surface elevations at or below the base flood or the 100-year frequency flood elevation. Floodplains may also include detached special flood hazard areas, ponding areas, etc. The floodplain is also known as the special flood hazard area (SFHA). The floodplains are those lands within the jurisdiction of the city that are subject to inundation by the base flood or 100-year frequency flood. The SFHAs of the city of Des Plaines are generally identified as such on map 17031C panels 0208J, 0209J, 0212J, 0214J, 0216J, 0217J, 0218J, 0219J, 0236J, 0238J, 0356J, 0357J, 0376J dated August 19, 2008, respectively, of the countywide flood insurance rate map for Cook County prepared by the federal emergency management agency.
The SFHAs for those parts of unincorporated Cook County that are within the one and one-half (11/2) mile extraterritorial jurisdiction of Des Plaines and may be annexed into the city of Des Plaines are designated for Weller Creek, Des Plaines River, Prairie Creek and Farmers Creek on map 17031C and panels 0207J, 0228J, 0229J dated August 19, 2008, respectively, of the countywide flood insurance rate map for Cook County prepared by the federal emergency management agency.
FLOODPROOFING: Any combination of structural and nonstructural additions, changes or adjustments to structures which reduce or eliminate flood damage to real estate or improved real property, water and sanitary facilities, structures and their contents.
FLOODPROOFING CERTIFICATE: A form published by the federal emergency management agency that is used to certify that a building has been designed and constructed to be structurally dry floodproofed to the flood protection elevation.
FLOODWAY: See definition of Designated Floodway.
HISTORIC STRUCTURE: Any structure that is:
   A.   Listed individually in the national register of historic places or preliminarily determined by the secretary of the interior as meeting the requirements for individual listing on the national register.
   B.   Certified or preliminarily determined by the secretary of the interior as contributing to the historic district or a district preliminarily determined by the secretary to qualify as a registered historic district.
   C.   Individually listed on the state inventory of historic places by the Illinois historic preservation agency.
   D.   Individually listed on a local inventory of historic places that has been certified by the Illinois historic preservation agency.
HYDRAULICALLY EQUIVALENT COMPENSATORY STORAGE: Compensatory storage that can be shown by hydrologic and hydraulic analysis to offset the increase in flood elevations caused by a development.
HYDROLOGIC AND HYDRAULIC CALCULATIONS: Engineering analysis, which determines expected flood flows and flood elevations based on land characteristics and rainfall events.
IDNR/OWR: Illinois department of natural resources, office of water resources.
LETTER OF MAP AMENDMENTS (LOMA): Official determination by FEMA that a specific structure is not in a 100-year flood zone; amends the effective FIRM.
LETTER OF MAP REVISION (LOMR): Letter that revises base flood or 100-year frequency flood elevations, flood insurance rate zones, flood boundaries or floodways as shown on an effective FIRM.
LOWEST FLOOR: The lowest floor of the lowest enclosed area (including basement). An unfinished or flood resistant enclosure usable solely for parking of vehicles, building access or storage, in an area other than a basement area is not considered a building's lowest floor; provided that such enclosure is not built so as to render the structure in violation of the applicable nonelevation design requirements of this chapter.
MANUFACTURED HOME: A structure, transportable in one or more sections, which is built on a permanent chassis and is designated for use with or without a permanent foundation when connected to the required utilities. The term "manufactured home" also includes park trailers, travel trailers and other similar vehicles placed on site for more than one hundred eighty (180) days. The term "manufactured home" does not include a "recreational vehicle".
MANUFACTURED HOME PARK OR SUBDIVISION: A parcel (or contiguous parcels) of land divided into two (2) or more manufactured home lots for rent or sale.
MARKET VALUE: Current value of building only, as determined by an Illinois licensed appraiser.
MITIGATION: Includes those measures necessary to minimize the negative effects which floodplain development activities might have on the public health, safety and welfare. Examples of mitigation include excavation of compensatory storage, soil erosion, sedimentation control, and channel restoration. Mitigation may also include those activities taken to reduce a structure's susceptibility to flooding.
NAVD 88: National American vertical datum of 1988. NAVD 88 supersedes the national geodetic vertical datum of 1929 (NGVD).
NATURAL: When used in reference to channels means those channels formed by the existing surface topography of the earth prior to changes made by man. A natural stream tends to follow a meandering path; its floodplain is not constrained by levees; the area near the bank has not been cleared, mowed or cultivated; the stream flows over soil and geologic materials typical of the area with no substantial alteration of the course or cross section of the stream caused by filling or excavating. A modified channel may regain some natural characteristics over time as the channel meanders and vegetation is reestablished. Similarly, a modified channel may be restored to more natural conditions by man through regrading and revegetation.
NEW CONSTRUCTION: Structures for which the start of construction commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures.
OWR: Illinois department of natural resources, office of water resources.
ORDINARY HIGH WATER MARK (OHWM): The point on the bank or shore up to which the presence and action of surface water is so continuous so as to leave a distinctive mark such as by erosion, destruction or prevention of terrestrial vegetation, predominance of aquatic vegetation or other easily recognized characteristics.
PUBLIC BODIES OF WATERS: All open public streams and lakes capable of being navigated by watercraft, in whole or in part, for commercial uses and purposes, and all lakes, rivers, and streams which in their natural condition were capable of being improved and made navigable, or that are connected with or discharge their waters into navigable lakes or rivers within, or upon the borders of the state of Illinois, together with all bayous, sloughs, backwaters, and submerged lands that are open to the main channel or body of water directly accessible thereto.
PUBLIC FLOOD CONTROL PROJECT: A flood control project, which will be operated and maintained by a public agency to reduce flood damages to existing buildings and structures, including a hydrologic and hydraulic study of the existing and proposed conditions of the watershed. Nothing in this definition shall preclude the design, engineering, construction or financing, in whole or in part, of a flood control project by persons or parties who are not public agencies.
RECREATIONAL VEHICLE OR TRAVEL TRAILER: A vehicle, which is:
   A.   Built on a single chassis.
   B.   Four hundred (400) square feet or less when measured at the largest horizontal projection.
   C.   Designed to be self-propelled or permanently towable by a light duty truck.
   D.   Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.
REGIONAL PERMITS: Offered for preapproved projects, which are considered minor projects that are permissible per IDNR/OWR part 3708 rules for northeastern Illinois designated floodways. A complete listing of the terms and conditions for specific project types can be obtained from the IDNR/OWR website.
REGISTERED LAND SURVEYOR: A land surveyor registered in the state of Illinois, under the Illinois land surveyors act.
REGISTERED OR LICENSED PROFESSIONAL ENGINEER: An engineer registered in the state of Illinois, under the Illinois professional engineering practice act.
REGULATORY FLOODWAY: See definition of Designated Floodway.
REPAIR, REMODELING OR MAINTENANCE: Developing activities which do not result in any increases in the outside dimensions of a building or any changes to the dimensions of a structure.
REPETITIVE LOSS: Flood related damages sustained by a structure on two (2) separate occasions during a ten (10) year period for which the cost of repairs at the time of each such flood event, on the average, equals or exceeds twenty five percent (25%) of the market value of the structure before the damage occurred.
RETENTION/DETENTION FACILITY: A retention facility stores stormwater runoff without a gravity release. A detention facility provides for storage of stormwater runoff and controlled release of this runoff during and after a flood or storm.
RIVERINE SFHA: Any SFHA subject to flooding from a river, creek, intermittent stream, ditch, on stream lake system or any other identified channel. This term does not include areas subject to flooding from lakes, ponding areas, areas of sheet flow, or other areas not subject to overbank flooding.
RUNOFF: The water derived from melting snow or rain falling on the land surface, flowing over the surface of the ground or collected in channels or conduits.
SEDIMENTATION: The processes that deposit soils, debris, and other materials either on other ground surfaces or in bodies of water or watercourses.
SPECIAL FLOOD HAZARD AREA (SFHA): See definition of Floodplain.
START OF CONSTRUCTION: Includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition placement, or other improvement was within one hundred eighty (180) days of the permit date. The "actual start" means either the first placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; or placement of a manufactured home on a foundation.
STATEWIDE PERMITS: Offered for preapproved projects that are considered minor projects, which are permissible per the IDNR/OWR part 3700 rules. A complete listing of the statewide permits and permit requirements can be obtained from the IDNR/OWR website.
STRUCTURE: The results of a manmade change to the land constructed on or below the ground, including the construction, reconstruction or placement of a building or any addition to a building; installing a manufactured home on a site; preparing a site for a manufactured home or installing a travel trailer on a site for more than one hundred eighty (180) days.
SUBSTANTIAL DAMAGE: Damage of any origin sustained by a structure whereby the cumulative percentage of damage incurred during a ten (10) year period measured from the date of the most recent damage, and dating back to no earlier than January 1, 2009 (the effective date of this title), equals or exceeds fifty percent (50%) of the market value of the structure before the damage occurred, regardless of actual value of the repair work performed. The value of volunteer labor, donated materials, and other in-kind contributions, must be included in the calculation of substantial damage. This term includes repetitive loss buildings. (See definition of Repetitive Loss.)
SUBSTANTIAL IMPROVEMENT: Any repair, reconstruction, rehabilitation, addition, or improvement of a structure taking place during a ten (10) year period measured from the date of the most recent damage, and dating back to no earlier than January 1, 2009 (the effective date of this title), in which the cumulative percentage of improvements equals or exceeds fifty percent (50%) of the market value of the structure before the improvement or repair is conducted or installed. The value of volunteer labor, donated materials, and other in-kind contributions, must be included in the calculation of substantial improvement.
   A.   "Substantial improvement" is considered to occur when the first alteration of any wall, ceiling, floor, or other structural part of the building commences, whether or not that alteration affects the external dimensions of the building. This term includes structures, which have incurred repetitive loss or substantial damage, regardless of the actual work done.
   B.   "Substantial improvement" does not, however, include any project for improvement of a structure to comply with existing federal, state, or local health, sanitary, or safety code specifications that are solely necessary to assure safe living conditions.
TRANSITION SECTION: Reaches of the stream or floodway where water flows from a narrow cross section to a wide cross section or vice versa.
VIOLATION: The failure of a structure or other development to be fully compliant with the community's floodplain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance is presumed to be in violation until such time as that documentation is provided. (Ord. M-15-16, 6-6-2016)
14-1-3: HOW TO USE THIS CHAPTER:
The director of engineering and community development director shall be responsible for fulfilling all of the duties listed in section 14-1-4 of this chapter.
To fulfill those duties, the director of engineering and community development director first should use the criteria listed in section 14-1-5 of this chapter, to determine whether the development site is located within a floodplain. Once it has been determined that a site is located within a floodplain, the director of engineering and community development director must determine whether the development site is within a flood fringe, a designated floodway, or within an SFHA or floodplain on which no floodway has been identified. If the site is within a floodway, the director of engineering and community development director shall require that the minimum requirements of section 14-1-7 of this chapter be met. If the site is located within an SFHA or floodplain for which no detailed study has been completed and approved, the director of engineering and community development director shall require that the minimum requirements of section 14-1-8 of this chapter be met. If the site is within a flood fringe, the director of engineering and community development director shall require that the minimum requirements of section 14-1-6 of this chapter be met.
In addition, the general requirements of section 14-1-9 of this chapter shall be met for all developments meeting the requirements of section 14-1-6, 14-1-7 or 14-1-8 of this chapter. The director of engineering and community development director shall assure that all subdivision proposals shall meet the requirements of section 14-1-10 of this chapter.
If a variance is to be granted for a proposal, the director of engineering and community development director shall review the requirements of section 14-1-11 of this chapter to make sure they are met. In addition, the director of engineering and community development director shall complete all notification requirements.
In order to assure that property owners obtain permits as required in this chapter, the director of engineering and community development director may take any and all actions as outlined in section 14-1-13 of this chapter. (Ord. M-15-16, 6-6-2016)
14-1-4: DUTIES OF ENFORCEMENT OFFICIALS:
The director of engineering shall be responsible for the general administration and enforcement of this chapter, which shall include the following:
   A.   Determining The Floodplain Designation: Check all new development sites to determine whether they are in a special flood hazard area (SFHA). If they are in an SFHA, determine whether they are in a floodway, flood fringe or in a floodplain on which a detailed study has not been conducted which drains more than one square mile.
      1.   Check whether the development is potentially within an extended SFHA (with a drainage area less than 1 square mile), indicating that the development would have adverse impacts regarding storage, conveyance, or inundation which would be the basis for the applicant being required to delineate the floodplain and floodway and be subject to the remaining sections of this chapter.
   B.   Professional Engineer Review: If the development site is within a floodway or in a floodplain on which a detailed study has not been conducted which drains more than one square mile, then the permit shall be referred to a registered professional engineer (PE) under the employ or contract of the city for review to ensure that the development meets the requirements of section 14-1-7 of this chapter. In the case of an appropriate use, the PE shall state in writing that the developer's engineer will provide a detailed hydrologic and hydraulic analysis in conjunction with a detailed plan of the drainage basin and subbasins considered for any development site being submitted to the director of engineering for review.
   C.   Dam Safety Requirements:
      1.   Dams are classified as to their size and their hazard/damage potential in the event of failure.
      2.   The construction or major modification of all class I (high hazard) and class II (moderate hazard) dams require an IDNR/OWR dam safety permit.
      3.   Some class III (low hazard) dams require an IDNR/OWR dam safety permit, depending on the drainage area to the dam, the height of the dam and the impounding capacity behind the dam. Most off channel detention basins that have an embankment are nonjurisdictional class III dams. It is not required that IDNR/OWR "sign off" on all nonjurisdictional class III dams.
      4.   A consulting engineer with dam safety knowledge can estimate a hazard classification and determine if an IDNR/OWR dam safety permit is required.
      5.   A permit application submittal must be made to IDNR/OWR for the construction or major modification of jurisdictional dams.
      6.   Regulated dams may include weirs, restrictive culverts or impoundment structures.
   D.   Other Permit Requirements: Ensure any and all required federal, state and local permits are received prior to the issuance of a floodplain development permit.
   E.   Plan Review And Permit Issuance: Ensure that all development activities within the SFHAs of the jurisdiction of the city of Des Plaines meet the requirements of this chapter, and issue a floodplain development permit in accordance with the provisions of this chapter and other regulations of this community when the development meets the conditions of this chapter.
   F.   Inspection Review: Inspect all development projects before, during, and after construction to assure proper elevation of the structure and to ensure compliance with the provisions of this chapter; and schedule on an annual basis an inspection of the floodplain and document the results of the inspection.
   G.   Elevation And Floodproofing Certificates: Maintain in the permit files an elevation certificate certifying the elevation of the lowest floor (including basement) of a residential or nonresidential building or the elevation to which a nonresidential building has been subject to section 14-1-9 of this chapter for public inspection and provide copies of same.
   H.   Records For Public Inspection: Maintain for public inspection and furnish upon request base flood data, SFHA and regulatory floodway maps, copies of federal or state permit documents, variance documentation, conditional letter of map revision, letter of map revision, letter of map amendment and as built elevation and floodproofing or elevation and floodproofing certificates for all buildings constructed subject to this chapter.
   I.   State Permits: Ensure that construction authorization has been granted by the Illinois department of natural resources, office of water resources (IDNR/OWR), for all development projects subject to sections 14-1-7 and 14-1-8 of this chapter, unless enforcement responsibility has been delegated to the city. Upon acceptance of this chapter by IDNR/OWR and FEMA, responsibility is hereby delegated to the city as per 17 Illinois administrative code 3708 for construction in the designated floodway and floodplain when floodways have not been defined in sections 14-1-7 and 14-1-8 of this chapter. However, the following review approvals are not delegated to the city and shall require review or permits from IDNR/OWR:
      1.   Organizations which are exempt from this chapter, as per the Illinois Compiled Statutes;
      2.   IDNR/OWR projects, dams or impoundment structures as defined in section 14-1-2 of this chapter and all other state, federal or local unit of government projects, including projects of the city and county, except for those projects meeting the requirements of subsection 14-1-7B5 of this chapter;
      3.   An engineer's determination that an existing bridge or culvert crossing is not a source of flood damage and the analysis indicating the proposed flood profile, per subsection 14-1-7B2e of this chapter;
      4.   An engineer's analysis of the flood profile due to subsection 14-1-7B2d of this chapter;
      5.   Alternative transition sections and hydraulically equivalent compensatory storage as indicated in subsections 14-1-7B2a, B2b and B2h of this chapter;
      6.   Permit issuance of structures within or over publicly navigable rivers, lakes and streams;
      7.   Any changes in the base flood elevation or floodway locations; and
      8.   Base flood elevation determinations where none now exist.
   J.   Cooperation With Other Agencies: Cooperate with state and federal floodplain management agencies to improve the administration of this chapter. Submit data to OWR and the federal emergency management agency for proposed revisions of a designated map within six (6) months whenever a modification to the floodplain may change the base flood elevation or result in a change to the FIRM. Submit reports as required for the national flood insurance program. Notify the federal emergency management agency of any proposed amendments to this chapter.
   K.   Promulgate Regulations: Promulgate rules and regulations as necessary to administer and enforce the provisions of this chapter, subject however to the review and approval of OWR and FEMA for any chapter changes.
   L.   Damage Determinations: Make damage determinations of all damaged buildings in the SFHA after any damage to determine if any structures have been substantially damaged. Any structures found to be substantially damaged must comply with section 14-1-9 of this chapter. (Ord. M-15-16, 6-6-2016)
14-1-5: BASE FLOOD ELEVATION:
This chapter's protection standard is based on August 19, 2008, Cook County FIS prepared by FEMA.
If a base flood elevation or 100-year frequency flood elevation is not available for a particular site, then the protection standard shall be according to the best existing data available in the Illinois state water survey's floodplain information repository or from federal, state, or other sources.
When a party disagrees with the best available data, they shall submit a detailed engineering study needed to replace existing data with better data and submit it to IDNR/OWR and FEMA for review and consideration prior to any development of the site.
   A.   The base flood or 100-year frequency flood elevation for the SFHAs of the Des Plaines River, Prairie Creek, Farmers Creek, Willow Creek, Weller Creek, Higgins Creek, and Feehanville Ditch shall be as delineated on the 100-year flood profiles in the countywide flood insurance study of Cook County prepared by FEMA dated August 19, 2008, and such amendments to such study and maps as may be prepared from time to time.
   B.   The base flood or 100-year frequency flood elevation for the SFHAs of those parts of unincorporated Cook County that are within the one and one-half (11/2) mile extraterritorial jurisdiction of the city of Des Plaines or that may be annexed into the city of Des Plaines shall be as delineated on the 100-year flood profiles in the countywide flood insurance study of Cook County prepared by FEMA and dated August 19, 2008, and such amendments or revisions to such study and maps may be prepared from time to time.
   C.   The base flood or 100-year frequency flood elevation for each SFHA delineated as an AH zone or an AO zone shall be that elevation (or depth) delineated on the flood insurance rate map of the city.
   D.   The base flood or 100-year frequency flood elevation for each of the remaining SFHAs delineated as an A zone on the flood insurance rate map of the city shall be according to the best existing data available in the Illinois state water survey's floodplain information repository. The 100-year frequency flood event is that event which has a one percent (1%) statistical chance of occurring in any given year. When no base flood or 100-year frequency flood elevation data is available for a riverine SFHA, the 100-year frequency elevation shall be determined using hydrologic and hydraulic calculations as appropriate for the analysis circumstance that have been approved by FEMA or those models commonly used in this geographic area such as HEC-RAS, HEC-HMS, SWMM, TR-20, and Hydroflow. Flood flows should be based on anticipated future land use conditions in the watershed as determined from adopted local and regional land use plans. Along any watercourses draining more than one square mile, the above analyses shall be submitted to OWR for approval, once approved it must be submitted to the Illinois state water survey floodplain information repository for filing. For a nonriverine SFHA, the base flood elevation shall be the historic flood of record plus three feet (3'), unless calculated by a detailed engineering study and approved by the Illinois state water survey.
   E.   Prior to issuing a development permit the community development director or his designee shall determine the location of the subject property with respect to flood zones using the best information available. (Ord. M-15-16, 6-6-2016)
14-1-6: OCCUPATION AND USE OF FLOOD FRINGE AREAS:
Development in and/or filling of the flood fringe will be permitted if protection is provided against the base flood or 100-year frequency flood by proper elevation, and compensatory storage and other provisions of this chapter are met. No use will be permitted which adversely affects the capacity of drainage facilities or systems, including the temporary storage of materials for more than seven (7) calendar days. Developments located within the flood fringe shall meet the requirements of this section, along with the requirements of section 14-1-9 of this chapter.
   A.   Development Permit: No person, firm, corporation or governmental body not exempted by state law shall commence any development in the SFHA without first obtaining a development permit from the community development director and director of engineering.
      1.   Application for a development permit shall be made on a form provided by the community development director and director of engineering. The application shall be accompanied by drawings of the site, drawn to scale, showing property line dimensions and legal description for the property and sealed by a licensed engineer, or land surveyor; existing grade elevations in 1988 NAVD and all changes in grade resulting from excavation or filling; the location and dimensions of all buildings, the elevation of the lowest floor (including basement) and lowest adjacent grade shall be shown on the submitted plans and the development will be subject to the requirements of section 14-1-9 of this chapter.
      2.   Upon receipt of a development permit application, the director of engineering shall compare the elevation of the site to the base flood or 100-year frequency flood elevation. Any development located on land that is higher than the base flood elevation as determined pursuant to section 14-1-5 of this chapter is not in the SFHA and, therefore, not subject to the requirements of this chapter. The building official shall maintain documentation of the existing ground elevation at the development site and certification that this ground elevation existed prior to the date of the site's current effective FIRM.
      3.   A soil erosion and sedimentation control plan for disturbed areas shall be submitted. This plan, including all calculations, shall include a description of the sequence of grading activities and the temporary sediment and erosion control measures to be implemented to mitigate their effects. This plan shall also include a description of final stabilization and revegetation measures, and the identification of a responsible party to ensure postconstruction maintenance.
      4.   The community development director shall be responsible for obtaining from the applicant copies of all other local, state and federal permits, approvals or permit not required letters that may be required for this type of activity. The community development director shall not issue a permit unless all other local, state and federal permits have been obtained.
   B.   Preventing Increased Damages: No development in the flood fringe shall create a threat to public health and safety.
      1.   Remove Site From Floodplain: If fill is being used to elevate the site above the base flood or 100-year frequency flood elevation, the applicant shall submit sufficient data and obtain a letter of map revision (LOMR) from FEMA for the purpose of removing the site from the floodplain.
      2.   Compensatory Storage: Whenever any portion of a floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the base flood or 100-year frequency flood elevation shall be compensated for and balanced by a hydraulically equivalent volume or excavation taken from below the base flood or 100-year frequency flood elevation. The excavation volume shall be at least equal to one and one-tenth (1.1) times the volume of storage lost due to the fill or structure. In the case of streams and watercourses, such excavation shall be made in a hydraulically equivalent area to the areas so filled or occupied. All floodplain storage lost below the existing 10-year flood elevation shall be replaced below the proposed 10-year flood elevation. All floodplain storage lost above the existing 10-year flood elevation shall be replaced above the proposed 10-year flood elevation and under the 100-year elevation. All such excavations shall be constructed to drain freely and openly to the watercourse.
      3.   Construction Of The Lowest Floor Below The Base Flood Elevation (BFE): A person who has obtained a letter of map revision based on fill (LOMR-F) that removes a site in the flood fringe from the floodplain due to the use of fill to elevate the site above the BFE, may apply for a permit from the city of Des Plaines to construct the lowest floor of a residential building below the BFE in the flood fringe. The building official shall not issue such a permit unless the applicant has complied with all the criteria set forth in the following subsections:
      a.   Compensatory storage shall be provided.
      b.   The elevation of the lowest opening in the basement wall (i.e., window wells, accessways) shall be at two feet zero inches (2'0") above the base flood elevation (BFE).
      c.   The lowest adjacent grade to the foundation shall be at or above the FPE, for a minimum distance of ten feet (10') beyond the outside face of the structure. However, if site conditions are such that this requirement cannot be met, the building official may waive the ten foot (10') minimum setback if an Illinois licensed professional engineer certifies that an alternative method to protect the building from damage due to hydrostatic pressures has been met. The certifications shall be in the form of a detailed soils and structural design analysis, which shall be submitted to the building official for review. The building official may require such additional documentation as necessary to prove that the proposed shorter setback distance will keep the structure reasonably safe. In no case shall the setback distance be less than four feet (4').
      d.   The grade around the perimeter of the structure, measured at a distance of twenty feet (20') from the structure, shall be above the BFE. However, if site conditions are such that this requirement cannot be obtained, the building official may waive the twenty foot (20') minimum setback distance if an Illinois licensed professional engineer certifies that an alternative method to protect the building from damages due to hydrostatic pressures has been met. A detailed soils analysis and structural design proving that a shorter setback distance will keep the structure reasonably safe from flooding, shall be submitted to the city of Des Plaines for review. In no case shall the setback distance be less than four feet (4').
      e.   The ground around the building shall be compacted fill that meets all requirements of this subsection and is at least five feet (5') thick under the basement floor slab. Nothing in this subsection shall be interpreted to require the removal or replacement of fill that was placed as part of an LOMR-F, if such fill consists of material, including soils of similar classification and degree permeability, such as those classified as CH, CL, SC or ML according to ASTM standard D-2487, "Classification Of Soils For Engineering Purposes".
      f.   The fill material must be homogeneous and isotropic; that is, the soil must be all of one material, and the engineering priorities must be in the same direction.
      g.   All fill material and compaction shall be designed, certified and inspected by an Illinois licensed professional engineer, as warranted by the site conditions.
      h.   The basement floor shall be at an elevation that is no more than five feet (5') below the BFE.
      i. There shall be a granular drainage layer beneath the floor slab, and minimum of one-fourth (1/4) horsepower sump pump with a backup power supply shall be provided to remove seepage flow. The pump shall be rated at four (4) times the estimated seepage rate and shall discharge above the BFE and away from the building in order to prevent flooding of the basement or uplift of the floor under the effect of the seepage pressure.
      j.   The drainage system shall be equipped with a positive means of preventing backflow.
      k.   All foundation elements shall be designed to withstand hydrostatic pressure in accordance with accepted engineering practices.
      l.   If the applicant is unable to meet all of the requirements set forth in the preceding subsections of this section, the building official may allow the construction of a basement below the BFE only if the applicant demonstrates that the proposed fill and structure meet the guidelines and requirements set forth in FEMA technical bulletin 10-01 and are reasonably safe from flooding. In order to demonstrate that the proposed structure is reasonably safe from flooding, the applicant shall submit a detailed engineering analysis of the proposed fill and foundation wall. The engineered basement study shall be completed in accordance with the latest edition of FEMA technical bulletin 10-01, with the analysis of the fill being prepared by an Illinois licensed professional engineer.
      m.   In no case shall the depth of excavation in the front and side yards of the lot exceed eighteen inches (18"), as measured from the previously existing natural grade. The rear yard shall be permitted to have a greater depth of excavation, if necessary. All such excavation shall be constructed to drain freely and openly to the watercourse or storm sewer system. The use of mechanical means to drain the compensatory storage area will not be permitted.
   Elevation certificates will be required for all development within the 100-year floodplain that requires the issuance of a building permit by the city, or as directed by the director of public works and engineering.
   C.   Repair, Modification, Reconstruction: For repair of damaged homes, modification of existing homes, or reconstruction/replacement of existing homes, see subsections 14-1-9C1b and C2b of this chapter. (Ord. M-15-16, 6-6-2016)
14-1-7: OCCUPATION AND USE OF IDENTIFIED FLOODWAYS:
This section explains the procedures which are to be followed to determine if a site is within a floodway and sets the minimum requirements for all development within a floodway.
This section applies to proposed development, redevelopment, site modification or building modification within a designated floodway. The designated floodway for the Des Plaines River, Prairie Creek, Farmers Creek, Willow Creek, Weller Creek, and Feehanville Ditch shall be as delineated on designated FEMA flood insurance rate maps referenced in section 14-1-2 of this chapter. Only those uses and structures will be permitted which meet the criteria in this section. All floodway modifications shall be the minimum necessary to accomplish the purpose of the project. The development shall also meet the requirements of section 14-1-9 of this chapter.
   A.   Development Permit: No person, firm, corporation or governmental body not exempted by state law shall commence any development in a floodway without first obtaining a development permit from the community development director with approval from the director of engineering.
Development in the floodway will be limited to existing developments (redevelopment) on a limited basis or as deemed as necessary by the director of engineering, and shall be limited to appropriate uses of the floodway.
      1.   Application for a development permit shall be made on a form provided by the community development director. The application shall include the following information:
         a.   Name and address of applicant.
         b.   Site location (including legal description) of the property, drawn to scale of one inch equals twenty feet (1"=20') with the limits of the regulatory floodway delineated, indicating whether it is proposed to be in an incorporated or unincorporated area.
         c.   Name of stream or body of water affected.
         d.   Description of proposed activity.
         e.   Statement of purpose of proposed activity.
         f.   Anticipated dates of initiation and completion of activity.
         g.   Name and mailing address of the owner of the subject property if different from the applicant.
         h.   Signature of applicant or the applicant's agent.
         i.   If the applicant is a corporation, the president or other authorized officer shall sign the application form.
         j.   If the applicant is a partnership, each partner shall sign the application form.
         k.   If the applicant is a land trust, the trust officer shall sign the name of the trustee by him/her as trust officer. A disclosure affidavit shall be filed with the application identifying each beneficiary of the trust by name and address and defining the respective interests therein.
         l.   Plans of the proposed activity shall be provided which include as a minimum:
            (1)    A vicinity map showing the site of the activity, name of the waterway, boundary lines, names of roads in the vicinity of the site, graphical or numerical scale of one inch equals twenty feet (1" = 20') and north arrow.
            (2)    A plan review of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the structure or work, elevations using the 1988 NAVD, adjacent property lines and ownership, existing and proposed grades (spot elevations), existing and proposed elevation contours, drainage and flood control easements, location of any channels and any existing or future access roads, distance between proposed activity and navigation channel (when the proposed construction is near a commercially navigable body of water), designated floodway limit, floodplain limit, specifications and dimensions of any proposed channel modifications, delineation of basin and subbasin areas, location and orientation of cross sections, north arrow, and a graphical or numerical scale.
            (3)    Cross section views of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the work as shown in plan view, existing and proposed elevations, normal water elevation, 10-year frequency flood elevation, 100-year frequency flood elevation, and graphical or numerical scales (horizontal and vertical).
            (4)    A soil erosion and sedimentation control plan for disturbed areas, including outfalls. This plan shall include a description of the sequence of grading activities and the temporary sediment and erosion control measures to be implemented to mitigate their effects. This plan shall also include a description of final stabilization and revegetation measures, and the identification of a responsible party to ensure postconstruction maintenance.
            (5)    A copy of the designated floodway map, marked to reflect any proposed change in the regulatory floodway location.
         m.   Any and all other local, state and federal permits or approval letters that may be required for this type of development.
         n.   Engineering calculations and supporting data shall be submitted for hydrologic and hydraulic analysis as well as all sediment control and erosion protection measures showing that the proposed work will meet the permit criteria of subsection B of this section.
         o.   If the designated floodway delineation, base flood or 100-year frequency flood elevation will change due to the proposed project, the application will not be considered complete until IDNR/OWR has indicated conditional approval of the designated floodway map change. No structures may be built until a letter of map revision has been approved by FEMA.
         p.   The application for a structure shall be accompanied by drawings of the site, drawn to scale, showing property line dimensions and existing ground elevations and all changes in grade resulting from any proposed excavation or filling, and floodplain and floodway limits; sealed by a registered professional engineer, or registered land surveyor; the location and dimensions of all buildings and additions to buildings; and the elevation of the lowest floor (including basement) of all proposed buildings subject to the requirements of section 14-1-9 of this chapter.
         q.   If the proposed project involves a channel modification, the applicant shall submit the following information:
            (1)    A discussion of the purpose and need for the proposed work.
            (2)    A discussion of the feasibility of using alternative locations or methods to accomplish the purpose of the proposed work.
            (3)    An analysis of the extent and permanence of the impacts the project would have on the physical and biological conditions of the body of water affected.
            (4)    An analysis of the extent and permanence of the impacts each feasible alternative identified in subsections B1d and B1i of this section would have on the physical and biological conditions of the body of water affected.
            (5)    An analysis of the impacts of the proposed project considering cumulative effects on the physical and biological conditions of the body of water affected.
      2.   The director of engineering shall be responsible for obtaining from the applicant copies of all other local, state and federal permits and approvals that may be required for this type of activity. The community development director shall not issue the development permit unless all required federal and state permits have been obtained. A registered professional engineer, under the employ or contract of the city, shall review and approve applications reviewed under this section.
   B.   Preventing Increased Damages And A List Of Appropriate Uses: The only developments in a floodway which will be allowed are appropriate uses, which will not cause a rise in the base flood elevation, and which will not create a damaging or potentially damaging increase in flood heights or velocity or be a threat to public health and safety and welfare or impair the natural hydrologic and hydraulic functions of the floodway or channel, or permanently impair existing water quality or aquatic habitat. Construction impacts shall be minimized by appropriate mitigation methods as called for in this chapter. Only those appropriate uses listed in 17 Illinois administrative code 3708 will be allowed. Appropriate uses do not include the construction or placement of any new structures, fill, building additions, buildings on stilts, excavation or channel modifications constructed to accommodate otherwise misappropriate uses in the floodway, fencing (including landscaping or planting designed to act as a fence) and storage of materials except as specifically defined above as an appropriate use.
      1.   Appropriate Uses: The approved appropriate uses are as follows:
         a.   Flood control structures, dikes, dams and other public works or private improvements relating to the control of drainage, flooding, erosion or water quality or habitat for fish and wildlife.
         b.   Structures or facilities relating to the use of, or requiring access to, the water or shoreline, such as pumping and treatment facilities, and facilities and improvements related to recreational boating, commercial shipping and other functionally water dependent uses.
         c.   Storm and sanitary sewer outfalls.
         d.   Underground and overhead utilities.
         e.   Recreational facilities such as playing fields and trail systems including any related fencing (at least 50 percent open when viewed from any 1 direction) built parallel to the direction of flood flows and including open air pavilions. Replacement fences that do not result in greater obstructions to flood flows are permitted.
         f.   Bridges, culverts, roadways, sidewalks, railways, runways and taxiways and any modification thereto.
         g.   Parking lots and any modifications thereto (where depth of flooding at the 100-year frequency flood event will not exceed 1.0 foot) and aircraft parking aprons built at or below ground elevation.
=         h.   Designated floodway regrading, without fill, to create a positive nonerosive slope toward a watercourse.
         i.   Floodproofing activities to protect previously existing lawful structures including the construction of watertight window wells, elevating structures, or construction of floodwalls around residential, commercial or industrial principal structures where the outside toe of the floodwall shall be no more than ten feet (10') away from the exterior wall of the existing structure, and which are not considered substantial improvements to the structure.
         j.   The replacement, reconstruction, or repair of a damaged building, provided that the outside dimensions are not increased; provided, however, that if the building qualifies as substantially damaged, the building must be protected from flooding to the flood protection elevation.
         k.   Modifications to an existing building that would not increase the enclosed floor area of the building below the 100-year frequency flood elevation, and which will not block flood flows. Fireplaces, bay windows, decks, patios, and second story additions are permitted. If the modification constitutes a substantial improvement, the building must be protected to the flood protection elevation.
         l.   Elevation certificates will be required for all work within the 100-year floodplain that would require the issuance of a building permit by the city or as directed by the director of public works and engineering.
      2.   Construction Engineering And Mitigation Criteria: Within the designated floodway as identified on the designated floodway maps designated by OWR, the construction of an appropriate use will be considered permissible; provided, that the proposed project meets the following engineering and mitigation criteria and is so stated in writing with supporting plans, calculations and data by a registered professional engineer, and provided that any structure meets the protection requirements of section 14-1-9 of this chapter.
         a.   Preservation Of Flood Conveyance, So As Not To Increase Flood Stages Upstream: For appropriate uses other than bridge or culvert crossings, on stream structures or dams, all effective regulatory floodway conveyance lost due to the project will be replaced for all flood events up to and including the 100-year frequency flood. In calculating effective designated floodway conveyance, the following factors shall be taken into consideration:
            (1)    Regulatory floodway conveyance,
 
"K" = 1.486 AR 2/3
   n
 
Where "n" is Manning's roughness factor, "A" is the effective area of the cross section, and "R" is the ratio of the area to the wetted perimeter. (See "Open Channel Hydraulics", Ven Te Chow, 1959, McGraw-Hill Book Company, New York.)
            (2)    The same Manning's "n" value shall be used for both existing and proposed conditions unless a recorded maintenance agreement with a federal, state or local unit of government can assure the proposed conditions will be maintained or the land cover is changing from a vegetative to a nonvegetative land cover.
            (3)    Transition sections shall be provided and used in calculations of effective regulatory floodway conveyance. The following expansion and contraction ratios shall be used unless an applicant's engineer can prove to OWR through engineering calculation or model tests that more abrupt transitions may be used with the same efficiency:
               (A)   When water is flowing from a narrow section to a wider section, the water should be assumed to expand no faster than at a rate of one foot (1') horizontal for every four feet (4') of the flooded stream's length.
               (B)   When water is flowing from a wide section to a narrow section, the water should be assumed to contract no faster than at a rate of one foot (1') horizontal for every one foot (1') of the flooded stream's length.
               (C)   When expanding or contracting flows in a vertical direction, a minimum of one foot (1') vertical transition for every ten feet (10') of stream length shall be used.
               (D)   Transition sections shall be provided between cross sections with rapid expansions and contractions and when meeting the regulatory floodway delineation on adjacent properties.
               (E)   All cross sections used in the calculations shall be located perpendicular to flood flows.
         b.   Preservation Of Floodway Storage So As Not To Increase Downstream Flooding: Compensatory storage shall be provided for any designated floodway storage lost due to the proposed work from the volume of fill or structures placed and the impact of any related flood control projects. Compensatory storage for fill or structures shall be equal to at least one and one-tenth (1.1) times the volume of floodplain storage lost. Artificially created storage lost due to a reduction in head loss behind a bridge shall not be required to be replaced. The compensatory designated floodway storage shall be placed between the proposed normal water elevation and the proposed 100-year flood elevation. All designated floodway storage lost below the existing 10-year flood elevation shall be replaced below the proposed 10-year flood elevation and all regulatory storage lost above the existing 10-year flood elevation shall be replaced above the 10-year flood elevation and below the 100-year elevation. All such excavations shall be constructed to drain freely and openly to the watercourse. If the compensatory storage will not be placed at the location of the proposed construction, the applicant's engineer shall demonstrate to OWR through a determination of flood discharges and water surface elevations that the compensatory storage is hydraulically equivalent. Finally, there shall be no reduction in floodway surface area as a result of a floodway modification.
         c.   Preservation Of Floodway Velocities So As Not To Increase Stream Erosion Or Flood Heights: For all appropriate uses, except bridges or culverts or on stream structures, the proposed work will result in no more than a ten percent (10%) increase in velocities or stage for all flood events up to and including the 100-year frequency event. However, in the case of bridges or culverts or on stream structures built for the purpose of backing up water in the stream during normal or flood flows, velocities may be increased at the structure site if scour, erosion and sedimentation will be avoided by the use of riprap or other design measures.
Any increase in stage associated with construction in the floodway is contrary to city policy, unless the increase in stage is associated with a necessary public flood control project and there is no increase in off site flood damages.
         d.   Construction Of New Bridges Or Culvert Crossings And Roadway Approaches: The proposed structure shall not result in an increase of upstream flood stages greater than one-tenth foot (0.1') when compared to the existing vertical extensions of the channel banks such as within the design protection grade of existing levees or floodwalls or within recorded flood easements. If the proposed construction will increase upstream flood stages greater than one-tenth foot (0.1'), the developer must contact OWR, dam safety section for a dam safety permit or waiver. Any increase in stage associated with construction in the floodway is contrary to city policy, unless the increase in stage is associated with a necessary public flood control project and there is no increase in off site flood damages.
            (1)    The engineering analysis of upstream flood stages must be calculated using the flood study flows, and corresponding flood elevations for tail water conditions for the flood study specified in section 14-1-5 of this chapter. Culverts must be analyzed using the HY-8 or other hydraulic calculations approved by the director of public works and engineering for the selection of highway culverts. Bridges must be analyzed using the IDOT drainage manual.
            (2)    Lost floodway storage must be compensated for per subsection B2b of this section.
            (3)    Velocity increases must be mitigated per subsection B2c of this section.
            (4)    If the crossing is proposed over public water that is used for recreational or commercial navigation, an army corps of engineers and IDNR/OWR permit must be received.
            (5)    The hydraulic analysis for the backwater caused by the bridge showing the existing condition and proposed regulatory profile must be submitted to OWR for concurrence that a CLOMR is not required by subsection 14-1-8B of this chapter.
            (6)    All excavations for the construction of the crossing shall be designed per subsection B2h of this section.
         e.   Reconstruction Or Modification Of Existing Bridges, Culverts And Approach Roads:
            (1)    The bridge or culvert and roadway approach reconstruction or modification shall be constructed with no more than one-tenth foot (0.1') increase in backwater over the existing flood profile for all flood frequencies up to and including the 100-year event, if the existing structure is not a source of flood damage.
            (2)    If the existing bridge or culvert and roadway approach is a source of flood damage to buildings or structures in the upstream floodplain, the applicant's engineer shall evaluate the feasibility of redesigning the structure to reduce the existing backwater, taking into consideration the effects on flood stages on upstream and downstream properties.
            (3)    The determination as to whether or not the existing crossing is a source of flood damage and should be redesigned must be prepared in accordance with the IDNR/OWR 17 Illinois administrative code 3708 (floodway construction in northeastern Illinois) and submitted to the division for review and concurrence before a permit is issued.
         f.   On Stream Structures Built For The Purpose Of Backing Up Water: Any increase in upstream flood stages greater than zero feet (0.0') when compared to the existing conditions, for all flood events up to and including the 100-year frequency event shall be contained within the channel banks (or within existing vertical extensions of the channel banks) such as within the design protection grade of existing levees or floodwalls or within recorded flood easements. A permit or letter indicating a permit is not required must be obtained from OWR, dam safety section for a dam safety permit or waiver for any structure built for the purpose of backing up water in the stream during normal or flood flow. All dams and impoundment structures as defined in section 14-1-2 of this chapter shall meet the permitting requirements of 17 Illinois administrative code 3702 (construction and maintenance of dams). If the proposed activity involves a modification of the channel or floodway to accommodate an impoundment, it shall be demonstrated that:
            (1)    The impoundment is determined to be in the public interest by providing flood control, public recreation or regional stormwater detention.
            (2)    The impoundment will not prevent the migration of indigenous fish species, which require access to upstream areas as part of their life cycle, such as for spawning.
            (3)    The impoundment will not cause or contribute to degraded water quality of habitat conditions. Impoundment design should include gradual bank slopes, appropriate bank stabilization measures, and a presedimentation basin.
            (4)    A nonpoint source control plan has been implemented in the upstream watershed to control the effects of sediment runoff as well as minimize the input of nutrients, oil and grease, metals and other pollutants. If there is more than one municipality in the upstream watershed, the municipality in which the impoundment is constructed should coordinate with upstream municipalities to ensure comprehensive watershed control.
            (5)    Will require the approval of the director of engineering.
            (6)    The project otherwise complies with the requirements of this section.
         g.   Floodproofing Of Existing Habitable, Residential And Commercial Structures: If construction is required beyond the outside dimensions of the existing building, the outside perimeter of the floodproofing construction shall be placed no farther than ten feet (10') away from the outside of the building. Compensation of lost storage and conveyance will not be required for floodproofing activities.
         h.   Excavation In The Floodway: When excavation is proposed in the design of bridges and culvert openings, including the modifications to and replacement of existing bridge and culvert structures, or to compensate for lost conveyance for other appropriate uses, transition sections shall be provided for the excavation. The following expansion and contraction ratios shall be used unless an applicant's engineer can prove to OWR through engineering calculations or model tests that more abrupt transitions may be used with the same efficiency:
            (1)    When water is flowing from a narrow section to a wider section, the water should be assumed to expand no faster than at a rate of one foot (1') horizontal for every four feet (4') of the flooded stream's length;
            (2)    When water is flowing from a wide section to a narrow section, the water should be assumed to contract no faster than at a rate of one foot (1') horizontal for every one foot (1') of the flooded stream's length; and
            (3)    When expanding or contracting flows in a vertical direction, a minimum of one foot (1') vertical transition for every ten feet (10') of stream length shall be used;
            (4)    Erosion/scour protection shall be provided inland upstream and downstream of the transition sections.
         i.   Channel Modifications: If the proposed activity involves a channel modification, it shall be demonstrated that:
            (1)    There are no practicable alternatives to the activity, which would accomplish its purpose with less impact to the natural conditions of the body of water affected. Possible alternatives include levees, bank stabilization, floodproofing of existing structures, removal of structures from the floodplain, clearing the channel, high flow channel or the establishment of a streamside buffer strip or greenbelt. Channel modification is acceptable if the purpose is to restore natural conditions and improve water quality and fish and wildlife habitat.
Channel modifications are particularly sensitive activities because of their potential direct impacts on channel stability, conveyance, water quality, habitat and aesthetics. In general, watercourse modifications should be avoided unless necessary to achieve the purposes of an appropriate use, such as habitat restoration or a public flood control project. Rigorous enforcement of mitigation requirements for necessary modifications can eliminate some of the temporary and most of the permanent impacts of modification;
            (2)    Water quality, habitat and other natural functions would be significantly improved by the modification and no significant habitat area may be destroyed, or the impacts are offset by the replacement of an equivalent degree of natural resource values;
            (3)    The activity has been planned and designed and will be constructed in a way which will minimize its adverse impacts on the natural conditions of the body of water affected, consistent with the following criteria:
               (A)   The physical characteristics of the modified channel shall match as closely as possible those of the existing channel in length, cross section, slope and sinuosity. If the existing channel has been previously modified, restoration of more natural physical conditions should be incorporated into channel modification design, where practical.
               (B)   Hydraulically effective transitions shall be provided at both the upstream and downstream ends of the project, designed such that they will prevent erosion.
               (C)   Clearing of vegetation shall be limited to that which is essential for construction of the channel.
               (D)   Channel banks shall be constructed with a side slope no steeper than three to one (3:1) horizontal to vertical, wherever practicable. Natural vegetation and gradual side slopes are the preferred methods for bank stabilization. Where high velocities or sharp bends necessitate the use of alternative stabilization measures, natural rock or riprap are preferred materials. Artificial materials such as concrete, gabions, or construction rubble should be avoided unless there are no practicable alternatives.
               (E)   All disturbed areas associated with the modification shall be seeded or otherwise stabilized as soon as possible upon completion of construction. Erosion blanket or an equivalent material shall be required to stabilize disturbed channel banks prior to establishment of the vegetative cover.
               (F)   If the existing channel contains considerable bottom diversity such as deep pools, riffles and other similar features, such features shall be provided in the new channel. Spawning and nesting areas and flow characteristics compatible with fish habitat shall also be established, where appropriate.
               (G)   A sediment basin and other erosion protection devices shall be installed at the downstream end of the modification to reduce sedimentation and degradation of downstream water quality.
               (H)   New or relocated channels should be built in the dry and all items of construction, including vegetation, should be completed prior to diversion of water into the new channel.
               (I)   There shall be no increases in stage or velocity as the channel enters or leaves the project site for any frequency flood unless necessitated by a public flood control project or unless such an increase is justified as part of a habitat improvement or erosion control project.
               (J)   Unless the modification is for a public flood control project, there shall be no reduction in the volume of floodwater storage outside the floodway as a result of the modification.
            (4)    The project otherwise complies with the requirements of this section.
         j.   Seeding And Stabilization Plan: For all activities located in a floodway, a seeding and stabilization plan shall be submitted by the applicant.
         k.   Soil Erosion And Sedimentation Measures: For all activities in the floodway, including grading, filling and excavation, in which there is potential for erosion of exposed soil, soil erosion and sedimentation control measures shall be employed consistent with the following criteria:
            (1)    The construction area shall be minimized to preserve the maximum vegetation possible. Construction shall be scheduled to minimize the time soil is exposed and unprotected. In no case shall the existing natural vegetation be destroyed, removed or disturbed more than fifteen (15) days prior to the initiation of improvements.
            (2)    Temporary and/or permanent soil stabilization shall be applied to denuded areas as soon as possible. As a minimum, soil stabilization shall be provided within fifteen (15) days after final grade is reached on any portion of the site, and within fifteen (15) days to denuded areas, which may not be at final grade but will remain undisturbed for longer than sixty (60) days.
A schedule outlining the method and employment of sediment and erosion protection methods prior to, during and after all construction, must be submitted to the director of engineering.
            (3)    Sedimentation control measures shall be installed before any significant grading or filling is initiated on the site to prevent the movement of eroded sediments off site or into the channel. Potential sediment control devices include filter fences, straw bale fences, check dams, diversion ditches and sediment basins.
            (4)    A vegetated buffer strip of at least twenty five feet (25') in width shall be preserved and/or reestablished, where possible, along existing channels (subsection B2p of this section). Construction vehicle use of channels shall be minimized. Temporary stream crossings shall be constructed, where necessary, to minimize erosion. Necessary construction in or along channels shall be restabilized immediately.
            (5)    Soil erosion and sedimentation control measures shall be designed and implemented consistent with "Procedures And Standards For Urban Soil Erosion And Sedimentation Control In Illinois" (1988) also known as the "Green Book" and "Standards And Specifications For Soil Erosion And Sediment Control" (IEPA, 1987).
         l.   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 OWR 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 easements for all flood events up to and including the 100-year frequency event.
         m.   General Criteria For Analysis Of Flood Elevations:
            (1)    The flood profiles, flows and floodway data in the regulatory floodway study, referenced in section 14-1-5 of this chapter must be used for analysis of the base conditions. If the study data appears to be in error or conditions have changed, OWR shall be contacted for approval and concurrence on the appropriate base conditions data to use.
            (2)    If the 100-year designated floodway elevation at the site of the proposed construction is affected by backwater from a downstream receiving stream with a larger drainage area, the proposed construction shall be shown to meet the requirements of this section for the 100-year frequency flood elevations of the designated floodway conditions and conditions with the receiving stream at normal water elevations.
            (3)    If the applicant learns from OWR, local governments or a private owner that a downstream restrictive bridge or culvert is scheduled to be removed, reconstructed, modified, or a regional flood control project is scheduled to be built, removed, constructed or modified within the next five (5) years, the proposed construction shall be analyzed and shown to meet the requirements of this section for both the existing conditions and the expected flood profile conditions when the bridge, culvert or flood control project is built.
         n.   Conditional Letter Of Map Revision: If the appropriate use would result in a change in the designated floodway location or the 100-year frequency flood elevation, the applicant shall submit to OWR and to FEMA all the information, calculations and documents necessary to be issued a conditional designated floodway map revision and receive from OWR a conditional approval of the regulatory floodway change before a permit is issued. However, the final designated floodway map will not be changed by OWR until as built plans or record drawings are submitted and accepted by FEMA and OWR. In the case of nongovernment projects, the municipality in incorporated areas and the county in unincorporated areas shall concur with the proposed conditional designated floodway map revision before OWR approval can be given. No filling, grading, dredging or excavating shall take place until a final letter of map revision (LOMR) is issued by FEMA and OWR.
         o.   Professional Engineer's Supervision: All engineering analyses shall be performed by or under the supervision of a registered professional engineer.
         p.   Protection From Construction: For all activities in the floodway involving construction within twenty five feet (25') of the channel, the following criteria shall be met:
            (1)    A natural vegetation buffer strip shall be preserved within at least twenty five feet (25') of the ordinary high water mark of the channel.
            (2)    Where it is impossible to protect this buffer strip during the construction of an appropriate use, a vegetated buffer strip shall be established upon completion of construction.
            (3)    The use of native riparian vegetation is preferred in the buffer strip. Access through this buffer strip shall be provided, when necessary, for stream maintenance purposes.
After receipt of conditional approval of the designated floodway change and issuance of a permit and a conditional letter of map revision, construction as necessary to change the designated floodway may proceed but no buildings or structures or other construction that is not an appropriate use may be placed in that area until the designated floodway map is changed and a final letter of map revision is received. The designated floodway map will be revised upon acceptance and concurrence by OWR and FEMA of the as built plans.
      3.   State Review: For those projects listed below located in a designated floodway, the following criteria shall be submitted to OWR for their review and concurrence prior to the issuance of a permit:
         a.   OWR will review an engineer's analysis of the flood profile due to a proposed bridge pursuant to subsection B2d of this section.
         b.   OWR will review an engineer's determination that an existing bridge or culvert crossing is not a source of flood damage and the analysis indicating the proposed flood profile, pursuant to subsection B2e of this section.
         c.   The OWR will review alternative transition sections and hydraulically equivalent storage pursuant to subsections B2a, B2b and B2h of this section.
         d.   The OWR will review and approve, prior to the start of construction, any department projects, dams (as defined in this chapter) and all other state, federal or local units of government projects, including projects of the municipality or county.
      4.   Other Permits: In addition to the other requirements of this chapter, a development permit for a site located in a floodway shall not be issued unless the applicant first obtains a permit or written documentation that a permit is not required from OWR and the army corps of engineers, issued pursuant to 615 Illinois Compiled Statutes 5/5. No permit from OWR shall be required if the division has delegated this responsibility to the city.
      5.   Dam Safety Permits: Any work involving the construction, modification or removal of a "dam" as defined in section 14-1-2 of this chapter per 17 Illinois administrative code 3702 (rules for construction of dams) shall obtain an Illinois division of water resources dam safety permit prior to the start of construction of a dam. If the director of engineering finds a dam that does not have an OWR permit, the director of engineering shall immediately notify the dam safety section of the division of water resources. If the director of engineering finds a dam, which is believed to be in an unsafe condition, the director of engineering shall immediately notify the owner of the dam, OWR, dam safety section in Springfield and the Illinois emergency management agency (IEMA).
      6.   Activities That Do Not Require A Registered Professional Engineer's Review: The following activities may be permitted without a registered professional engineer's review. Such activities shall still meet the other requirements of this chapter, including the mitigation requirements.
         a.   Underground and overhead utilities that:
            (1)    Do not result in any increase in existing ground elevations, or
            (2)    Do not require the placement of aboveground structures in the floodway, or
            (3)    In the case of underground stream crossings, the top of the pipe or encasement is buried a minimum of three feet (3') below the existing streambed, and
            (4)    In the case of overhead utilities, supporting towers are placed in the watercourse and are designed in such a fashion as not to catch debris.
         b.   Storm and combined sewer outfalls that:
            (1)    Do not extend riverward or lakeward of the existing adjacent natural bank slope, and
            (2)    Do not result in an increase in ground elevation, and
            (3)    Are designed so as not to cause stream erosion at the outfall location.
         c.   Construction of sidewalks, athletic fields (excluding fences), properly anchored playground equipment and patios at grade.
         d.   Construction of shoreline and stream bank protection that:
            (1)    Does not exceed one thousand feet (1,000') in length.
            (2)    Materials are not placed higher than the existing top of bank.
            (3)    Materials are placed so as not to reduce the cross sectional area of the stream channel or bank of the lake.
            (4)    Vegetative stabilization and gradual side slopes are the preferred mitigation methods for existing erosion problems. Where high channel velocities, sharp bends or wave action necessitate the use of alternative stabilization measures, natural rock or riprap are preferred materials. Artificial materials such as concrete, construction rubble and gabions should be avoided unless there are no practicable alternatives.
            (5)    Use of artificial shoreline and stream bank materials for the convenience of site design for private developments is not supported. Construction activities involving one thousand feet (1,000') of shoreline or stream bank are not minor and should be subject to the review of a registered professional engineer.
         e.   Temporary stream crossings in which:
            (1)    The approach roads will be five-tenths foot (0.5') or less above natural grade.
            (2)    The crossing will allow stream flow to pass without backing up the water above the stream bank vegetation line or above any drainage tile or outfall invert.
            (3)    The top of the roadway fill in the channel will be at least two feet (2') below the top of the lowest bank. Any fill in the channel shall be nonerosive material, such as riprap or gravel.
            (4)    All disturbed stream banks will be seeded or otherwise stabilized as soon as possible upon installation and again upon removal of construction.
            (5)    The access road and temporary crossing will be removed within one year after authorization. (Ord. M-15-16, 6-6-2016)
14-1-8: OCCUPATION AND USE OF SPECIAL FLOOD HAZARD AREAS WHERE FLOODWAYS ARE NOT IDENTIFIED:
In SFHAs or floodplains, where no floodways have been identified and no base flood or 100-year frequency flood elevations have been established by FEMA or the OWR, and draining more than a square mile, no development shall be permitted unless the cumulative effect of the proposals, when combined with all other existing and anticipated uses and structures, shall not significantly impede or increase the flow and passage of the floodwaters nor significantly increase the base flood or 100-year frequency flood elevation.
   A.   Development Permit: No person, firm, corporation or governmental body, not exempted by state law, shall commence any development in an SFHA or floodplain without first obtaining a development permit from the director of engineering and community development director. Application for a development permit shall be made on a form provided by the director of engineering and community development director. The application shall be accompanied by drawings of the site, drawn to scale, showing property line dimensions; and existing grade elevations and all changes in grade resulting from excavation or filling, sealed by a licensed engineer or surveyor; the location and dimensions of all buildings and additions to buildings; and the elevation of the lowest floor (including basement) of all proposed buildings subject to the requirements of section 14-1-9 of this chapter.
      1.   The application for a development permit shall also include the following information:
         a.   A detailed description of the proposed activity, its purpose and intended use.
         b.   Site location (including legal description) of the property, drawn to scale, on the designated floodway maps, indicating whether it is proposed to be in an incorporated or unincorporated area.
         c.   Anticipated dates of initiation and completion of activity.
         d.   Plans of the proposed activity shall be provided which include as a minimum:
            (1)    A vicinity map showing the site of the activity, name of the waterway, boundary lines, names of roads in the vicinity of the site, graphical or numerical scale, and north arrow;
            (2)    A plan view of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the structure or work, elevations in 1988 NAVD, adjacent property lines and ownership, drainage and flood control easements, distance between proposed activity and navigation channel (when the proposed construction is near a commercially navigable body of water), floodplain limit, location and orientation of cross sections, north arrow, and a graphical or numerical scale;
            (3)    If the required plans include a delineation of the floodway for both existing and proposed conditions. This floodway delineation, made by the applicant, should be consistent with the requirements of section 14-1-5 of this chapter and the definition of the "designated floodway" in section 14-1-2 of this chapter. Floodplain and floodway delineations should be based on ultimate future watershed land use conditions. This delineation should be verified and approved by the office of water resources;
            (4)    Cross section views of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the work as shown in plan view, existing and proposed elevations, normal water elevation, 10-year frequency flood elevation, 100-year frequency flood elevation and graphical or numerical scales (horizontal and vertical); and
            (5)    A soil erosion and sedimentation control plan for disturbed areas. This plan shall include a description of the sequence of grading activities and the temporary sediment and erosion control measures to be implemented to mitigate their effects. This plan shall also include a description of final stabilization and revegetation measures, and the identification of a responsible party to ensure postconstruction maintenance.
         e.   Engineering calculations and supporting data shall be submitted showing that the proposed work will meet the criteria of subsection B of this section.
         f.   Any and all other local, state and federal permits or approvals that may be required for this type of development.
      2.   Based on the best available existing data according to the Illinois state water survey's floodplain information repository, the director of engineering shall compare the elevation of the site to the base flood or 100-year frequency flood elevation. Should no elevation information exist for the site, the developer's engineer shall calculate the elevation according to subsection 14-1-5D of this chapter. Any development located on land that is higher than the base flood elevation as determined pursuant to section 14-1-5 of this chapter is not in the SFHA and, therefore, not subject to the requirements of this chapter. The community development director shall maintain documentation of the existing ground elevation at the development site and certification that its ground elevation is higher than the base flood elevation.
      3.   The director of engineering and community development director shall be responsible for obtaining from the applicant copies of all other local, state and federal permits, approvals or permit not required letters that may be required for this type of activity. The director of engineering and community development director shall not issue the development permit unless all required local, state and federal permits have been obtained.
   B.   Preventing Increased Damages: No development in the SFHA, where a floodway has not been determined, shall create a damaging or potentially damaging increase in flood heights or velocity or threat to public health, safety and welfare or impair the natural hydrologic and hydraulic functions of the floodway or channel, or impair existing water quality or aquatic habitat. Construction impacts shall be minimized by appropriate mitigation methods as called for in this chapter.
      1.   Interim Floodway: Within all SFHAs where a designated floodway has not been defined, it is recommended that an interim floodway be defined by the applicant for purposes of this chapter. This interim floodway would be subject to the appropriate use, engineering and mitigation requirements of section 14-1-7 of this chapter. A suggested interim floodway determination approach was discussed in the commentary to this section. As a minimum, all channels within the SFHA should be considered floodways for purposes of this chapter and the following standards shall apply:
         a.   The developer shall have a registered professional engineer state in writing and shown through supporting plans, calculations and data that the project meets the engineering requirements of subsections 14-1-7B2a through B2l of this chapter for the entire floodplain as calculated under the provisions of subsection 14-1-5D of this chapter. As an alternative, the developer should have an engineering study performed to determine a floodway and submit that engineering study to OWR for acceptance as a designated floodway. Upon acceptance of their floodway by the OWR, the developer shall then demonstrate that the project meets the requirements of section 14-1-7 of this chapter for the designated floodway. The "floodway" shall be defined according to the definition in section 14-1-2 of this chapter.
         b.   A development permit shall not be issued unless the applicant first obtains a permit from OWR or written documentation that a permit is not required from OWR.
         c.   No permit from OWR shall be required if the office has delegated permit responsibility to the city per 17 Illinois administrative code 3708 for regulatory floodways, per OWR's statewide permit entitled "construction in floodplains with no designated floodways in northeastern Illinois".
         d.   Any work involving the construction, modification or removal of a "dam" or an on stream structure to impound water as defined in section 14-1-2 of this chapter shall obtain an Illinois office of water resources dam safety permit or letter indicating a permit is not required prior to the start of construction of a dam. If the director of engineering finds a dam that does not have an OWR permit, the director of engineering shall immediately notify the dam safety section of the office of water resources. If the director of engineering finds a dam, which is believed to be in unsafe condition, the director of engineering shall immediately notify the owner of the dam and the Illinois emergency management agency (IEMA) and the OWR dam safety section in Springfield.
         e.   The following activities may be permitted without a registered professional engineer's review or calculation of a base flood elevation and regulatory floodway. Such activities shall still meet the other requirements of this chapter:
            (1)    Underground and overhead utilities that:
               (A)   Do not result in any increase in existing ground elevations, or
               (B)   Do not require the placement of aboveground structures in the floodway, or
               (C)   In the case of underground stream crossings, the top of the pipe or encasement is buried a minimum of three feet (3') below the existing streambed, and
               (D)   In the case of overhead utilities, no supporting towers are placed in the watercourse and are designed in such a fashion as not to catch debris;
            (2)    Storm and combined sewer outfalls that:
               (A)   Do not extend riverward or lakeward of the existing adjacent natural bank slope, and
               (B)   Do not result in an increase in ground elevation, and
               (C)   Are designed so as not to cause stream bank erosion at the outfall location;
            (3)    Construction of shoreline and streambed protection that:
               (A)   Does not exceed one thousand feet (1,000') in length or two (2) cubic yards per linear foot of streambed.
               (B)   Materials are not placed higher than the existing top of bank.
               (C)   Materials are placed so as not to reduce the cross sectional area of the stream channel by more than ten percent (10%).
               (D)   Vegetative stabilization and gradual side slopes are the preferred mitigation methods for existing erosion problems. Where high channel velocities, sharp bends or wave action necessitate the use of alternative stabilization measures, natural rock or riprap are preferred materials. Artificial materials such as concrete, construction rubble and gabions should be avoided unless there are no practicable alternatives.
Use of artificial shoreline and stream bank materials for the convenience of site design for private developments is not supported. Construction activities involving one thousand feet (1,000') of shoreline or stream bank are not minor and should be subject to the review of a registered professional engineer. The city recommends there be no reduction in the cross sectional area of the channel;
            (4)    Temporary stream crossings in which:
               (A)   The approach roads will be 0.5 foot (1/2 foot) or less above natural grade.
               (B)   The crossing will allow stream flow to pass without backing up the water above the stream bank vegetation line or above any drainage tile or outfall invert.
               (C)   The top of the roadway fill in the channel will be at least two feet (2') below the top of the lowest bank. Any fill in the channel shall be nonerosive material, such as riprap or gravel.
               (D)   All disturbed stream banks will be seeded or otherwise stabilized as soon as possible upon installation and again upon removal of construction.
               (E)   The access road and temporary crossings will be removed within one year after authorization;
            (5)    The construction of light poles, signposts and similar structures, unless the structure is cantilevered which then requires the review and approval of a registered professional engineer;
            (6)    The construction of sidewalks, driveways, athletic fields (excluding fences), patios and similar surfaces which are built at grade;
            (7)    The construction of properly anchored, unwalled, open structures such as playground equipment, pavilions and carports built at or below existing grade that would not obstruct the flow of floodwaters;
            (8)    The construction of additions to existing buildings which do not increase the first floor area by more than twenty percent (20%), which are located on the upstream or downstream side of the existing building, which do extend beyond the sides of the existing building that are parallel to the flow of floodwaters.
         f.   The flood carrying capacity within any altered or relocated watercourse shall be maintained.
      2.   Compensatory Storage: Whenever any portion of a floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the base flood or 100-year frequency flood elevation shall be compensated for and balanced by a hydraulically equivalent volume of excavation taken from below the base flood for 100-year frequency flood elevation. The excavation volume shall be at least equal to one and one-tenth (1.1) times the volume of storage lost due to the fill or structure. In the case of streams and watercourses, such excavation shall be made opposite or adjacent to the areas so filled or occupied. All floodplain storage lost below the existing 10-year flood elevation shall be replaced below the proposed 10-year flood elevation. All floodplain storage lost above the existing 10-year flood elevation shall be replaced above the proposed 10-year flood elevation and below the 100-year elevation. All such excavations shall be constructed to drain freely and openly to the watercourse. (Ord. M-15-16, 6-6-2016)
14-1-9: PERMITTING REQUIREMENTS APPLICABLE TO ALL FLOODPLAIN AREAS AND PROTECTION OF BUILDINGS:
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)
14-1-10: OTHER DEVELOPMENT REQUIREMENTS:
The city council shall take into account flood hazards, to the extent that they are known in all official actions related to land management, use and development.
   A.   Review Of Development Documents: New subdivisions, manufactured home parks, annexation agreements and planned unit developments (PUDs) within the SFHA shall be reviewed to assure that the proposed developments are consistent with sections 14-1-6, 14-1-7, 14-1-8 and 14-1-9 of this chapter and the need to minimize flood damage. Plats or plans for new subdivisions, mobile home parks and planned unit developments (PUDs) shall include a signed statement by a registered professional engineer that the plat or plans account for changes in the drainage of surface waters in accordance with the plat act 1
.
   B.   Data Shown: Proposals for new subdivisions, manufactured home parks, travel trailer parks, planned unit developments (PUDs) and additions to manufactured home parks and additions to subdivisions shall include base flood or 100-year frequency flood elevation data and floodway delineations. All new plans recorded must show the location of any SFHA, which appears on the plat and must be signed, sealed and certified by an Illinois registered land surveyor as per the requirements of Public Act 85-267. Where this information is not available from an existing study filed with the Illinois state water survey, the applicant's engineer shall be responsible for calculating the base flood or 100-year frequency flood elevation per subsection 14-1-5D of this chapter and the floodway delineation per the definition in section 14-1-2 of this chapter and submitting it to the state water survey and OWR for review and approval as best available regulatory data.
   C.   Preservation Of Natural Streams: Streets, blocks, lots, parks and other public grounds shall be located and laid out in such a manner as to preserve and utilize natural streams and channels. Wherever possible, the floodplains shall be included within parks or other public grounds.
   D.   Compliance With Chapter Required: The city council shall not approve any planned unit development (PUD) or plat of subdivision located outside the corporate limits unless such agreement or plat is in accordance with the provisions of this chapter.
   E.   Detached Single-Family Garages And Sheds: All new construction of or substantial improvements to detached single-family garages and sheds located in an SFHA (zone A) or property shown as being lower than the base flood elevation, shall be constructed in accordance with the requirements set forth in this chapter and the following requirements:
      1.   Floodway Location Prohibited: The structure shall not be located in the floodway.
      2.   Location On Single-Family Lot Required; Accessory To Principal Structure: The structure must be constructed or located, if already existing, as the case may be, on an existing single- family lot of record and be accessory to a principal structure on the same lot.
      3.   Location Of Floor: The floor of the structure shall be located at the existing ground elevation; however, the top of the foundation elevation shall be two feet (2') above the base flood elevation. (See exhibits C through F of this section for details.)
 
 
 
 
      4.   Fees: The fees for new construction or substantial improvements to detached single-family garages and sheds are set forth in title 10, chapter 13 of this code.
      5.   Materials: The structure shall be constructed of materials that will not be damaged by flooding and shall be constructed in accordance with all applicable provisions of the Des Plaines building code and ordinance.
      6.   Utilities: All utilities shall be located a minimum of two feet (2') above the base flood elevation.
      7.   Storage Of Vehicles And Tools: The structure shall only be used for the storage of vehicles and tools and shall not have any rooms, such as a workshop, greenhouse, etc.
      8.   Square Footage And Value Maximums: The structure shall not exceed five hundred (500) square feet and shall have a maximum value of no more than eight thousand dollars ($8,000.00) ($15,000.00 if brick) excluding the costs for a driveway.
      9.   Recordation Requirement: It must be recorded on the title that the structure is built in a floodplain.
      10.   Compliance Bond: The compliance bond shall be at least one thousand dollars ($1,000.00) to assure compliance. A higher compliance bond may be set by the building official if deemed necessary.
      11.   Requirements Of Section 14-1-6 Of This Chapter: The requirements of section 14-1-6 of this chapter shall be met, to the extent determined by the director of engineering.
      12.   Compliance Documents: Upon completion of the permit work the following compliance documents must be submitted for approval by the director of engineering and the building official prior to occupancy and refund of the compliance bond:
         a.   As constructed plans certified by a professional engineer or registered land surveyor; and
         b.   Copy of the recorded title identifying that the structure built is within the SFHA. (Ord. M-15-16, 6-6-2016)
14-1-11: VARIANCES:
No variances shall be granted to any development located in a "designated floodway" (except as stipulated in subsection C of this section) as defined in section 14-1-2 of this chapter. However, when a development proposal is located outside of a designated floodway, and whenever the standards of this chapter place undue hardship on a specific development proposal, the applicant may apply to the engineering committee (planning and zoning board or floodplain commission) for a variance. The director of engineering shall review the applicant's request for a variance and shall submit his recommendation to the city council.
   A.   No variance shall be granted unless the applicant demonstrates that:
      1.   The development activity cannot be located outside the SFHA;
      2.   An exceptional hardship would result if the variance were not granted;
      3.   The relief requested is the minimum necessary;
      4.   There will be no additional threat to public health, safety, beneficial stream uses and functions, especially aquatic habitat or creation of a nuisance;
The criteria for granting a variance should recognize and include the fact that there are legitimate stream uses and functions, which may be adversely affected by the granting of the variance. These uses include aesthetics, aquatic habitat and recreation. Since these uses have a definite, though difficult to quantify, economic value, the applicant should demonstrate that these uses will not be impaired by the proposed activity as part of the application for a variance;
      5.   There will be no additional public expense for flood protection, lost environmental stream uses and functions, rescue or relief operations, policing or repairs to stream beds and banks, roads, utilities or other public facilities;
      6.   The provisions of sections 14-1-6 and 14-1-9 of this chapter shall be met;
      7.   The activity is not in a designated floodway;
      8.   The applicant's circumstances are unique and do not represent a general problem; and
      9.   The granting of the variance will not alter the essential character of the area involved, including existing stream uses.
   B.   The director of engineering shall notify an applicant in writing that a variance from the requirements of section 14-1-9 of this chapter that would lessen the degree of protection to a building will:
      1.   Result in increased premium rates for flood insurance up to amounts as high as twenty five dollars ($25.00) for one hundred dollars ($100.00) of insurance coverage;
      2.   Increase the risks to life and property; and
      3.   Require that the applicant proceed with knowledge of these risks and that he will acknowledge in writing that he assumes the risk and liability.
   C.   Variances may be issued for the repair or rehabilitation of historic structures upon a determination that the proposed repair or rehabilitation will not preclude the structure's continued designation as a historic structure and the variance is the minimum necessary to preserve the historic character and design of the structure. (Ord. M-15-16, 6-6-2016)
14-1-12: DISCLAIMER OF LIABILITY:
The degree of flood protection required by this chapter is considered reasonable for regulatory purposes and is based on available information derived from engineering and scientific methods of study. Larger floods may occur or flood heights may be increased by manmade or natural causes. This chapter does not imply that development, either inside or outside of the SFHA, will be free from flooding or damage. This chapter does not create liability on the part of the city or any officer or employee thereof for any flood damage that results from reliance on this chapter or any administrative decision made lawfully hereunder. (Ord. M-15-16, 6-6-2016)
14-1-13: PENALTY:
Failure to comply with the requirements of a permit or conditions of a variance resolution shall be deemed to be a violation of this chapter. Upon due investigation, the director of engineering may determine that a violation of the minimum standards of this chapter exists. The director of engineering shall notify the owner in writing of such violation.
   A.   If such owner fails after ten (10) days' notice to correct the violation:
      1.   The city may make application to the circuit court for an injunction requiring conformance with this chapter or make such other order as the court deems necessary to secure compliance with this chapter, and the city will be obliged to take whatever actions will be necessary to ensure compliance with this chapter.
      2.   Any person who violates this chapter shall, upon conviction thereof, be fined not less than two hundred dollars ($200.00) nor more than five thousand dollars ($5,000.00) for each offense.
      3.   A separate offense shall be deemed committed upon each day during or on which a violation occurs or continues.
      4.   The city may record a notice of violation on the title to the property.
   B.   The director of engineering shall inform the owner that any such violation is considered a wilful act to increase flood damages and, therefore, may cause coverage by a standard flood insurance policy to be suspended.
   C.   Nothing herein shall prevent the city from taking such other lawful action to prevent or remedy any violations. All costs connected therewith shall accrue to the person or persons responsible. (Ord. M-15-16, 6-6-2016)
14-1-14: ABROGATION AND GREATER RESTRICTIONS:
This chapter is not intended to repeal, abrogate or impair any existing easements, covenants or deed restrictions. Where this chapter and other ordinance, easements, covenants or deed restrictions conflict or overlap, whichever imposes the more stringent restrictions shall prevail. This chapter is intended to repeal the original ordinance or resolution, which was adopted to meet the national flood insurance program regulations, but is not intended to repeal the resolution, which the city passed in order to establish initial eligibility for the program. (Ord. M-15-16, 6-6-2016)

 

Notes

1
1. 765 ILCS 205/2.