Chapter 15-64
DEVELOPMENT IN SPECIAL FLOOD HAZARD AREAS*
Sections:
15-64-030 General requirements.
15-64-040 Duties of the enforcement official.
15-64-050 Base flood elevation.
15-64-060 Occupation and use of flood fringe areas.
15-64-070 Occupation and use of identified floodways.
15-64-080 Occupation and use of SFHA areas where floodways are not identified.
15-64-090 Permitting requirements applicable to all floodplain areas.
15-64-100 Other development requirements.
15-64-120 Disclaimer of liability.
15-64-140 Abrogation and greater restrictions.
* Prior ordinance history: Ords. 2127 and 2265.
Editor’s note—Chapter 15-64 was amended by Ordinance 3213. Those amendments have not been incorporated herein. Ordinance 3213 is on file with the city clerk.
15-64-010 Purpose.
The ordinance codified in this chapter is enacted pursuant to the police powers granted to this city by Illinois Compiled Statutes, Chapter 65, Sections 5/12-1, 5/11-12-12, 5/11-30-8, and 5/11-31-2. The ordinance codified in this chapter is adopted in order to accomplish the following specific purposes:
A. To meet the requirements of Chapter 615, paragraph 5/189 of the Illinois Compiled Statutes, “An Act in Relation to the Regulation of the Rivers, Lakes and Streams of the State of Illinois,” approved June 10, 1911, as amended;
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; and
F. To make federally subsidized flood 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. (Ord. 2964 § 200.0, 1996)
15-64-020 Definitions.
For the purposes of this chapter, the following definitions are adopted:
“Act” means “an Act in Relation to the Regulation of the Rivers, Lakes and Streams of the State of Illinois,” Illinois Compiled Statutes 1992, Chapter 615, paragraph 5/5, et seq.
“Applicant” means any person, firm, corporation or agency which submits an application.
“Appropriate use” means only uses of the regulatory floodway that are permissible and will be considered for permit issuance. The only uses that will be allowed are as specified in Section 15-64-070B.
“Base flood” means the flood having a one-percent probability of being equaled or exceeded in any given year. The base flood is also known as the one hundred (100) year frequency flood event. Application of the base flood elevation at any location is as defined in Section 15-64-050 of this chapter.
“Building” means a structure that is principally above ground and is enclosed by walls and a roof. The 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.
“Compensatory storage” means an artificially excavated, hydraulically equivalent volume of storage within the special flood hazard area used to balance the loss of natural flood storage capacity within the floodway. The uncompensated loss of natural floodway storage can increase off-site floodwater elevations and flows.
“Conditional approval of a regulatory floodway map change” means preconstruction approval by DWR and the Federal Emergency Management Agency 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)” means a letter which indicates that the Federal Emergency Management Agency will revise base flood elevations, flood insurance rate zones, flood boundaries or floodways as shown on an effective flood hazard boundary map or flood insurance rate map, once the as-built plans are submitted and approved.
“Dam” means 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. Underground water storage tanks are not included.
“Designated floodway” means the channel, including on-stream lakes, and that portion of the floodplain adjacent to a stream or watercourse as designated by IDNR/OWR, which is needed to store and convey the existing one hundred (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 increase in velocities.
1. The floodways are designated Little Calumet River and the Calumet Union Drainage Ditch on the following map number 17031C and panels 0643F, 0644F, 0731F, 0732F, 0734F and 0751F dated November 6, 2000, respectively, of the countywide flood insurance rate map for Cook County prepared by the Federal Emergency Management Agency.
2. The floodways for those parts of unincorporated Cook County that are within the one and half mile extraterritorial jurisdiction of the city and may be annexed into the city are designated for Little Calumet River, Dixie Creek and the Calumet Union Drainage Ditch on the following map number 17031C and panels 0727E and 0733F dated November 6, 2000, respectively, of the countywide flood insurance rate map for Cook County prepared by the Federal Emergency Management Agency.
3. 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.
“Development” means any man-made change to real estate, including:
1. Construction, reconstruction, repair or placement of a building or any addition to a building;
2. 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;
3. Drilling, mining, installing utilities, construction of roads, bridges, or similar projects;
4. Construction or erection of levees, walls, fences; filling, dredging, grading, excavating, paving, or other nonagricultural alterations of the ground surface; storage of materials;
5. Any other activity of man that might change the direction, height or velocity of flood or surface water.
Development does not include maintenance of existing buildings and facilities such as reroofing or resurfacing of roads when there is no increase in elevation, or gardening, plowing, and similar agricultural practices that do not involve filling, grading or construction of levees.
“DWR” means Illinois Department of Transportation, Division of Water Resources.
“Elevation certificate” means a form published by the Federal Emergency Management Agency that is used to certify the elevation to which a building has been elevated.
“Exempt organizations” means organizations which are exempt from this chapter per the Illinois Compiled Statutes including state, federal or local units of government such as Metropolitan Water Reclamation District.
“FEMA” means the Federal Emergency Management Agency and its regulations at 44 CFR 59-79 effective as of October 1, 1988. This incorporation does not include any later editions or amendments.
“Flood” means 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 fringe” means that portion of the flood plain outside of the regulatory floodway.
“Flood insurance rate maps (FIRM)” means a map prepared by the Federal Emergency Management Agency that depicts the special flood hazard area (SFHA) within a community. This map includes insurance rate zones and flood plains and may or may not depict floodways.
“Floodplain” means that land typically adjacent to a body of water with ground surface elevations at or below the base flood or the one hundred (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).
1. The floodplains are those lands within the jurisdiction of the city that are subject to inundation by the base flood or one hundred (100) year frequency flood. The SFHAs of the city are generally identified as such on the following map number 17031C and panels 0643F, 0644F, 0731F. 0732F, 0734F and 0751F dated November 6, 2000, respectively, of the countywide flood insurance rate map for Cook County prepared by the Federal Emergency Management Agency.
2. The SFHAs for those parts of unincorporated
Cook County that are within the one and half mile extraterritorial jurisdiction of the city and may be annexed into the city are designated for Little Calumet River, Dixie Creek and the Calumet Union Drainage Ditch on the following map number 17031C and panels 0727F and 0733F dated November 6, 2000, respectively, on the countywide flood insurance rate map for Cook County prepared by the Federal Emergency Management Agency.
“Floodproofing” means 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” means 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.
“Flood protection elevation (FPE)” means the elevation of the base flood or one hundred (100) year frequency flood plus one foot of freeboard at any given location in the SFHA.
“Freeboard” means an increment of elevation added to the base flood elevation to provide a factor of safety for uncertainties in calculations, unknown localized conditions, wave actions and unpredictable effects such as those caused by ice or debris jams.
“Hydrologic and hydraulic calculations” means engineering analysis which determine expected flood flows and flood elevations based on land characteristics and rainfall events.
“Letter of map amendment (LOMA)” means official determination by FEMA that a specific structure is not in a one hundred (100) year flood zone; amends the effective flood hazard boundary map or FIRM.
“Letter of map revision (LOMR)” means letter that revises base flood or one hundred (100) year frequency flood elevations, flood insurance rate zones, flood boundaries or floodways as shown on an effective FHBM or FIRM.
“Manufactured home” means 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 homes also includes park trailers, travel trailers and other similar vehicles placed on site for more than one hundred eighty (180) consecutive days.
“Manufactured home park or subdivision” means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
“NGVD” means National Geodetic Vertical Datum of 1929. Reference surface set by the National Geodetic Survey deduced from a continental adjustment of all existing adjustments in 1929.
“Public flood control project” means a flood control project which will be operated and maintained by a public agency to reduce flood damages to existing buildings and structures which includes 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.
“Publicly navigable waters” means all streams and lakes capable of being navigated by watercraft.
“Registered land surveyor” means a land surveyor registered in the state of Illinois, under the Illinois Land Surveyors Act (Illinois Compiled Statutes 1992, Chapter 225, paragraphs 330 et seq.).
“Registered professional engineer” means an engineer registered in the State of Illinois, under the Illinois Professional Engineering Act (Illinois Compiled Statutes 1992, Chapter 225, paragraph 325, et seq.).
“Repair, remodeling or maintenance” means development activities which do not result in any increases in the outside dimensions of a building or any changes to the dimensions of a structure.
“Riverine special flood hazard area” means 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.
“Special flood hazard area (SFHA)” means any base flood area subject to flooding from a river, creek, intermittent stream, ditch, or any other identified channel or ponding and shown on a flood hazard boundary map or flood insurance rate map as Zone A, AO, A1-30, AE, A99, AH, VO, V30, VE, V, M or E.
“Structure” means the results of a man-made 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 improvement” means any repair, reconstruction or improvement of a structure, the cost of which equals or exceeds fifty (50) percent of the market value of the structure either: (a) before the improvement or repair is started, or (b) if the structure has been damaged, and is being restored, before the damage occurred. For the purposes of this definition “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 structure. The term does not, however, include either: (1) any project for improvement of a structure to comply with existing state or local health, sanitary or safety code specifications which are solely necessary to assure safe living conditions; or (2) any alteration of a structure listed on the National Register of Historic Places or a State Inventory of Historic Places.
“Transition section” means reaches of the stream or floodway where water flows from a narrow cross-section to a wide cross-section or vice versa. (Ord. 3066 §§ 1, 2, 2000; Ord. 2964 § 300.0, 1996)
15-64-030 General requirements.
A. The director of the department of building and planning shall be responsible for fulfilling all of the duties listed in Section 15-64-040.
B. To fulfill those duties, the director of the department of building and planning first should use the criteria listed in Section 15-64-050, base flood elevations, 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 the department of building and planning must determine whether the development site is within a flood fringe, a regulatory floodway, or within an SFHA or floodplain on which no floodway has been identified. If the site is within a flood fringe, the director of the department of building and planning shall require that the minimum requirements of Section 15-64-060 be met. If the site is within a floodway, the director of the department of building and planning shall require that the minimum requirements of Section 15-64-070 be met. If the site is located within a SFHA or floodplain for which no detailed study has been completed and approved, the director of the department of building and planning shall require that the minimum requirements of Section 15-64-080 be met.
C. In addition, the general requirements of Section 15-64-090 shall be met for all developments meeting the requirements of Section 15-64-060, 15-64-070 or 15-64-080. The director of the department of building and planning shall assure that all subdivision proposals shall meet the requirements of Section 15-64100.
D. If a variance is to be granted for a proposal, the director of building and planning shall review the requirements of Section 15-64-110 to make sure they are met. In addition, the director of building and planning shall complete all notification requirements.
E. In order to assure that property owners obtain permits as required in this chapter, the director of the department of building and planning may take any and all actions as outlined in Section 15-64-130. (Ord. 2964 § 400.0, 1996)
15-64-040 Duties of the enforcement official.
The director of the department of building and planning 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 a 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;
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 the city engineer, being a registered professional engineer (P.E.) under the employ or contract of the city, for review to ensure that the development meets the requirements of Section 15-64070. In the case of an appropriate use, the city engineer, shall state in writing that the development meets the requirements of Section 15-64-070;
C. Dam Safety Requirements. Ensure that an DWR dam safety permit has been issued or a letter indicating no dam safety permit is required. If the proposed development activity includes construction of a dam as defined in Section 15-64-020. Regulated dams may include weirs, restrictive culverts or impoundment structures;
D. Other Permit Requirements. Ensure that 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 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 they comply with the provisions of this chapter;
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 floodproofed, using a floodproofing certificate, for all buildings subject to Section 15-64-090 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 flood-proofing certificates for all buildings constructed subject to this chapter;
I. State Permits. Ensure that construction authorization has been granted by the Illinois Division of Water Resources, for all development projects subject to Sections 15-64-070 and 15-64-080 of this chapter, unless enforcement responsibility has been delegated to the city. Upon acceptance of this chapter by DWR and FEMA, responsibility is hereby delegated to the city as per 92 Illinois Administrative Code 708 for construction in the regulatory floodway and floodplain when floodways have not been defined in Sections 1564-070 and 15-64-080 of this chapter. However, the following review approvals are not delegated to the city and shall require review or permits from DWR:
1. Organizations which are exempt from this chapter, as per the Illinois Revised Statutes,
2. Department of transportation projects, dams or impoundment structures as defined in Section 15-64020 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 Section 15-64-070(B)(5),
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 Section 15-64-070(B)(1Xe),
4. An engineer’s analysis of the flood profile due to Section 15-64-070(B)(1)(d),
5. Alternative transition sections and hydraulically equivalent compensatory storage as indicated in Section 15-64-070(B)(1), (2) and (7),
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 base flood or one hundred (100) year frequency flood and floodway data and to improve the administration of this chapter. Submit data to DWR and the Federal Emergency Management Agency for proposed revisions of a regulatory map. 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 DWR and FEMA for any ordinance changes. (Ord. 2964 § 500.0, 1996)
15-64-050 Base flood elevation.
This chapter’s protection standard is based on the flood insurance study for the city. If a base flood elevation or one hundred (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. When a party disagrees with the best available data, he/she may finance the detailed engineering study needed to replace existing data with better data and submit it to DWR and FEMA.
A. The base flood or one hundred (100) year frequency flood elevation for the SFHAs of Little Calumet River, Dixie Creek and the Calumet Union Drainage Ditch shall be delineated on the one hundred (100) year flood profiles in the countywide Flood Insurance Study for Cook County prepared by the Federal Emergency Management Agency and dated November 6, 2000 and such amendments to such study and maps as may be prepared from time to time.
B. The base flood or one hundred (100) year frequency flood elevation for the SFHAs of those parts of unincorporated Cook County that are within the one an half mile extraterritorial jurisdiction or that may be annexed into the city shall be as delineated on the one hundred (100) year flood profiles in the countywide flood insurance study for cook county prepared by the federal emergency management agency and dated November 6, 2000 and such amendments or revisions to such study and maps as may be prepared from time to time.
C. The base flood or one hundred (100) year frequency flood elevation for each SFHA delineated as an “AH zone” or “AO zone” shall be that elevation (or depth) delineated on the flood insurance rate map of the city.
D. The base flood or one hundred (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 Floodplain Information Repository. When no base flood or one hundred (100) year frequency flood elevation exists, the base flood or one hundred (100) year frequency flood elevation for a riverine SFHA shall be determined from a backwater model, such as HEC-II, WSP-2, or a dynamic model such as HIP. The flood flows used in the hydraulic models shall be obtained from a hydrologic model, such as HEC-I TR-20 or HIP, or by techniques presented in various publications prepared by the United States Geological Survey for estimating peak flood discharges. 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 DWR 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, unless calculated by a detailed engineering study and approved by the Illinois State Water Survey. (Ord. 3066 §§ 3, 4, 2000; Ord. 2964 § 600.0, 1996)
15-64-060 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 one hundred (100) year frequency flood by proper elevation and other provisions of this chapter are met. No use will be permitted which adversely affects the capacity of drainage facilities or systems. Developments located within the flood fringe shall meet the requirements of this section, along with the requirements of Section 15-64-090.
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 director of the department of building and planning.
1. Application for a development permit shall be made on a form provided by the director of the department of building and planning. 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, architect or land surveyor; existing grade elevations in mean sea level, 1929 adjusted datum or NGVD and all changes in grade resulting from excavation or filling; the location and dimensions of all buildings and additions to buildings. For all proposed 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 15-64090 of this chapter.
2. Upon receipt of a development permit application, the director of the department of building and planning shall compare the elevation of the site to the base flood or one hundred (100) year flood elevation. Any development located on land that can be shown to have been higher than the base flood elevation as of the site’s first flood insurance rate map identification is not in the SFHA and, therefore, not subject to the requirements of this chapter. The director of the department of building and planning 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 first flood insurance rate map identification.
3. The director of the department of building and planning 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 the department of building and planning shall not issue a permit unless all other local, state and federal permits have been obtained.
4. Preventing Increased Damages. No development in the flood fringe shall create a threat to public health and safety. If fill is being used to elevate the site above the base flood or one hundred (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. (Ord. 2964 § 700.0, 1996)
15-64-070 Occupation and use of identified floodways.
This section applies to proposed development, redevelopment, site modification or building modification within a regulatory floodway. The regulatory floodway for the Little Calumet River, Dixie Creek and the Calumet Union Drainage Ditch shall be as delineated on the regulatory floodway maps designated by DWR and referenced in Section 15-64-020. 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 1564-090.
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 director of the department of building and planning.
1. Application for a development permit shall be made on a form provided by the director of the department of building and planning. 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, on the regulatory floodway map, 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:
i. A vicinity map showing the site of the activity, name of the waterway, boundary lines, names of roads in the vicinity of the site, graphic or numerical scale, and north arrow,
ii. 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 mean sea level (1929 adjustment) datum or NGVP, adjacent property lines and ownership, drainage and flood control easements, proposed activity and navigation channel (when the proposed construction is near a commercially navigable body of water), regulatory floodway limit, floodplain limit, location and orientation of cross-sections, north arrow, and a graphic or numerical scale,
iii. 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, one hundred (100) year frequency flood elevation, and graphic or numerical scales (horizontal and vertical),
iv. A copy of the regulatory 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 showing that the proposed work will meet the permit criteria of subsection B of this section;
o. If the regulatory floodway delineation, base flood or one hundred (100) year frequency flood elevation will change due to the proposed project, the application will not be considered complete until DWR has indicated conditional approval of the regulatory 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 flood-plain and floodway limits; sealed by a registered professional engineer, licensed architect 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 15-64-090 of this chapter.
2. The director of building and planning 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 director of the department of building and planning shall not issue the development permit unless all required federal and state permits have been obtained. The city engineer, being a registered professional engineer, shall review and approve applications reviewed under this section.
B. Preventing Increased Damages and a List of Appropriate Uses.
1. The only development in a floodway which will be allowed is 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. Only those appropriate uses listed in 92 Illinois Administrative Code 708 will be allowed. Appropriate uses do not include the construction or placement of any new structures, fill, building additions, buildings on stilts, fencing (including landscaping or planting designed to act as a fence) and storage of materials except as specifically defined above as an appropriate use. 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 fifty (50) percent open when viewed from any one direction) built parallel to the direction of flood flows, and including open air pavilions;
f. Detached garages, storage sheds, or other nonhabitable accessory structures without toilet facilities to existing buildings that will not block flood flows, nor reduce floodway storage;
g. Bridges, culverts, roadways, sidewalks, railways, runways and taxiways and any modification thereto;
h. Parking lots and any modifications thereto (where depth of flooding at the one hundred (100) year frequency flood event will not exceed one foot) and aircraft parking aprons built at or below ground elevation;
i. Regulatory floodway regrading, without fill, to create a positive nonerosive slope toward a watercourse;
j. 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 away from the exterior wall of the existing structure, and, which are not considered substantial improvements to the structure;
k. In the case of damaged or replacement buildings, reconstruction or repairs made to a building that are valued at less than fifty (50) percent of the market value of the building before it was damaged or replaced, and which do not increase the outside dimensions of the building;
1. Additions to existing buildings above the base flood elevation that do not increase the building’s footprint and are valued at less than fifty (50) percent of the market value of the building.
2. Within the regulatory floodway as identified on the regulatory floodway maps designated by DWR, the construction of an appropriate use, will be considered permissible provided that the proposed project meets the following engineering 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 15-64-090 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 one hundred (100) year frequency flood. In calculating effective regulatory floodway conveyance, the following factors shall be taken into consideration:
i. Regulatory floodway conveyance,
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|
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)
ii. 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.
iii. 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 DWR through engineering calculations 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 horizontal for every four feet 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 horizontal for every one foot of the flooded stream’s length.
(C) When expanding or contracting flows in a vertical direction, a minimum of one foot vertical transition for every ten feet 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-section 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 regulatory flood-way 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 the volume of floodway 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 regulatory floodway storage shall be placed between the proposed normal water elevation and the proposed one hundred (100) year flood elevation. All regulatory floodway storage lost below the existing ten-year flood elevation shall be replaced below the proposed ten-year flood elevation. All regulatory floodway storage lost above the existing ten-year flood elevation shall be replaced above the proposed ten-year flood 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 DWR through a determination of flood discharges and water surface elevations that the compensatory storage is hydraulically equivalent.
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 not result in an increase in the average channel or regulatory floodway velocities. 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.
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 0.1 foot when compared to the existing conditions for all flood events up to and including the one hundred (100) year frequency event; or the upstream flood stage increases will 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 flood walls or within recorded flood easements. If the proposed construction will increase upstream flood stages greater than 0.1 feet, the developer must contact DWR, Dam Safety Section for a dam safety permit or waiver.
i. The engineering analysis of upstream flood stages must be calculated using the flood study flows, and corresponding flood elevations for tailwater conditions for the flood study specified in Section 15-64-050 of this chapter. Culverts must be analyzed using the U.S. DOT, Federal Highway Administration Hydraulic Chart for the Selection of Highway Culverts. Bridges must be analyzed using the U.S. DOT/Federal Highway Administration Hydraulics of Bridge Waterways calculation procedures.
ii. Lost floodway storage must be compensated for per subsection (B)(2)(b) of this section.
iii. Velocity increases must be mitigated per subsection (B)(2)(c) of this section.
iv. If the crossing is proposed over a public water that is used for recreational or commercial navigation, a Department of Transportation permit must be received.
v. The hydraulic analysis for the backwater caused by the bridge showing the existing condition and proposed regulatory profile must be submitted to DWR for concurrence that a CLOMR is not required by this subsection.
vi. All excavations for the construction of the crossing shall be designed per subsection (B)(2)(h) of this section.
e. Reconstruction or Modification of Existing Bridges, Culverts and Approach Roads.
i. The bridge or culvert and roadway approach reconstruction or modification shall be constructed with no more than 0.1 foot increase in backwater over the existing flood profile for all flood frequencies up to and including the one hundred (100) year event, if the existing structure is not a source of flood damage.
ii. 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.
iii. 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 Department of Transportation Rules, 92 Illinois Administration Code 708 (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 0.0 foot when compared to the existing conditions, for all flood events up to and including the one hundred (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 flood walls or within recorded flood easements. A permit or letter indicating a permit is not required must be obtained from DWR, 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 15-64-020 shall meet the permitting requirements of 92 Illinois Administration Code 702 (Construction and Maintenance of Dams).
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 further than ten feet 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 DWR through engineering calculations or model tests that more abrupt transitions may be used with the same efficiency:
i. 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 horizontal for every four feet of the flooded stream’s length;
ii. 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 horizontal for every one foot of the flooded stream’s length; and iii. When expanding or contracting flows in a vertical direction, a minimum of one foot vertical transition for every ten feet of stream length shall be used.
iv. Erosion/scour protection shall be provided inland upstream and downstream of the transition sections.
i. Seeding and Stabilization Plan. For all activities located in a floodway, a seeding and stabilization plan shall be submitted by the applicant.
j. 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 DWR 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 one hundred (100) year frequency event.
k. General Criteria for Analysis of Flood Elevations.
i. The flood profiles, flows and floodway data in the regulatory floodway study, referenced in Section 15-64-050, must be used for analysis of the base conditions. If the study data appears to be in error or conditions have changed, DWR shall be contacted for approval and concurrence on the appropriate base conditions data to use.
ii. If the one hundred (100) year regulatory 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 one hundred (100) year frequency flood elevations of the regulatory floodway conditions and conditions with the receiving stream at normal water elevations.
iii. If the applicant learns from DWR, 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 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.
l. Conditional Letter of Map Revision. If the appropriate use would result in a change in the regulatory floodway location or the one hundred (100) year frequency flood elevation, the applicant shall submit to DWR and to FEMA all the information, calculations and documents necessary to be issued a conditional regulatory floodway map revision and receive from DWR a conditional approval of the regulatory floodway change before a permit is issued. However, the final regulatory floodway map will not be changed by DWR until as-built plans or record drawings are submitted and accepted by FEMA and DWR. In the case of nongovernment projects, the municipality in incorporated areas and the county in unincorporated areas shall concur with the proposed conditional regulatory floodway map revision before DWR approval can be given. No filling, grading, dredging or excavating shall take place until a conditional approval is issued. No further development activities shall take place until a final letter of map revision (LOMR) is issued by FEMA and DWR.
m. Professional Engineer’s Supervision. All engineering analyses shall be performed by or under the supervision of a registered professional engineer.
After receipt of conditional approval of the regulatory floodway change and issuance of a permit and a conditional letter of map revision, construction as necessary to change the regulatory floodway designation may proceed but no buildings or structures or other construction that is not an appropriate use may be placed in that area until the regulatory floodway map is changed and a final letter of map revision is received. The regulatory floodway map will be revised upon acceptance and concurrence by DWR and FEMA of the as-built plans.
3. State Review. For those projects listed below located in a regulatory floodway, the following criteria shall be submitted to DWR for their review and concurrence prior to the issuance of a permit:
a. DWR will review an engineer’s analysis of the flood profile due to a proposed bridge pursuant to subsection (B)(2)(d) of this section.
b. DWR 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 Section 15-64-070(B)(2)(e).
c. The DWR will review alternative transition sections and hydraulically equivalent storage pursuant to Section 15-64-070(B)(2)(a), (b) and (h).
d. The DWR will review and approve prior to the start of construction any Department projects, dams (as defined in Section 15-64-020) 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 code, 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 DWR, issued pursuant to Illinois Revised Statutes, Chapter 19, Section 52 et seq. No permit from DWR 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 15-64-020 per 92 Illinois Administration Code 702 (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 the department of building and planning finds a dam that does not have a DWR permit, the director of the department of building and planning shall immediately notify the Dam Safety Section of the Division of Water Resources. If the director of the department of building and planning finds a dam which is believed to be in unsafe condition, the director of the department of building and planning immediately notify the owner of the dam, DWR, Dam Safety Section in Springfield and the Illinois Emergency Services and Disaster Agency (ESDA).
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 code, including the mitigation requirements.
a. Underground and overhead utilities that:
i. Do not result in any increase in existing ground elevations, or
ii. Do not result in any increase in existing ground structures in the floodway, or
iii. In the case of underground stream crossings, the top of the pipe or encasement is buried a minimum of three feet below the existing streambed, and iv. 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;
b. Storm and sanitary sewer outfalls that:
i. Do not extend riverward or lakeward of the existing adjacent natural bank slope, and ii. Do not result in an increase in ground elevation, and iii. 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 streambank protection that:
i. Does not exceeds one thousand (1,000) feet in length,
ii. Materials are not placed higher than the existing top of bank,
iii. Materials are placed so as not to reduce the cross-sectional area of the stream channel or bank of the lake;
e. Temporary stream crossings in which:
i. The approach roads will be one-half foot or less above natural grade.
ii. 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.
iii. The top of the roadway fill in the channel will be at least two feet below the top of the lowest bank.
iv. All disturbed stream banks will be seeded or otherwise stabilized as soon as possible upon installation and again upon removal of construction.
v. The access road and temporary crossings will be removed within one year after authorization. (Ord. 2964 § 800.0, 1996)
15-64-080 Occupation and use of SFHA areas where floodways are not identified.
In SFHA or floodplains, where no floodways have been identified and no base flood or one hundred (100) year frequency flood elevations have been established by FEMA, 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 one hundred (100) year frequency flood elevation.
A. Development Permit.
1. No person, firm, corporation or governmental body, not exempted by state law, shall commence any development in a SFHA or floodplain without first obtaining a development permit from the director of the department of building and planning. Application for a development permit shall be made on a form provided by the director of the department of building and planning. 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, architect or surveyor, the location and dimensions of all buildings and additions to buildings; and the elevations of the lowest floor (including basement) of all proposed buildings subject to the requirements of Section 15-64-090 of this chapter. 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 regulatory 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:
i. A vicinity map showing the site of the activity, name of the waterway, boundary lines, names of roads in the vicinity of the site, graphic or numerical scale, and north arrow,
ii. 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 mean sea level (1929 adjustment) datum or NGVP, 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,
iii. 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, ten-year frequency flood elevation, one hundred (100) year frequency flood elevation, and graphical or numerical scales (horizontal and vertical); and 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 Flood Plain Information Repository, the director of the department of building and planning shall compare the elevation of the site to the base flood or one hundred (100) year frequency flood elevation. Should no elevation information exist for the site, the developer’s engineer shall calculate the elevation according to Section 15-64-050D. Any development located on land that can be shown to have been higher than the base flood elevation as of the site’s first flood insurance rate map identification is not in the SFHA and, therefore, not subject to the requirements of this chapter. The director of the department of building and planning 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 first flood insurance rate map identification.
3. The director of the department of building and planning 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 the department of building and planning 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.
1. Within all riverine SFHAs where the flood-way has not been determined, the following standards shall apply:
a. The developer shall have a Registered Professional Engineer state in writing and show through supporting plans, calculations and data that the project meets the engineering requirements of Section 15-64-070(B)(2) for the entire floodplain as calculated under the provisions of Section 15-64050D of this chapter. As an alternative, the developer should have an engineering study performed to determine a floodway and submit that engineering study to DWR for acceptance as a regulatory flood-way. Upon acceptance of their floodway by the department, the developer shall then demonstrate that the project meets the requirements of Section 15-64-070 for the regulatory floodway. The flood-way shall be defined according to the definition in Section 15-64-020 of this chapter.
b. A development permit shall not be issued unless the applicant first obtains a permit from DWR or written documentation that a permit is not required from DWR.
c. No permit from DWR shall be required if the Division has delegated permit responsibility to the city per 92 Illinois Administration Code, Part 708 for regulatory floodways, per DWR’ Statewide Permit entitled “Construction in Flood Plains with No Designated Floodways in Northeastern Illinois.”
d. Dam Safety Permits. Any work involving the construction, modification or removal of a darn or an on-stream structure to impound water as defined in Section 15-64-020 shall obtain an Illinois Division 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 the department of building and planning finds a dam that does not have a DWR permit, the director of the department of building and planning shall immediately notify the Dam Safety Section of the Division of Water Resources. If the director of the department of building and planning finds a dam which is believed to be in unsafe condition, the director of the department of building and planning shall immediately notify the owner of the darn and the Illinois Emergency Services, DWR, Dam Safety Section in Springfield and Disaster Agency (ESDA).
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.
i. 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 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;
ii. Storm and sanitary 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;
iii. Construction of shoreline and streambed protection that:
(A) Does not exceed one thousand (1,000) feet in length,
(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;
iv. Temporary stream crossings in which:
(A) The approach roads will be one-half 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 below the top of the lowest bank,
(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;
v. The construction of light poles, sign posts and similar structures;
vi. The construction of sidewalks, driveways, athletic fields (excluding fences), patios and similar surfaces which are built at grade;
vii. 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;
viii. The placement of properly anchored buildings not exceeding seventy (70) square feet in size, nor ten feet in any one dimension (e.g., animal shelters and tool sheds);
ix. The construction of additions to existing buildings which do not increase the first floor area by more than twenty (20) percent, which are located on the upstream or downstream side of the existing building, and which do extend beyond the sides of the existing building that are parallel to the flow of floodwaters;
x. Minor maintenance dredging of a stream channel where:
(A) The affected length of stream is less than one thousand (1,000) feet,
(B) The work is confined to reestablishing flows in natural stream channels, or
(C) The cross-sectional area of the dredged channel conforms to that of the natural channel upstream and downstream of the site.
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 one hundred (100) year frequency flood elevation shall be compensated for and balanced by a hydraulically equivalent volume of excavation taken from below the base flood or one hundred (100) year frequency flood elevation. The excavation volume shall be at least equal to 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 ten-year flood elevation shall be replaced above the proposed ten-year flood elevation. All such excavations shall be constructed to drain freely and openly to the watercourse. (Ord. 2964 § 900.0, 1996)
15-64-090 Permitting requirements applicable to all floodplain areas.
In addition to the requirements found in Sections 15-64-060 through 15-64-080 for development in flood fringes, regulatory floodways and SFHA or floodplains where no floodways have been identified (Zones A, AO, AH, AE, A-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.
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.
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.
1. All buildings located within a one hundred (100) year floodplain also known as an SFHA, shall be protected from flood damage below the flood protection elevation. However, existing buildings located within a regulatory floodway shall also meet the more restrictive appropriate use standards included in Section 15-64-070. This building protection criteria applies to the following situations:
a. Construction or placement of a new building;
b. A structural alteration to an existing building that either increases the first floor area by more than twenty (20) percent or the building’s market value by more than fifty (50) percent;
c. 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 mobilehome to the same site it lawfully occupied before it was removed to avoid flood damage; and d. Installing a travel trailer on a site for more than one hundred eighty (180) days. This building protection requirement may be met by one of the following methods.
2. 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 or above the flood protection elevation.
b. The fill shall be placed in layers no greater than one foot deep before compaction and should extend at least ten feet 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 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 or surface drainage from or onto neighboring properties.
3. A residential or nonresidential building may be elevated in accordance with the following:
a. The building or improvements shall be elevated on crawl space, stilts, piles, walls, or other foundation that is permanently open to floodwaters and not subject to damage by hydrostatic pressures of the base flood or one hundred (100) year frequency flood. The permanent openings shall be no more than one foot above grade, and consist of a minimum of two openings. 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 and utility meters shall be located at or above 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.
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 connections.
e. 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 Tie-Down Act issued pursuant to 77 Illinois Administration Code 870.
4. Only a 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 one hundred (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.)
Tool sheds and detached garages on an existing single-family platted lot, may be constructed with the lowest floor below the flood protection elevation in accordance with the following:
a. The building is not used for human habitation.
b. All areas below the base flood or one hundred (100) year frequency flood elevation shall be constructed with waterproof material. Structures located in a regulatory floodway shall be constructed and placed on a building site so as not to block the flow of floodwaters and shall also meet the appropriate use criteria of Section 15-64-070. In addition, all other requirements of Sections 15-64-060 through 15-64-080 must be met.
c. The structure shall be anchored to prevent flotation.
d. Service facilities such as electrical and heating equipment shall be elevated or floodproofed to the flood protection elevation.
e. The building shall be valued at less than seven thousand five hundred dollars ($7,500.00) and be less than five hundred (500) square feet in floor size.
f. The building shall be used only for the storage of vehicles or tools and may not contain other rooms, workshops, greenhouses or similar uses.
5. Nonconforming structures located in a regulatory floodway may remain in use, but may not be enlarged, replaced or structurally altered. A nonconforming structure damaged by flood, fire, wind or other natural or man-made disaster may be restored unless the damage exceeds fifty (50) percent of its market value before it was damaged, in which case it shall conform to this chapter. (Ord. 2964 § 1000.0, 1996)
15-64-100 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. New subdivisions greater than five acres or fifty (50) lots, 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 15-64-060 through 15-64-080 of this chapter and the need to minimize flood damage. Plats or plans for the aforementioned 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 (Illinois Revised Statutes, Chapter 109, Section 2).
B. Proposals for the 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 one hundred (100) year frequency flood elevation data and floodway delineations. 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 one hundred (100) year frequency flood elevation per Section 15-64-050D and the floodway delineation per the definition in Section 15-64-020 and submitting it to the State Water Survey and DWR for review and approval as best available regulatory data.
C. 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. 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. (Ord. 2964 § 1100.0, 1996)
15-64-110 Variances.
No variances shall be granted to any development located in a regulatory floodway as defined in Section 15-64-020. However, when a development proposal is located outside of a regulatory floodway, and whenever the standards of this chapter place undue hardship on a specific development proposal, the applicant may apply to the city for a variance. In the case where the development is an uninhabited accessory building (detached garage, tool shed, etc.), the applicant may apply directly to the director of the department of building and planning. In all other cases the applicant may apply to the planning and zoning commission for a variance. The director of the department of building and planning shall then review the applicant’s request for a variance and shall submit its recommendation to the planning and zoning commission.
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;
5. There will be no additional public expense for flood protection, rescue or relief operations, policing or repairs to roads, utilities, or other public facilities;
6. The provisions of Sections 15-64-060(B) and 15-64-080(B) shall still be met;
7. The activity is not in a regulatory floodway.
B. The director of the department of building and planning shall notify an applicant in writing that a variance from the requirements of Section 15-64-090 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 requested in connection with restoration of a site or building listed on the National Register of Historical Places or documented as worthy of preservation by the Illinois Historic Preservation Agency may be granted using criteria more permissive than the requirements of subsections A and B of this section. (Ord. 3462 § 9, 2022; Ord. 2964 § 1200.0, 1996)
15-64-120 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 man-made 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 thereunder. (Ord. 2964 § 1300.0, 1996)
15-64-130 Violation—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 the department of building planning may determine that a violation of the minimum standards of this chapter exists. The director of the department of building and planning shall notify the owner in writing of such violation.
A. If such owner fails after ten 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.
2. Any person who violates this chapter shall, upon conviction thereof, be fined as laid out in Chapter 3-01, Fees, Fines, Insurance and Guarantee Requirements, 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 the department of building and planning 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 in this chapter 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. 3494 § 2(B), 2024; Ord. 2964 § 1400.0, 1996)
15-64-140 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 ordinances, 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 an order to establish initial eligibility for the program. (Ord. 2964 § 1500.0, 1996)