§ 55.064 FLOODWAY STANDARDS.

   (A)   The only development in a regulatory floodway which will be allowed are appropriate uses which will not cause an increase in flood heights or velocities for all flood events up to and including the base flood. Only those appropriate uses listed below will be allowed in the regulatory floodway.

   (B)   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 below as an appropriate use. If the development is proposed for the regulatory floodway portion of the regulatory floodplain, the following standards apply in addition to the standards for the regulatory floodplain.

      (1)   Only the construction, modification, repair or replacement of the following appropriate uses will be allowed in the regulatory floodway:

         (a)   Public flood control structures and private improvements relating to the control of drainage and flooding of existing buildings, erosion, water quality or habitat for fish and wildlife;

         (b)   Structures or facilities relating to functionally water dependent uses such as additions, modifications and improvements to existing wastewater treatment plants (except for additions to habitable structures on the site) and facilities and improvements relating to recreational boating (this does not include new wastewater treatment plants);

         (c)   Storm and sanitary sewer outfalls;

         (d)   Underground and overhead utilities;

         (e)   Recreational facilities such as playing fields, open pavilions and trail systems including any related fencing (at least 50% open when viewed from any one direction) built parallel to the direction of flood flows;

         (f)   Detached garages, storage sheds, boat houses or other non-habitable structures without sanitary facilities that are accessory to existing buildings and will not block flood flows nor reduce regulatory floodway storage;

         (g)   Bridges, culverts and associated roadways, sidewalks and railways, required for crossing the regulatory floodway or for access to other appropriate uses in the regulatory floodway and any modification thereto;

         (h)   Parking lots built at or below existing grade provided that either:

            1.   The BFE is less than one foot above the proposed parking lot; or

            2.   The parking lot is accessory to short-term outdoor recreational facilities and the owner agrees to restrict access during periods of inundation and agrees to accept liability for all damage caused by vehicular access during flooding events.

         (i)   Regulatory floodway grading, without fill, to create a positive non-erosive slope toward a channel;

         (j)   Floodproofing activities to protect previously existing lawful structures including the construction of water-tight window wells, elevating structures or the construction of flood walls or berms around residential, commercial or industrial principal structures where the outside toe of the floodwall or berm shall be no more than ten feet away from the exterior wall of the existing structure, and, which are not considered to be substantial improvements to the structure;

         (k)   The repair, replacement or reconstruction of a damaged building, provided that none of the outside dimensions of the building are increased and provided that the cost of repair is less than 50% of the building’s value before it was damaged. When damage is 50% or more (a substantial improvement), the activity shall conform to § 55.062(C) of this chapter; and

         (l)   Modifications to an existing building that would not increase the enclosed floor area of the building below the BFE and which will not block flood flows. These modifications include fireplaces, bay windows, decks, patios and second story addition. No enclosed floor areas may be built on stilts. The modifications may not singularly or cumulatively equal 50% or more of the building’s market value.

      (2)   Additions or changes to the above list of appropriate uses must be approved by the Committee prior to the adoption by the County Board and IDNR/OWR.

      (3)   All development in the regulatory floodway shall require a permit from IDNR-OWR and must be in accordance with all provisions of this chapter.

      (4)   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 prepared and signed by a professional engineer.

         (a)   All effective regulatory floodway conveyance lost due to the development of appropriate uses, other than bridge or culvert crossings or on-stream structures or dams, shall be replaced for all flood events up to and including the base flood.

         (b)   The following expansion and contraction ratios shall be used to determine transition sections in calculations of effective regulatory floodway conveyance.

            1.   Flowing water will expand no faster than at a rate of one foot horizontal for every four feet of the flooded stream’s length.

            2.   Flowing water will contract no faster than at a rate of one foot horizontal for every one foot of the flooded stream’s length.

            3.   Flowing water will not expand or contract faster than one foot vertical for every ten feet of flooded stream length.

            4.   All cross-sections used in the calculations shall be located perpendicular to flood flows.

            5.   Transition sections must be used to determine the effective conveyance areas on adjacent properties.

         (c)   Development of an appropriate use will not result in an increase in the average channel or regulatory floodway velocities or stage. 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 rip-rap or other design measures.

      (5)   In the case of on-stream structures built for the purpose of backing up water during normal or flood flows, the increase in flood stage when compared to existing conditions for all storm events up to and including the base flood event shall be contained within recorded easements or the channel banks. A dam safety permit or letter indicating a dam safety permit is not required must be obtained from IDNR/OWR for the structures.

      (6)   IDNR/OWR will issue permits for any IDNR/OWR projects, dams and the like and for all other state, WCSMC or certified community projects.

(Res. 02-441, passed 10-17-2002; Res. 02-495, passed 11-21-2002; Res. 04-87, passed 3-17-2004)

§ 55.065 RIVERINE FLOODPLAIN.

   (A)   These standards apply to riverine regulatory floodplains without a regulatory floodway.

   (B)   The applicant shall obtain approval from IDNR/OWR for all development any portion of which is located partially or completely within the regulatory floodplain (without a delineated regulatory floodway) with a tributary drainage area of 640 acres or more.

      (1)   The development shall not singularly or cumulatively result in an obstruction of flood flows or potential flood damages outside the site due to an increase in flood heights, velocities or loss of floodplain area storage.

      (2)   A professional engineer shall submit a study that demonstrates one of the following:

         (a)   Determine a floodway which meets the definition of a regulatory floodway and demonstrate that the proposed development meets the floodway standards in § 55.064; or

         (b)   Determine a BFE and demonstrate that the proposed development will maintain the existing conditions conveyance, will not increase flood velocities, will not increase flood profiles and will compensate for any lost floodplain storage.

(Res. 02-441, passed 10-17-2002; Res. 02-495, passed 11-21-2002; Res. 04-87, passed 3-17-2004)

§ 55.066 BRIDGE AND CULVERT STANDARDS.

   These standards are for the reconstruction, modification or new construction of bridges, culvert crossings and roadway approaches located in the regulatory floodplain.

   (A)   A proposed new structure shall not result in an increase of upstream flood stages greater than one- tenth foot when compared to the existing conditions for all flood events up to and including the base flood event unless contained within the channel banks or recorded easements. The evaluation must be submitted to the IDNR-OWR for review and a permit obtained.

   (B)   If the proposed new structure will increase upstream flood stages greater than one-tenth foot, the applicant must contact IDNR/OWR for a dam safety permit or waiver. The Director shall be copied on all related correspondence.

   (C)   Lost regulatory floodplain storage must be replaced as required in § 55.063, compensatory storage volume standards, except that artificially created storage lost due to a reduction in head loss behind an existing bridge or culvert crossing shall not be required to be replaced, provided no flood damage will be incurred downstream.

   (D)   Velocity increases must be mitigated by use of appropriate measures to avoid scour, erosion and sedimentation at the structure.

   (E)   For modification or replacement of existing structures, the existing structure must first be evaluated in accordance with IDNR/OWR Rules (17 Ill. Adm. Code Part 3708) to determine if the existing structure is a source of flood damage. If the structure is a source of flood damage, the applicant’s engineer shall submit justification to allow the damage to continue and evaluate the feasibility of relieving the structure’s impact. Modifications or replacement structures shall not increase flood stages (0.0 feet) compared to the existing condition for all flood events up to and including the base flood event. The evaluation must be submitted to IDNR/OWR, for review and concurrence before a permit is issued. The Director shall be copied on all related correspondence.

   (F)   If any work is proposed in, near or over a public body of water, a permit or letter indicating a permit is not required must be obtained from IDNR/OWR.

   (G)   The hydraulic analysis for the backwater caused by the bridge showing the existing condition and proposed regulatory profile must be submitted to IDNR/OWR for concurrence that a CLOMR is not required.

   (H)   (1)   Construction vehicles shall cross-streams by the means of existing bridges or culverts.

      (2)   Where an existing crossing is not available, a temporary crossing that has been issued a permit or waiver by IDNR/OWR shall be constructed in which:

         (a)   The approach roads will be 0.5 feet or less above existing 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;

         (c)   The top of the roadway fill in the channel will be at least two feet below the top of the lowest bank. Any fill in the channel shall be non-erosive material, such as rip-rap or gravel; and

         (d)   The access road and temporary crossings will be removed within one year after installation, unless an extension of time is granted by the Administrator.

(Res. 02-441, passed 10-17-2002; Res. 02-495, passed 11-21-2002; Res. 04-87, passed 3-17-2004)

STORMWATER MANAGEMENT PERMIT SUBMITTAL REQUIREMENTS

§ 55.080 GENERAL REQUIREMENTS.

   (A)   Stormwater management and other permits required.

      (1)   A stormwater management permit shall be required if:

         (a)   The development or a substantial improvement is located in the regulatory floodplain or there is regulatory floodplain within the property boundary; or

         (b)   The development disturbs more than one acre (43,560 square feet) of ground cover, unless the development solely involves one or more of the following:

            1.   Installation, renovation or replacement of a septic system, potable water service line or other utility to serve an existing structure;

            2.   Excavation or removal of vegetation in rights-of-way or public utility easements for the purpose of installing or maintaining utilities not including storm sewers;

            3.   Maintenance, repair or at grade replacement of existing lawn areas not otherwise requiring a stormwater permit under this chapter; or

            4.   Maintenance of an existing stormwater facility, not requiring other state or federal permits or approvals.

      (2)   All development shall secure all appropriate stormwater management related approvals, including, without limitation, an IDNR-OWR floodway/floodplain construction permit, a USACOE 404 permit and an IDNR-OWR dam safety permit if required, from all federal, state and regional authorities and other appropriate federal, state and regional approvals prior to the issuance of a stormwater management permit for areas of a site requiring other approvals.

   (B)   Permit review fees. All permit fees shall be paid at the time of application. Permit fees shall be established by separate resolution of the permitting authorities. Fees may include, but are not limited to, the cost of permit administration, review and inspections prior to construction, during construction and within the permanent cover establishment period following construction.

   (C)   Professional seals and certifications required.

      (1)   The design of stormwater facilities, calculations for the determination of the regulatory floodplain or calculations of the impacts of development shall meet the standards of this chapter and shall be prepared, signed and sealed by a professional engineer. The professional engineer shall provide an opinion that the technical submittal meets the criteria required by this chapter or the applicable certified community ordinance.

      (2)   (a)   For structures (not including earth embankments) that are subject to a differential water pressure greater than three feet, the submittal shall include evidence that the subject design has been reviewed by a qualified professional who shall, as a minimum, have registration as a professional engineer. The reviews shall include stability of the structure under design conditions considering the protection of downstream life and property in the event of a failure. When directed by the Administrator, the calculations submitted for the structures shall be reviewed, signed and sealed by a registered structural engineer.

         (b)   For projects which include earth embankments which are subjected to a differential water pressure, the submittal shall include evidence that the embankment design and construction specifications are adequate for the design conditions. This review shall include consideration of the existing foundation soils for the embankment, the materials from which the embankment is to be constructed, compaction requirements for the embankment and protection of the embankment from failure due to overtopping. Construction and materials specifications for all embankments shall be included with the plan set submittal. When directed by the Administrator, or when the impounded water pressure differential exceeds three feet, or when appropriate considering the volume impounded and water surface elevation differential to which the embankment is subjected, these calculations may be required to be reviewed, signed and sealed by a qualified geotechnical or structural engineer.

      (3)   A topographical map of the site, record drawings and other required drawings shall be prepared, signed and sealed by a professional land surveyor or professional engineer and tied to NAVD 88 and any FEMA benchmarks.

(Res. 02-441, passed 10-17-2002; Res. 02-495, passed 11-21-2002; Res. 04-87, passed 3-17-2004; Ord. 18-305, passed 11-15-2018)

§ 55.081 DURATION AND REVISION TO PERMITS.

   (A)   Permit expiration. Permits expire December 31 of the third year following the date of permit issuance or upon expiration of state or federal permits required for stormwater management.

   (B)   Permit extension. If the permitted activity has been started but is not completed by the expiration date of the permit, and the permittee intends to pursue the permitted activity, then the permittee may submit a written request that the expiration date be extended. Upon receipt of the request, the Administrator may extend the expiration date in one-year increments a maximum of three times for permitted activities outside regulatory floodplains and floodways. Expiration dates for permitted activities in regulatory floodplains and floodways may be extended in one-year increments a maximum of three times provided the activity is in compliance with the then current requirements of this chapter or the applicable certified community ordinance.

   (C)   Permit revision. If, after permit issuance, the permittee decides to revise the approved plans, the permittee shall submit revised plans to the Director or the Administrator, along with a written request for approval. If the Director or the Administrator determines that the revised plans are in compliance with the then current requirements of this chapter or the applicable certified community ordinance, an approval of the revised plans may be issued.

(Res. 02-441, passed 10-17-2002; Res. 02-495, passed 11-21-2002; Res. 04-87, passed 3-17-2004)

§ 55.082 REQUIRED SUBMITTALS.

   (A)   Generally. All permit submittals shall include the material listed in the sections noted in Table 2 for the applicable type of development, unless the submittal requirements are specifically modified by the procedure in division (B) below.

Table 2: Permit Submittal Requirements
	Required Submittals (refer to Sections listed for specific material)
	Section No./Description
	55.082(C)	55.082(D)	55.082(E)	55.082(F)	55.083(A)	55.083(B)	55.084
	Application and Project Overview	Plan Set Submittal	Stormwater Submittal	Floodplain Submittal	Performance Security	Maintenance Schedule and Funding	Record Drawings
All requiring a permit	X	X			X	X	X
All developments on sites with floodplains	X	X		X	X	X	X
All developments on sites with or adjacent to waters of the United States	X	X			X	X	X
All applications requesting variances	X	X	X	If on site	X	X	X
All requiring detention/retention	X	X	X		X	X	X
Note:   Corporations with a bond rating of “A” of higher from a major investment firm, (i.e. Standard and Poor, Moody or equivalent), would be judged to have met the long term maintenance funding requirement

 

   (B)   Modification of submittal requirements. The Administrator may, at his or her discretion, modify the submittal requirements on a case-by-case basis considering the size, complexity and likelihood that a development will affect the discharge of stormwater. The modifications shall be requested and answered in writing. The Administrator’s response shall note the relevant findings, and be specific as to what submittal requirements are changed. The Director shall be copied on all related correspondence. The Administrator may not modify submittal requirements for any aspect of the development requiring state or federal permits or approvals, nor for any application in which any variance of the permitting authorities ordinance is requested.

   (C)   Application and project overview. The applicant shall provide the following information as a minimum, on forms or in a format approved by the Administrator:

      (1)   The name and legal address of the owner(s) of the site and the permit applicant;

      (2)   The common address, legal description, property identification number (PIN) of the site;

      (3)   The name of the project, area of the site in acres, type of development;

      (4)   A general narrative description of the development, existing and proposed conditions, and project planning principles considered, including best management practices used;

      (5)   Affidavits signed by the owner or the applicant’s authorized representative attesting to their understanding of the requirements of this chapter or the applicable certified community ordinance and their intent to comply therewith;

      (6)   A statement of opinion by a qualified person either denying or acknowledging the presence of floodplain on the development site;

      (7)   Copies of other stormwater related permits or permit applications as required;

      (8)   A subsurface drainage investigation report; and

      (9)   An engineer’s estimate of probable construction cost of the stormwater facilities.

   (D)   Plan set submittal. All applicants for a stormwater permit shall provide the following basic plan exhibits: site topographic map, general plan view drawing, sediment/erosion control plan and a vicinity topographic map. Each exhibit may be on more than one drawing for clarity. The specific information to be included on each exhibit shall be as noted below.

      (1)   Site topographic map meeting the following requirements shall be submitted:

         (a)   Map scales as one inch equals 100 feet (or less) and accurate to +/- 0.5 feet;

         (b)   Existing and proposed contours on-site and within 100 feet of site;

         (c)   Existing and proposed drainage patterns and watershed boundaries;

         (d)   Delineation of pre-development regulatory floodplain/floodway limits;

         (e)   Delineation of post-development regulatory floodplain/floodway limits;

         (f)   Location of cross-sections and any other hydrologic/hydraulic computer modeled features;

         (g)   Location of all on-site drain tiles;

         (h)   Boundary of all wetlands, lakes, ponds and the like with normal water elevation noted;

         (i)   Location of all existing buildings and those to remain on the site noted;

         (j)   Nearest base flood elevations;

         (k)   FEMA and any site-specific benchmarks (tied to county benchmarks) used; and

         (l)   Highlight all contours used in the calculation of depressional storage.

      (2)   General plan view drawing meeting the following requirements shall be submitted:

         (a)   Drawing at the same scale as the site topographic map;

         (b)   Existing major and minor stormwater systems;

         (c)   Proposed major and minor stormwater systems;

         (d)   Design details for stormwater facilities (i.e. structure and outlet work detail drawings and the like);

         (e)   Scheduled maintenance program for permanent stormwater facilities including BMP measures;

         (f)   Planned maintenance tasks and schedule;

         (g)   Identification of entities responsible for maintenance;

         (h)   Permanent public access maintenance easements granted or dedicated to, and accepted by, a government entity;

         (i)   Proposed regulatory floodplain and floodway location (with the base flood and flood protection elevations noted); and

         (j)   Highlight all plan areas at elevations below the 100-year high water elevation of site runoff storage facilities.

      (3)   Sediment and erosion control plan meeting the following requirements shall be submitted:

         (a)   Drawings at the same scale as the site topographic map;

         (b)   Sediment/erosion control installation measures and schedule;

         (c)   Existing and proposed roadways, structures, parking lots, driveways, sidewalks and other impervious surfaces;

         (d)   Limits of clearing and grading;

         (e)   Floodplain/floodway locations;

         (f)   Proposed buffer location, existing soil types, vegetation and land cover conditions; and

         (g)   List of maintenance tasks and schedule for sediment/erosion control measures.

      (4)   Vicinity topographic map meeting the following requirements shall be submitted:

         (a)   Vicinity topographic map identifying all off-site areas draining to the development and downstream to the receiving intermittent or perennial stream. (A two foot contour map is preferred at a scale readable by the reviewer but a USGS quadrangle map is acceptable);

         (b)   Watershed boundaries for areas draining through or from the development;

         (c)   Soil types related to hydrologic soils group, vegetation and land cover affecting runoff upstream of the site for any area draining through the site;

         (d)   Location of development site within the major watershed(s); and

         (e)   Show the overland flow path from the downstream end of the development to the receiving intermittent or perennial stream.

   (E)   Stormwater submittal. The stormwater submittal shall include narrative discussion and calculations to support a finding that the proposed development complies with the technical requirements of the permitting authorities ordinance. The submittal shall consist of, at a minimum, the following material:

      (1)   A narrative description of the existing and proposed site drainage patterns and conditions. Include description of off-site conditions, which help to identify stormwater issues considered in the design;

      (2)   A schedule for implementation of the site stormwater plan;

      (3)   On-site and off-site runoff calculations which address the following:

         (a)   Documentation of the procedures/assumptions used to calculate hydrologic and hydraulic conditions for sizing major and minor systems;

         (b)   Cross-section data for open channels;

         (c)   Hydraulic grade line and water surface elevations under design flow conditions; and

         (d)   Hydraulic grade line and water surface elevations under base flood flow conditions.

      (4)   Site runoff storage calculations, which address the following:

         (a)   Calculation of hydraulically connected impervious area and corresponding retention volume;

         (b)   Documentation of the procedures/assumptions used to calculate hydrologic and hydraulic conditions for determining the allowable release rate;

         (c)   Documentation of the procedures/assumptions used to calculate on-site depressional storage;

         (d)   Documentation of the procedures/assumptions used to calculate hydrologic and hydraulic conditions for determining the storage volume;

         (e)   Elevation-area-storage data and calculations for site runoff storage;

         (f)   Elevation-discharge data and calculations specifically related to the outlet control structure depicted in the plan exhibits; and

         (g)   The general plan view drawing of division (C)(2) above shall indicate the areas of directly connected impervious areas and any offsetting landscaped areas as defined in § 55.022(E).

   (F)   Floodplain submittal. The applicant shall obtain approval from IDNR-OWR and FEMA for all new base flood and floodway determinations for those cases in which their permitting authority applies or as noted in § 55.061 of this chapter. The stormwater management permit will not be issued until approval is received. Documentation supporting a finding that the proposed development is in compliance with §§ 55.060 and 55.061 shall be submitted with the application. At a minimum, the following material shall be submitted for approval with the application:

      (1)   Regulatory floodplain boundary determination:

         (a)   Provide source of flood profile information; and

         (b)   Provide all hydrologic and hydraulic study information for site-specific floodplain studies, unnumbered Zone A area elevation determinations and floodplain map revisions.

      (2)   Floodway hydrologic and hydraulic analyses for the following conditions:

         (a)   Existing conditions (land used and stream systems);

         (b)   Proposed conditions (land used and stream systems);

         (c)   Tabular summary of 100-year flood elevations and discharges for existing and proposed conditions;

         (d)   Calculations used for model development; and

         (e)   Hydraulic/hydrologic computer model input/output.

      (3)   Floodplain fill and compensatory storage calculations for below and above ten-year flood elevation up to the base flood elevation:

         (a)   Tabular summary for below and above ten-year flood elevation of fill, compensatory storage and compensatory storage ratios provided in proposed plan; and

         (b)   Cross-sections used for the above calculations.

      (4)   Floodproofing measures: narrative discussion of floodproofing measures including material specifications, calculations and design details, operation summary; and

      (5)   Flood easements when required by this chapter or the applicable certified community ordinance.

(Res. 02-441, passed 10-17-2002; Res. 02-495, passed 11-21-2002; Res. 04-87, passed 3-17-2004)