(A) General requirements.
(1) A stormwater management permit is required if:
(a) The project requires a building permit, is not a residential building and the impervious area is increased on the site; or
(b) The project requires the approval of a plat of subdivision.
(2) All appropriate stormwater management related approvals and permits, including, without limitation, an IDNR-OWR floodway/floodplain construction permit, a United States Army Corps of Engineers 404 permit, and an IDNR-OWR dam safety permit, if required, shall be obtained from all federal, state and regional authorities prior to the issuance of a stormwater management permit.
(3) All permit fees shall be paid prior to the issuance of a stormwater management permit.
(4) The design of stormwater management facilities, calculations for the determination of the regulatory floodway/floodplain and calculations of the impact of development shall meet the standards of this chapter and shall be prepared by or under the direction of, signed and sealed by a professional engineer. The signature and seal of such professional engineer shall stand as his or her opinion that the submittals which accompany the permit application meet the requirements of this chapter.
(a) For projects which include earth embankments which are subject 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 embankment is to be constructed, compaction requirements for the embankment, and protection of the embankment from failure due to overtopping. Specifications for the construction and materials for all such embankments shall be included in the submittal. When directed by the Village Engineer, or when the impounded water pressure differential exceeds three feet or when appropriate considering the volume of impounded water, 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 registered structural engineer.
(b) For structures (not including earth embankments) that are subject to differential water pressure greater than three feet, the submittal shall, at a minimum, be reviewed by a professional engineer. Such 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 Village Engineer, the calculations submitted for such structures shall be reviewed, signed and sealed by a registered structural engineer.
(c) A topographical map of the site, as-built record drawings, and other required drawings shall be prepared, signed and sealed by a professional land surveyor or professional engineer, and referenced to the National Geodetic Vertical Datum, 1929 adjustment, and any FEMA benchmarks. Plats for new subdivisions more than ten acres in size shall be submitted to the Village Engineer in one of the electronic formats designated by the village.
(B) Duration and revision of permits.
(1) If construction has not started within 12 months after the date of issuance, the permit shall become null and void. If construction starts within 12 months of the date of issuance, the permit expires on December 31 of the second year following the date of their issuance.
(2) If the permitted activity has begun but is not complete by the expiration date of the permit, the permittee may submit a written request for an extension to the Village Engineer. Upon receipt of such request, the Village Engineer may extend the expiration date of the permit for up to two years for permitted activities outside special management areas. Expiration dates for permitted activities within special management areas may also be extended for up to two years provided that the activity is in compliance with the then current requirements of this chapter. A permittee may apply for only two extensions before reapplication is required.
(3) If the permittee revises the approved plans after issuance of the permit, the permittee shall submit the revised plans to the Village Engineer along with a written request for approval. If the Village Engineer determines that the revised plans are in compliance with the then current requirements of this chapter, an amended permit may be issued.
(C) Application and project overview.
(1) The applicant shall, at a minimum, provide the following information on the approved forms or in a format approved by the Village Engineer:
(a) The names and legal addresses of all owners of the site;
(b) The names and legal addresses of the developer or developers responsible for completing the development according to the plans submitted, the terms and conditions of the permit, and the requirements of this chapter;
(c) The common address, legal description and parcel identification number (PIN) of all parcels which comprise the site;
(d) The name of the project, area of the site in acres and the type of development;
(e) A general narrative description of the development, existing and proposed conditions and the project planning principles considered, including best management practices used;
(f) Copies of all other permits or permit applications as required;
(g) A subsurface drainage investigation report; and
(h) An engineer’s estimate of probable construction cost of the stormwater facilities and the installation and maintenance of soil erosion and sediment control measures.
(2) The application shall be signed by all owners and developers identified in division (C)(1) above and shall contain their attestation that they have read and understand the provisions of this chapter and agree to bind themselves to the permitting authority to comply therewith. If any time prior to completion and final inspection and approval of the development the identity of the persons required to be disclosed in division (C)(1) above changes, the applicant shall immediately file an amended application containing the current information and the permit shall be amended accordingly.
(D) Required submittals.
(1) All applicants for a stormwater permit shall provide the following basic plan exhibits: site topographical map; general plan view drawing; sediment/erosion control plan; and vicinity topographical map. Each exhibit may be on more than one drawing for clarity.
(2) The specific information to be included on each exhibit shall be as noted below.
(a) Site topographical map.
1. Map scale at one inch equals 100 feet (or less) and accurate to ±1.0 foot;
2. Existing and proposed contours on site (maximum contour interval is two feet) and within 100 feet of the site (one-foot contour interval may be required if deemed necessary by the Village Engineer);
3. Existing and proposed drainage patterns and watershed boundaries;
4. Delineation of predevelopment regulatory floodplain and floodway limits;
5. Delineation of post development regulatory floodplain and floodway limits;
6. Location of cross-sections and any other hydrologic or hydraulic computer modeled features;
7. Location of all on-site drain tiles;
8. Boundaries of all watercourses, wetlands, lakes, ponds and the like with normal water elevations noted (show areas of wetlands to be impacted under permit);
9. Location of all existing buildings and those to remain on the site noted;
10. Nearest base flood elevations;
11. FEMA and reference benchmarks used; and
12. All contours used in the calculation of depressional storage highlighted.
(b) General plan view drawing.
1. Drawing at the same scale as the site topographical map;
2. Existing major and minor stormwater systems;
3. Proposed major and minor stormwater systems;
4. Design details for stormwater facilities (i.e., structure and outlet detail drawings and the like);
5. Scheduled maintenance program for permanent stormwater facilities including BMP;
6. Planned maintenance tasks and schedule;
7. Identification of persons responsible for maintenance;
8. Proposed regulatory floodplain and floodway location (with the base flood elevation noted);
9. Existing wetlands and required buffers;
10. All plan areas at elevations below the 100-year high water elevation of site runoff storage facilities highlighted; and
11. Where a 500-year regulatory floodplain is available, the plan limit of the 500-year floodplain.
(c) Sediment and erosion control plan.
1. Drawings at the same scale as the site topographical map;
2. Erosion and sediment control installation measures and schedule;
3. Existing and proposed roadways, structures, parking lots, driveways, sidewalks and other impervious surfaces;
4. Limits of clearing and grading;
5. Special management areas and proposed buffer locations located on the plan;
6. Existing soil types, vegetation and land cover conditions;
7. List of maintenance tasks and schedule for erosion and sediment control measures; and
8. The name, address and phone number of the person or persons responsible for erosion and sediment control.
(d) Vicinity topographical map.
1. Identify all off-site areas draining into the development and downstream to the receiving stream (a two-foot contour map is preferred at a scale readable by the reviewer but a USGS quadrangle map is acceptable);
2. Identify the watershed boundaries for areas draining through or from the development;
3. Identify the soil types related to hydrologic soils group, vegetation and land cover affecting runoff upstream of the site for any area draining through the site;
4. Identify the location of the site within the major watershed(s); and
5. Show the overland flow path from the downstream end of the development to the receiving stream.
(E) Stormwater submittal. The stormwater submittal shall include a narrative discussion and calculations to support a finding by the qualified review specialist that the proposed development complies with the technical requirements of this chapter. The submittal shall consist, at a minimum, of 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 and assumptions used to calculate the hydrologic and hydraulic conditions for sizing major and minor stormwater systems;
(b) Cross-section data for open channels, along with calculated depths of flow and velocities in the channels; and
(c) The hydraulic grade line calculations may be required for the design flow and base flood flow conditions, if requested by the Village Engineer.
(4) Site runoff storage calculations, which address the following:
(a) Documentation of the procedures and assumptions used to calculate the hydrologic and hydraulic conditions for the site runoff storage facility;
(b) Calculations for the time of concentration and a drawing showing the location of calculated time of concentration path;
(c) Calculations for the allowable release rate for the required storm events;
(d) Calculations for the generation of the inflow hydrographs for the required storm events;
(e) Calculations for the routing of the inflow hydrographs through the storage facility;
(f) Hydraulic and hydrologic computer model input and output;
(g) Elevation area storage data and calculations;
(h) Elevation discharge data and calculations specifically related to the outlet control structure depicted in the plans; and
(i) Calculations for the overflow structure capacity.
(F) Floodplain submittal. The applicant shall obtain approval from the IDNR-OWR and FEMA, when required, for all new base flood and floodway determinations or as required by these agencies. Documentation showing evidence of approval by or application to these agencies shall be submitted with the application. At a minimum, the following material shall be submitted for approval with the application:
(1) Regulatory floodplain determination:
(a) Provide source of flood profile information; and
(b) Provide all hydrologic and hydraulic study information for site-specific floodplain studies and floodplain map revisions.
(2) Floodway hydrologic and hydraulic analyses for the following conditions:
(a) Existing conditions;
(b) Proposed conditions;
(c) Tabular summary of 100-year flood elevations and discharges for existing and proposed conditions;
(d) Calculations used for development of the hydraulic model; and
(e) Hydraulic and hydrologic computer model input and output.
(3) Floodplain fill and compensatory storage calculations for below and above the ten-year flood elevation up to the base flood elevation:
(a) Tabular summary for below and above the ten-year flood elevation of fill and compensatory storage in the plan; and
(b) Special flood hazard area easements when required by this chapter.
(4) Statewide and regional self-issuing permits (statewide permits numbers 1 through 14 and regional permit number 3). Such information as shall show that the development qualifies for the particular permit in question under the regulations established by the IDNR-OWR.
(G) As-built record drawings. The permittee is required to submit as-built record drawings of all permitted stormwater facilities. The record drawings shall be signed and sealed by a professional engineer or professional land surveyor who shall state that the project as constructed is substantially in conformance with the development as permitted. Record drawings shall also be submitted electronically in AutoCAD format version 2007 or later unless authorized by the Village Engineer.
(Prior Code, § 4-4-5) (Ord. 2015-17, passed 8-3-2015)