Chapter 14.32 OCCUPATION AND USE OF SFHAS

Chapter 14.32
OCCUPATION AND USE OF SFHAS

WHERE FLOODWAYS ARE NOT IDENTIFIED

Sections:

14.32.010 Occupation and use of SFHAs where floodways are not identified.

In SFHA or floodplains (including AE, AH, AO and unnumbered A zones) where no floodways have been identified and no base flood or one-hundred-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-year frequency flood elevation. (Ord. 2008-22 § 15.900, 2008)

14.32.020 Development permit.

A. 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 building and zoning.

B. Application for a development permit shall be made on a form provided by the director of building and zoning.

1. The application shall be accompanied by drawings of the site, drawn to scale showing property line dimensions; 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 Chapter 14.36 RMC.

2. The application for a development permit shall also include the following information:

a. A detailed description of the proposed activity, its purpose, and intended use;

b. Site location (including legal description) of the property, drawn to scale, on the designated floodway maps, indicating whether it is proposed to be in an incorporated or unincorporated area;

c. Anticipated dates of initiation and completion of activity;

d. Plans of the proposed activity shall be provided which include as a minimum:

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, using the North American Vertical Datum of 1988, adjacent property lines and ownership, drainage and flood control easements, distance between proposed activity and navigation channel (when the proposed construction is in or 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 perpendicular to the flow of floodwater 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-year frequency flood elevation, and graphical or numerical scales (horizontal and vertical); and

iv. A soil erosion and sedimentation control plan for disturbed areas. This plan shall include a description of the sequence of grading activities and the temporary sediment and erosion control measures to be implemented to mitigate their effects. This plan shall also include a description of final stabilization and revegetation measures, and the identification of a responsible party to ensure post-construction maintenance.

3. Engineering calculations and supporting data shall be submitted showing that the proposed work will meet the criteria of RMC 14.32.030.

4. Any and all other federal, state, and local permits or approvals that may be required for this type of development.

C. Based on the best available existing data according to federal, state or other sources, the director of building and zoning shall compare the elevation of the site to the base flood or one-hundred-year frequency flood elevation.

1. Should no elevation information exist for the site, the developer’s engineer shall calculate the elevation according to RMC 14.20.010(D).

2. Any development located on land that can be shown to have been higher than the base flood elevation of the current flood insurance rate map identification is not in the SFHA and, therefore, not subject to the requirements of this title.

3. The director of building and zoning 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.

4. The director of building and zoning shall be responsible for obtaining from the applicant copies of all other federal, state, and local permits, approvals or waivers that may be required for this type of activity. The director of building and zoning shall not issue the development permit unless all required federal, state, and local permits have been obtained. (Ord. 2008-22 § 15.901, 2008)

14.32.030 Preventing increased damages.

A. No development in the SFHA where a floodway has not been determined shall create a damaging or potentially damaging increase in flood heights or velocity or threat to public health, safety and welfare or impair the natural hydrologic and hydraulic functions of the floodway or channel, or impair existing water quality or aquatic habitat. Construction impacts shall be minimized by appropriate mitigation methods as called for in this title.

B. Within all riverine SFHAs where the floodway has not been determined, the following standards shall apply:

1. The developer shall have a licensed professional engineer state in writing and show through supporting plans, calculations, and data that the project meets the engineering requirements of RMC 14.28.030(C) through (C)(9) for the entire floodplain as calculated under the provisions of RMC 14.20.010(D).

a. As an alternative, the developer should have an engineering study performed to determine a floodway and submit that engineering study to IDNR/OWR and FEMA for acceptance as a designated floodway.

b. Upon acceptance of the floodway by IDNR/OWR and FEMA, the developer shall then demonstrate that the project meets the requirements of Chapter 14.28 RMC for the designated floodway. The floodway shall be defined according to the definition in RMC 14.08.010.

2. A development permit shall not be issued unless the applicant first obtains a IDNR/OWR permit or a determination has been made that an IDNR/OWR permit is not required.

3. Permits for Dams.

a. Any work involving the construction, modification or removal of a dam as defined in RMC 14.08.010 per 17 Ill. Admin. Code 3702 (Rules for Construction of Dams) shall obtain an IDNR/OWR permit prior to the start of construction of a dam.

b. If the director of building and zoning finds a dam that does not have an IDNR/OWR permit, the director of building and zoning shall immediately notify the IDNR/OWR.

c. If the director of building and zoning finds a dam which is believed to be in unsafe condition, the director of building and zoning shall immediately notify the owner of the dam, the IDNR/OWR, and the Illinois Emergency Management Agency (IEMA).

C. The following activities may be permitted without a licensed professional engineer’s review or calculation of base flood elevation and designated floodway. Such activities shall still meet the other requirements of this title.

1. Bridge and culvert crossings of streams in rural areas meeting conditions of IDNR/OWR Statewide Permit No. 2;

2. Barge fleeting facilities meeting conditions of IDNR/OWR Statewide Permit No. 3;

3. Aerial utility crossings meeting conditions of IDNR/OWR Statewide Permit No. 4;

4. Minor boat docks meeting conditions of IDNR/OWR Statewide Permit No. 5;

5. Minor, nonobstructive activities meeting conditions of IDNR/OWR Statewide Permit No. 6 (activities not involving fill or positive change in grade are covered by this permit);

6. Outfall structures and drainage ditch outlets meeting conditions of IDNR/OWR Statewide Permit No. 7;

7. Underground pipeline and utility crossings meeting the conditions of IDNR/OWR Statewide Permit No. 8;

8. Bank stabilization projects meeting the conditions of IDNR/OWR Statewide Permit No. 9;

9. Accessory structures and additions to existing residential buildings meeting the conditions of IDNR/OWR Statewide Permit No. 10;

10. Minor maintenance dredging activities meeting conditions of IDNR/OWR Statewide Permit No. 11;

11. Bridge and culvert replacement structures and bridge widenings meeting conditions of IDNR/OWR Statewide Permit No. 12;

12. Temporary construction activities meeting conditions of IDNR/OWR Statewide Permit No. 13;

13. Special uses of public waters meeting conditions of IDNR/OWR Statewide Permit No. 14; and

14. Any development determined by IDNR/OWR to be located entirely within a flood fringe area shall be exempt from state floodway permit requirements.

D. The flood carrying capacity of any altered or relocated watercourse shall be maintained.

E. Compensatory Storage.

1. 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-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-year frequency flood elevation.

2. The excavation volume shall be at least equal to one and one-half times the volume of storage lost due to the fill or structure.

3. In the case of streams and watercourses, such excavation shall be made opposite or adjacent to the areas so filled or occupied.

4. All floodplain storage lost below the existing ten-year flood elevation shall be replaced below the proposed ten-year flood elevation. All floodplain 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. (Ord. 2008-22 § 15.902, 2008)