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VILLAGE OF ADDISON CODE
Chapter 26 – Stormwater and Floodplain Management
Article
3. Floodplain Management.
Sec.
26-301. Duties of the Enforcement Official. [back
to top]
The
Village Engineer 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 a registered professional engineer (P.E.)
under the employ or contract of the Village for review to ensure that the
development meets the requirements of Sections 26-303 through 26-307. In the
case of an appropriate use, the P.E. shall state in writing that the development
meets the requirements of Sections 26-303 through 26-307.
(C) Dam Safety
Requirements. Ensure that a 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 SubSection 26-302(B).
Regulated dams may include weirs, restrictive culverts or impoundment
structures.
(D) Other Permit
Requirements. Ensure that any and all required federal, state, county, 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 SFHA's of the
jurisdiction of the Village 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 condition
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 non-residential building or the elevation to which a
non-residential building has been floodproofed, using a Floodproofing
Certificate, for all buildings subject to Section 26-306 of this Chapter for
public inspection and provide copies of same.
(H) Records for Public
Inspection. Maintain for public inspection and furnish upon request, base flood
data, SFHA and regulatory floodway maps, copies of federal or state permit
documents, variance documentation, Conditional Letter of Map Revision, Letter of
Map Revision, Letter of Map Amendment, and "as-built" elevation and
floodproofing or elevation and floodproofing certificates for all buildings
constructed subject to this Chapter.
(I) State Permit. Ensure
that construction authorization has been granted by the Illinois Division of
Water Resources, for all development projects subject to Sections 26-304 and
26-305 of this Chapter, unless enforcement responsibility has been delegated to
the Village. Upon acceptance of this Chapter by DWR and FEMA, responsibility is
hereby delegated to the Village as per 92 Ill.Adm.Code 708 for construction in
the regulatory floodway and floodplain when floodways have not been defined in
Sections 26-304 and 26-305 of this Chapter. However, the following review
approvals are not delegated to the Village 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
SubSection 26-103(B) and all other state federal or local unit of government
projects, including projects of the Village and County, except for those
projects meeting the requirements of Section 26-304(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 26-304(B)(2)(e).
(4) An engineer's
analysis of the flood profile due to Section 26-304(B)(2)(d).
(5) Alternative
transition Sections and hydraulically equivalent compensatory storage as
indicated in Section 26-304(B)(2) (a), (b) and (h).
(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.
(8) Base Flood Elevation
determinations where none now exist.
(J) Cooperation with
Other Agencies. Cooperate with state, county, and federal floodplain management
agencies to improve base flood or 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 chapter changes.
Sec.
26-302. Base Flood Elevation.
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This
Chapter's protection standard is based on the Flood Insurance Study for the
Village. If a base flood elevation or 100-year frequency flood elevation is not
available for a particular site, then the protection standard shall be according
to the best existing data available in the Illinois State Water Survey's
Floodplain Information Repository. 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, FEMA, and the
Village.
(A) The base flood or
100-year frequency flood elevation for the SFHA's of Salt Creek and Westwood
Creek shall be as delineated on the 100-year flood profiles in the Flood
Insurance Study of the Village prepared by FEMA and dated January 16, 1987, and
such amendments to such study and maps as may be prepared from time to time.
(B) The base flood or
100-year frequency flood elevation for the SFHA's of those parts of
unincorporated DuPage County that are within the extraterritorial jurisdiction
of the Village or that may be annexed into the Village shall be as delineated on
the 100-year flood profiles in the Flood Insurance Study of DuPage County
prepared by FEMA and dated October 15, 1981, and such amendments or revisions to
such study and maps as may be prepared from time to time.
(C) The base flood or
100-year frequency flood elevation for each SFHA delineated as an "AH Zone" or
"AO Zone" shall be that elevation (or depth) delineated on the Flood Insurance
Rate Map of the Village.
(D) The base flood or
100-year frequency flood elevation for each of the remaining SFHA's delineated
as an "A Zone" on the Flood Insurance Rate Map of the Village shall be according
to the best existing data available in the Illinois State Survey Floodplain
Information Repository. When no base flood or 100-frequency flood elevation
exists, the base flood or 100-year frequency flood elevation for a Riverine SFHA
shall be determined from a backwater model, such as HEC-2, 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-l 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
non-riverine SFHA, the Base Flood Elevation shall be the historic Flood of
Record plus 3 feet, unless calculated by a detailed engineering study and
approved by the Illinois State Water Survey.
Sec.
26-303. Occupation and Use of Flood Fringe Areas.
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Development in and/or filing of the flood fringe will be permitted if protection
is provided against the base flood or 100-year frequency flood by proper
elevation, and compensatory storage and other provisions of this Chapter are
met. No use will be permitted which adversely affects the capacity of drainage
facilities or systems. Developments located within the flood fringe shall meet
the requirements of this Section, along with the requirements of Section 26-306.
(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 Village Engineer.
(1) Application for a
development permit shall be made on a form provided by the Village Engineer.
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 M.S.L., 1929 adj. datum or N.G.V.D. 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 26-306 of this Chapter.
(2) Upon receipt of a
development permit application, the Village Engineer shall compare the
elevation of the site to the base flood or 100-year frequency 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 Village
Engineer's office 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 Village Engineer
shall be responsible for obtaining from the applicant, copies of all other
local, state, county, and federal permits, approval or permit-not- required
letters that may be required for this type of activity. The Village Engineer
may not issue a permit unless all other local, state, and federal permits have
been obtained.
(B) Preventing Increased
Damages. No development in the flood fringe shall create a threat to public
health and safety.
(1) If fill is being used
to elevate the site above the base flood or 100-year frequency flood
elevation, the applicant shall submit sufficient data and obtain a letter of
map revision (LOMR) from FEMA for the purpose of removing the site from the
floodplain.
(2) Compensatory
Storage. Whenever any portion of a floodplain is authorized for use, the
volume of space which will be occupied by the authorized fill or structure
below the base flood or 100-year frequency flood elevation shall be
compensated for and balanced by one and one-half times the hydraulically
equivalent volume of excavation taken from below the base flood or 100-year
frequency flood elevation. The excavation volume shall be at least one and
one-half times the volume of storage lost due to the fill or structure. In
the case of streams and watercourses, such excavation shall be made opposite
or adjacent to the areas so filled or occupied. All floodplain storage lost
below the existing 10-year flood elevation shall be replaced below the
proposed 10-year flood elevation. All floodplain storage lost above the
existing 10-year flood elevation shall be replaced above the proposed 10-year
flood elevation. All such excavations shall be constructed to drain freely
and openly to the watercourse.
Sec.
26-304. Occupation and Use of Identified Floodways.
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This
Section applies to proposed development, redevelopment, site modification, or
building modification within a regulatory floodway. The regulatory floodway for
Salt Creek and Westwood Creek shall be as delineated on the regulatory floodway
maps designated by DWR according and referenced in Section 26-103. 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 26-306.
(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 Village Engineer.
(1) Application for a
development permit shall be made on a form provided by the Village Engineer.
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 includes 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 (1 29 adjustment) datum or N.G.V.D., adjacent
property lines and ownership, drainage and flood control easements,
location of any channels and any existing or future access roads,
regulatory floodway limit, floodplain limit, specifications and dimensions
of any proposed channel modifications, 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, 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, county, 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 Section 26-304(B).
(o) If the regulatory
floodway delineation, base flood, or 100-year frequency flood elevation will
change due to the proposed project, the application will not be considered
complete until 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
floodplain 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 26-306 of this Chapter.
(q) If the proposed
project involves a channel modification, the applicant shall submit the
following information:
(i) A discussion of the
purpose of and the need for the proposed work.
(ii) A discussion of the
feasibility of using alternative locations or methods to accomplish the
purpose of the proposed work.
(iii) An analysis of the
extent and permanence of the impacts the project would have on the
physical and biological condition of the body of water affected.
(2) The Village Engineer
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 Village Engineer may not issue the development permit
unless all required federal and state permits have been obtained. A
Registered Professional Engineer, under the employ or contract of the Village
shall review and approve applications reviewed under this Section.
(B) Preventing Increased
Damages and a List of Appropriate Uses. The only developments in a floodway
which will be allowed are Appropriate Uses, which will not cause a rise in the
base flood elevation, and which will not create a damaging or potentially
damaging increase in flood heights or velocities or be a threat to public health
and safety and welfare or impair the natural hydrologic and hydraulic functions
of the floodway or channel, or permanently impair existing water quality or
aquatic habitat. Construction impacts shall be minimized by appropriate
mitigation methods as called for in this Chapter. Only those Appropriate Uses
listed in 92 Ill.Adm.Code 708 will be allowed. Appropriate uses do not include
the construction or placement of any new structures, fill, building additions,
buildings on stilts, excavation or channel modifications done to accommodate
otherwise nonappropriate uses in the floodway, fencing (including landscaping or
planting design to act as a fence), and storage of materials except as
specifically defined above as an Appropriate Use.
(1) The approved
Appropriate Uses are as follows:
(a) Flood control
structures, dikes, dams, and other public works or private improvements
relating to the control of drainage, flooding, erosion, or water quality or
habitat for fish and wildlife.
(b) Structures or
facilities relating to the use of, or requiring access to, the water or
shoreline, such as pumping and treatment facilities, and facilities and
improvements related to recreational boating, commercial shipping, and other
functionally water dependent uses.
(c) Storm and sanitary
sewer outfalls.
(d) Underground and
overhead utilities.
(e) Recreational
facilities such as playing fields and trail systems including any related
fencing (at least 50 percent open when viewed from any 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) Bridge, culverts,
roadways, sidewalks, railways, runways and taxiways and any modification
thereto.
(h) Parking lots and any
modifications thereto (where depth of flooding at the 100-year frequency
flood event will not exceed l.0 feet) and aircraft parking aprons built at
or below ground elevation.
(i) Regulatory floodway
regrading, without fill, to create a positive non-erosive 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 10 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 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.
(l) Additions to
existing buildings above the BFE that do not increase the building's foot
print and are valued at less than 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 and mitigation
criteria and is so stated in writing with supporting plans, calculations, and
data by a registered professional engineer and provided that any structure
meets the protection requirements of Section 26-306 of this Chapter.
(a) Preservation of Flood
conveyance so as Not to Increase Flood Stages Upstream. For appropriate uses
other than bridge or culvert crossings, on-stream structures or dams, all
effective regulatory floodway conveyance lost due to the project will be
replaced for all flood events up to and including the 100-year frequency
flood. In calculating effective regulatory floodway conveyance, the
following factors shall be taken into consideration:
(i) Regulatory floodway
conveyance,
"K" = 1.486 AR2/3
n
where "n" is Manning's roughness factor, "A" is the
effective area of the cross- Section, and "R" is the ratio of the area to
the wetted perimeter. (See Open Channel Hydraulics, Ven Te Chow, 1959, Mc
Graw-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 non-vegetative 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 4 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 10 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-Sections
used in the calculations shall be located perpendicular to flood flows.
(b) Preservation of
Floodway Storage so as Not to In-crease Downstream Flooding. Compensatory
storage shall be provided for any regulatory floodway storage lost due to
the proposed work from the volume of fill or structures placed and the
impact of any related flood control projects. Compensatory storage for fill
or structures shall be equal to at least l.5 times 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 100-year flood elevation. All regulatory floodway storage lost
below the existing 10-year flood elevation shall be replaced below the
proposed 10-year flood elevation. All regulatory floodway storage lost
above the existing 10-year flood elevation shall be replaced above the
proposed 10-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. Finally, there shall be no reduction in
floodway surface area as a result of a floodway modification, unless such
modification is necessary to reduce flooding at existing structure.
(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 more than a ten percent an
increase in the average channel or regulatory floodway velocities or stage
for all flood events up to and including the 100-year frequency event.
However, in the case of bridges or culverts or on-stream structures built
for the purpose of backing up water in the stream during normal or flood
flows, velocities may be increased at the structure site if scour, erosion,
and sedimentation will be avoided by the use of riprap or other design
measures.
(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.l
foot when compared to the existing conditions for all flood events up to and
including the 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.l 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 26-302 of this Chapter. Culverts must be
analyzed using the U.S. DOT, FHWA-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 Section 26-304(B)(2)(b).
(iii) Velocity increase
must be mitigated per Section 26-304(B)(2)(c).
(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 Section 26-304(B) (2)(n).
(vi) All excavations for
the construction of the crossing shall be designed per Section 26-304(B).
(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.l foot increase in backwater over the
existing flood profile for all flood frequencies up to and including the
100-year event, if the existing structure is not a source of flood damage.
(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 Ill.Adm.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 stream
flood stages greater than 0.l foot when compared to the existing conditions,
for all flood events up to and including the 100-year frequency event shall
be contained within the channel banks (or within existing vertical
extensions of the channel banks) such as within the design protection grade
of existing levees or 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
26-103(B) shall meet the permitting requirements of 92 Ill. Adm. Code 702
(Construction and Maintenance of Dams). If the proposed activity involves a
modification of the channel or floodway to accommodate an impoundment, it
shall be demonstrated that:
(i) The impoundment is
determined to be in the public interest by providing flood control, public
recreation, or regional storm water detention.
(ii) The impoundment will
not prevent the migration of indigenous fish species, which require access
to upstream areas as part of their life cycle, such as for spawning.
(iii) The impoundment will
not cause or contribute to degraded water quality or habitat conditions.
Impoundment design should include gradual bank slopes, appropriate bank
stabilization measures, and a presedimentation basin.
(iv) A non-point source
control plan has been implemented in the upstream watershed to control the
effects of sediment runoff as well as minimize the input of nutrients, oil
and grease, metals, and other pollutants. If there is more than one
municipality in the upstream watershed, the municipality in which the
impoundment is constructed should coordinate with upstream municipalities
to ensure comprehensive watershed control.
(v) The project otherwise
complies with the requirement of Section 26-304.
(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 10 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 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 4 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.
(iii) When expanding or
contracting flows in a vertical direction, a minimum of one foot vertical
transition for every 10 feet of stream length shall be used.
(iv) Erosion/scour
protection shall be provided inland upstream and downstream of the
transition Sections.
(i) If the proposed
activity involves a channel modification, it shall be demonstrated that:
(i) There are no
practicable alternatives to the activity which would accomplish its
purpose with less impact to the natural conditions of the body of water
affected.
(ii) The activity has
been planned and designed and will be constructed in a way which will
minimize its adverse impacts on the natural conditions of the body of
water affected, consistent with the following criteria:
a. The physical
characteristics of the modified channel shall match as closely as possible
those of the existing channel in length, cross-Section, slope and
sinuosity.
b. Hydraulically
effective transitions shall be provided at both the upstream and
downstream ends of the project, designed such that they will prevent
erosion.
c. One-sided
construction of a channel shall be used when feasible. Removal of
streamside (riparian) vegetation should be limited to one side of the
channel, where possible, to preserve the shading and stabilization effects
of the vegetation.
d. Clearing of
vegetation shall be limited to that which is essential for construction of
the channel.
e. Channel banks shall
be constructed with a side slope of no steeper than 4:l horizontal to
vertical, wherever practicable. Natural vegetation and gradual side
slopes are the preferred method for bank stabilization. Where high
velocities or sharp bends necessitate the use of alternative stabilization
measures, natural rock or riprap are preferred materials. Artificial
materials such as concrete, gabion, or construction rubble should be
avoided unless there are no practicable alternatives.
f. All disturbed areas
associated with the modification shall be seeded or otherwise stabilized
as soon as possible upon completion of construction. Erosion blanket or
an equivalent material shall be required to stabilize disturbed channel
banks prior to establishment of the vegetative cover.
g. If the existing
channel contains considerable bottom diversity such as deep pools,
riffles, and other similar features, such features shall be pro-vided in
the new channel. Spawning and nesting areas and flow characteristics
compatible with fish habitat shall also be established where appropriate.
h. The project otherwise
complies with the requirements of Section 26-304.
(j) Seeding and
Stabilization Plan. For all activities located in a floodway, a seeding and
stabilization plan shall be submitted by the applicant.
(k) Soil Erosion and
Sedimentation Measures. For all activities in the floodway, including
grading, filling, and excavation, in which there is potential for erosion of
exposed soil, soil erosion, and sedimentation, control measures shall be
employed consistent with the following criteria:
(i) The construction
area shall be minimized to preserve the maximum vegetation possible.
Construction shall be scheduled to minimize the time soil is exposed and
unprotected. In no case shall the existing natural vegetation be
destroyed, removed, or disturbed more than 15 days prior to the initiation
of improvements.
(ii) Temporary and/or
permanent soil stabilization shall be applied to denuded areas as soon as
possible. As a minimum, soil stabilization shall be provided within 15
days after final grade is reached on any portion of the site, and within
15 days to denuded areas which may not be at final grade but will remain
undisturbed for longer than 60 days.
(iii) Sedimentation
control measures shall be installed before any significant grading or
filling is initiated on the site to prevent the movement of eroded
sediments off-site or into the channel. Potential sediment control devices include filter fences, straw bale fences,
check dams, diversion ditches, and sediment basins.
(iv) A vegetated buffer
strip of at least 25 feet in width shall be preserved and/or re-
established, where possible, along exiting channels (see Section
26-304(B)(2)(p). Construction vehicle use of channels shall be
minimized. Temporary stream crossings shall be constructed, where
necessary, to minimize erosion. Necessary construction in or along
channels shall be restabilized immediately.
(v) Soil erosion and
sedimentation control measures shall be designed and implemented
consistent with "Procedures and Standards for Urban Soil Erosion and
Sedimentation Control in Illinois" (1988) also known as the "Green Book"
and "Standards and Specifications for Soil Erosion and Sediment Control"
(EPA, 1987).
(l) Public Flood Control
Projects. For public flood control projects, the permitting requirements of
this Section will be considered met if the applicant can demonstrate to 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 100-year frequency event.
(m) General Criteria for
Analysis of Flood Elevations.
(i) The flood profiles,
flows, and floodway data in the regulatory floodway study, referenced in
Section 26-302, 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 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 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.
(n) Conditional Letter of
Map Revision. If the Appropriate Use would result in a change in the
regulatory floodway location or the 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
non-government 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.
(o) Professional
Engineer's Supervision. All engineering analyses shall be performed by or
under the supervision of a registered professional engineer.
(p) For all activities in
the floodway involving construction within 25 feet of the channel, the
following criteria shall be met:
(i) A natural vegetation
buffer strip shall be preserved within at least 25 feet of the ordinary
high water mark of the channel.
(ii) Where it is
impossible to protect this buffer strip during the construction of an
Appropriate Use, a vegetated buffer strip shall be established upon
completion of construction.
(iii) The use of native
riparian vegetation is preferred in the buffer strip. Access through this
buffer strip shall be provided, when necessary, for stream maintenance
purposes.
(q) 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 Section 26-304(B)(2)(d).
(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 shall indicate the proposed flood
profile, pursuant to Section 26-304(B)(2)(e).
(c) The DWR will review
alternative transition Sections and hydraulically equivalent storage
pursuant to Section 26-304(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 26-103), and all other state, federal or local units
of government projects, including projects of the municipality or county.
(4) Other Permits. In
addition to the other requirements of this Chapter, a development permit for a
site located in a floodway shall not be issued unless the applicant first
obtains a permit or written documentation that a permit is not required from
DWR, issued pursuant to 615 ILCS 5/5 et seq. No permit from DWR shall
be required if the Division has delegated this responsibility to the Village.
(5) Dam Safety Permits.
Any work involving the construction, modification or removal of a dam as
defined in Section 26-103 per 92 Ill.Adm.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 Village Engineer finds a
dam that does not have a DWR permit, he/she shall immediately notify the Dam
Safety Section of the Division of Water Resources. If the Village Engineer
finds a dam which is believed to be in unsafe condition, he/she shall
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 requirement of this
Chapter, 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 require the
placement of above 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 3 feet below the existing stream bed, 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 exceed
l,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.
(iv) Vegetative
stabilization and gradual side slopes are the preferred mitigation methods
for existing erosion problems. Where high channel velocities, sharp bends
or wave action necessitate the use of alternative stabilization measures,
natural rock or rip-rap are preferred materials. Artificial materials
such as concrete, construction rubble, and gabions should be avoided
unless there are no practicable alternatives.
(e) Temporary stream crossings in which:
(i) The approach roads
will be 0.5 feet (l/2-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 lest 2 feet below the top of the
lowest bank. All fill in the channel shall be non-erosive materials, such
as riprap or gravel.
(iv) All disturbed stream
banks will be seeded or otherwise stabilized as soon as possible upon
installation and again upon removal of the crossing.
(v) The access road and
temporary crossings will be removed within one year after authorization.
Sec.
26-305. Occupation and Use of SFHA Areas where Floodways Are Not Identified.
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In SFHA
or floodplains, where no floodways have been identified and no base flood or
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 100-year
frequency flood elevation.
(A) Development Permit.
No person, firm, corporation, or governmental body, not exempted by state law,
shall commence any development in a SFHA or floodplain without first obtaining a
development permit from the Village Engineer. Application for a development
permit shall be made on a form provided by the Village Engineer. 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 elevation at the
lowest floor (including basement) of all proposed buildings subject to the
requirements of Section 26-306 of this Chapter.
(1) The application for a
development permit shall also include the following information:
(a) A detailed
description of the proposed activity, its purpose, and intended use.
(b) Site location
(including legal description) of the property, drawn to scale, on the
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 review 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 N.G.V.D., adjacent
property lines and ownership, drainage and flood control easements,
floodplain limit, location and orientation of crosssections, north arrow,
and a graphical or numerical scale.
(iii) Cross-section view
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 elevations, 10-year
frequency flood elevation, 100-year frequency flood elevation, and
graphical or numerical scales (horizontal and vertical).
(e) Engineering
calculations and supporting data shall be submitted showing that the
proposed work will meet the criteria of Section 26-305(B).
(f) Any and all other
local, state and federal permits or approval that may be required for this
type of development.
(2) Based on the best
available existing data according to the Illinois State Water Survey's
Floodplain Information Repository, the Village Engineer shall compare the
elevation of the site to the base flood or 100-year frequency flood
elevation. Should no elevation information exist for the site, the
developer's engineer shall calculate the elevation according to Section
26-302. 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, is not subject to the
requirements of this Chapter. The Building Department 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 Village Engineer
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 Village Engineer 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
velocities or threat to public health, safety, and welfare or impair the natural
hydrologic and hydraulic functions of the floodway or channel.
(1) Within all riverine
SFHA's where the floodway 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 26-304(B) (2) for the entire floodplain,
as calculated under the provisions of Section 26-302(D) 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 floodway. Upon acceptance of their floodway by the
Department, the developer shall then demonstrate that the project meets the
requirements of Section 26-304 for the regulatory floodway. The floodway
shall be defined according to the definition in Section 2-106(B) 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
Village per 92 Ill. Adm. Code, Part 708 for regulatory floodways, per DWR
Statewide Permit entitled "Construction in Floodplains with No Designated
Floodways in Northeastern Illinois."
(d) Dam Safety Permits.
Any work involving the construction, modification or removal of a dam or an
on-stream structure to impound water as defined in Section 26103(B) 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 Village Engineer finds a dam that does not have a DWR permit,
he shall immediately notify the Dam Safety Section of the Division of Water
Resources. If the Village Engineer finds a dam which is believed to be in
unsafe condition, he shall immediately notify the owner of the dam, the
Illinois Emergency Services and Disaster Agency (ESDA), and the DWR, Dam
Safety Section in Springfield.
(e) The following
activities may be permitted without a Registered Professional Engineer's
review or calculation of a base flood elevation and regulatory floodway.
Such activities shall still meet the other requirements of this Chapter:
(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 above-ground 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 3 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.
b. Do not result in an
increase in ground elevation.
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 l,000
feet in length or 2 cubic yards per lineal foot of streambed.
b. Materials are not
placed higher than the existing top of bank.
c. Materials are placed
so as not to reduce the cross-sectional area of the stream channel by more
than 10 percent.
d. Vegetative
stabilization and gradual side slopes are the preferred mitigation methods
for existing erosion problems. Where high channel velocities, sharp bends
or wave action necessitate the use of alternative stabilization measures,
natural rock or riprap are preferred materials. Artificial materials,
such as concrete, construction rubble, and gabions should be avoids unless
there are no practical alternatives.
(iv) Temporary stream
crossings in which:
a. The approach will be
0.5 feet (l/2 foot) or less above natural grade.
b. The crossing will
allow stream flow to pass without backing up the water above the stream
bank vegetation line or above any drainage tile or outfall invert.
c. The top of the
roadway fill in the channel will be at least 2 feet below the top of the
lowest bank. Any fill in the channel shall be non-erosive materials, such
as riprap or gravel.
d. All disturbed stream
banks will be seeded or otherwise stabilized as soon as possible upon
installation and again upon removal of construction.
e. The access road and
temporary crossings will be removed within one year after authorization.
(v) The construction of
light poles, sign posts, and similar structures.
(vi) The construction of
sidewalks, drive-ways, 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 flood waters.
(viii) The placement of
properly anchored buildings not exceeding 70 square feet in size nor 10
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 20 percent, which are located on the upstream or downstream
side of the existing building, and which do not extend beyond the sides of
the existing building that are parallel to the flow of flood waters.
(x) Minor maintenance
dredging of a stream channel where:
a. The affected length
of stream is less than l,000 feet.
b. The work is confined
to re-establishing flows in natural stream channels.
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 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 100-year frequency flood
elevation. The excavation volume shall be at least equal to one and one half
(1-1/2) times the volume of storage that is lost due to the fill or
structure. In the case
of streams and watercourses, such excavation shall
be made opposite or adjacent to the areas so filled or occupied. All
floodplain storage lost below the existing 10-year flood elevation shall be
replaced below the proposed 10-year flood elevation. All floodplain storage
lost above the existing 10-year flood elevation shall be replaced above the
proposed 10-year flood elevation. All such excavations shall be constructed
to drain freely and openly to the watercourse.
Sec.
26-306. Permitting Requirements Applicable to all Flood Plain Areas.
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In
addition to the requirements found in Sections 26-303, 26-304, and 26-305 for
development in flood fringes, regulatory floodways, and SFHA or floodplains
where no floodways have been identified (Zones A, AO, AH, AE, A1-A30, A99, VO,
V1-30, VE, V, M, or E), the following requirements shall be met:
(A) Public Health
Standards
(1) No developments in
the SFHA shall include locating or storing chemicals, explosives, buoyant
materials, animal wastes, fertilizers, flammable liquids, pollutants, or other
hazardous or toxic materials below the FPE.
(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 above ground openings
located below the FPE are watertight.
(B) Carrying Capacity and
Notification. For all projects involving channel modifications, fill, or stream
maintenance (including levees), the flood carrying capacity of the water course
shall be maintained. In addition, the Village shall notify adjacent communities
in writing 30 day prior to the issuance of a permit for the alteration or
relocation of the watercourse.
(C) Protecting Buildings.
All buildings located within a 100-year floodplain, also known as a 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 26-304.
(1) The building criteria
apply 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 20 percent or the building's market value by more than 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
mobile home to the same site it lawfully occupied before it was removed to
avoid flood damage.
(d) Installing a travel
trailer on a site for more than 180 days.
(2) This building
protection requirement may be met by one of the following methods.
(a) A residential or
non-residential building, when allowed, may be constructed on permanent
landfill in accordance with the following:
(i) The lowest floor
(including basement) shall be at or above the flood protection elevation.
(ii) The fill shall be
placed in layers no greater than l-foot deep before compaction and should
extend at least 10 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 10-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 of surface drainage from or onto neighboring
properties.
(b) A residential or
non-residential building may be elevated in accordance with the following:
(i) The building or improvement shall be
elevated on crawl space, stilts, piles, walls, or other foundation that is
permanently open to flood waters and not subject to damage by hydrostatic
pressures of the base flood or 100-year frequency flood. The permanent
openings shall be no more than one foot 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.
(ii) 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.
(iii) 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 water-proofed service facilities may be located below the flood
protection elevation.
(iv) No area below the
flood protection elevation shall be used for storage of items or
materials.
(v) Manufactured homes
and travel trailers to be installed on a site for more than 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 Ill. Adm. Code 870.
(c) Only a
non-residential building may be structurally floodproofed (in lieu of
elevation) provided that a registered professional engineer shall certify
that the building has been structurally dry floodproofed below the flood
protection elevation, the structure and attendant utility facilities are
watertight and capable of resisting the effects of the base flood or
100-year frequency flood. The building design shall take into account flood
velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the
effects of buoyancy, and impacts from debris or ice. Floodproofing measures
shall be operable without human intervention and without an outside source
of electricity (levees, berms, floodwalls, and similar works are not
considered floodproofing for the purpose of this subsection).
(d) Non-conforming
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 50 percent of its market value before it
was damaged, in which case it shall conform to this Chapter.
(3) Detached garages of
single-family homes may be "wet- proofed" provided that all of the following
conditions apply:
(a) The garages are not
located in the floodway.
(b) The garages are only
used for the storage of vehicles and tools.
(c) The garages are not
habitable and do not contain other rooms or uses (such as a shop,
greenhouse, bedroom, etc.
(d) All the utilities are
above the base flood elevation.
(e) All the materials
that are located below the base flood elevation are flood-resistant.
(f) The garages cover
less than 500 square feet of land.
Sec.
26-307. Other Development Requirements.
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The Board
of Trustees 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,
manufactured home parks, annexation agreements, and Planned Unit Developments (PUD's)
within the SFHA shall be reviewed to assure that the proposed developments are
consistent with Sections 26-303, 26-304, 26-305, and 26-306 of this Chapter and
the need to minimize flood damage. Plats or plans for new subdivisions, mobile
home parks, and PUD's 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 (765 ILCS 205/2).
(B) Proposals for new
subdivisions, manufactured home parks, travel trailer parks, and PUD's additions
to manufactured home parks, and additions to subdivisions shall include base
flood or 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 100-year frequency flood elevation per Section
26-302(D) and the floodway delineation per the definition in Section 26-103(B)
and submitting it to the State Water Survey and DWR for review and approval as
best available regulatory data.
(C) Street, 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 Board of Trustees
shall not approve any PUD or plat of subdivision located outside the corporate
limits unless such agreement or plat is in accordance with the provisions of
this Chapter.
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