G-223 - 09/27/1977 - SUBDIVISION - Ordinances 1
ORDINANCE NO.
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AN ORDINANCE AMENDING CHAPTER 12, ARTICLE V, SECTION 12-362 a OF THE CODE OF
ORDINANCES, AND ORDINANCE NO. G-140, AS AMENDED, THE SUBDIVISION REGULATIONS
ORDINANCE, OF THE VILLAGE OF OAK BROOK, DU PAGE AND COOK COUNTIES, ILLINOIS, TO
REGULATE DEVELOPMENT OF FLOOD PLAINS AND WET LANDS.
WHEREAS, the Plan Commission of the Village of Oak Brook, Du Page and Cook
Counties, Illinois, has studied the threats to public health, safety and welfare of the Village resulting
from the uncontrolled development of flood plain and wetland areas within the Village and its
environs; and
WHEREAS, the Plan Commission and Zoning Board of Appeals have held a joint public
hearing pursuant to statutory public notice, to hear testimony on the problems presented by
development of flood plains and solutions thereto, and to consider the matters contained herein; and
WHEREAS, the Plan Commission has made a written recommendation to the President
and Board of Trustees concerning regulation of development of flood plains and wetlands; and
WHEREAS, the President and Board of Trustees of the Village of Oak Brook deem the
.passage of this Ordinance to be in the best interest and in furtherance of the general welfare of the
Village of Oak Brook.
NOW, THEREFORE, BE IT ORDAINED by the President and Board of Trustees of the
Village of Oak Brook, Du Page and Cook Counties, Illinois, that:
SECTION 1: The provisions of the preamble hereinabove set forth are hereby restated herein as
though herein fully set forth.
SECTION 2: Article IV, Section 2A of Ordinance No. G-140, as amended, is hereby amended to add
thereto subsections IA, 1B, 5A, 8A, 8B, 8C, 8D, 8E, 10A, 19A, 39, and 40 to read as follows:
(1A) Area of Special Flood Hazard: The land within the floodplain which is
subject to a one percent chance of flooding annually. This area may also be
identified as that which is subject to the one hundred year flood.
(1B) Base Flood Elevation: The elevation at all locations at which there is a
one percent chance of flooding annually.
(5A) Compensatory Storage: An artificially .excavated volume of storage
used to balance the loss of natural flood storage capacity when artificial fill
or structures are placed within the floodplain.* The uncompensated loss of
natural floodplain storage can increase off-site floodwater elevations and
flows.
(8A) Flood: The condition existing where the waters of any river, stream,
creek, watercourse, lake, or pond temporarily rise to a height above their
normal levels and overflow the boundaries within which they are ordinarily
contained.
(8B) Floodplain: The area of special flood hazard adjoining a watercourse
whose surface elevation is lower than the Base Flood Elevation and which is
subject to periodic inundation during floods.
(8C) Flood Profile: Graphical representations of the elevations of the water
surface of the one hundred year flood along the watercourses of the Village.
(8D) Floodwaters: The waters of any stream, river, creek, watercourse, lake
or pond which overflow the boundaries within which said waters are normally
contained. .
(8E) Floodway: The channel of a watercourse and those portions of the
adjoining floodplains which are reasonably required to carry and discharge the
water of the one hundred year flood.
(I OA) High Water Elevation: The elevation of floodwaters of the one hundred
year flood at any given point (see 1B above).
(19A) One Hundred Year Flood: A flood magnitude with a one percent
t statistical chance of being equaled or exceeded during any year. A flood this
large would be reached once during a 100-year period, on the average.
However, the occurrence of such an event does not diminish the chance of its
recurring again at any time.
(39) Watercourse: Any stream, creek, brook, branch, natural or artificial
depressions, slough, gulch, wetland, reservoir, lake, pond, or natural or
manmade drainageway in or into which stormwater runoff and floodwaters
flow either regularly or intermittently.
(40) Wetlands: 1. The land areas in which the groundwater table or zone of
saturation periodically intersects the surface and which contain wetland plant
species that are listed in Norman C. Fassett, A Manual of Aquatic Plants
(Madison: University of Wisconsin Press, 1957) and/or Floyd Swink, Plants of
the Chicago Region, Second Edition (Lisle, Illinois: The Morton Arboretum,
1974), and/or Henry A. Gleason, The New Britton and Brown Illustrated Flora
of the Northeastern United States and Adjacent Canada, New York: Hafner
Press, 1952 . Wetland plants are distinguished from aquatic in that they are
limited to species that can complete their life cycle without submersion but
which have the ability to withstand a permanent or seasonally long
submersion of at least the plant root system. 2. Wetlands, for the purposes
of this Ordinance, are also defined to include areas of poorly drained soils
with a water table within two (2) feet of the ground surface for at least three
(3) months of the year.
SECTION 3: Article V, Section 3 of Ordinance No. G-140, as amended, is hereby amended to add
thereto subsection (D) to read as follows:
(D) Information Required for Subdivision Involving a Flood lain:
Accompanying the preliminary pat of each proposed subdivision which
involves any portion of a floodplain as described by the official maps of this
Village, there shall be furnished the following information and data:
(1) Contour Map: A topographic map with one-foot interval
contours of the land to be subdivided and such adjoining land the
topography of which may affect the layout or drainage of the
subdivision. On such a map there shall be shown the following:
(i) The location of streams and other watercourses, their
normal channels, the extent of their floodplains at the
established high water elevations, and the limits of the
floodway, all properly identified.
(ii) The normal shoreline of all watercourses, their
floodplains and lines of inflow and outflow, if any.
(iii) The location of farm and/or field drains and their
inlets and outlets.
(iv) Culverts, storm and sanitary sewers, and sewer inlets
and outfalls.
(v) Septic systems and outlets, if any.
(vi) Seeps, springs, and flowing and other wells.
(vii) Location of existing structures that will remain.
(2) Channel Profiles: Profile drawings of each stream, channel,
pond, and basin showing elevations of the following:
(i) The streambed.
(ii) Channel banks, if any.
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(iii) Waterway openings of existing culverts and bridges
within and near the tract.
(iv) Size and elevation of sewer and drain outlets into the
stream channel or basin.
(v) The Flood Profile.
SECTION 4: Article V, Section 3 of Ordinance No. G-140, as amended, is hereby amended to add
thereto subsection (E) to read as follows.
(E) Maps and Profiles: The maps and profiles listed, or from the sources
listed, in each subsection below, shall govern the classification of land within
the Village for the purposes of this Ordinance, insofar as the information
related thereby is certified as accurate by the Village Engineer.
(1) Village Maps: Official maps prepared by the Village which
depict the floodplains, floodways, floodway fringes, and flood-
way encroachment lines, and maps prepared by the following
organizations:
(i) Floods in the Hinsdale Quadrangle, Illinois.
Hydrologic Investigation Atlas HA-86
Published by U.S. Geological Survey, 1964.
(ii) Floods in Wheaton Quadrangle, Illinois
Hydrologic Investigation Atlas HA-148
Published by U.S. Geological Survey, 1965.
(iii) Des Plaines River Flood Plain Information Maps and
Profiles prepared by Des Plaines River Steering Committees,
December, 1975.
(iv) Upper Salt Creek Watershed Work Plan prepared with
the assistance of Soil Conservation Service of the U.S.
Department of Agriculture, May, 1973.
(v) Federal Insurance Administration.
(2) Flood Profiles: Flood profiles which describe the expected
elevation of floods along the center lines of the principal
watercourses of this Village prepared by the Village, and
profiles prepared by the following organizations:
(i) Floods in Hinsdale Quadrangle, Illinois
Hydrologic Investigation Atlas HA-86
Published by U.S. Geological Survey, 1964.
(ii) Floods in Wheaton Quadrangle, Illinois
Hydrologic Investigation Atlas HA-148
Published by U.S. Geological Survey, 1965.
(iii) Des Plaines River Flood Plain Information Maps and
Profiles prepared by Des Plaines River Steering Committees,
December, 1975.
(iv) Upper Salt Creek Watershed Work Plan prepared with
the assistance of Soil Conservation Service of the U.S.
Department of Agriculture, May, 1973.
(v) Federal Insurance Administration.
(3) Conflicts Between Maps and Profiles: In the event a conflict
arises between the information depicted by the official Village
floodplain maps and profiles, and in the absence of any
{ overriding information to the contrary, the data prescribed by
the profiles will govern.
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Aft . ar
(4) 1. One Hundred Year Flood: Information pertaining to
the one hundred year flood incorporated in this Ordinance,
including maps and profiles, has been extracted from and is
based on the studies and reports listed in subsections (1) and (2)
above.
2. Flood of Record: Information pertaining to the flood
of record incorporated in this Ordinance, including maps and
profiles, has been extracted from and is based on the studies
and reports listed in subsections (1) and (2) above. .
(5) Official Elevations: The system of official Bench Marks and
elevations already established in the area by the U.S. Coast and
Geodetic Survey (First Order Level Networks) or the U.S.
Geological Survey shall hereafter be taken by engineers,
surveyors, architects, and contractors when making topographi-
cal surveys and maps, and when setting grades and elevations of
buildings, pavements, drainage facilities, and other structures
of works publicly constructed or regulated by the Village.
(6) Lateral Transfer of Elevations: For purposes of this
Ordinance, the high-water elevation applicable to a specific
site, if not otherwise depicted by the official maps and profiles
described above, shall be that elevation established for the
adjoining stream or channel measured at right angles to the
general direction of flow in that stream or channel.
SECTION 5: Article VII, Section 3 (D) of Ordinance No. G=140, as amended, is hereby amended to
add thereto subsection (4) to read as follows:
(4) Storm water drainage and detention systems of residential subdivisions of
more than five (5) acres in area and all commercial, ORA, business and
institutional subdivisions shall be designed and constructed to service the
entire subdivision to carry off water from all sump pumps, inlets, catch
basins, or open drainageways and be connected with an adequate outf all. The
storm drainage system shall be separate and independent of the sanitary
sewer system. It shall consist of sewers, manholes, inlets, catch basins and
other necessary facilities to adequately drain the subdivision, protect
roadway pavements, and prevent standing water except in designed retention
basins. Open ditches shall be avoided if possible.
(a) Storm water drainage and detention systems shall conform
to the long range needs of the Village of Oak Brook. The storm
sewer system shall be designed and installed to meet the
requirements for sewer construction of the Village of Oak
Brook.
(b) The maximum release rate shall not exceed 0.10 cfs per acre
provided:
1. The amount of runoff from the proposed improvement
shall not exceed the existing capacity of downstream structures
or the increased capacity of downstream structures as
improved.
2. The size of the release control structure shall have a
diameter of not less than four (4) inches.
(c) Roof top detention is acceptable.
(d) Parking lot detention is acceptable provided:
1. Maximum water depth equals nine (911) inches.
2. Such parking lot is the last area to flood and first area
to drain.
(e) Overflow shall be provided to safely discharge flows in
excess of design storm or flows created by malfunction of the
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detention facility.
(f) Detention required by the development of property shall be
provided in addition to existing natural detention.
(g) Detention basin design shall be based on a storm having a 1%
chance of being exceeded or equaled in any given year (100
year storm). Rainfall intensity shall be taken for the northwest
section as specified in Technical Letters Numbers 1 and 4 re:
Rainfall Frequencies, as published by the State Water Survey
Division.
(h) Storm drainage systems running full (not surcharged), shall
be designed to carry the runoff from a storm having a 10%
chance of being exceeded or equaled in any given year (10 year
storm).
SECTION 6: Article VII, Section 3 of Ordinance No. G-140, as amended, is hereby amended to add
thereto subsection (M) to read as follows:
(M) The following rules shall govern the design of land improvements with
respect to floods:
(1) General: All proposed subdivision and other developments,
within the floodplain, shall be reviewed to assure that the
proposed developments are consistent with the need to mini-
mize flood damage, that all public utilities and facilities (such
as sewer, gas, electrical, and water systems) are located and
constructed to minimize or eliminate flood damage and that
adequate drainage is provided.
(2) Design: Streets, blocks, depths of lots, parks, and other
public grounds shall be located and laid out in such a manner as
to preserve and utilize natural streams, channels, and detention
basins. Whenever possible, the larger streams and floodplains
shall be included within parks or other public grounds.
(3) Channel Straightening: Sharply meandering streams or
channels may be partially straightened and minor changes made
in other channels, subject to the approval of the President and
Board of Trustees after its review of a Plan Commission
recommendation, provided: a. The hydraulic capacity of the
floodplain storage outside the floodway is maintained; b. The
volume of floodwater storage outside the floodway is not
reduced; and c. Provision is made to stabilize the banks of the
modified channel to control erosion.
(4) Floodplain Lots: Land lying partially in a floodplain may be
laid out and platted as building lots or parcels, providing a
building site not lower than the applicable high-water elevation .
plus three (3) feet exists on the high. part of the lot or parcel
within the buildable area as defined in Ordinance No. G-60, as
amended, the Zoning Ordinance of the Village of Oak Brook, of
such lot or parcel.
(5) Compensatory Storage: Such filling as may be required or
permitted in.a floodplain shall be compensated for and balanced
by at least an equal volume of excavation taken from below the
high-water elevation. In case of streams and channels, such
excavation shall be made opposite or just upstream from the
area which is to be filled and shall be constructed to drain
freely and openly to the watercourse.
(6) Street Pavements: The crown of street pavements hereafter
constructed in floodplains shall not be lower than the
established high water elevation plus one (1) foot in the case of
collector or higher classification streets and plus zero (0) feet
in the case of local streets.
(7) Rear Lot Lines: Whenever the plans call for the passage of
floodwaters, surface runoff, or excess stormwater along rear lot
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lines, the grading of all such lots shall be prescribed and
established as part of the subdivision plat. Within these
floodway areas so designated for the passage of such waters, no
structure or fences may be erected, no shrubbery or trees may
be planted, and no changes may be made to the prescribed
( grades and contours of the specified floodwater or stormwater
runoff channels.
(8) Manholes: All sanitary sewer manholes constructed in a
floodplain must have a rim elevation of a minimum of three (3)
feet above the base flood elevation or shall have waterproof
covers.
(9) Water Supply and Sanitary Sewer Systems: The design of
water supply and sanitary sewer systems to be located in the
floodplain shall minimize or eliminate the discharges from the
system into .the floodwaters and the infiltration of floodwaters
into the system. On-site waste disposal systems shall be
located so as to avoid impairment of them or contamination
from them during or subsequent to the one hundred year flood.
SECTION 7: Section 12-362 (a) of the Code of Ordinances of the Village of Oak Brook, Illinois, is
hereby amended to read as follows:
Section 12-362 Regulations: Permits Required.
(a) W Construction is prohibited in any area subject to Village
Ordinances, rules or regulations regarding flood plains or
wetlands unless the requirements of all. such Ordinances, rules,
or regulations are satisfied.
(ii) Construction is prohibited in any area which contains
inadequate drainage facilities, unless the owner agrees to make
all necessary improvements, and agrees to all necessary
covenants which will comply with (a) the standards set forth in
subparagraphs (a) through (h) inclusive of subsection (4) of
Section 3 (D) of Article VII of Ordinance No. G-140, the
Subdivision Regulations of Oak Brook, as amended, which by
this reference are hereby incorporated herein as though herein
fully set forth, and (b) such additional standards as shall in the
opinion of the Village Engineer, make such construction safe for
occupancy and provide necessary safeguards for adjacent
property which would be affected by the grading, drainage, or
other changes being required or permitted for such construc-
tion. A permit for any such construction must be obtained from
C the Village Engineer.
SECTION 8: The title of Article V of Chapter 12 of the Code of Ordinances of Oak Brook, Illinois, is
hereby amended to read as follows:
ARTICLE V. STORM WATER MANAGEMENT
SECTION 9: This Ordinance shall be in full force and effect from and after its passage and approval
as by Statute in such case made and provided. This Ordinance shall be published in pamphlet form.
SECTION 10: All ordinances, rules, and regulations of the Village of Oak Brook which are in conflict
with the provisions of this Ordinance are hereby repealed to the extent of the conflict.
SECTION 11: If any section, subsection, sentence, clause, or phrase of this Ordinance is for any
reason held to be invalid, such determination shall not affect the validity of any remaining portion of
this Ordinance.
n�rs
PASSED this 'r ; day of ����, . ,_ , 1977.
AYES: `7
NAYS: c)
ABSENT:
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APPROVED this L — day of �S„' , , 1977.
Pr,e�ident
ATTEST:
VaL
Village'Clerk
Filed in the Office of the Village Clerk and published in pamphlet form by authority of the President
and Board of Trustees of the Village of Oak Brook this :A day of
Village Clerk
1
APP OVED as to f
s
illa Attor e
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