G-1538 Ordinance No. G-1538
AN ORDINANCE
AN ORDINANCE ADOPTING SUPPLEMENTARY SUBDIVISION, ZONING, AND BUILDING
CONSTRUCTION REGULATIONS DESIGNED TO LESSEN OR AVOID HAZARDS TO PERSONS
AND DAMAGE TO PROPERTY CAUSED BY FLOODING AND OTHERWISE PROMOTE PUBLIC
HEALTH, SAFETY, COMFORT, MORALS, AND WELFARE.
BE IT ORDAINED BY THE MAYOR AND CITY COUNCIL OF THE CITY OF ELGIN, COUNTIES
OF KANE AND COOK, ILLINOIS.
ARTICLE 1
GENERAL
SECTION 1. SCOPE - PERMITS
(a) This ordinance amends and supplements the following ordinances:
(1) subdivision ordinance - short title
(2) zoning ordinance - short title
(3) building code - short title
(b) The provisions of this ordinance further regulate and restrict:
(1) The subdivision, layout, and improvement of land, including
drainage, underground utilities, and service facilities.
(2) The excavating, filling, and grading of lots and other par-
cels and areas of flood plains, the storing of certain
materials thereon, stream and other floodwater runoff chan-
nels, and detention ponds, and basins.
(3) The location, construction, and elevation of buildings and
other structures and parts and appurtenances thereof, and
the drainage of parking and' other paved lots or areas.
(c) Before starting any of the work regulated by this ordinance, an
applicant shall comply with requirements set forth in the afore-
mentioned ordinances with respect to submission and approval of
preliminary and final subdivision plats, improvement plans, build-
ing and zoning permits, inspections, appeals, and similar matters
along with those set forth in this ordinance and as required by
State statute and regulations of any department of the State of
Illinois.
SECTION 2. STREAMS AND FLOODWATER RUNOFF CHANNELS AND BASINS
The United States Geological Survey maps entitled "Floods in Elgin
Quadrangle and Floods in Streamwood Quadrangle" are designated as the
"Official Floodwater Drainage Maps", dated 1965. Accompanying and
(Pk identified as a part of this ordinance, are incorporated herein for
the purpose of establishing the following:
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(a) Locations - Identifications
Locations of certain existing streams and other floodwater runoff
channels and detention ponds and basins and names or other identi-
fying designations thereof. Such locations shall be subject to
approved straightenings and relocations as provided for in the
ordinance.
(b) Floodway Widths
Widths or limits of floodways on or along the streams and channels
established herein.
A floodway consists of the deeper parts of the total flood plain,
including the trench or channel and adjoining parts, which are
reasonably required for the downstream movement of floodwater or
flood flows as distinguished from the shallower parts of the
flood plain where the speed of flow or current is lessened by the
friction of bottom materials and growth; while the function of
the flood plain is essentially that of slow-moving storage of
floodwater.
(c) Detention Basin Boundaries
Boundaries or limits of the existing detention ponds and basins
established herein.
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(d) Areas of Waterway Openings
Minimum areas of waterway openings to be provided whenever new cul-
verts and bridges are built at various points on the streams and
channels established herein.
SECTION 3. HIGH-WATER ELEVATIONS
(a) Profiles
The United States Geological Survey maps entitled ' Floods in Elgin
Quadrangle and Floods in Streamwood Quadrangle" and associated sheets
of profile drawings and schedules entitled "High-Water Elevations,"
dated 1965, accompanying and identified as a part of this ordinance,
are incorporated herein for the purpose of establishing high-water
elevations on or along the streams, channels, and basins established
in Section 2 hereof.
(b) Definitions
High-water elevation means the highest level of floodwater observed
during past floods or that may reasonably be expected. Flood plain
means such land whose surface elevation is lower than the high-water
elevation established under Section 3 (a) hereof.
(c) Datum
The high-water and other elevations shown on the profiles are in
feet above mean sea level datum at New York City or Elgin datum
when so designated (19.96 feet above USGS).
(d) Applicable Elevation
For purposes of these regulations, the high-water elevation appli-
cable to a building, building site, or part of a lot, parcel, or
other area of land shall be the elevation established for:
(1) the adjoining or nearest stream or other floodwater runoff
channel measured at right angles to the general direction
of flow in the stream or channel, or
(2) the adjoining or nearest floodwater detention pond or basin,
whichever is the highest.
(e) Higher Future Floods
The establishment by this ordinance of high-water elevations for
the purpose of regulating future development in order to lessen
or avoid hazards to persons and damage to property from floodwaters
is not intended nor shall it be construed to imply or assure owners,
occupants, or prospective purchasers of property that no flood of
higher elevation will ever occur in the future.
SECTION 4. OFFICIAL BENCH MARKS
There is hereby established a system of points or marks of known eleva-
tions above the mean sea datum at New York City from which elevations
shall hereafter be taken by engineers, surveyors, architects, and con-
tractors when making topographical surveys and maps and settings, grades,
and elevations for buildings, pavements, drainage facilities, and other
structures or work publicly built or regulated by the City of Elgin.
The identifying designation, description, location, and elevation of
the points or marks constituting a system of Official Bench Marks are
on file in the office of the City Engineer.
ARTICLE 2
SUBDIVISION & IMPROVEMENT REGULATIONS
SECTION 5. REQUIRED INFORMATION
Accompanying the preliminary plans of each proposed subdivision sub-
mitted for preliminary approval, there shall be furnished the following
information and data:
(a) Contour Map - A (1 foot) interval contour map of the land to be
subdivided and such adjoining land whose topography may affect
the layout or drainage of the subdivision. On such map shall be
shown the following:
(1) The flowlines of streams and other floodwater runoff channels,
their normal shorelines and the shoreline of the established
high-water elevations
(2) Normal shoreline of lakes, ponds, swamps, and other detention
basins, the shoreline of high-water elevations established
under Section 3, lines of inflow and outflow, if any
(3) Farm drains, inlets and outfalls
()4) Storm, sanitary and combined sewers and outfalls
(5) Septic tank systems, outlets if any
(6) Seeps, springs, flowing and other wells
(b) Channel Profiles - Profile drawings of each stream, channel, pond,
and basin showing elevations of the following:
(1) The stream bed or flowline
(2) Channel banks, if any
(3) Waterway openings of existing culverts and bridges within
and near the tract
(4) Size and elevation of sewer and drain outlets into the stream,
channel, or basin
(5) The high-water elevations established under Section 3 of this
ordinance
Where a limited number of high-water observations or determinations have
been established on a stream or channel, the subdividers engineer shall,
in drawing his profiles, extend or project the established high-water
elevation upstream or downstream from a single elevation approximately
parallel to the streambed or flowline as surveyed by him.
If a subdivider believes that the established high-water elevation or
profile unreasonably restricts the layout of his proposed subdivision
or its development or that an error has been made in its establishment,
he may appeal to the Plan Commission for a review thereof, and for
recommendation to the City Council for an amendment to the elevations.
No such amendment shall be made until a duly-advertised public hearing
on the amendment has been held on the proposed amendment before the
Plan Commission or City Council.
(c) Comprehensive Drainage Plan
A comprehensive drainage plan, first in preliminary form, is
designed to handle safely the floodwater runoff following the
heavier rainstorms.
The plan shall provide or be accompanied by maps or other descrip-
tive material showing the following:
(1) The extent and area of each watershed tributary to the drainage
channels in the subdivision.
(2) The street storm sewers and other storm drains to be built,
the basis of their design, the outfall and outlet locations
and elevations, receiving stream or channel and its high-water
elevation, and the functioning of the drains during high-water
conditions.
(3) The parts of the proposed street storm sewer system along
which overhead sewers in buildings is advised to prevent
sewage backups in basements during the heavier rainstorms.
(4) The parts of the proposed street system where pavements are
planned to be depressed sufficiently to convey or temporarily
store overflow from storm sewers and over-the-curb runoff
resulting from the heavier rainstorms and the outlets for
such overflow.
(5) Existing streams and floodwater runoff channels to be main-
tained, enlarged, altered otherwise, and eliminated; and
new channels to be constructed, their locations, cross sec-
tions and profiles.
(6) Existing culverts and bridges, drainage areas, elevation,
and adequacy of waterway openings; and new culverts and
bridges to be built, their materials, elevations, waterway
openings and basis of design.
(7) Existing detention ponds and basins to be maintained, enlarged,
altered otherwise, and new ponds or basins to be built with
dams, and their design.
SECTION 6. SUBDIVISION DESIGN AND DRAINAGE
The following rules shall govern the design of the improvement with
respect to the drainage of floodwater runoff.
(a) 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, including
wherever possible the larger streams and flood plains within parks
or other public grounds.
(b) Channel Straightening
Sharply meandering streams or channels may be partly straightened
and minor changes made in other channels, subject to approval of
the City Council, provided:
(1) the floodway dimensions of the stream or channel are maintained
(2) the volume of floodwater storage outside the floodway is not
reduced
(3) the changes and channels comply with the provisions of Section 6
(c) Lesser Channel Locations
Generally acceptable locations of the lesser floodwater runoff
channels in the design of a subdivision include the following:
(1) In a depressed median of a double-roadway street or parkway,
provided the median is wide enough to permit flat side slopes
along the floodway.
(2) Centered on the rear lot lines in a block, or entirely within
the rear yards of a single row of lots or parcels, provided
in either case the lots are deep enough to permit flat side
slopes along the floodway and a building site above the
established high-water elevation plus 2 feet on the front part
of the lot.
In each of the foregoing cases, a floodway easement, at least 20
feet wide shall be provided and shown on the plat. The easement
shall permit necessary public channel maintenance and improvement
work and access of equipment, therefore, but shall prohibit build-
ings and other obstructing structures thereon by the owner.
(d) Uppermost Reaches of Drainage Channels
The smaller uppermost reaches of drainage channels and swales
forming the natural drainage system near the watershed divide may
be relocated or eliminated and incorporated into the planned system
of storm sewers and/or open channels upon a showing that the system
is adequate and can safely handle the floodwater runoff following
the heavier rainstorms.
(e) Within-Block Drainage
A continuous easement shall be provided along rear lot lines and
drawn on the subdivision plat within which utility lines and
drainage may be located and maintained, but on which no accessory
buildings may be located or built. The utility-drainage easement
shall be at least 10 feet wide, 5 feet on each lot.
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(f) Flood Plain Lots
Land lying wholly or partly in a flood plain may be laid out and
planned as building lots or parcels, provided a building site,
not lower than the applicable high-water elevation plus 2 feet:
(1) exists on the front part of the lot or parcel, or
(2) will be built up during execution of the subdivision improve-
ment plan through general excavation and filling, or
(3) can be provided with excavation taken from within the area
of the lot or parcel when it is built upon.
Such filling as may be required or permitted in this ordinance for
a building site or as may otherwise be done on flood plain land
(which eliminates space previously available for storing and moving
floodwater) shall be compensated for or balanced by at least an
equal volume of excavation below high-water elevation. In the
case of streams and channels, such excavation shall be made opposite
or just upstream from the filled-in area.
(g) Street Pavements Near Streams
The crown of street pavements hereafter built adjoining or near
stream, floodwater runoff channels or detention basins shall not
t be lower than the established high-water elevation plus 2 feet,
in the case of major streets, and plus 1 foot, in the case of
other streets.
(h) Detention Basin Dams
Dams constructed to form floodwater detention ponds, basins, or
lakes shall be designed to maintain a permanent low-water pool and
a temporary floodwater storage pool and shall be provided with out-
lets which may be set or regulated to detain or empty slowly the
storage pool following periods of runoff according to the capacity
of the downstream channel to carry the flow safely.
ARTICLE 3
ZONING REGULATIONS
SECTION 7. BUILDINGS ON AND USE OF FLOOD PLAINS
Except as regulated by this or other ordinances and State statutes, any
building or structure may be placed or erected on and storage or other
use may be made of the flood plain that is permitted by the regulations
of the zoning district in which such flood plain is located.
SECTION 8. PRESERVATION OF FLOODWAYS AND DETENTION BASINS
All buildings, other structures, inoperable motor vehicles and similar
machinery, and fills of any kind of materials hereafter made, placed
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or erected on the flood plain shall be set back at least the distances
required to preserve and maintain open and unobstructed:
(a) the widths of floodways established for streams and other flood-
water runoff channels, and
(b) the boundaries or limits of floodwater detention ponds and basins,
as established in Section 2 and as otherwise regulated in this
ordinance.
SECTION 9. OPEN STORAGE OF FLOATABLE MATERIALS
Logs, tree stumps and branches, lumber, lumber products, and other
floatable material may be placed, displayed, or stored in the open on
floodplain land, where permitted by the zoning district regulations
applicable to such land, and by State statutes, provided the area so
used is enclosed by an open wire fence properly anchored to restrain
such materials from floating downstream during times of high water.
SECTION 10. OPEN STORAGE OF OTHER MATERIALS
The open storage or display on flood plain land of inoperable motor
vehicles and similar machinery and other non-floatable materials and
products, where permitted by the regulations of the zoning district
applicable to such land, and by State statutes shall be considered
the same as the placement of fill on the flood plain and shall be subject
to the regulations of this ordinance relating to making fills.
ARTICLE 4
BUILDING REGULATIONS
SECTION 11. BUILDING WALL OPENINGS
A door sill, window sill, or the base of any other opening in the outer
walls of a main building or structure, including drain conduits, shall
be constructed at an elevation not lower than the established high-
water elevation plus 3.5 feet, unless surrounded by a water-tight
areaway whose top is not lower than the aforesaid minimum elevation.
SECTION 12. OUTER WALLS AND BASEMENT FLOORS
The outer walls, basement floor, and areaways of a building which enclose
open space that is below the established high-water elevation plus 3.5
feet, shall be constructed of masonary materials up to the minimum eleva-
tion, shall be water-tight and be designed to withstand the hydrostatic
pressure caused by floodwater standing at high-water elevation adjoining
the building site.
SECTION 13. STORM WATER DETENTION IN UNSEWERED AND SEPARATE SEWERED AREAS
(a) General. It is recognized that the receiving streams within the
area of the City do not have the capacity to receive and convey
the increased storm water runoff resulting from rapid urbanization
occuring in many areas. These receiving streams are subject to
periodic flooding which results in a growing rate of property damage.
It is the intent of this Section to require developers to parti-
cipate in providing detention storage to eliminate excessive runoff
during heavy storm periods. It is proposed that well maintained
landscaped lakes would be provided to act jointly as detention
reservoirs and recreation facilities or aesthetic focal points in
developments. Other control methods to regulate the rate of storm
water discharge which would be acceptable include detention on flat
roofs, parking lots, streets, lawn, underground storage, oversized
storm sewers with restricted outlets, etc.
It is recognized that in order to better serve the long-range
interests of the City comprehensive basin-wide planning for flood
control should be formulated, adopted and implemented. Comprehensive
planning is far more beneficial than on-site detention, although on-
site detention does provide protection and is acceptable for com-
pliance with this Ordinance.
(b) Requirements. Pursuant to the provisions of this Section, no final
plat should be approved unless detention of storm water runoff is
provided as set forth in the following criteria:
(1) A combination of storage and controlled release of storm
/► water runoff is required for all commercial developments
[ exceeding 5 acres in area, for all residential developments
exceeding 10 acres in area and for all residential develop-
ments between 5 and 10 acres which have an imperviousness
of 60 percent or greater. However, a residential development
of 10 acres or less must have an adequate outlet as
determined by the City Engineer. If the outlet is not
adequate, then detention, as determined by the City Engineer,
will be required to store that portion of the runoff exceed-
ing the outlet capacity.
(2) The release rate of storm water from all developments re-
quiring detention shall not exceed the storm water runoff
rate from the area in its natural undeveloped state.
Because of the flat conditions of the land in this area,
channel configurations cut by nature are generally unable
to handle the runoff from the high intensity rainfalls and
results in flood plain storage or spreading of runoff over
the land areas during the larger storm periods. In order
not to increase the runoff from such areas after development,
the release rate must be limited to the carrying capacity of
these natural channels.
The City will accept the release rate of not greater than that
calculated from a storm of three (3) year frequency with a
runoff rate coefficient of 0.15, unless the applicant can
show by his detail calculations, which are acceptable by the
City, that the discharge rate of the natural outlet channel
serving the area is greater.
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(3) Drainage systems shall have adequate capacity to bypass through
the development the flow from all upstream areas for a storm
of design frequency assuming that the land is in a fully developed
state under present zoning or zoning proposed under a Comprehensive
Plan. The bypass flaw rate shall be computed utilizing a runoff
coefficient of not less than 0.35. An allowance will be made for
upstream detention when such upstream detention and release rate
has previously been approved by the City and that evidence of its
construction can be shown.
(4) The live detention storage to be provided will be calculated on
the basis of the 100-year frequency rainfall as published by the
U.S. Weather Bureau for this area. The detention volume required
will be that necessary to handle the runoff of a 100-year rainfall,
for any and all durations, from the fully developed drainage area
tributary to the reservoir, less that volume discharged during that
same duration at the approved release rate.
Sample calculations reflecting the provisions hereof will be
furnished by the City Engineer upon request.
SECTION 14. BUILDING SITE
Each main building or structure shall have or be provided with a building site
or yard that is not lower than the established high-water elevation plus 2
feet and extends outside the building walls at least 5 feet. The finished
grade or surface of this yard shall be sloped to drain away from the walls for
a distance of at least 5 feet.
Such filling as may- be done on the flood plain to provide a building site or
for other purposes (which eliminates space previously available for storing
and moving of flood water) shall be compensated for or balanced by at least
an equal volume of excavation in the flood plain below high-water elevation.
In the case of streams and channels, such excavation shall be made opposite
or just upstream from the filled in area.
SECTION 15. EFFECTIVE DATE
This ordinance shall be in full force and effect from and after its passage,
approval, and publication as provided by law.
s/ W. E. Rauschenberger
Mayor of Elgin
Presented: August 23, 1972
Adopted: August 23, 1972
Vote: Yeas 6 Nays 0
Recorded: August 23, 1972
Attest:
A,
s/ Margaret A. Glink
Margaret A. Glink, City Clerk