HomeMy WebLinkAboutORDINANCES-2007-065-O-07• Effective dates July 26, 2007 6/19/2007
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AN ORDINANCE
Establishing Stormwater Control Regulations
WHEREAS, pursuant to 70 ILCS 2605, stormwater management
in Cook County is under the general supervision of the Metropolitan Water
Reclamation District of Greater Chicago; and
WHEREAS, pursuant to 70 ILCS 2605, the City may regulate
stormwater management and planning in a manner consistent with the plans,
rules, and ordinances adopted by the Metropolitan Water Reclamation District
of Greater Chicago; and
• WHEREAS, through stormwater regulation the City seeks to
reduce the damaging effects caused by the uncontrolled release of stormwater
runoff from developments that include impervious areas; and
WHEREAS, through stormwater regulation, the City seeks to
preserve the capacity and useful life of the City sewer system; and
WHEREAS, through stormwater regulation, the City seeks to
enhance the separation of stormwater runoff from wastewater; and
WHEREAS, through stormwater regulation, the City seeks to
reduce the frequency and severity of the discharge of pollutant -laden combined
stormwater runoff and wastewater into waterways; and
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WHEREAS, through stormwater regulation, 'the City seeks to •
recharge groundwater; and
WHEREAS, through stormwater regulation, the City seeks to
enhance and help protect the public health and safety.
NOW, THEREFORE, BE IT ORDAINED BY THE CITY COUNCIL
OF THE CITY OF EVANSTON, COOK COUNTY, ILLINOIS:
SECTION 1: That Title 4 of the City Code, as amended, is hereby
further amended by adding Chapter 24, Stormwater Control:
CHAPTER 24: STORMWATER CONTROL
24-1: DEFINITIONS, PURPOSES, OTHER AGENCY REQUIREMENTS:
24-1-1: DEFINITIONS:
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The followingterms are defined for the use of this Ordinance as follows:
ALLOWABLE RELEASE RATE: The rate of stormwater runoff that is allowed to
be discharged from a development site into the City Sewer System by means of
the control system.
APPLICANT: Person(s) or agent(s) representing a property owner who desires
to develop property in the City.
BULLETIN 70: A publication entitled "Frequency Distributions and Hydroclimatic
Characteristics of Heavy Rainstorms in Illinois," by Floyd A. Huff and James R.
Angel, as published by the Illinois State Water Survey, Champaign, Illinois, 1989.
�he magnitudes of rainfall events having storm durations of twenty-four (24)
hours and frequencies from two (2) to one -hundred (100) years are found in
Table 13 of said publication and are adopted by the City to be used by applicants
for calculations necessary for compliance with this Ordinance.hbl)
CITY SEWER SYSTEM: The networks of closed pipes, conduits, and drainage
structures within the City which consists of three operational parts - the Storm
Sewer System, which conveys stormwater only; the Combined Sewer System, is
conveys a combination of stormwater and wastewater; and the Relief
Combined Sewer System, which conveys stormwater during most ordinary
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• rainfall events, until the Combined Sewer System capacity is reached, at which
point the Combined Sewer System discharges into the Relief Combined
Sewer System.
CONTROL SYSTEM: Structures that contain restriction, backflow prevention,
storage and conveyance features that are necessary for the safe, efficient control
and discharge of detained stormwater runoff from the development into the City
Sewer System at a rate no greater than the allowable release rate, up to the
occurrence of the one hundred (100) -year frequency rainfall (twenty-four (24)
hour duration) event. ;This system should,[U] be located on the development
property, must meet the City's current construction standards, and must be fully
accessible to the City for inspection purposes and to the applicant for
maintenance purposes.ilbsl
DETAINED STORMWATER VOLUME: The volume of stormwater that is
tributary to the development site that exceeds the volume that is allowed to be
discharged into the City Sewer System at the allowable release rate. This
volume is calculated by the applicant and submitted to the Director for his review
and approval.ba] This volume accounts for rainfall that is infiltrated into the soil
by virtue of the permeability of the surface and subsurface materials. Also called
the "Stormwater Detention Volume."
• DETENTION: The temporary storage of stormwater runoff, typically in a closed
or open detention basin or retention basin, or in oversized storm sewer pipes,
followed by releasing the runoff gradually into an outlet waterway or the City
Sewer System. The discharge flow rate of stormwater exiting the detention area
is typically controlled by a control structure. Also called "Stormwater Detention."
For purposes of this Ordinance, the terminology "detention" shall mean either
detention or retention, as appropriate.
DETENTION BASIN: A facility located within the development site that is
designed to store stormwater runoff temporarily on, below, or above the ground
surface, accompanied by the controlled release of the stored stormwater runoff.
The limits of the detention basin are to be depicted on the final development
plans and designated thereon as the "detention basin" (or "retention basin,"
whichever is appropriate).kb5] Detention basins may be closed -type (concrete
vaults or oversized storm sewer pipes) or open -type (having grassed,
landscaped, bioengineered, or, when necessary to drain, paved bottoms). !All
detained stormwater must be drained from the detention basin by gravity, by
pumping, or by infiltration into the groundwater, effectively draining the storage
facility completely between rainfallevents Kb6j For purposes of this Ordinance, the
terminology "detention basin" shall mean either detention basin or retention basin
• or a combination of these, as appropriate.
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DEVELOPMENT: Any activity, excavation or fill, alteration, subdivision or •
resubdivision, change in land use, or practice including, without limitation,
redevelopment or rehabilitation. Development may be undertaken by private or
public entities or a combination thereof. Development does not include
maintenance of stormwater control facilities; the maintenance of existing
buildings; gardening or plowing that does not involve filling, grading, or the
construction of levees; or the resurfacing of existing paved roads, drives,
or parking lots.
DIRECTOR: Refers to the Director of the Public Works Department or his or
her designee.
DISCHARGE: The rate at which stormwater moves through an open channel or
closed pipe, usually measured in cubic feet per second.
DRAINAGE AREA: The surface area from which stormwater runoff originates
at a given point or location on a stream, waterway, or within pipes or channels,
usually measured in acres. Also called, "Tributary Drainage Area" or
"Tributary Area."
FLOOD FRINGE: That portion of the regulatory floodplain that is outside of
the regulatory floodway. •
IMPERVIOUS SURFACE: Natural or man-made materials through which water,
roots, or air cannot penetrate. This type of material prevents the movement of
surface water down to the water table.
INFILTRATION: The movement or passage of water into the soil from a surface
that is permeable. (Infiltration may be used as an alternative to the detention or
retention of stormwater runoff as a means to provide all or part of the required
detained stormwater volume. This is possible under natural or man-made
conditions in which deep, permeable layers of sandy soils or other materials with
voids are present.kb7]
ONE HUNDRED -YEAR FREQUENCY RAINFALL: A rainfall event that has a
one percent (1 %) probability of being equaled or exceeded in any given year. On
average, an event of this size or larger will occur once every one -hundred (100)
years. It is also called the "Design Storm." The magnitude of this rainfall amount
for a variety of frequencies and storm durations is found in Table 13 of
Bulletin 70.
OUTFALL/OUTLET: The point, location, or structure where stormwater runoff
discharges from a stormwater facility to a receiving body of water or into the City •
Sewer System.
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PERMEABLE: Having voids, pores, or openings through which liquids may pass.
PUBLIC WORKS STORMWATER CONTROL REGULATIONS: A document
published by the Evanston Public Works Department which outlines the
methodology for calculating the detained stormwater volume.
RECHARGE: Replenishment of groundwater reservoirs by infiltration through
permeable soils or other granular materials.
REGULATORY FLOODPLAIN: Lands that are adjacent to bodies of water (Lake
Michigan or the North Shore Channel in the City) and that may be inundated by
water up to the base flood elevation, as regulated by the Federal Emergency
Management Agency ("FEMA"). The floodplain is mapped by FEMA as part of
the National Flood Insurance Program. The floodplains within the City are
identified as Special Flood Hazard Areas ("SFHAs") on map no. 17031CO253F,
no. 17031 CO255F, no. 17031 CO260F, no. 17031 CO265F, and no. 17031 CO270,
which are part of the series of Flood Insurance Rate Maps ("FIRMs") for Cook
County, Illinois, having an effective date of November 6, 2000. Floodplains
consist of two parts - the floodway and the flood fringe.
• REGULATORY FLOODWAY: That portion of the regulatory floodplain that is
necessary for the conveyance of the base flood. The regulatory floodway is
depicted on the FEMA FIRM maps (see description for Regulatory
Floodplain above).
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RELEASE RATE: A rate of stormwater runoff that is being discharged from a
development site into the City Sewer System by means of the control structure,
measured in cubic feet per second.
RUNOFF/STORMWATER RUNOFF: Water which moves through the landscape
either as surface or subsurface flows. It originates from atmospheric precipitation
in the form of rain or snow and does not recharge the groundwater reservoirs.
WETLAND: An area that is inundated or saturated by surface water or
groundwater at a frequency and duration sufficient to support, and under normal
circumstances do support, a prevalence of vegetation typically adapted for life in
saturated soil conditions. The determination that an area is a wetland follows a
procedure that is outlined by the US Army Corps of Engineers ("USACE"). No
activity or development that will adversely impact a wetland is allowed by the
USACE unless a permit from that agency is granted.
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24-1-2: PURPOSES:
The purposes for this Ordinance are to (1) reduce the damaging effects caused
by the uncontrolled release of stormwater runoff from developments that include
impervious areas, (2) preserve the capacity and useful life of the City Sewer
System, (3) enhance the separation of stormwater runoff from wastewater,
(4) reduce the frequency and severity of the discharge of pollutant -laden
combined stormwater runoff and wastewater into waterways, (5) recharge
groundwater, (6) enhance and help protect the public health and safety, and
(7) be consistent with the Cook County Stormwater Management Plan, as
approved and the latest revision_ thereof.
24-1-3: OTHER AGENCY REQUIREMENTS:
All work related to this Ordinance shall be done in accordance with all other
federal, state, county, or regional agencies having jurisdiction, including, but not
limited to the US Army Corps of Engineers ("USAGE"), US Environmental
Protection Agency ("USEPA"), Illinois Department of Natural Resources ("IDNR"),
Illinois Environmental Protection Agency ("IEPA"), and Metropolitan Water
Reclamation District of Greater Chicago ("MWRD").
24-2: STORMWATER CONTROL REQUIREMENTS:
24-2-1: DEVELOPMENTS REQUIRING STORMWATER CONTROL:
All new developments shall provide stormwater control for the entire property.
Additionally, any developments (1) where the final building footprint is greater
than five -thousand square feet (5,000 sq.ft.), and (2) having construction costs
greater than one -hundred percent (100%) of the latest property value as
published by the Cook County Assessor's Office for the existing tax parcel(s)
affected by the development as of the effective date of this Ordinance shall
provide stormwater control for the entire property. This provision shall also apply
to staged developments or multiple independent developments for which the
aggregate construction costs exceed one -hundred percent (100%) of the
property value for the tax parcel(s) existing at the time of the initial development
after the effective date of this Ordinance. Stormwater control includes both
(1) the need to detain a certain stormwater volume, and (2) the need to control
the release rate of stormwater as it is discharged from the development site and
enters the City Sewer System.
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• 24-2-2: EXEMPT DEVELOPMENTS:
The following developments are exempt from the provisions of this Ordinance:
(A) Developments Prior to Ordinance. All developments that have
been submitted to the City's Plan Commission or Planning & Development
Committee, approved and permitted for construction, or are under construction
as of the effective date of this Ordinance. Such exempt developments must be in
compliance with the City's Department of Public Works "Administrative Policy
201, January 2000, Private and Public Development, Detention Requirements."
(B) Development of one-, two-, or three-family residential structures on
one or two adjacent parcels, provided that neither parcel is larger than one (1.0)
acre in area.
(C) Existing paved parking lots that are resurfaced, or milled and
resurfaced, where there is no change to existing drainage that increases runoff to
the City Sewer System. A paved parking lot is not exempt whenever parts or all
of the lot is redeveloped for a different use or a parking structure is constructed,
at which point stormwater control is required for the entire development, including
the parking lot.
• (D) Any new development for which the stormwater control
requirements under this Ordinance have been fully satisfied for the existing and
proposed development conditions based on installation of all required stormwater
control during a prior development, and the stormwater control facilities have
been maintained and are fully functional and operating. The applicant shall
demonstrate compliance with this Ordinance by submitting to the City's
Department of Public Works all calculations and documents in support of a
finding that no additional stormwater control facilities are required.
24-3: STORMWATER CONTROL FACILITIES:
24-3-1: GENERAL:
Control of the detained stormwater volume must be provided by facilities that are
entirely within the development property and are fully accessible for inspection by
the City. These facilities shall be designed to store the required detained
stormwater volume temporarily on, below, or above the ground surface in a
detention or retention basin, and to subsequently release the stored detained
stormwater volume at a rate no greater than the allowable release rate by means
of a restrictor within the control structure for final discharge into the City Sewer
• System. The stormwater control system shall be located such that (1) adjacent
properties are not impacted by stormwater from the development and (2) facilities
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are accessible to the City for inspection and accessible to the applicant for •
maintenance.
The stormwater control system must meet the City's current construction
standards for stormwater control structures having restriction, overflow, backflow
prevention, and inspection/maintenance capabilities.
24-3-2: CALCULATIONS:
The stormwater detention volume and the allowable release rate shall be
calculated using the methodology described in the Public Works Stormwater
Control Regulations available from the Public Works Department.
24-3-3: MEANS FOR STORING RUNOFF:
The storage of detained stormwater volume must be accomplished by any of the
following means:
(A) Open detention basin. The basin may be of any shape. The active
storage depth of the detention basin is a maximum of 2 feet, with an additional
one foot (1') freeboard. The basin must be landscaped, or have a bioengineered
surface. Side slopes must be no steeper than a four -to -one ratio (4:1) (four (4) •
horizontal to one (1) vertical), and the bottom slope must be one to two percent
(1 %-2%) to facilitate the complete drainage of all stormwater runoff into the
control structure by gravity, or by the use of pumps if a retention basin is
proposed. Inflow pipes to the open detention basin must carry only stormwater
runoff, and a backflow preventing device, such as a flap gate, must be installed
within a structure and must be provided on each inflow pipe to prevent basin
stormwater from flooding any development structures.
(B) Reinforced concrete pipe or ductile iron pipe storage, constructed
to the City's current construction standards.
(C) Reinforced concrete vaults, constructed in accordance with the
design by an Illinois licensed Structural Engineer.
(D) Parking lot surface storage, with the depth of stormwater storage
limited to six inches (6") or less.
(E) Rooftop storage, with the depth of stormwater limited to six inches
(6") or less, based on a determination by an Illinois licensed Structural Engineer
that the roof is structurally adequate to resist all loading, including the additional
water load (considered to be live load). •
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• (F) Infiltration of the detained stormwater volume, provided that the
applicant submits an engineered infiltration field design by an Illinois licensed
Professional Engineer. The design must include the calculations and supporting
documents necessary to demonstrate that the proposed infiltrated detained
stormwater volume meets the storage requirement.
(G) Other means or combination of means which the applicant may
use, subject to the approval by the Director prior to the issuance of all necessary
construction permits.
24-3-4: CONTROL SYSTEM:
(A) The control system must contain those restriction, backflow
prevention, storage and conveyance features that are necessary for the safe,
efficient control and discharge of detained stormwater volume from the
development into the City Sewer System at a rate no greater than the allowable
release rate, up to the occurrence of the one -hundred (100) -year frequency
rainfall (twenty-four (24) hour) event. This system must be located on the
development property unless waived by the Director, must meet the City's
current construction standards, and must be fully accessible to the City for
inspection purposes and to the applicant for maintenance purposes. The system
• shall contain adequate provisions for the emergency release of stormwater in
excess of the required storage volume or runoff rate that may be associated with
more extreme rainfall events or unforeseen debris or ice buildup within the
structure. The emergency release shall commence only after the required
detained stormwater volume has been stored on the development site. The
emergency release must discharge onto the development property. A backflow
preventing feature, such as a flap gate, shall also be provided such that no
stormwater or wastewater from the City Sewer System can flow back onto the
development site. The backflow preventing device shall be installed in a
structure located immediately outside of the structure containing the restrictor.
(B) Stormwater control systems shall not be located within any part of a
regulated floodplain, either the floodway or flood fringe, within the City, as
depicted on the FEMA FIRM map panels for Cook County, Illinois. Any work in
the floodplain or in wetlands requires the applicant to obtain all permits that may
be required from the USACE, USEPA, IDNR, IEPA, MWRD, and any other
federal, state, or regional agency as may be required. The applicant shall not
begin construction until the applicant has applied for and obtained these permits.
In the event that any of these permits include conditions that are more or less
stringent than the provisions of this Ordinance, the more stringent of the permit
conditions or ordinance provisions shall apply.
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24-3-5: CONNECTION TO CITY SEWER SYSTEM: •
The applicant is responsible for all construction and restoration work that is
needed within the public right-of-way to achieve the connection to the City Sewer
System. This work shall be performed in accordance with the City's current
construction standards.
Whenever more than one of the City's Sewer System components is adjacent
to, or in close proximity to the development, the applicant's stormwater control
system shall discharge detained stormwater into that component which is both
feasible and most advantageous to the City. Generally, but not always, the
Storm Sewer System is the most advantageous outlet, followed by the Relief
Combined Sewer System, followed by the least advantageous Combined
Sewer System. The use of a particular outlet City Sewer System component
may not be possible due to circumstances such as the presence of other
conflicting utilities or if the component is buried deep below the surface.
Applicants shall work with the City's Department of Public Works to ascertain
which one of the City Sewer System components shall be used as the outlet
from the development.
24-4: FEE IN LIEU OF STORMWATER CONTROL:
In the event that an applicant cannot physically provide all the necessary control •
of the required detained stormwater volume on the development property, the
applicant shall:
(A) Provide proof that is satisfactory to the Director that the
development site conditions limit his capacity to fully meet the detained
stormwater volume, and
(B) Provide stormwater control for that volume of detained stormwater
which the applicant is able to provide in accordance with the requirements of this
Chapter, and
(C) Pay a fee in lieu of providing the balance of the excess stormwater
control volume that the applicant cannot provide on site. The fee in lieu of
providing stormwater volume shall be initially set at twelve dollars ($12.00) per
cubic foot of required detained stormwater volume; however the total fee shall
not exceed five percent (5%) of the construction costs of the development. The
fee in lieu shall increase each January thereafter by the percent increase
indicated for the year ending in January by the United States Department of
Labor Bureau of Labor Statistics Consumer Price Index ("CPI") for the Chicago
metropolitan area (Chicago -Gary -Kenosha). The City will use this fee for any of •
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• the purposes served by this Ordinance that the Director deems suitable in
furthering the City's interest in providing for stormwater control.
24-5: CITY REVIEW AND INSPECTION:
24-5-1: CITY REVIEWS:
The Director shall review all elements of the stormwater control facilities, drawing
plans, sketches, details, calculations and any other evidence and supporting
documents that are submitted by the applicant for the proposed development.
The Director must review all developments, regardless of whether physical
stormwater control facilities or fees in -lieu of stormwater control facilities are
being requested by the applicant. The Director may meet with the applicant to
discuss the proposed stormwater facilities and/or prepare written review
comments regarding the applicant's submittal when the submittal has not
satisfied all appropriate provisions of this Ordinance. The applicant shall respond
to the Director's review comments and perform the necessary design changes,
then submit the revised submittal documents for further review by the Director.
This process of submittals, review, and revisions shall continue until all
provisions of this Ordinance are met to the satisfaction of the Director. The
applicant shall not receive a building permit for the proposed development until
• all provisions of this Chapter are met.
24-5-2: CITY INSPECTION DURING CONSTRUCTION:
The Director may inspect the applicant's stormwater control system during the
construction to ascertain whether the applicant is constructing or has constructed
the system in accordance with the approved plan. Any deficiencies in the
construction shall be corrected by the applicant at his expense, regardless of
when the Director determines that such deficiencies exist.
24-5-3: CERTIFICATE OF OCCUPANCY:
The stormwater control system must be installed and functioning before the
Certificate of Occupancy for the development will be issued.
24-5-4: MAINTENANCE:
The stormwater control system shall be maintained by the applicant or current
owner in a fully functioning and operating condition.
24-6: INSPECTION FEE:
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All developments that are required to provide stormwater control shall pay to the
City an initial inspection fee of one -hundred and fifty dollars ($150.00) and
thereafter, an annual inspection fee of one -hundred and fifty dollars ($150.00).
24-7: PENALTY:
If the Director determines that any stormwater control system required by this
Chapter does not comply with the provisions of this Chapter, the Director shall
notify the applicant or current owner in writing of such non-compliance. The
applicant or current owner shall have thirty (30) calendar days from the date of
receipt of such notice to comply with the provisions of this Chapter. If at the end
of the thirty (30) calendar days the applicant or current owner is not in
compliance with the provisions of this Chapter, a two -hundred and fifty dollars
($250.00) fine shall be imposed and the applicant or current owner shall have an
additional thirty (30) calendar days to comply. If at the end of the thirty (30)
additional days for compliance, the applicant or current owner is not in
compliance with the provisions of this Chapter, a fine of not less than two -
hundred and fifty dollars ($250.00) shall be imposed for each day thereafter in
which the applicant or current owner is not in compliance.
SECTION 2: That all ordinances or parts of ordinances in conflict
herewith are hereby repealed.
SECTION 3: That this Ordinance shall be in full force and effect
from and after its passage, approval, and publication in the manner provided by
law.
Introduced: 2� , 2007 Approved:
Adopted: , 2007) , 2007
Lorraine H. Morton, IVlayor
Attest: Applov as to form:
Mary o is ity Clerk C046oration Counsel
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