G-930 - 07/13/2010 - STORMWATER - Ordinances Supporting DocumentsITEM 6.G.2)
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AGENDA ITEM
Regular Board of Trustees Meeting
of
July 13, 2010
SUBJECT: Revision to Title 9 of the Code: Stormwater, Floodplain, and Sedimentation and
Erosion Control Regulations
FROM: Philip Laures, E.I., Civil Engineer I PL
BUDGET SOURCE/BUDGET IMPACT: N/A
RECOMMENDED MOTION: That the Village Board approve the attached Ordinance G-
930 amending Chapter 5 of Title 9 ( "Stormwater, Floodplain, and Sedimentation and
Erosion Control Regulations ") of the Village Code of the Village of Oak Brook.
Backeround/History:
Through discussions with DuPage County and The Oak Brook Area Chamber of Commerce, a
stormwater exemption pertaining to re- development of commercial properties was brought to our
attention. The DuPage County Board has previously approved this revision/exemption to the
DuPage County Countywide Stormwater and Flood Plain Ordinance. As a full- waiver
community (i.e. we enforce the Stormwater Ordinances instead of DuPage County), Oak Brook
enforces the County standards and our Title 9 Ordinance mirrors the County Ordinance except in
those areas where we are more restrictive. Therefore, it is appropriate to incorporate these
DuPage County revisions into our Code, since it will provide benefits to promote commercial re-
development.
The revisions pertain to the requirements for detention on commercial parcels, more specifically
lowering the requirements for parcels with an existing eighty percent (80 %) impervious
coverage. If that criterion is met, then the redeveloped parcel will only need to design and
provide detention for the 2 year rainfall event rather than the 100 year rainfall event. This will
ease the re- development of certain commercial properties such as Oakbrook Center and some
Enterprise Drive parcels by allowing them to meet detention requirements when providing
detention for the entire 100 year rainfall event is not practicable and cost prohibitive given the
use and size of the lots.
Last saved by administmtorJ: \Utten\Agenda \Title 9 rev Cty 7- 13- 10.doc
Last printed 7/8/2010 8:50 AM
This ordinance can be used in the marketing of these lots to potential commercial clients looking
to move into town or existing owners to improve their sites. Using GIS data a list of sites that
would apply for this exemption has already been compiled and will be available to the
commercial community if the ordinance revision is passed.
Recommendation:
That the Village Board approve the Ordinance.
Last saved by administratorJ: \Letters\Agenda \Title 9 rev Cry 7- 13- 10.doc
Last printed 7/8/2010 8:50 AM
ORDINANCE 2010- SWM -RR -G -930
AN ORDINANCE AMENDING CHAPTER 5 OF TITLE 9
( "STORMWATER, FLOODPLAIN AND SEDIMENTATION
AND EROSION CONTROL REGULATIONS ")
OF THE VILLAGE CODE OF THE VILLAGE OF OAK BROOK
WHEREAS, the Village of Oak Brook is located almost entirely within DuPage County, which
adopted a Countywide Stormwater and Floodplain Ordinance, (the "County Ordinance ") on September 24,
1991, in accordance with Illinois Compiled Statutes, Chapter 34, paragraph 5 -1062; and
WHEREAS, on February 11, 1992, the Village of Oak Brook passed and approved "An Ordinance
Adopting Various Provisions of the DuPage County Countywide Stormwater and Floodplain Ordinance"
(Ordinance S -728); and
WHEREAS, on March 24, 1992, the County designated the Village of Oak Brook as a complete
waiver community for the enforcement of the County Ordinance; and
WHEREAS, the Village of Oak Brook, as a complete waiver community, is required to adopt
certain standards contained within the current County Ordinance as the minimum standards effective
within its territorial jurisdiction although it may impose higher standards; and
WHEREAS, the Village has from time to time amended its stormwater and floodplain regulations
to conform with changes made by the County to the County Ordinance; and
WHEREAS, on March 8, 2005, the DuPage County Board approved certain revisions to the
County Ordinance; and
WHEREAS, it is in the best interests of the Village of Oak Brook that Title 9 be amended to
incorporate the revisions to the County Ordinance as set forth below.
NOW, THEREFORE, BE IT ORDAINED BY THE PRESIDENT AND BOARD OF TRUSTEES OF
THE VILLAGE OF OAK BROOK, DU PAGE AND COOK COUNTIES, ILLINOIS, as follows:
Section 1: That the provisions of the preamble hereinabove set forth are hereby adopted as
though fully set forth herein.
Section 2: That Section 9 -5 -1C. ( "General Information ") of Title 9 ( "Stormwater, Floodplain, and
Sedimentation and Erosion Control Regulations ") of the Village Code be amended with the addition of the
following language:
9. The development is greater than one acre and the existing parcel(s) is greater than
eighty percent (80 %) impervious on March 8, 2005, in which the following specific
requirements are met:
a. Where there are no known off -site flooding problems that the development is
contributory to, sufficient site runoff storage shall be provided in pervious
(vegetative) areas such that the probability of the post development release
rate exceeding 0.04 cfs /acre of development shall be less than fifty percent
(50 %) per year (2 -yr event), unless the applicant demonstrates to the
Administrator why this criteria can't be met and the following specific
requirements are met:
Ordinance 2010- SWM -RR -G -930
Amending Chapter 5
of Title 9 of the Village Code
Page 2 of 3
(1) Where detention storage is provided in impervious areas (i.e.
underground tanks, parking lots, etc.) best management practices as
described in Section 9 -5 -3L of this Ordinance shall be required and
the applicant shall demonstrate that these practices are appropriate
and effective for the site conditions.
(2) Where the required site runoff storage cannot be provided on -site,
the shorted storage shall be provided off -site or by payment into an
approved detention variance fee program as determined in Section 9-
5-5 of this Ordinance.
b. The required storage in Section 9- 5 -1C9a is required for the total project,
regardless of phasing.
c. Site runoff storage facilities shall meet the requirements of Section 9 -5 -4 of
this Ordinance.
d. Where there are known off -site flooding problems, the Administrator may
require additional site runoff storage, best management practices or other
measures to reduce the flood potential.
e. The post development site runoff storage shall not be less than the existing
site runoff storage.
f. There shall be no increase in peak release rates up to and including the one
percent probability of occurrence (100 -yr) per year.
g. Additions to an existing site that increase the imperviousness above the
eighty (80 %) threshold are subject to providing the full storage such that the
probability of the release rate exceeding 0.1 cfs /acre of new development is
less than one percent (1.0 %) per year, providing the new development is
greater than 25,000 square feet.
h. Approved Stormwater plans or permits that contain more stringent criteria
than Section 9 -5 -1 C9 will apply.
Section 3: That this ordinance shall be in full force and effect from and after its passage, approval
and publication in pamphlet form in the manner provided by law.
Section 4: That all ordinances or parts thereof in conflict with the provisions of this ordinance are
hereby repealed to the extent of such conflict.
APPROVED THIS 13th day of June, 2010.
PASSED THIS 13"' day of June, 2010.
Ayes:
John W. Craig
Village President
Ordinance 2010 -SW M -RR -G -930
Amending Chapter 5
of Title 9 of the Village Code
Page 3 of 3
ATTEST:
Charlotte K. Pruss
Village Clerk
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