HomeMy WebLinkAboutORDINANCES-2000-093-O-00• 08/15/2000
10/5/2000
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AN ORDINANCE
Revising Title 4, Chapter 16, The Ordinance
Regulating Development in Special Floodplain Areas
NOW, THEREFORE, BE IT ORDAINED BY THE CITY COUNCIL OF THE CITY OF
EVANSTON, COOK COUNTY, ILLINOIS:
SECTION 1: That Section 4-16-2 of the Evanston City Code of 1979, as amended,
is hereby further amended, by deleting the definition of "Regulatory Floodway", adding, in
appropriate alphabetical order, the definition of "Designated Floodway" and by amending
• the definition of "Floodplain", to read as follows:
SECTION 4-16-2: DEFINITIONS
"Designated Floodway" -
a. The channel, including on -stream lakes, and that portion of the
floodplain adjacent to a stream or watercourse, as designated
by Illinois Department of Natural Resources/Office of Water
Resources (IDNR/OWR), which is needed to store and convey
the existing 100-year frequency flood discharge with no more
than a one -tenth foot (0.1') increase in stage due to the loss of
flood conveyance or storage, and no more than a ten percent
(10%) increase in velocities.
b. The floodways are designated for the North Shore Channel
and Lake Michigan on the following map number 17031 C and
panels 0253F, 0255F, 0260F, 0265F, and 0270F all dated
November 6, 2000, of the countywide Flood Insurance Rate
Map for Cook County prepared by the Federal Emergency
Management Agency and for the North Shore Channel and
• Lake Michigan on the Regulatory Floodplain Map prepared by
Illinois Department of Natural Resources/Office of Water
Resources and dated November 6, 2000. When two floodway
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maps exist for a waterway, the more restrictive floodway limit
shall prevail.
C. To locate the designated floodway boundary on any site, the
designated floodway boundary should be scaled off the
designated floodway map and located on a site plan using
reference marks common to both maps. Where interpretation
is needed to determine the exact location of the designated
floodway boundary, IDNR/OWR should be contacted for the
interpretation.
"Floodplain" — That land typically adjacent to a body of water with
ground surface elevations at or below the base flood or the 100-year
frequency flood elevation. Flood plains may also include detached
special flood hazard areas, ponding areas, etc. The flood plain is also
known as the special flood hazard area ("SFHA"). The floodplains are
those lands within the jurisdiction of the City that are subject to
inundation by the base flood or 100-year frequency flood. The
SFHA's of the City are generally identified as such on the following
map number 17031 C and panels 0253F, 0255F, 0260F, 0265F, and •
0270F all dated November 6, 2000, of the countywide Flood
Insurance Rate Map for Cook County prepared by the Federal
Emergency Management Agency.
SECTION 2: That Section 4-16-5-1 of the Evanston City Code of 1979, as
amended, is hereby further amended, to read as follows:
4-16-5-1: BASE FLOOD ELEVATION, A ZONE:
The floodplains are those lands within the jurisdiction of the City that
are subject to inundation by the base flood or 100-year frequency
flood. The SFHA's of the City are generally identified as such on the
following map number 17031 C and panels 0253F, 0255F, 0260F,
0265F, and 0270F all dated November 6, 2000, of the countywide
Flood Insurance Rate Map for Cook County prepared by the Federal
Emergency Management Agency. When no base flood or 100-year
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-11, 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-1, TR-20, or HIP, or •
by techniques presented in various publications prepared by the
United States Geological Survey for estimating peak flood discharges.
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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 analysis shall be submitted to DWR for approval;
once approved, it must be submitted to the Illinois State Water Survey
Flood Plain Information Repository for filing. For a nonriverine SFHA,
the base flood elevation shall be the historic flood of record plus three
feet (T), unless calculated by a detailed engineering study and
approved by the Illinois State Water Survey.
SECTION 3: That all ordinances or parts of ordinances in conflict herewith are
hereby repealed.
SECTION 4: That this ordinance shall be in full force and effect upon passage and
approval.
Introduced: i _ ( ;--'- , 2000
Adopted:. ' ) 2000
ATTEST:
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=�j
n Counsel
IL
Approv d:
ayor
t: , 2000
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