HomeMy WebLinkAboutORDINANCES-2000-133-O-00•
12/5/00
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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 revising the definition of "Regulatory Floodway", to read as
follows:
Section 4-6-2: 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, and 0270F all dated November 6, 2000, of the
countywide Flood Insurance Rate Map for Cook county prepared by
the Federal Emergency Management Agency.
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.
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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
S€-#A's base flood elevations of the City are generally identified ac
en the felle-wing map , ?�`\F, 9260 =,
A27OF� delineated on the 100-vear flood orofiles and dated November
6, 2000, of the countywide Flood Insurance Rate Map Study for Cook
County prepared by the Federal Emergency 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. 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 (3'), unless calculated by a detailed engineering study
and approved by the Illinois State Water Survey.
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 upon passage,
approval, and publication in the manner provided by law.
Introduced: eJ'J'_%%'��'�- {� , 2000
Adopted: %- .=-r'" —' �_ f { , 2000
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ATTEST:
(V# Clerk
A rov t rm: l
n r_
,`�r ��bu� el
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Approved: '� ��1� ��-� , 2 0
IV,
Mayor
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