ICS design recommendations
existing conditions. The project could thus affect
upstream property owners.
We recommend an ICS consisting of nine 5-ft-
diameter 10-ft-tall cylindrical piers spaced with 12-ft
Cazenovia Creek flows through a steep-walled val-
ley from East Aurora to Mill Road. There are few struc-
gaps to reduce ice-jam flood damages along Cazenovia
tures located within this valley that are vulnerable to
Creek. The ICS should be located at the same cross
flooding. Table 3 lists such structures from the ICS to
section as the original weir-with-pier ICS, and the top
Transit Road, the upstream limit of this analysis. Fig-
of the cylindrical piers should be at EL 644 ft.
ure 15 shows the topography of this reach. Most prop-
The design ice loads on each pier (at a cumulative-
erties that abut the creek do not have structures within
probability level of 99.9%) can act simultaneously and
the valley.
are as follows:
The objectives here are to determine the maximum
Md = 2.0 106 ft-lb (downstream overturning moment)
water level caused by the ICS for all locations upstream
Fx = 0.45 106 lb (downstream force)
and to determine the location beyond which the ICS
essentially has "no effect." We have taken this latter
Mx = 0.90 106 ft-lb (transverse overturning moment)
condition to be the location where the maximum water
Fy = 0.20 106 lb (transverse force).
level induced by the ICS is below the 100-year open-
water elevation under existing conditions. The infor-
Riprap, consisting of stone with D50 of about 2.0 ft,
mation sought here is needed to determine the real estate
should be installed along the right bank at least 150 ft
requirements (e.g., flow easements, buy-outs, flood
upstream and downstream of the ICS to prevent scour
protection) to construct the ICS. We used a numerical
and ice erosion. The top of the riprap should be at EL
icehydraulic model, with input from the physical
643 ft.
model, to determine upstream effects of the ICS.
Dry, select-grade 12-in.-diameter wooden posts
should be installed 6-ft on-center along the gaps in the
Ice breakup with ice-control structure
trees along the right bank near the ICS. These posts
The physical model tests indicated that the ICS will
should protrude 4 ft above the local top-of-bank eleva-
arrest a breakup ice run and retain the resulting ice jam
tions. Insofar as possible, existing trees on the flood-
to discharges exceeding 6000 cfs without catastrophic
plain should not be disturbed during construction.
ice releases (see Table 2). For the recommended ICS
(12-ft-gaps), 1-ft-thick ice of moderate strength should
start to wash out through the gaps at 70008000 cfs.
UPSTREAM EFFECTS
The ICS should retain stronger or thicker ice to higher
Upstream issues
discharges. For example, the 12-ft-gap ICS held 1.0-ft-
thick strong ice to 8600 cfs, even after we manually
The cylindrical-pier ICS will arrest ice arriving from
released ice at one of the gaps (test 21). Also, the 10-ft-
several miles upstream. It will retain the resulting ice
gap ICS held 1.1-ft-thick strong ice and 1.5-ft-thick
jam at discharges much higher than the maximum dis-
moderate-strength ice to 10,000 and 11,000 cfs, respec-
charge at which an ice jam would remain in the natural
tively, without major releases (tests 16 and 19). Smaller
channel. While this should significantly reduce ice-jam
floes did wash out slowly (through the ICS gaps and
flood damages downstream, water levels during ice
onto the floodplain) during all tests, reducing the ice
events will be higher upstream of the ICS than under
Table 3. Structures within the Cazenovia Creek valley from the
ICS site to Transit Road. Most properties that abut the creek do
not have structures within the valley.
Distance
Flood
upstream of elevation
Name
Description
ICS (miles) (ft-NGVD)
Kotecki Grove
Commercial, picnic areas
0.270.36
648650
Leydecker House
Single residence
1.1
660
Leydecker Road
Bridge
1.2
666
(low steel)
Winspear Subdivision
Several residences
1.82.0
672
Brady's House
Single residence
2.1
676
Upstream House
Single residence
2.2
676
12
TO CONTENTS
Previous Page
