should be done from just downstream of the usu-
bridge to about 1.25 miles upstream; and
al jam location to upstream of the jam location, so
About 1 mile downstream of the Highway
maps showing the probable maximum upstream
92 bridge to about 1.5 miles downstream of
and downstream ends of dusting should be pre-
the Highway 92 bridge.
pared and on file. Maps showing the proposed
These three sites were selected based on previous
1982 dusting sites are on file in the Hydraulics
jamming locations and on aerial reconnaissance
Section of U.S. Army Engineer District, Omaha.
flights on 5, 16 and 25 February. A brief warm-up
2) Identify dusting material, availability and suit-
in mid-February broke up the lower Elkhorn Riv-
ability. There are many suitable materials avail-
er ice and cleared most of the Platte below the
able for dusting, but not all may be available as
Elkhorn. However, the river remained mostly ice-
needed on short notice. A ready source of dusting
covered above the Elkhorn, and the ice showed
material should be identified. Dry material works
few signs of deterioration at that time. By the end
best, so it is important that a means of drying the
of February, river-ice thickness still exceeded 2 ft
material be secured if necessary. The selected
along Union Dike.
source of material should be contacted every year
A decision to dust was made on 28 February,
to assure that the required material can be deliv-
and plans were finalized by 2 March. A rapid
ered if needed. Alternate materials should be iden-
warm-up began on 1 March and continued for
tified ahead of time in case the selected material is
several days. The ice began to rapidly deteriorate
unexpectedly unavailable or is designated as en-
with the warmup as the remaining snow cover
vironmentally unacceptable.
melted and began to crack following completion
3) Identify needed equipment. Equipment needs
of the dusting operation. The dusting operation
and availability should be identified ahead of time.
used material from the same source as in 1979.
This includes airplanes or helicopters equipped
Three aircraft were used to apply the material.
for dusting, a means of conveying the dusting
Larger pieces of material applied after noon on 3
material into the aircraft holding bay, and a means
March were observed to have penetrated the ice
of marking the dusting strips. An airport that is
surface by as much as 4 inches by 5:00 p.m. the
central to the dusting sites should be identified as
same day. Smaller particles did not penetrate as
a base of operations, and permission to use the
rapidly but made up the bulk of the material ap-
airport should also be secured.
plied. The dusted strips showed significant de-
4) Estimate the cost of planned dusting operations.
cay, but the surrounding ice deteriorated rapidly
Unit costs of materials and equipment should be
as well. The Platte River above the Elkhorn began
periodically verified and updated if necessary.
breaking up on 6 March with increasing flows,
Table 20 is designed to be used to assist in esti-
and no ice jams were reported in the areas dusted,
mating operation costs. It is also helpful for iden-
although an ice jam causing minor overbank flows
tifying areas where dusting efforts can be cut back
was reported about one mile upstream of the up-
if funding is limited.
permost dusting site.* No damage was reported.
5) Secure any applicable permits prior to the opera-
tion. Permit requirements will vary state by state
Blasting as a
but will generally include some review by local,
mitigation alternative
state and Federal environmental agencies. USAED,
Blasting should be considered only as a last
Omaha (1994) provided a complete discussion on
alternative to ice-jam removal because of cost and
potentially applicable Federal regulations. In this
safety reasons. Explosives have been widely used
case the Nebraska Department of Environmental
in ice and ice-jam removal in many countries, with
Quality determined that the planned 1994 dust-
widely varying results. Explosives used in the past
ing would have no significant environmental im-
have included TNT, dynamite, C-4, C-3, tetrytol,
pact and did not require a permit.
ammonium nitratefuel oil (ANFO), ammonite,
black powder, thermite and even bombs and rock-
Summary of 1994 ice dusting
ets. The relative effectiveness of various explo-
Three locations on the Platte River were dust-
sives varies. Often the explosive used has been
ed on 3 and 4 March 1994. The locations dusted
were:
From Highway 64 bridge to about 3 miles
* Information from DATACOL (now called HYDRO-
upstream;
MET), the daily output of the NWS River Forecast Cen-
Both channels upstream of the Highway 92
ter and Pleasant Hills, Kansas.
45
Previous Page
