FLOOD03848

• County: Denver
• County: Jefferson
• Community: Denver County
• Stream Name: South Platte River
• Basin: South Platte
• Title: Stream Stability Investigation South Platte River
• Date: 11/1/1983
• Prepared For: UDFCD Denver
• Prepared By: Michael Stevens
• Floodplain - Doc Type: Floodplain Report/Masterplan

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9. Monitor the stabilized reache~ after construction to ensure that
the armor coat, bank protection, and levees are performing as
designed. When maintenance 1s required, do it immediately. The
damage usually increases with time so procrastination (for whatever
reason) can be very costly. Most maintenance funds will be needed
'1nmedhtely after large floods.
The above program is a staged One extending over a long period of
time. There is no one construction period 1n which al' river work is done
1naveryshortperiodoftl~. The Corps ofE:ngfneers' changes to the
reach of the South Platte River between Columbine Valley and West Oxford
Avenue is an example of the latter. The program proposed herein calls for
the expenditure of construction funds only as they are needed. Such staged
construction is less expensive than the other for two reasons. Firstly,
less construction is necessary as the river forces are employed to do part
of the work. Secondly, there is less "interest.on.rroney" cost for
staged construction whereas the benefits are the same in both cases.
In those subreaches where it is not feasible for political, tech.
nical, economic or environmental reasons to follow the above plan, one can
revert to constructing drops on the bed of the river to arrest the degrada.
tion. The drops should be low, causing no appreciable backwater effect
. upstream. The drops should be COnstructed after it has been detennined that
the river will not armor itself. The distance between drops will depend on
.the size of bed material in the subreach.

In those subreaches where it is not feasible to obtain the desired
alfgment, the river can be stabilized by protecting both banks. DegradatiOn
can be controlled by using cobbles or drop structures to stabiliZe the
crossings which control the riverbed profile.
Gravel mining can be incorporated into the proposed program of
development in these ways:
1. Mining can be used to move the river into the desired alignment.
2. Carefully controlled ane! selective mining of the channel bed can be
used to speed up the degradation process if that is desired.
3. Mining on the f1oodp1aln on the inside of bends can be continued.
'if there is no threat for creating river instability problems.
Unwanted sediment is being deposited in the upstream flood control
reservoirs. Much of this sediment has been segregated into various sizes
as it ent~rs the reservoir. Mining these new deposits would have two bene.
fits. First, loss of reservoir capacity would be reduced. Secondly, th",
mined gravel has a market value.
In the program proposed above, the need to combine political
realities wfthin the framework of sound river engineering is addressed. Ir.
addition, the need to gather numerous samples of material from beneath the
bed of the river is avoided as well as many degradation calculations of

questionable value.
produce an enhanced
area to enjoy.

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The program is flexible and cost effective and will
riverine environment for the people of the Denver urban

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