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VALUE STUDY - DISPOSITION OF IDEAS
PROJECT: Chicago Ditch Dam Rehabilitation
VALUE STUDY ELEMENTS CONSIDERED AS POTENTIAL PROPOSALS AND THEIR DISPOSITION
IDEA
DISPOSITION
32
Clarify the 404 permit requirements and
Environmental Assessment activities
required.
According to the Fish and Wildlife
Service, this had not been considered
in the time allotted for the project.
Permits may add a three to six months
time to project schedules.
Improve the site-specific hydraulic and
hydrology knowledge the site.
Recommended as an "Additional Idea for
Further Consideration."
Coordinate with the "HYDROSPHERE" study
Concept was researched by the study
team and is addressed in the various
proposals.
Use a prisoner work programs to clean
debris from areas affected.
This was not considered a practical
solution to clean the debris. Also, it
may be costly.
Take out water at a low level intake
area so as to reduce the amount of
debris drawn to the structure.
It was determined that there was not
enough water depth at this site to
make this a useful option.
Realign intake channel to reduce
sediment and debris attraction.
The worth of this idea was outweighed
by the cost.
Rechannel the Rio Grande to achieve a
higher head at the intake area.
The worth of this idea was outweighed
by the cost.
Use weir or slide gates in place of
radial gates.
The various gates were assessed by the
team in evaluation of the proposals.
The added worth of the radial gate was
determined to justify its added cost
through an incremental worth versus
incremental cost analysis.
Use concrete debris in place of riprap
to prevent erosion around the dam
structure.
In this environment, concrete is not
as durable as riprap. The idea was
dropped from further consideration.
Avoid the debris by diverting the water
into the Ditch by use of a siphon.
The worth of this idea was outweighed
by the cost. The water has suspended
sediment, the depth of entry is small,
danger to public too great, etcetera.
Use the water from the closed basin
exclusively to meet mission objectives.
This was considered outside the scope
of the project review. Further, the
amount of water, the cost of obtaining
additional rights, the long recovery
period, and other features made
examination of this idea unattractive.