ETL 111 O-2-546
30 Sep 95
economic and hydraulic performance
erosion, rutting, etc. is not certain, planned
characteristics. To facilitate the risk-based
maintenance is designed to take place on an
analysis for project sizing, an implicit
as needed basis. Therefore, routine inclusion
assumption embedded in that guidance is that
of adjustments to levee heights due to
all other parameters are known with
account for lack of maintenance should not
certainty.
be included. In the future, reliability analysis
should allow more realistic estimates of
recurring maintenance requirements. In
5. Policy and Procedures for Establishing
the Final Top of Levee Grade.
addition, probabilistic life cycle analysis,
similar to that conducted for major
The risk-based analysis directly accounts for
rehabilitation, will allow explicit tradeoffs
the hydraulic uncertainties set forth in
between the costs of design that require less
paragraph
1) and establishes a nominal
maintenance, but cost more to construct, and
top of protection. Geotechnical engineers
the future costs of maintenance.
will perform deterministic analyses using
physical properties of the foundation and
7. Action. The design and evaluation of
embankment materials to set the top of levee
levees should be accomplished in accordance
to account for the following factors:
with the provisions in this ETL. Full
coordination between hydraulic and
a. Settlement the foundation and
geotechnical engineers is required in order to
embankment, embankment shrinkage,
properly set the final levee grade.
cracking, and geologic subsidence.
FOR THE DIRECTOR OF CIVIL WORKS:
b. Construction tolerances.
6. Planned Maintenance of Levee Height.
a. Erosion, rutting and other factors may
J.
P.E.
reduce the top of protection of levees during
Acting Chief, Engineering Division
the service life. The Operation,
Directorate of Civil Works
Maintenance, Repair, Replacement and
Rehabilitation Manual for the project should
contain provisions for surveying and
maintaining the top of protection used in
estimating the project's economic and
engineering performance. The project NED
cost estimate must include future
maintenance to counteract decrease in levee
b. Although the timing and amount of
2
Previous Page
