12 December 2001
HARBOR AND COASTAL MAINTENANCE
INTRODUCTION. After a navigation project has been designed and
constructed, operation and maintenance are required to sustain safe and efficient use
of the project. Operation and maintenance requirements and costs can be substantial.
They are typically estimated with care and optimized against initial construction costs in
planning and designing a navigation project. Anticipated maintenance costs are based
on predictions of physical changes after the project is constructed.
A completed navigation project must be monitored to insure safe
operation and to plan for maintenance activities as needed; see CEM Section V-2-1-q.
Monitoring typically includes hydrographic surveys, beach profile surveys, tide and wave
data collection, and navigation structure condition surveys. Surveys are typically done
on a planned schedule, such as annually, and before and after periods of maintenance
and repair. Surveys should be analyzed comparatively to determine rates of erosion,
shoaling, and structure deterioration. The recommended source for information on this
subject is CEM Section V-4-3.
HARBOR AND CHANNEL SEDIMENTATION AND MAINTENANCE.
Often periodic dredging to maintain project depths is the major maintenance need
(CEM, Appendix VII-4). Maintenance dredging intervals are dependent on factors such
as shoaling rate, dredge availability, and dredge mobilization costs. Typical
maintenance intervals are on the order of 1-3 years at some projects. However,
environmental forces impacting a navigation project are highly variable. The number
and intensity of storms affecting a project each year can only be predicted in terms of
probabilities. Maintenance needs are often strongly influenced by storm events. A
single severe storm can cause major shoaling and structure damage. Consequently,
monitoring and maintenance activities may occasionally need to respond quickly to
maintain project integrity. See CEM Section V-4-3 for further information.
Navigation Aids. Information on Navigation Aids can be found in the
Code of Federal Regulations: 33 CFR Part 62 and 33 CFR Part 209.325.
INSPECTION AND REPAIR OF MARINE IMPROVEMENTS. The
recommended source for information on this topic is the "ASCE Standard for Shore
Protection Systems - Draft," August 20, 1997.
Revetments. The recommended source for information on this topic is
the "ASCE Standard for Shore Protection Systems - Draft" (ASCE, 1997).
Beach Nourishment. The recommended sources for information on this
topic are the CEM Chapter V-3-3-a(1) and "ASCE Standard for Shore Protection
Systems Draft," August 20, 1997.