MIL-HDBK-1025/5
2.2.3.3
Nearby Water Area Structures
Structures in the water area outside the harbor entrance may
a)
cause shoaling, especially along shorelines where littoral transport is a
problem.
This type of structure tends to impound sediments.
Periodic maintenance operations at another harbor located up
b)
drift from the problem harbor may result in deposition of excessive sediment
transported downcoast toward it.
On rivers, any structure upstream or across from the harbor
c)
may alter the current flow and cause excessive shoaling at the harbor site.
2.2.3.4
Redistribution of Bottom Materials
Shifting of bottom materials in some water areas by natural
a)
processes such as wind waves within the water area, may cause redeposition of
these materials in navigation channel and harbor entrances. This will cause
the channel characteristics to continually change, requiring channel marking
with buoys, and redredging to maintain navigability.
Rivers meander from flood plain and delta aggradation. River
b)
flow continuously erodes material from concave bends where currents
concentrate. The material is then deposited on convex bars further downstream
where the current is slower. An investigation of local silting and
maintenance dredging operations should be done before design depth is
selected.
2.2.4
Geological Factors
2.2.4.1
Basin Excavation. Where berthing basins require excavation, obtain
characteristics of the subsurface below mudline (submarine soil types, their
degree of consolidation or firmness, and the depth of bedrock) to determine
the best method of their removal.
Foundations and Material Sources. Obtain geotechnical data and
2.2.4.2
information on suitable borrow pits for fill and construction materials,
nearby aggregate and quarry stone locations for jetties, breakwaters, and
revetments, and where channel or basin dredging is required, the adequacy of
dredged fines and sands for site fill requirements.
2.2.4.3
Seismic Activity. For earthquake-prone harbor sites, determine the
seismic-risk zone designated for the site. Use seismic-design criteria
applicable to that zone for design of berthing facilities and all structural
components.
(Refer to MIL-HDBK-1025/l, Piers and Wharves.)
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