15 August 2002
CRITERIA. This chapter presents data and information as criteria for the
construction of a drydock body, the entrance closure, supporting facilities and
accessories, and mechanical and electrical equipment.
Approach. Criteria for the drydock body are intended to guide the
designer by indicating basic construction problems encountered, depending on the type
of drydock chosen. They are also intended to assist in the preparation of construction
specifications as well as design drawings. References to construction of the drydock
body are based on the use of concrete. Phases of construction are presented in
chronological order of the work.
Clearing and Demolition. A site must be cleared of all interfering
structures above and below water. Dispose of removed material according to contract
requirements. Remove all objects that will interfere with excavation.
Rerouting Utility Lines. Essential mechanical and electrical services that
will be interrupted by construction work must be rerouted before demolition. Possible
extensions of the services to the new drydock, when completed, must be considered in
Excavation. Excavation is the first major step in the construction of a
drydock. It is necessary to make room for construction of the drydock body, and often
the removal of unsuitable foundation materials is required. Excavation may be done by
dredging or in the dry, depending on the type of material, method of dewatering, or
intention to construct the drydock by underwater methods. Dredging is generally the
most economical method.
Dredging. A Department of the Army, Corps of Engineers permit must be
obtained for dredging work in navigable waters and material disposal. Dredging may be
done by hydraulic methods, or mechanical methods such as clamshell bucket or
dragline. If soil is removed by hydraulic dredging, it may be piped to approved disposal
areas, to yard locations for fill, or to stockpiles for future use. If dredging is done by
clamshell or dragline, the removed soil must be barged to a disposal point.
Hydraulic dredging is not feasible for certain soils such as stiff clays or
those containing boulders or rock. Blasting may be necessary for very hard materials,
after which a clamshell or dragline is used for its removal. For additional information on
dredging operations, refer to UFC 4-150-06 Military Harbors and Coastal Facilities.
Water Removal. If water can be removed and kept excluded from a site
with reasonable effort, construct drydocks in the dry. This method affords the greatest
economies in material and the best quality of completed construction. The method of