UFC 4-150-06
12 December 2001
Table 5-6 Required Clearances
LOCATION
SOFT BOTTOM
HARD BOTTOM
CATEGORY
1. Outer channel
0.9 m (3.0 ft) for 15.24m (50 ft)
1.22 m (4.0 ft) for <
depth
15.85 m (52 ft) depth
1.34 m (4.4 ft) for 16.46 m (54
ft) depth
1.68 m (5.5 ft) for >
17.68 m (58 ft) depth
1.68 m (5.5 ft) for > 17.68 m (58
ft) depth
2. Special berths
1.82 m (6 ft) (min.) coupled with
6 ft. (min.) coupled
discharge diffusers
with discharge
diffusers
5-6.1.6.6
Determine the contract depth by adding the advanced maintenance
dredging requirement to the design depth requirement. The advanced maintenance
dredging is the additional depth to reduce life-cycle maintenance costs by decreasing
the frequency of dredging. Base the quantity on the anticipated local channel
sedimentation rates corresponding to the anticipated dredging cycle. Use a dredging
frequency of not less than 3 yr., but based on local conditions. Include a minimum of 1
ft advanced maintenance dredging to prevent contractor change orders for differing site
conditions on future maintenance dredging contracts. This minimum also provides the
Contracting Officer field flexibility if the contractor does not achieve the contract depth
in spot locations. The dredging tolerance, or overdredge, is the additional depth below
the contract depth paid for by the dredging contract. The contract permits this
additional depth because of inaccuracies in the dredging process. It is normally either
+1 or +2 feet. Local conditions and anticipated dredging equipment may warrant a
different value. NAVFAC Textbook DM 38.2, "Dredging Equipment" provides additional
information.
5-6.1.6.7
Determine the permitted depth by adding the dredging tolerance, or
overdredge, to the contract depth. Material samples for environmental testing should
be accomplished at least to this depth.
5-6.1.6.8
OPNAVINST 11010.20E, Part 5 designates responsibilities of the Chief of
Naval Operations, Lead Activities, Shore Activities having assigned water areas, Public
Works Centers and Public Works Lead Activities, Naval Facilities Engineering
Command and Engineering Field Divisions, and Major Claimants regarding dredging
coordination.
Lead Activities and Shore Activities having assigned water areas
determine dredge depth requirements for Nimitz class aircraft carriers
following procedures contained herein.
5-36
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