visual surveys, taken between 1960 and
are qualitative and subjective,
both in time and between inspections. Repairs to the structures typically
involved adding new armor stone to damaged sections, usually returning the
structure to the original design geometry or to the existing geometry of
surrounding undamaged sections. Repairs or modifications, which include
adding a structure or lengthening an existing structure, have been made at 36
of the 52 projects. Of the 30 projects which have had structures repaired,
several of these could also be considered modified in terms of changes in
stone sizes, geometry, or shortening of a structure from its original or pre-
viously repaired condition. Where repairs have been fairly frequent, flatter
side slopes and/or larger stone sizes have been used to increase the struc-
tural stability. Localized damage and subsequent unraveling appear to be the
major problem areas concerning NED structures. Several structures have had
their landward ends sand tightened with additional stone placed along their
seaward side slopes. The following projects best illustrate repair histories
River, Kennebunk River, Isles of Shoals,
of structures within NED:
Hampton Harbor, Newburyport Harbor, Rockport Harbor, Gloucester Harbor, Green
Harbor, Cape Cod Canal, Nantucket Harbor, Hyannis Harbor, Sakonnet Harbor,
Point Judith, and Block Island.
6. None of the structures have been model tested for stone slope
stability. Hudson's equation and depth- or fetch-limited wave heights are
used in selecting armor stone sizes. Case histories of the project structures
are included in Tables 1-52. Pertinent summary information on each project i
s
presented in the following listing:
Project
Type
Armor
Date of
Location
Table
Type**
Length Origin Improvementt
1961
N
485
Eastport Harbor, Maine
725
N
S
Lubec Channel, Maine
19
81
3
N
S
400
Moosabec Bar, Maine
(Continued)
* Indicates type and number of structures: B-breakwater
indicates one
breakwater),
Indicates armor type: S-stone armor, C-concrete sheet pile or wall,
SSP-steel sheet pile, B-stone blocks.
N-none (no repairs or modifications since construction), R-repair,
M-modification.
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