CETN III-47
(3/92)
Since completion of construction, no repair work has been
necessary.
Current observations reveal that two stones have been
dislodged from the end of the Deal Lake groin.
This is a
successful record of service and depicts possible benefits to be
gained from using a properly designed and placed asphaltic
mixture for sealing.
Manasquan
Inlet. New Jersey, Jettv Rehabilitation:
Jetties at Manasguan Inlet, originally completed in 1931, were
constructed with stone and steel sheet-pile cores.
The jetties
had crest elevations of +14 ft mlw, were capped with 2-ton stone,
and extended to the -14 ft contour. Steel sheet-pile cores (el
+8 ft), which extended the entire lengths.of the jetties, were
very effective in preventing sediment movement through the
structures and into the navigation channel.
The jetties,
however, were repeatedly damaged by storms through the mid
1970's. As the structures deteriorated, the inner sheet-pile
cores developed large holes and severe corrosion, and became a
less effective sand barrier. Sediment began moving through the
jetty trunks directly into the navigation channel.
Rehabilitation of the jetties was accomplished between 1980 and
1 9 8 2 . The jetties were disassembled with the sand and dislodged
stone being excavated. The original sheet-pile core was left in
place, and 300-lb to three-ton core stone was placed to an el of
+8 ft. The core stone was overlaid with armor stone ranging from
5 to 12 tons, except for the outer ends of the jetties, where a
two layer system of randomly placed 16-ton reinforced dolosse was
used as primary armoring.
The rehabilitated core has provided an effective barrier with
respect to sand movement through the structures.
Prior to
rehabilitation, the channel was dredged every 1 1/2 years on the
average, and since project improvements (1982), no dredging has
been required (Gebert and Hemsley 1991).
Saco River, Maine, North Jettv Raising and Sealinq:
Jetty construction was initiated at the mouth of the Saco River
in 1866. The original structures were loosely built, low-crested
(+5.5 ft el mlw), and very porous.
Sand readily migrated through
the north jetty into the navigation channel after construction.
In 1989 the north jetty was widened and raised to +15 ft. It was
noted, that during storms, sediment continued to penetrate the
structure, resulting in sand in the navigation channel.
In 1968,
the shoreward 850 ft of the north jetty was raised to +17 f t . A
sealing blanket of 1 to 150-lb stone was first placed on the
seaward slope of the jetty and capped with a 0.5 to l-ton cover
stone, which was placed very tightly and resulted in a relatively
smooth surface.
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