Submerged Narrow-Crested Breakwaters
695
Figure 12. Average settlement after 33 months for the first 57 units and after 20 months for the remaining 273 units at the P.E.P. Reef installation at
Midtown Palm Beach (after Dean and Chen, 1996).
general sediment deficiency in the area. The remaining loss
with 11 modular adjustable groins placed perpendicular to
of sediment in the lee and downdrift to the south was a result
the shore. The groins used the P.E.P. Reef units as a core
of the trapping of water behind the reef with flow along the
covered with rock (ATM, 1996).
landward side of the reef to both the north and south direc-
AVALON, NEW JERSEY, PROJECT
tions with a predominant flow to the south. The measured
sediment volume change patterns and shoreline response
A Beachsaver Reef was constructed in the Atlantic Ocean
support this hypothesis.
at Avalon, NJ in July 1993, as part of the State of New Jersey
This installation was removed in 1995, as it was deemed
Pilot Reef Project (BRUNO et al., 1996a). The submerged con-
ineffective in reducing wave energy or retaining sand on the
crete artificial breakwater was connected to the end of the
beach. The ongoing erosion was mitigated by placement of
8th Street jetty, which is the south jetty for Townsends Inlet.
around 611,680 cu m (800,000 cu yd) of beach fill between
The Borough of Avalon occupies the northern half of Seven
DEP monuments R-95a and R-100a, which was stabilized
Mile Island, a barrier island along the southern New Jersey
Atlantic coast approximately 35 km (22 miles) south of At-
lantic City (Figure 13). Townsends Inlet is a downdrift offset
inlet separating Ludlam Island to the north and Seven Mile
Island to the south. The inlet is unstructured on the north,
but has an inlet shore-parallel timber bulkhead with a toe
rock revetment and three shore normal short rock groins to
stabilize the shoreline on south side of the inlet throat. The
inlet throat revetment extends seaward from the shore as a
small jetty (more apply called a terminal groin) located at the
seaward end of 8th Street on the north end of Avalon to sta-
bilize the highly dynamic shoreline adjacent to the inlet. This
area has long had a history of erosion, with the loss of be-
tween six and seven blocks of land area due to waves and
tidal currents since the community was established in 1892
(FARREL, 1995). Although the predominant drift is to the
south along this section of the New Jersey coast, a localized
northward drift is also active at the north end of Avalon, as-
sociated with wave refraction around the ebb shoal complex
of the inlet (HERRINGTON and BRUNO, 1998).
The inlet channel has historically migrated downdrift to
Figure 13. Location of the Beachsaver Reef installation at Avalon, New
the south, eroding the north end of Avalon. A beach nourish-
Jersey.
ment project on Sea Isle City, to the north on Ludlam Island
Journal of Coastal Research, Vol. 19, No. 3, 2003