National Erosion Control Development and Demonstration
Program (Section 227)
Cape May Point, N.J.
Description
Cape May Point, New Jersey, is a 1.7- km (1.1-mile) beachfront community vulnerable to
beach erosion and storm damage. Existing shore protection structures include a series of
nine groins and a rubble revetment armoring the shoreline in the easternmost groin cell
constructed in the 1950's, and two concrete prefabricated breakwaters called Beachsaver
ReefsTM that were installed in groin cells 2 and 3 in 1994 as part of an experimental State
of New Jersey Pilot Reef Project. Beach-fill material was placed in groin cells 3 and 4 in
2000 to mitigate for dune erosion. The present demonstration project consists of the con-
struction of an additional Beachsaver ReefTM in cell 5 with an improved geotextile cloth
base to prevent settling and an innovative inverted prefabricated concrete parking garage
floor called a Double-T sill in cell 6. Additional beach nourishment material was placed
later. The project goal is to create a perched beach and maintain sand within the two groin
cells using the prefabricated structures. These two low-cost structures will be evaluated to
assess their ability to retain beach sand, maintain their structural integrity and save money
by reducing the renourish-
ment interval after the
beach fill is placed.
Issue
The shoreline of Cape
May Point is vulnerable to
storm damage through
wave attack, erosion, and
inundation. This unstable
shoreline necessitated
repeated local action in the
form of construction and
rehabilitation of nine
groins, dune
construction, seawall
fortification, and some
beach nourishment since Prefabricated concrete Beechsaver ReefTM is installed
the 1930's. These actions
have made much of the shoreline relatively stable, fluctuating between periods of erosion
and accretion. The extensive man-made dune system that has been developed over the
years along the western portion of Cape May Point has been particularly effective in
providing shore protection for that area. However, while these efforts have for the most
part "held-the-line" in most shoreline sections with regard to erosion, that "line" is at a
critical position. There is virtually no beach in front of the dunes to act as a buffer to deal
with forces due to storm events, which can severely damage the area and also contribute to
the saltwater intrusion to Lower Cape May Meadows.
Technology
The Beachsaver Reef is a reinforced prefabricated concrete breakwater. The breakwater is
narrow-crested due to its triangular shape, with the smallest dimension at the crest width.
Each unit is 1.8 m (6 ft) high, 3 m (10 ft) long and 4.5 m (15 ft) wide, with a crest width of
0.45 m (1.5 ft), and weight of around 186,825.3 N (21 tons). The units interlock with each
U.S. Army Engineer Research and Development Center
May 2005
www.erdc.usace.army.mil
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