CETN-II-36
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HISTORY
Construction of the P.E.P. reef began with the placement of 56 units by mid-August 1992. O n
August 24, 1992, the area was impacted by Hurricane Andrew. Following the passage of Andrew,
the 57th unit was placed and the area was surveyed. This survey determined that the reef had
exceeded the limits of settlement expectations, and further installation of the units was postponed
while the settlement issue and P.E.P. reef performance criteria were analyzed. Further monitoring
over a 4-month period indicated that additional settlement was minimal, and the reef units appeared
to be approaching an equilibrium depth. In May 1993 construction resumed, and in August 1993
placement of 273 additional units was completed.
MONITORING
A monitoring program has been under way since completion of the P.E.P. reef installation. The
University of Florida's Department of Coastal and Oceanographic Engineering has performed
physical monitoring of the project and has produced several reports (University of Florida 1994a,
1994b). A four-month monitoring report on the P.E.P. reef was prepared by Coastal Technology
Corporation (1992). Physical surveys were performed in July 1992, April 1993, August 1993,
December 1993, and July 1994. Each survey consisted of 75 profile lines. Wave gauges were
placed landward and seaward of the reef in about 1.8 m (6.0 ft) and 3.7 m (12.0 ft) of water,
respectively. Volumetric analyses for the 356,736-sq-m
(3,840,000-sq-ft) area were performed based on the four surveys. Volumetric changes were
analyzed for each of the following six regions: landward and seaward of the structure along the
1,220-m (4,000-f?) reach of shoreline west of the reef (cells 1 and 2, respectively), landward and
seaward of an extension of the reefs axis along the 610-m (2,000-ft) northern reach (cells 3 and 4,
respectively), landward and seaward of the structure along the 610-m (2,000-ft) reach south of the
structure (cells 5 and 6, respectively).
SETTLEMENT
Updated measurements of the settlement of the concrete units were taken during the two 1994
surveys; the 57 units placed in 1992 appear to have stabilized at an average settlement of
0.8 m (2.7 A). The remaining 273 units have settled an average of 0.5 m (1.6 ft) and are approaching
equilibrium. The greater settlement (0.3 m (1.1 R)) of the original 57 units is attributed to the effects
of Hurricane Andrew immediately following placement of the units. During this period, the scour
rods indicated scour depths around the reef ranging from 0 to over 0.6 m (2 ft).
WAVES
The wave gauges landward and seaward of the structure were operational for the study period, and
continued to indicate transmission coefficients of 0.65 for larger waves to 0.85 for smaller waves.
These values are lower than those predicted by theory for the structure placed at the design crest
elevation. In order to determine the difference in wave height attenuation due to the structure, and
due to shoaling effects, additional field wave gauges were placed first adjacent to the long-term
gauges, and then as control gauges at similar water depths as the long-term gauges 500 ft to the
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