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Bob Dean, with the University of Florida, has also proposed a hypothesis that a continuous submerged breakwater (e.g. the.Midtown P.E.P. Reef) can cause increased erosion by creating increased currents adjacent the beach. These increased currents have not been measured in the field however, they were observed under very speck conditions during the Vero Beach physical model study (U of F 1994). During this study, staff worked with the U of F to find a P.E.P. Reef configuration that would minimize this effect. The currently proposed staggered alignment is the result. One thing the U of F physical model study could not do is predict the P.E.P. Reef effect upon the beaches. Staff petitioned the DEP that it was not practical to model the Reefs effect and that the County should be allowed to install the Reef. The DEP was insistent and suggested the County perform a worst case study by using an existing computer program and assuming the P.E.P. Reef behaved like a emergent breakwater with a higher wave transmission coefficient. Staff recommended using the Florida Institute of Technology to computer model the P.E.P. Reef because their model was the only model, within a reasonable cost, capable .of including a submerged breakwater. The draft results of FIT were submitted to the County on February 15, 1995 and the final model runs are currently being completed. Staff asked FIT to model several wave climates including the wave events that caused erosion during 1994. These results indicate that the P.E.P. Reef will not stop erosion during sever or moderately severtevents. The P.E.P. does provide some wave height reduction and it did reduce some of currents between the breakwater and the beach (i.e., it did not agree with Bob Deans hypothesis). Also, during small wave events some sediment accretion was predicted at the south end of the project. The FIT model is not calibrated and its results must be weighed by the fact that it is just a computer model. However, it does agree with the results of the Palm Beach Midtown project and preliminary results of the New Jersey Avalon project. The Midtown project has experienced sediment accretion at the southern 1/4 of the project. The remaining project area has experienced erosion. The New Jersey project has also experienced erosion but, the project investigators feel the erosion may have been less than if the breakwater was not installed. To date, there have been no reports as to the Midtown projects ability to slow the erosion rate. The other New Jersey projects are too recent to determine their performance. Staff recently talked to Dr. Bob Sorenson, with Leigh University, regarding a submerged rubble mound breakwater he installed in the Caribbean. This breakwater is slightly larger than the P.E.P. Reef and is exposed at low tide. During recent storms (approx. 4 ft waves) the beach did experience some erosion. However, Dr. Sorenson felt the breakwater had helped to slow down the erosion. In all cases the submerged breakwaters are not stopping erosion. They may be slowing it down, but even moderate storms are likely to cause beach loss. The reason for this is due to the fact that under most storm conditions the wind will increase the nearshore water level, and the deeper the top of the breakwater the less its ability to reduce wave heights. 19 BOOK 94 Pt�a LMARCH 28, 1995