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wT. ma Starting in 1994, Indian River County Staff has been monitoring the beach losses due to storm events at Wabasso and Humiston Beaches. Three storms caused significant erosion (i.e., greater than 1 cubic yard per foot loss) at these beaches. The first storm occurred in February, the second in October and the third (Tropical Storm GORDON) was in November. Each of these storms had waves, recorded by the Sebastian Inlet Taxing District wave gauge, in excess of 4.5 ft. (see Exhibit A). The storms average wave height and erosion rate (measured at Wabasso Beach) are as follows: Event Avg. Wave Ht. (Ft.) Avg. Loss February 1994 Storm 5.9 4 CuYd/Ft October 1994 4.5 3 CuYd/Ft Gordon Nov. '94 6.3 5 CuYd/Ft. The October storm did not have as large of waves but it did occur during a time when the tides were higher. Also, it had a longer duration than did the February storm or Tropical Storm Gordon. All of these storms did cause an increase in water levels over the predicted tide stage. P.E.P. REEF The P.E.P. Reef was recommended by the Indian River County Shore and Beach Advisory Committee as a way to reduce the erosion adjacent the City of Vero Beach. Principally, the P.E.P. will reduce the wave heights that reach the beach and thereby reduce the erosion rate. It was also hoped, but not required, to help build a beach during less energetic storms. Project Design A submerged breakwater is a significant asset to beach protection if it can trap some sand during smaller waves or significantly slow down the loss of beaches or, preferably both. It is clear that a submerged breakwater must work with the nearshore beach, dune and other upland structures to reduce losses. If the submerged breakwater reduces waves, but doesn't increase the nearshore sand deposits (during small events),then a stone is still going to remove sand when the higher water levels eliminate the reefs effect. The result is the submerged breakwater will perhaps reduce the rate of erosion, but the savings of that reduced rate will have to be gained over a long period of time. The Vero Beach area experiences, on average, one storm a year that will cause erosion with orwithout the P.E.P. Reef (Ref. FIT Study). The P.E.P. Reef will provide wave height reduction of a least 10%. Erosion will be reduced by no more than 10% and not less than 0%. Considering the estimated erosion rate is between 1 and 2 cubic yards per foot per year. Staff estimates the-P.E.P. Reefs -best performance -will yield an erosion rate reduction to between .9 and 1.8 cubic yards per foot per year. At current cost estimates of $10.00 per cubic yard of sand, trucked and placed, a 3,000 P.E.P. Reef will provide a return of between $3,000 to $6,000 per year, considering sand benefits only. If by chance, the P.E.P. can reduce to erosion rate to zero, it would provide a return of $30,000.00 to $60,000.00 per year. The results of other projects and the County's own model studies do not indicate that this scenario is true. Certainly the P. E. P. is expected to provide a better performance at Vero Beach than the Midtown and the Avalon projects. This is due to the reduced settlement and the greater updrift sand supply at the Vero Beach project. In addition, the marine life growing on the structures may increase its wave height reduction by increasing its size. The fact remains, that no project has shown an ability to significantly reduce erosion and iri all cases sand will have to be replaced along the project area due to storm erosion. 16 MARCH 28, 1995