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ENHANCED NUTRIENT REMOVAL USING CONSTRUCTED LIVING OYSTER REEFS WITHIN THE SPOONBILL MARSH RESTORATION SITE The purpose of this proposed project is to increase the long term nutrient uptake capacity of the Spoonbill Marsh site. The Spoonbill Marsh site has successfully removed nitrogen and phosphorus from the Indian River Lagoon during the first two years of operation. The Spoonbill Marsh has in fact significantly reduced the total inorganic nitrogen concentration to levels below the threshold concentration that defines oligotrophic waters. Most of the nitrogen and phosphorus discharged from the Spoonbill Marsh is in the organic forms. This project would develop an oyster reef across the terminal end of one of the four runnels discharging to the pre-existing mangrove community along the eastern side of the site. This oyster reef would further reduce the overall total nitrogen and total phosphorus concentrations leaving the constructed portion of the site. However, it would provide an important additional benefit in that the oyster reef is capable of filtering inorganic and organic forms of nitrogen and phosphorus. Thus this oyster reef could become a primary removal mechanism for reducing the organic portion of the nutrients passing through the site. This project proposes to construct an oyster reef across Runnel 3 in the general location shown by Figure 1 . The oyster reef would extend across the runnel from bank to bank as shown by Figure 2. The reef would be constructed using oyster blocks stacked from the sediments to an elevation approximately equal to the mean high water line. The blocks will be loosely fitted together to produce a structure with a pore (void) space approximately equal to 40 percent to 60 percent of the cross sectional area of the runnel at the point where the reef is constructed. This should allow the water to pass through the reef without increasing the water depth upstream of the reef. Oysters within and along the outer surface will continue to grow and expand the width of the reef. The reef will be designed to allow the upstream side of the reef to be periodically broken away from the structure to expand the base of the reef up the course of the runnel. Task 1 . Oyster Reef Construction Ecotech Consultants, Inc. (ETC) and Sembler & Sembler, Inc. (S&S) will construct the oyster reef in the location shown by Figure 2. The general dimensions of the reef will be as follows : Base of reef - 3 .0 feet to 4.0 feet wide Top of reef - approximately 3 .0 feet wide Height of reef - from sediments to an elevation approximately equal to the mean high water line Length - from the north bank to the south bank Geometry of side slopes - to be determined in the field Project pore space (or void volume) - approximately 40 percent to 60 percent of the cross sectional area of the existing channel. Page 1 of 4