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the structure in a wet condition. As with other structural PCDs, the collected organic material may decompose and release the stored nutrients back into solution. To avoid the release of these nutrients, the stnicture must be cleaned relatively frequently. Indian River County will be utilizing a continuous operating rake and bar screen combination to remove vegetative debris from the water column. This will prevent the decay and release of nutrients back into the water. In addition, a sediment and materials handling pump will be positioned in the bottom sump of the vortex unit to continuously remove settled material so that it has no opportunity to be reintroduced to the canal water. Because these units are expected to remove relatively large amounts of material, an automated system will be employed for frequent removal of the collected material. The vortex unit will be integrated with self-cleaning fixed bar screens and traveling rakes to remove large masses of vegetative debris such as hyacinths, water lettuce, duckweed and grasses and floating trash before the water enters the vortex unit. Annual loading of vegetative debris has recently been estimated at 10 million wet pounds. This represents a very significant muck and nutrient source to the Indian River Lagoon. Based upon tissue analysis, this loading represents 21500 lbs. of phosphorus and 20,000 lbs. of nitrogen on a dry weight basis. In addition, the vortex unit itself is designed to remove suspended sediments as well as floating debris. Based on water quality data for the Main Relief Canal and projected removal efficiencies of the Main Relief Canal Pollution Control Structure at a design flow rate of 294 efs, the following annual pollutant load reductions are estimated: TSS = 11207,989 lbs. TN = 31,234 lbs TP = 7,722 Total nutrient removal for the combined treatment systems is in the range of TN=51,234 lbs. and TP=10,222 lbs. This one project provides a significant opportunity for Indian River County to make great strides in meeting the proposed TMDLs for this basin of the Indian River Lagoon and improving estuarine habitat and water quality for this segment of the Indian River Lagoon. PROJECT OBJECTIVE(S): There are 17 segments of the Indian River Lagoon basin that were identified on the Florida Department of Environmental Protection (DEP) 1998 303(d) list as impaired by nutrients, dissolved oxygen, or chlorophyll a and were scheduled for TMDL development by June 30, 2003. All of these segments fall within the FL DEP Indian River lagoon Group 5 Basin and, as a result, were scheduled for TMDL development by FL DEP in September 2004. The segments in Indian River County that will be addressed by this project are named South Indian River WBID 5003C, IRL Segments 16-20. The Main Relief canal basin is segment #19. Due to the extensive network of canals that carry stormwater nmoff in this region, Indian River County is in a unique position to capture and treat a significant portion of its total runoff. The Main Relief Canal conveys approximately half of the total runoff from the Indian River Farms Water Control District to the Indian River Lagoon. The proposed vortex unit/bar screen system will remove a significant quantity of nutrients and muck contributing solids front canal discharges. (TSS=549,086 Kg, TN=14,197 Kg, TP=3,510 Kg). In addition to the nutrients associated with suspended sediment, annual loading of vegetative debris has recently been estimated at 10 million wet pounds. This represents a very significant muck and nutrient source to the Indian River Lagoon. Based upon tissue analysis, this loading represents 2,500 lbs. of phosphorus and 20,000 tbs. of nitrogen on a dry weight basis. Removing these nutrient loads will move the County closer to meeting the TMDLs for this segment of the lagoon. Specific Project Objectives- ( 1) bjectives:(1) To demonstrate that a combination of treatment technology (i.e. self-cleaning bar screens and vortex technology) can be used to effeciently remove large amounts of floating and suspended material from an existing canal. (2) To demonstrate that if the collected material is removed from the system within a reasonable time, there is nelgible release of nutrients back into the water from the captured material. (3) To demonstrate that a large stormwater pollution control device if maintained on a regular basis, can remove significant amounts of pollutants. (4) To demonstrate that if large quantities of aquatic plant material and algae are removed from the system, then large amounts of nutrients (nitrogen and phosphoms) associated with that plant material and algae are also removed. PROJECT DESCRIPTION: The Indian River Farms Water Control District (1RFWCD) in Indian River County, Florida is an area over 53,000 acres that is drained by an extensive network of man-made canals. The IRFWCD discharges into the Indian River Lagoon, an Estuary of National Significance and a St. Johns River Water Management District (SJRWMD) Surface Water Improvement and Management (SWIM) program priority water body. In the East Indian DEP Agreement No. G0182, Attachment A, Page 3 of 10