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Contract #25245 EXHIBIT "A" — STATEMENT OF WORK INDIAN RIVER COUNTY EGRET MARSH REGIONAL STORM WATER PARK I. INTRODUCTION/BACKGROUND Indian River County proposes to construct Egret Marsh Regional Stormwater Park (Egret Marsh) on a 35 -acre, county owned site in southwest Indian River County to treat nutrient rich storm water runoff and groundwater base flow from a portion of the Indian River Farms Water Control District (IRFWCD) canal system. IRFWCD is a Florida Statutes Chapter 298 drainage district with a total basin size of over 50,000 acres. The watershed in this portion of the district is 80% agricultural and drains approximately 9,000 acres through the Lateral D Canal, which flows into the Main Relief Canal, which discharges into the Indian River Lagoon (IRL). The IRL is an Estuary of National Significance and a St. Johns River Water Management District (SJRWMD) Surface Water Improvement and Management (SWIM) Program priority water body. Egret Marsh's primary purpose is to remove dissolved nutrients (nitrogen and phosphorus) from the canal water. The facility will use an aquatic plant based system, a patented Algal Turf Scrubber (ATS), to accomplish most of the dissolved nutrient removal. Additional nutrients that are bound to solid particles will be removed through settling in the facility's concrete headwork structure or in one of three polishing ponds. The project includes the following: mechanical pre-screening to remove all solids greater than one -inch before the water enters the treatment facility; a large pumping station in the Lateral D Canal that will pump 10 mgd of canal water into Egret Marsh for treatment; the main treatment engine, a 4.6 acre ATS; approximately 9.5 acres of deep wet ponds for primary, intermediate, and final polishing treatment; and an approximate 3 -acre wood stork habitat area. Algae will be harvested from the ATS from time -to -time and composted. The compost will be used by the County Parks Division as a soil supplement. The project is anticipated to reduce total suspended solids by 60.9 tons per year, total phosphorus by 1.7 tons per year, and total nitrogen by 7.3 tons per year. With respect to the total IRFWCD basin loadings, this represents a reduction of 7.7 percent phosphorus, 4.5 percent nitrogen, and 1.7 percent suspended solids. This full-scale treatment project is also a demonstration project to familiarize the agricultural interests in the IRFWCD with managed aquatic plant systems as a viable agricultural Best Management Practice (BMP). Monitoring will be performed to determine the system's treatment effectiveness. When funds become available, the system will also serve as a park where displays will be constructed to educate the public about stormwater pollution and treatment. II. OBJECTIVES The primary objective of this project is to remove dissolved nutrients and settleable suspended solids from water in the IRFWCD's Lateral D Canal. Accomplishment of this objective will result in lower pollutant levels in the IRL. Page 12