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Page 2 <br />Egret Marsh — New Harvest Rake for Egret Marsh <br />BCC Meeting — October 7, 2014 <br />September 16, 2014 <br />plugging and overloading during harvest events. During normal growing season, the <br />harvested algae may consist of thick ropelike strands many feet in length, entering the <br />harvest screen individually or in huge mats. In winter months the algae loses some of <br />its stringy characteristics, but still enters the harvest screen in large mats or clumps. In <br />each instance, the algae tends to wrap around and/or clog the harvest screen parts, <br />requiring the assignment of at least one and frequently two staff members to physically <br />keep the screen free of wrapped/clogged algae and thus operational during a harvest <br />event. The extra time added to the harvest is considerable and when the screen <br />becomes clogged, large amounts of harvested algae may bypass the screen and flow <br />directly into the polishing pond, causing harm to that system. <br />Duperon has worked with staff since the algae capture issues were realized to design <br />and implement various improvements to the original harvest screen, but none have <br />solved the issues. Staff subsequently provided Duperon significant input and <br />suggestions for an upgraded screen design that will solve the issues experienced with <br />the existing design. Duperon has implemented staffs suggestions into its new design. <br />(Osprey Marsh Stormwater Park will also use the new Duperon harvest screen design.) <br />If the second -generation screen is installed at Egret Marsh, staff harvest time will be <br />greatly reduced, resulting in much more efficient use of staff time. Bypass of algae into <br />the polishing pond system will be drastically reduced and likely eliminated, resulting in <br />longer service life for the polishing pond system and a healthier environment for the <br />wildlife that lives in or depends on the ponds. <br />Perhaps most importantly, operator safety will be greatly increased if the harvest screen <br />upgrade is installed. Because of the existing screen's direction of travel, cleaning and <br />maintenance must be performed manually using potato rakes or similar tools while the <br />screen is operating. Cleaning operations are performed on and around moving steel <br />links and sprockets and the real possibility of serious personal injury is always present. <br />Because the upgraded screen rotates in the opposite direction as the existing screen, if <br />the upgraded screen becomes plugged, it may be cleaned using a high pressure water <br />hose with the operator standing a safe distance away from any moving part. Because <br />of the nature of its rotational direction and other factors, the upgraded screen will also <br />be significantly safer for any wildlife that falls into the harvest flume and flows into the <br />screen. The existing screen kills most wildlife that enters it. Finally, because algal <br />removal rates will increase during harvest events with the implementation of the new <br />harvest screen design, the Indian River Lagoon (IRL) will ultimately benefit since all <br />water treated at Egret Marsh flows into the IRL. <br />The amount of the FDEP Grant is $175,000 and no matching funds are required. The <br />delivered cost for the new Harvest Rake is $223,000 and the County will be reimbursed <br />for the full grant amount upon screen delivery to Egret Marsh. Staff estimates that <br />installation will cost approximately $5,000. Therefore, the estimated County cost for the <br />purchase and installation of the new harvest screen is $53,000. <br />2 <br />66 <br />