Environmental rejuvenation, page-245

Florida Department of Environmental Protection
State 404 Program Public Notice May 11 2021
The applicant seeks authorization to implement a chemical application project within Lake Prima Vista involving a combined low dose water column treatment using alum and FLORIDA DEPARTMENT OF Environmental Protection Central District Office 3319 Maguire Blvd., Suite 232 Orlando, Florida 32803 Ron DeSantis Governor Jeanette Nuñez Lt. Governor Noah Valenstein Secretary File Name: Lake Prima Vista Phoslock FDEP File No.: 0396431-002-SFI Page 2 of 4 sediment nutrient inactivation of phosphorus using Phoslock. The use of the alum is intended to provide immediate light availability to promote the growth of submerged aquatic vegetation while the Phoslock will reduce phosphorus release over a much longer duration during which time additional structural treatment solutions will be developed. A total of approximately 28 cubic yards of treatment material will be sprayed into the 19.5-acre lake, with two deeper portions being more specifically targeted. The target alum application rate will be 10mg/L as Al, depending on the results of a jar test immediately prior to the treatment application. Alum will be applied initially to clear the water column. The target Phoslock application will be 60mg/L and the Phoslock will be applied in two phases. Over the course of the first application day, several boats equipped with spray bars will apply approximately 12,000 gallons of alum to Lake Prima Vista. Approximately 24 hours following the alum application, the first Phoslock application (6,000 pounds) will be applied using boats equipped with a mixing device which prepares a slurry for liquid application using a manifold system. A second application of Phoslock (approximately 30,000 pounds) will be applied following the first phase in a more concentrated slurry to target the two deeper “hot spot” areas as identified in the Lake Prima Vista Hydrologic/Nutrient Loading Study. In addition to the routine quarterly and monthly monitoring conducted by the City of Ocoee (City), Wood Environment & Infrastructure Solutions, Inc. (Wood), will be measuring water quality one day prior and one day after the alum and Phoslock applications.