This water quality retrofit project involved converting a failed dry retention pond within the Lake Apopka basin. The retention pond, originally permitted to meet the Lake Apopka Basin Phosphorous Load Reduction Goal (PLRG) set by the SJRWMD, did not provided sufficient treatment for the 79-acre drainage area and had maintenance concerns. SAI evaluated several innovative treatment alternatives to retrofit the existing pond to provide the required treatment. The alternatives included floating wetland systems, modular wetlands, stormwater harvesting, and conversion to a wet pond with an upflow filtration system. At the request of the client and the homeowners association, a wet detention pond design was selected. However, wet detention along would not provide sufficient pollutant removal capacity to meet the permit requirements, and the Lake Apopka PLRG. The final design included a wet detention pond that was to be constructed in series with a specialized filter unit, which has a floating skimmer/baffle system and upflow filter. The baffle system diverts runoff from the wet detention pond through the upflow filter unit for a majority of storms while allowing higher flow rates to bypass the filter. The filter unit contains specialized media that will provide the necessary phosphorous removal. The filter media (BOLD & GOLD™ media) was developed by researchers at the University of Central Florida's Stormwater Academy. The final design provides approximately 92% phosphorous removal.
SAI prepared the construction plans and specifications for the project, performed pollutant loading calculations, and coordinated with the SJRWMD to successfully permit the project. SAI provided limited construction support throughout construction of the project.