| This first phase of this project will evaluate the basin-wide feasibility of significantly reducing phosphorus loads to Lake Okeechobee using permeable reactive barriers (PRBs) to intercept phosphorus before entering water in drainage ditches in the Lake Okeechobee Basin (LOB). The second phase will design location-specific PRBs, including physical, chemical, and biological considerations. This research is needed prior to demonstration of field-scale implementation. Total phosphorus loading to Lake Okeechobee from its surrounding drainage basin is approximately 600 metric tons per year. Intensive phosphorus management strategies are needed to reduce loads from the Lake Okeechobee Basin (LOB) and to meet the current Total Maximum Daily Load (TMDL) target of 140 metric tons by the year 2015. Due to the high phosphorus loadings and generally high phosphorus concentrations in the watershed north of the lake, it is unlikely that strictly ecologically engineered systems alone (e.g, Stormwater Treatment Areas, STAs) will be adequate in reducing loads to the extent needed to meet the TMDL target for Lake Okeechobee. Therefore, additional remedial measures may be needed to meet this goal. The extensive ditch network in the Basin acts as a rapid transport conduit for water and associated solutes (including phosphorus) from the watershed to the Lake. This project proposes to intercept phosphorus before it contaminates water in the ditches using permeable reactive barrier (PRB) walls for interception and long-term sequestration of phosphorus before water entering the ditches. PRB technology has a long history of successful application for groundwater remediation. The lifespan of a successful PRB is expected to be measured in decades. Other important advantages of this technology are that PRBs are completely passive and do not require continual maintenance after installation. Furthermore, because PRBs are installed in the subsurface, they are transparent to the land user and do not require any land use concessions. |
