Bioretention system as an alternative method for restoration of Lake Apopka, Florida

The eutrophication of the lake has become a worldwide environmental issue since mid-twentieth century. As the fourth largest lake in Florida, Lake Apopka was polluted leading to the hypereutrophic consequences mainly resulted from the drainage of its large floodplain marsh, which has a high concentration of nutrients, for agricultural development. The hypereutrophic water of Lake Apopka has resulted in the loss of recreational function and atheistic values to the public. In response to this hypereutrophic issue, the St. John River Water Management District (SJRWMD) in charge of the Lake Apopka Basin has prepared a comprehensive management plan named Surface Water Improvement and Management (SWIM) Plan for Lake Apopka to restore and preserve the lake and its environment. In this SWIM Plan, a marsh flow-way close to the outlet of the lake has been designed and operated as a major project to remove the high concentration of nutrients presented in the lake water, which could remove 30 percent total phosphorus (TP) and 80 to 90 percent total suspended solids (TSS) from the inflow of lake water. To improve the pollutant removal efficiency in Lake Apopka, the bioretention system, one implementation of stormwater Best Management Practices (BMP), was researched and designed as an alternative method to treat lake water, subsequently, was compared with the marsh flow-way in three aspects: land area, removal efficiency, and cost. With a flow rate of three hundred seventy two thousand cubic meters per day (37.2×10⁴ m³d⁻¹), the land area of bioretention system to treat lake water would be approximately 20 percent of the marsh flow-way. The established pollutant removal efficiencies of the bioretention system are remarkably higher than those of the marsh flow-way, with TP of 60 percent, TN of 30 percent, TSS of 90 percent, respectively. However, the preliminary analysis indicated that the cost of building bioretention system would be much higher than that for constructing marsh flow-way.M.S.Includes bibliographical referencesby jinfei Y