PREFERRED RISK REDUCTION ALTERNATIVE FOR REACH 1A OF HERBERT HOOVER DIKE

Herbert Hoover Dike (HHD) encircles the 720 square mile (143 mile perimeter) Lake Okeechobee in south central Florida. Original Congressional authorization for construction of HHD followed catastrophic damages and massive losses of life during overtopping events produced by hurricanes of 1926 and 1928. Flood damage reduction has been accomplished for more than 75 years; however, concerns related to seepage instability have existed at HHD since the early 1980’s. They have since become more pronounced during high lake events and through project evaluations, and are generally due to the lack of hydraulic controls and the characteristics of embankment and foundation materials. Following thorough evaluation of numerous alternatives to address stability concerns, the preferred comprehensive risk reduction alternative for (the 4.9 mile long) Reach 1A of HHD requires the construction of two primary components: a partial-depth seepage/piping barrier through the embankment and near-surface consolidated strata, and a landward seepage berm, which is coupled with a relief well system for blanket aquifer foundation condition regions. This paper offers an overview of HHD seepage-related aspects, alternatives considered for addressing Reach 1A stability concerns, and design approaches for the preferred risk reduction alternative. A summary of developed and implemented interim risk reduction measures for Reach 1A is also provided.