As 2016 turns into 2017, staff at the U.S. Army Corps of Engineers Jacksonville District continue the monumental task of rehabilitating the Herbert Hoover Dike surrounding Lake Okeechobee in south Florida.
The highlight of 2016 was approval of a dam safety modification report in August that identified the features the Corps will build in the coming years to reduce the risk of dike failure. Approval of the report provided Jacksonville District engineers with a definitive path for completion of the rehabilitation program in the mid-2020s.
“The intent of the study that produced the report was to identify the risks around the dike and develop structural and non-structural options for mitigation,” said Mike Rogalski, Jacksonville District’s program manager for Herbert Hoover Dike rehabilitation. “We conducted this study while we continued construction of features to reduce the risk to the dike.”
The dam safety modification report calls for installation of additional seepage barrier, commonly known as a partial cutoff wall, in the dike. It also recommends construction of floodwalls at two water control structures, and embankment armoring at a bridge on the northwest side of the lake.
Since 2001, the Corps has invested more than $870 million in rehabilitation. That investment has paid for installation of 21.4 miles of cutoff wall between Port Mayaca and Belle Glade on the southeast side of the lake. It has also funded a huge program to replace old water control structures, commonly known as culverts, around the lake. The Corps identified the condition of the culverts as the greatest risk for dike stability due to significant erosion of material around the structures.
“By the end of 2016, we’ve taken action on 24 of the 32 structures that need to be addressed,” said Rogalski. “We’ve removed one structure, completed replacements of four others, with the remaining 19 in various phases of construction. Over the next three years, we plan to award contracts to replace five other structures, and we plan to seal off three structures no longer in use near the city of Okeechobee.”
In 2017, the Corps plans to award the first contract to resume installation of cutoff wall west of Belle Glade. Engineers plan to install 35 miles of the seepage barrier through Lake Harbor, Clewiston, and Moore Haven. Additional cutoff wall is planned near the community of Lakeport on the west side of the lake.
“The partial cutoff wall consists of a concrete-like substance that forms a barrier to seepage,” said Rogalski. “Reducing the seepage leads to a reduction in internal erosion of the earthen structure, which increases our confidence that the dike will withstand the forces of nature it often faces.”
The Corps estimates the remaining construction at the dike will cost a little more than $800 million. Based on funding projections in the coming years, the Corps estimates that rehabilitation of the dike could be completed by the mid-2020s, perhaps in the year 2025.