Toledo Bend Dam is a 108-foot high zoned earthfill dam that spans 11,000 feet and is located along the border of Texas and Louisiana. In 2010, a Freese and Nichols climbing team conducted an inspection of the tainter gates, hoists, and associated mechanical and electrical equipment. The team found areas of severe corrosion and section loss in the structural gate members.
Freese and Nichols developed a four-phase rehabilitation program for the 11-tainter-gate spillway for Toledo Bend Dam, owned and operated by Sabine River Authority of Texas and Sabine River Authority for the State of Louisiana. Phase One, the pilot phase, consisted of the primary design and rehabilitation effort centered on a single gate – Gate 7. This particular gate was observed to be in the worst condition of the 11 gates based on a detailed inspection by Freese and Nichols. The degree of corrosion and section loss varied from gate to gate, which made developing rehabilitation designs applicable to all gates challenging. It was not possible to identify and quantify each and every area of section loss during the climbing inspection primarily due to splashing and spraying water and heavy organic buildup.
The pilot program was initiated to fully investigate and rehabilitate one gate and apply lessons learned to the rehabilitation of the remaining 10 gates. The purpose was to develop efficiencies and better understand the total effort and overall costs required for subsequent rehabilitations. After coating removal from the pilot gate, additional gate components were identified for repair; the repairs were performed immediately. From the pilot study, the owner, engineer and contractor developed a higher level of confidence and understanding of what would be required to rehabilitate the remaining 10 gates, which will consist of the following: Gate Set One: a two-gate rehabilitation project in Fiscal Year 2013; Gate Set Two: a four-gate rehabilitation project in Fiscal Year 2014; and Gate Set Three: a final four-gate rehabilitation project in Fiscal Year 2015.