Nicholson Construction has announced that US-based Tennessee Valley Authority (TVA) has selected it in joint venture with Treviicos South to construct a diaphragm cut off wall at Boone Dam.
The cut off wall is the final part of a major remediation scheme to address seepage issues at the earth embankment dam and will allow the reservoir to begin a refilling phase.
Seepage issues at the dam were discovered in October 2014 during investigation into internal erosion resulting from flows through the underlying limestone around the original grout curtain and identified the dam at risk of failure as a result.
Earlier phases in the remediation have involved widening the dam, drilling and grouting and installation of 220,00t of rock to strengthen the earthen embankment. Nicholson has been involved in these earlier stages.
Under the latest phase, Nicholson will work with Treviicos on the cut off wall and TVA has said that it expects the reservoir to be operating normally by summer 2022.