The Bagatelle Dam project is located on the Terre Rouge River, circa 20 km southeast of Port Louise and is a new dam reservoir used as a water retention system for the regional drinking water supply.

The installed plastic concrete cut-off wall provides the necessary vertical underground sealing below the actual earthfill dam section for a new water reservoir and extends over a length of 2.4 km.

The cast in-situ plastic concrete cut-off wall has a nominal wall thickness of 800 mm throughout the entire length, but was divided into three main sections (Left Bank, Central Part and Right Bank) as defined in the technical specifications mainly due to the strong variation of the local geology.

Approximately 57,000 m² cut-off wall was completed in May 2015 which included a large percentage (20,000 m²) of excavation through moderately weathered and slightly weathered basalt in order to reach the designed toe levels.

The average excavation depth was 24 m with the maximum depth reaching up to 44 m. Within the Central Area up to 28 m heavy basalt layers had to be excavated to reach the specified toe level of the cut-off wall. The works were executed by utilizing up to three BAUER cutter units type BC 40 and two grab units over a construction period of 14 months.

Scope of work:

• Installation of approximately 57,000 m² cut-off wall into basalt rock