Lake Manchester Dam Upgrade

Background

Lake Manchester Dam was built in 1916 and required significant upgrade to meet ANCOLD safety guidelines. The spillway capacity was deemed inadequate to cope with large floods.

Project scope

Leed was awarded this separable part based on our reputation and track record in the successful planning, programming and execution of complex water retaining structures.

Leed’s brief was to construct a new reinforced concrete primary spillway including:

  • the development and implementation of a Design Drill and Blast Strategy for the 80,000 m3 bulk earthworks of the left-hand embankment
  • shotcrete protection works of the excavated surfaces from the top of the embankment to the toe of the spillway
  • design and installation of a steel coffer dam immediately upstream of the existing spillway to prevent flooding of the works during construction
  • demolition of the existing spillway
  • installation of ground and rock anchors that were then tied into the new reinforced concrete works
  • new ogee and training walls with 3,000 m3 reinforced concrete and complex 3D formwork to tie the new concrete works into the existing dam structure and the left-hand rock embankment.

Outcomes

In order to maintain structural integrity of the existing dam during drilling and blasting works, Leed developed an innovative solution for fracturing the rock to achieve the required bulk excavation results.

Through careful planning and staging, project timelines were successfully met.

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