Client: Tweed Shire Council

Project Design:

NSW Public Works

Contract Sum:  $5.4M

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Clarrie Hall Dam Spillway Upgrade

Clarrie Hall Dam is a rock-filled embankment dam located on Doon Doon Creek, a tributary of the Tweed River, approximately 4 km south west of Uki. The 15,000 ML litre reservoir provides the drinking water for the Tweed Region. Tweed Council is upgrading the Spillway to meet the Dam Safety Committee’s Requirements and to ensure that the dam can continue to safely pass extreme flood events.
The spillway upgrade works involve widening and extending the entrance of the existing spillway chute. A parapet wall across the dam crest will be raised to prevent water from flowing over the dam wall in an extreme flood event and enable the water to be released safely through the spillway. The parapet wall will not increase the water storage capacity of the dam and the dam storage will remain at current levels.

Works Include:

• Structural Concrete works associated with Raising the spillway wall by 2m
• Extending the existing spillway entrance by 35m.
• Strengthening the flip bucket downstream of the spillway

Key Aspects:

• Working in operating dam environment where water levels are to be maintained
• Design and construction of temporary coffer dams.
• No existing access to work area. All plant and materials need to be craned out. Scaffolding access for workers needed to be built
• Protection of works during flooding
• Working at heights (10.5m walls)
• Setting up and constructing pre-cast area for onsite casting of parapet units (220 No. units)