QLD – Seqwater’s Dam Improvement Program

Author: Michel Raymond. In 2012-13, Seqwater commissioned a Portfolio Risk Assessment of its 26 regulated dams. The assessment has identified a program of work needed to ensure our dams meet the requirements of ANCOLD and Queensland guidelines into the future. Seqwater plans to upgrade some dams and has already reduced the water levels of other dams until such time as upgrade works can be completed.

In recent years, Seqwater has upgraded Lake Manchester Dam (2008), Borumba Dam (2008), Hinze Dam (2011), North Pine Dam (2012) and Ewen Maddock Dam (2012).

Dams identified for improvement works over the next five years include: Ewen Maddock (Stage 2), Lake Macdonald, Sideling Creek (Lake Kurwongbah), Bill Gunn, Leslie Harrison, Moogerah and Maroon.

Project update – Moogerah Dam

Upgrade works were conducted at Moogerah Dam from June 2014 to January 2015. Moogerah Dam is a 38m high double curvature thin arch concrete dam that was built in 1961 and supplies water for irrigation use.  The ANCOLD 2015 Post Conference Tour will visit Moogerah Dam which is located in the Scenic Rim region of South East Queensland.

Stage 1a works will improve flood security and resilience from flood overtopping at the dam.  The Stage 1a Works at Moogerah Dam included:

• Construction of a structural concrete block at the base of the dam to protect from overtopping events.
• Anchoring the structural concrete block to the foundation rock below using tension anchors.
• An upgrade of the existing access track, widening of the spillway access and crane hardstand area.

Stage 1b and Stage 2 works are scheduled for after 2025, subject to approvals and future requirements.

Construction works

To complete the Stage 1a works at Moogerah Dam:

• 450 cubic metres of reinforced concrete was added to the structural concrete block at the base of the dam wall.
• 203 metres of 12 strand tension anchors were attached from the dam wall to the structural concrete block.
• 83 cubic metres of reinforced concrete was used to widen the spillway access road.
• 150 cubic metres of retaining wall wire baskets were installed beside the crane hardstand area.

Key achievements for this project:

Practical completion was achieved ahead of the 2014/15 wet season. During construction the dam continued to supply water to surrounding communities and remained fully operational for the duration of the project. Seqwater kept its dam neighbours, the local community and customers informed for the duration of the projects.