In 2016, divers and sonar scanning identified some significant erosion of the concrete lined plunge pool below the spillway of Devils Gate Dam which is submerged all year round. The repair is one of the most critical event to be done as the Devils Gate Power Station is due to a major refurbishment in 2018.
The erosion was properly exposed in March 2017 when the plunge pool was drained for the 1st time since diversion tunnel closure in 1969. Once the damage had been fully assessed, a fast-paced programme of rectification works commenced which consisted of high strength reinforced concrete overlays over the whole area of damage. The repair methodology was developed and implemented BridgePro Engineering team.
- Project: Devils Gate Refurbishment
- Client: Hydro Tasmania
- Client Contact:
- Project Value:
- Contract Mechanism: Purchase Order
- Key Personel: Aaron Brimfield, Ed Millinson, Nam Do; Craig Saunders, Zane Longley
- Start Date: March 2017
- Date for Practical Completion: June 2017
- Design Engineers: BridgePro, Hydro, GHD
Key challenges of the project are included:
- Construction barges were used to cart trucks and equipment in and out of the dam site
- Provide a truck access to plunge pool by building a secondary coffer dam.
- Repair work was carried out during the daytime while the power station was returned to service at each night, 6 days/week.
- Draining water out of the pool every day to ensure the safe working area.
- Complicated lining shapes at the bottom of the pool where more than 350 m3 of specialised concrete was laid in 8 sections/panels.
- New 600mm depth concrete lining was anchored to rock 4m depth and bonded to existing concrete with special bonding agent.
Relevance to B3, R2 Prequalification Categories
- Construction using coffer dams (B4)
- Large / Significant concrete pours (B4)
- Complex foundations (rock drilling)
- Complex geometry