THE PROJECT
Located in the headwaters of the Derwent hydropower scheme, the Lake King William (LKW) Upgrade Works will form a new upstream connection for the proposed Tarraleah Redevelopment project. The works comprise an inlet structure, 1 km unlined tunnel and downstream portal. This project marks an important first step as Hydro Tasmania upgrades the existing Tarraleah scheme’s water conveyance to meet future energy market needs with increased capacity, flexibility and renewable energy output.
As a part of Hydro Tasmania’s Integrated Owners Engineering Team, PSM was engaged to provide geotechnical and hydrogeological services, including:
- Site investigation
- Geotechnical and hydrogeological model development
- Ground support design for the surface and tunnel excavation
- Digital engineering and BIM support
- Construction Phase Services (CPS) responsible for overseeing excavation and ground support for surfaces works elements
- Ground support design lead throughout tunnel construction
ENGINEERING AND TECHNICAL OPPORTUNITIES
- Variable ground condition including Quaternary glacial sediments and high-strength, blocky Jurassic dolerite within complex corridor of faulting and geological structure.
- Deep excavation adjacent to lake with fluctuating levels.
- Overbreak and blast damage associated with brittle rock mass and persistent geological structure.
- Groundwater seepage/inflow during excavation.
- Remote site with temperature extremes.
- Data acquisition and method improvement trials to support the Tarraleah Redevelopment.
APPROACH AND INNOVATION
A “toolbox’ of flexible support types coupled with robust design verification throughout construction.
Drill-and-blast excavation methods and staged excavation sequence.
In surface and tunnel grouting to control operational water leakage and ensure long-term asset integrity.
Advanced observational methods such as LiDAR scanning and digital mapping of exposed rock faces to manage geological uncertainty during construction.
3D modelling to proactively assess and mitigate risks of large-scale kinematic instability during the excavation.
OUTCOMES
PSM’s involvement in Hydro Tasmania’s Owners Engineering Teams spanned the project site investigation through to construction and delivery. Leveraging our wealth of recent D&C experience delivering large scale infrastructure projects, PSM provided practical solutions while bolstered Hydro Tasmania’s delivery capabilities in proactively managing geotechnical construction risk.
Services: #Hydropower #Tunnelling #Geotechnical #Hydrogeology #RenewableEnergy
