Lake Walls Remediation

A feature of Canberra’s Central National Area, Lake Burley Griffin, is often seen as the ‘Grande Dame’ of the nation’s capital. At over 56 years of age, large sections of the lake’s ageing stone and concrete walls needed remediation to extend their useful life for another 50 years. Since the lake was filled in 1963, wind and wave attrition have weakened mortar joints between rocks, leading to the loss of soil from behind the walls. In some cases, stones have dislodged, and paving has become loose on the top of walls.

The NCA has initiated a three-year program to remediate and improve the condition of the walls of Lake Burley Griffin. Innovative processes such as ground-penetrating radar and resin injection are being used to improve wall stability. The total program cost is around $3 million.

This program included:

• Over four kilometres of rock and stone lake wall has been strengthened through expanding resin injection
• A large number of holes have been drilled at a depth of 1.5 metres behind the lake walls. About 4,000 holes were required to inject the resin over a distance of six kilometres
• 3.4 km of walls were scanned with Ground Penetrating Radar
• Over 40 tonnes of resin has been used through to the end of August 2020
• 72 trip hazards will be repaved along the RG Menzies Walk and Lennox Gardens by the end of September 2020

The resin injection works were completed in 21 weeks. An arborist has assessed fifty trees adjacent to the lake walls. Three dying trees will be removed. Repairs and remediation are planned to be finalised late 2021.

While the age and condition profiles of NCA’s lake walls are regularly checked, the NCA works to keep the lake walls in excellent condition. Therefore, ongoing maintenance and management of Lake Burley Griffin and its associated infrastructure, such as the lake walls, is required to keep it in a safe and serviceable condition for all to enjoy.