Road & Transport Infrastructure
Greens Road Reconstruction
Client
Public Works Authority (PWA)/Hawkesbury
City Council
Duration
June 2021 – July 2022
Location
Lower Portland NSW
Expertise
Concrete and Retaining Structures, Flood Remediation and Landslips, Road Construction
A total of 718m of road was damaged in the March 2021 floods and further damaged during two flooding events in 2022, with one section of the road closed due to significant landslides.
Project Scope
- Relocation of Telstra services
- Vegetation removal
- Excavation of the road embankments
- Road widening
- Road realignment (vertical & horizontal)
- Stormwater works (culvert removal and strip/dish drain construction and stabilisation)
- Construction of additional new pavement
- Shotcrete
- MagnumStone retaining wall
- Rock bolts
- Soil nails
- Meshing
- Installation of semi-rigid safety barriers
- Sealing
- Line marking and signage
Key Challenges
Collaboration with the Community to Maintain Resident Access
For two years, many residents had no direct access to their properties and relied on a 45‑minute detour, while load limits restricted flood‑recovery works. To address this, an access strategy was developed that provided 3–4 daily windows for residents to safely travel through the site, supported by 24/7 traffic control and UHF communication. This allowed residents to schedule deliveries and begin repairing their properties.
In addition, as local households relied solely on tank water and could not receive water deliveries due to landslip damage, a temporary water‑supply solution was provided free of charge throughout construction.
Large overhanging boulder exposed during flooding of the construction site
Due to a heavy rainy season, we experienced two floods during construction which exposed a large overhanging boulder that had developed a crack. This boulder became apparent after the second flood and was a clear a safety risk that could have been exacerbated by vibrations caused by construction works. We identified this safety risk and developed an alternative design solution that supported the rock through soil nail and rock bolting the boulder into place with shotcreting. This resulted in a safe structure that we could work around and that wouldn’t pose a risk to residents once the road reopened.
Accelerating the program to meet a Christmas deadline
As the residents had not had access for two years, they had been able to rebuild homes damaged by the first flood. Delaney Civil set a Christmas deadline to have the road opened for residents. Achieving this required 24/7 split shifts for two months leading up to this. We increased resourcing by working closely with a number of local internal employees and were successfully able to open the road for Christmas deliveries for residents.
Inaccuracies in rock depth design
Once we dug through the materials from the floods, we discovered that the areas where we had to build the footing were deeper than indicated, at more than 5m below the water level on the design drawings. Our team worked closely with designers and Council to develop a solution for the Christmas deadline. Our solution involved a mass pour of the 5m+ footing which allowed the retaining wall to be built, allowing construction to continue to meet the deadline.
