Dumaresq Dam, Armidale

Project Challenges

Access:

The biggest challenge we faced was how to safely access the section of the wall to build the scaffold.

• The dam walls lip was only 500mm wide, so safely building from the top of the wall was not an option.
• Access to the toe of the wall was limited due to large boulders and rocky granite terrain.

To overcome the access barriers, earth works was completed on the toe of the dam wall to create a track suitable for an all-terrain boom lift. This required consultation with our client and sourcing a local boom lift that would be suitable for the job, whilst still being cost effective.

Scaffolding Design:

The challenge here was designing a scaffold that met the clients requirements.

• The scaffold was required to be 1.2m wide, rated to carry 500kg per bay and anchored into a structure 9m above ground, so able to be built out of an elevated work platform.
• As the dam wall was built in the late 1800’s we had to find the best way to tie the scaffold to the structure, as it was cantilevered to the dam, without any support from the ground.

To ensure the project ran on time, numerous tests of the scaffold design took place. Firstly, base tests were completed in both our Tamworth and Forster yards to ensure that the build would be stable, and to walk through the design and build methodology with our scaffolding team. Once this was successful, we then went on site and built three test bays prior to the project commencing. This enabled us to test and be confident that our design was suitable and any changes that were required happened prior to the commencement of the project. Working this way enabled us to handover the completed scaffold a week before the project schedule.

After discussing different anchoring methods with our project engineer, we were able to create a design that was sturdy, durable and exceeded the requirements. This was really put to the test when the flood event in March caused the dam to overflow onto the scaffold, just after it had been completed. More on that in the Summary!

Work methodology required an EWP:

To build the scaffold at the required height and duty rating, an elevated work platform (EWP) was the logical option, but with it came it’s own set of challenges and additional risk factors.

• Heights – The access road was approx. 4m out from the toe of the dam wall, and because of the kick of the wall, approx. 9m up to where the scaffold was required to be erected and 11m up to the highest point.
• Terrain – Access to the toe of the dam was heavily restricted along the 150m base due to rough terrain.
• Training and Tickets – This project required our team to build the scaffold out of a jack boom, or in some areas, a mobile crane basket up to 11m high.

With each project we undertake, the preplanning stage is crucial to avoid unforeseen expenses or variations that could have been avoided. With this project it was especially important to research and acquire the best type of boom lift that suited the terrain, was able to access the height required, local to the area for ease of delivery and servicing if required, and within the contracts budget.

Using a specialty 4×4 articulating “jack boom lift” to build the scaffold from, we were able to navigate the freshly levelled access track and reach most of the required area. The section that was not accessible with the jack boom was completed with the help of the onsite crane contractor and built by using men in the crane and basket system.

To ensure each team member had the most up to date training and was confident in executing this unique and high risk project, a local training company was sourced to provide training and certification in Elevated Work Platforms.

Safety

The safety and wellbeing of our team is our top priority of all work we complete. There were numerous risks to control throughout this project.

• Working from an EWP
• Working on uneven ground
• Working from heights
• Working near water
• Weather – Project was completed in the heat of Summer/Autumn, rain events that occurred during the build period

The most effective way for us to mitigate and control risk in any project, is in the planning stage. With this project we created a clear work methodology, followed by a thorough safe work method statement. From there we ensured the team used on the project was not only appropriately licenced, but highly experienced in the specific type of scaffolding to execute the project safely and efficiently. They were trained on how to rescue a fall victim using the EWP or Gotcha fall arrest rescue kit. Daily toolbox’s and consultation were key to identifying and controlling the variable risks such as weather or site conditions, which played a big role in maintaining zero injuries or incidents throughout the project.