Waterways - asset or maintenance headache?

Mal Brown

Creating and maintaining urban waterways can be tricky, but with the right design and management plan, they are a valuable asset to property developments.

 Minimising risk on developments involving waterways:

  • Be prepared to invest adequate consultant hours in the design of the waterway and plan for its ongoing management - it will be cheaper in the long run and gives the greatest chance of bond recovery
  • Design the waterway well at the beginning to minimise the risk of hazards, such as algal blooms
  • Ensure your water & environment engineers have a track record in delivering long-term solutions for design and management of waterways

Designing and maintaining waterways can be challenging for everyone involved in the property development process.

Get it right, and the waterway is an attractive addition to a property that lifts the value for residents and the community.

But get it wrong, and a waterway can become an unsightly maintenance headache or, at worst, a health risk.

Northrop Consulting Engineers' waterways expert, Mal Brown, says with careful design, planning and maintenance, waterways can be an enduring and attractive addition within the urban environment.

Engineers typically work on one of three types of waterway projects:

  • revitalising existing urban creeks: these are often adjacent or within a reserve or parkland. Pollution is usually a factor, requiring engineers and environmental experts to stabilise the waterway and prepare for its handover to community groups for ongoing maintenance
  • wetland pond systems: typically in large communal areas such as parklands. These waterways may have inadvertently become stormwater ponds even though they were not designed for that purpose. Engineers are called in to redesign and reconfigure them in order to manage pollution inputs
  • waterways in new developments: pre-existing creeks within greenfield areas are often utilised by a developer. Engineers add value by adding water quality treatments such as wetlands, which ease ongoing maintenance tasks

Mr Brown says Northrop have been most actively involved in restoration and maintenance of existing waterways. It's important work, given the risk toxic algal blooms present. Waterways are prone to algal blooms in dry times - with less water flowing through the systems the water can become stagnant, increasing the likelihood of algae growth.

"Stagnancy is a big issue, particularly if water bodies have been designed too large to be effective," Mr Brown says. "By designing water systems smaller, you can restrict risks to a smaller area and reduce the chances of problems such as algal blooms. Smaller systems are also easier to maintain."

Risk mitigation is an important part of delivering waterways, not just in the design and construction of systems but through the delivery process and ongoing maintenance.

"No-one wants a poor performing waterway, and so it's important to spend sufficient time designing waterways that identify the potential problems and reduce risks, such as the potential for stagnation," Mr Brown says. "However, it's equally important that the design of waterways makes it easier for long-term, ongoing management well into the future."

Mr Brown says that in NSW the lack of regulatory guidelines, means that waterway maintenance is often overlooked, resulting in cost driven, inadequately designed low-maintenance waterways, which perform poorly and lead to disputes over maintenance funding.

Whereas Queensland and Victoria have implemented guidelines and governance, and provided funding for waterways. NSW has fallen behind, Mr Brown says.

"The NSW Government had previously taken a leadership role in stormwater management with the aim of improving waterways throughout the state," he says. "There was a good deal of progress made - stormwater projects were funded, and management plans were created. But in the mid 2000’s funding of the program diminished."

In the governance vacuum, it is vitally important developers, councils and others involved in the process engage experienced and qualified engineers to design solutions that deliver long-term results.

"Councils don't want to inherit problematic waterways, so there's increasing pressure on developers, and their engineers, to deliver trouble-free solutions," Mr Brown says.

"Typically councils will ask developers to provide lots of testing on how waterways will perform, especially those in new developments, and they may also require a hefty bond as a guarantee. Unless the waterway is designed properly and its future management accounted for, the bond is at risk."

"Sadly, we are seeing the forfeiture of developers' bonds more and more often in waterways projects, which is a disturbing trend."

The right technology for waterways management

While engineers take on ever more responsibility for designing waterways and plans for their future management, they can bank on technology to help.

Northrop Group Manager for Water & Environment, Mal Brown, says 'floating treatment wetlands' are a handy tool to help treat waterways and prevent hazards such as algal blooms.

These systems, such as Naturaft, combine floating mats, wetland plants, cages and anchors to help clean waterways. The water is treated by the root systems that hang beneath the raft like a curtain - the roots provide a surface area for biofilm that produce a 'bioreactor' for water treatment.

Mr Brown says such systems are effectively 'drought-proof' because they float on existing water bodies and rise or fall with fluctuating water levels. They also typically require less surface area than constructed wetlands.

Another technology engineer’s use is water level control structures positioned at a waterway's outflow. These controls allow the waterway to be drained and accessed for maintenance work.

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