The aging stormwater infrastructure poses significant challenges for the construction of additional medium-density housing in Canberra.
In response to the growing population and the need for diverse housing options, the ACT government is keen on increasing the availability of medium-density residences throughout the suburbs of Canberra. However, there are rising concerns regarding whether the city’s existing infrastructure, particularly its stormwater systems, can handle these developments amid a shifting climate.
A recent incident involving severe thunderstorms and flash flooding severely impacted Yarralumla Creek, located within the Curtin area, leading to notable destruction. This event underscores a critical issue raised by Julia Tresidder, the vice president of the Curtin Residents Association, during her testimony at an ACT Legislative Assembly inquiry focused on the necessity for more medium-density, often referred to as "missing middle," housing in the capital.
"The [stormwater] infrastructure requires significant upgrades to keep pace with the increasing number of residents, " remarked Ms. Tresidder.
She emphasized the importance of planning for new housing developments, including build-to-rent options, stating, "It's crucial for planners to ensure that 40 percent of land blocks are permeable to absorb some of the runoff during these sudden rainstorms.
"For instance, we experienced almost no rain in January, but then in just one evening, we received enough rainfall equivalent to two months’ worth, leading to visible damage throughout the area."
As medium-density housing projects increase in suburban neighborhoods, they result in a higher presence of hard surfaces, which are less able to absorb stormwater runoff created by heavy rainfall. Dr. Peter Coombes from Urban Water Cycle Solutions, who holds a fellowship with Engineers Australia, pointed out that while promoting denser living has been a long-standing strategy to accommodate population growth, it raises essential questions about the adequacy of existing infrastructure.
"It has often been viewed as a 'magic pudding' situation until you begin to consider whether densification can occur using the same infrastructure that currently exists," Dr. Coombes explained.
He added, "Stormwater infrastructure, including pipes and pits, has always been treated as a type of 'set-and-forget' system. Unfortunately, they do not receive the necessary level of maintenance and upgrading they require."
According to his analysis conducted nearly ten years ago, many regions in Canberra are already operating at or beyond the capacity of their stormwater systems. "There are specific areas where further densification cannot happen unless local solutions are implemented. Stormwater management must be integrated into planning policies before new areas are developed or existing areas are densified, " he advised.
Dr. Coombes cautioned, "If the approach to densification relies on outdated beliefs like managing issues solely at the bottom of the catchment, that strategy will fail."
On the other hand, James Bennett from the ACT City and Environment Directorate noted that the government has established new planning regulations for fresh constructions, ensuring that developers must incorporate stormwater management strategies and runoff considerations directly within their projects.
"Developers are now required to implement permeable surfaces and designated planting areas that retain water on their sites," Mr. Bennett stated.
Additionally, he mentioned, "For any water that exits the property and enters the stormwater network, we have initiated a comprehensive program of infrastructure assessments, capacity enhancements, and targeted measures. This ensures that we effectively manage stormwater impacts throughout the entire network."
But here's where it gets controversial: Are these measures enough to genuinely safeguard against the increasing severity of storms due to climate change? What do you think? Do you believe that the current infrastructure can withstand the pressures of increased housing density, or should more drastic changes be made? Share your thoughts in the comments below!
