New technologies need to be trialled and tested in order for them to be improved and optimised . With water sensitive urban design (WSUD), it is no different. Being an Early Adopter means you a play an invaluable role in this process. It also means encountering unexpected issues, as the new technologies are refined and mature. 

Revisiting a site 15 years after completion

In November 2017, we returned with ten other interested architects, water engineers and energy assessors to the Inkerman Oasis site in St Kilda, 15 years after its completion. The award-winning site received much acclaim for its innovative water recycling features, raising the bar for what could be achieved at the multi-residential scale. It included greywater recycling, with a four part treatment process (aeration tank, membrane bioreactor tank, chlorination, and UV disinfection). Stormwater was also harvested off the roofs, with primary treatment through a gross pollutant trap then biological filtration through 400m2 of on site wetlands.  

WSUD and IWM infrastructure going to waste

Unfortunately, we arrived to learn that all of these features were now non-operational. All of the WSUD infrastructure had been switched off and is now bypassed.

It was disheartening to see such a substantial investment in integrated water management (IWM) infrastructure be entirely discarded. But in order to avoid this happening continually…

We need to examine the why

• Where did it go wrong?

• Why did the costs outweigh the savings?

• How can we do it better? 

In the case of Inkerman Oasis, it seems that an intensive maintenance regime was the crux of the problem. A four part treatment process for its greywater, means four separate systems to clean, maintain and replace parts for. Likewise, the gross pollutant traps for the stormwater management require regular cleaning. The out-of-sight nature of the infrastructure can mean that issues or maintenance requirements can be missed, causing larger problems (and costs) later. The relative cheapness of potable water compounds the issue, creating a difficult case for economically viable water infrastructure. 

What is the case for WSUD assets now?

WSUD assets are now mandatory in many new developments through local council clauses. What happens beyond the design phase however is independently decided. With the demands of keeping rates low and fears in regards to the unfamiliar complexity of the infrastructure, many owner's corporations elect to simply switch off part or all of the technology that the site has invested in. 

In order for WSUD to be implemented effectively in developments, beyond the design phase, the maintenance needs to be straightforward and as efficient as possible. Moves towards digitalising systems and including sensors is a positive step in this direction. Simplifying processes as much as possible, while remaining within EPA public health guidelines, is essential.

Summary

It was very interesting to visit the Inkerman Oasis site and see where this pioneering WSUD project had landed. Thanks to building manager, Jarrad Hudson, for hosting us while we were there.

Thanks also to the City of Port Phillip, Inkerman Developments, South East Water and the rest of the project team for their groundbreaking work. Despite the fact that the infrastructure is not currently operational, the work that was achieved has contributed to making it easier for future developments to incorporate WSUD features, and the journey continues.

Josie McGushin.