Young designer’s clever solution nets award

University of Auckland graduand Marissa Porteous is celebrating winning a Lexus award for the compost chemigation system she designed.

While completing a conjoint Bachelor of Design and Bachelor of Science majoring in Psychology this year, she was handed a real-world problem – to come up with a design that would restore Te Ara Tukutuku, the Wynyard Quarter point once known as the Tank Farm, in central Auckland.

Massive silos off Hamer Street are reminders of petrochemical storage in the downtown waterfront area, where soil has become contaminated with PFAS – per- and polyfluoroalkyl substances.

A ‘forever chemical’ linked to firefighting foam, PFAS has harmful effects on human health, passes through the food chain, and is found in fish, dolphins and whales.

Auckland Council’s Auckland Urban Development organisation sought input from University students on how to restore the site, so it can be used as a new public space.

Porteous’ winning design features an underground irrigation system that would distribute organic liquid compost to improve soil health at Wynyard Point.

Enriching the soil would boost beneficial microbes that would speed up the breakdown of PFAS, which is called a ‘forever chemical’ because it’s so difficult to remove from the environment.

“The irrigation system would naturally heal the site, rather than treating chemicals with more chemicals,” she says.

Her system is designed to catch rainwater from roofs and concrete, mix it with liquid compost created without oxygen, and store the nutrient-rich water in large underground tanks.

This mixture would slowly disperse through the irrigation system, enhancing soil health while reducing stormwater overflow and minimising the risk of PFAS leaching into the harbour.

“My main focus was to find a natural way to treat the chemical contamination in the soil, but I also wanted to improve climate resilience by decreasing stormwater during extreme rainfall events.

“My final design ended up addressing three things in one go – it would reduce PFAS, stormwater overflow and food waste,” she says.

Porteous’ design includes growing crops on the Wynward Point site that could be used in a restorative cycle to help create liquid compost to enrich the soil.

“Food waste from nearby restaurants could be added to the compost, turning rubbish into a resource for restoring the land,” she says.

Auckland Urban Development has praised her clever design idea, but hasn’t yet decided to implement the system.

She hopes in the future it could be installed in parks, sports grounds or housing developments, particularly in flood-prone areas or places where the soil is depleted.

“There are lots of soil health issues in Auckland and around New Zealand. The soil often lacks the minerals needed to maintain its structure, so the compost chemigation system would be great to improve the soil in those places.”

Traditional chemigation involves chemicals being pumped through irrigation systems to fertilise soil or spread herbicides. Porteous’ system could offer an alternative way to enrich soil on farms.

With her degree under her belt, she has launched into a full-time role designing concept homes, something she has been passionate about since childhood, when she would sketch imaginary dream houses.

Excelling on the football field as well as the design field, Porteous plays for the West Coast Rangers, a team that just won the Auckland Women’s Premiership and competed in the nationals.

She will give a presentation on her award-winning system at Auckland Design Week in March next year.