Water Sensitive SA

Engaging communities in stormwater management

Engaging communities in stormwater management

20 May 2020

Innovative irrigation

Sections of the City of Onkaparinga’s urban landscape are flourishing after the installation of a stormwater reuse system for tree irrigation.

To make use of stormwater runoff, TREENET kerb inlets are being connected in areas where Council is undertaking streetscape improvements or rebuilding the kerbing.

Water that runs along the road’s kerb flows into an inconspicuous grate attached to a concealed collection pit in the verge. The detained water then soaks into the soil in the nature strip and passively feeds the roots of street trees. When it rains there is sufficient flow for the tree inlets to collect stormwater while simultaneously excluding leaves and other street debris.

Stormwater inlets were first installed about 10 years ago on Main Road, McLaren Flat, and have proven to be cost effective and low maintenance. The trees and plants in the street have flourished with the extra water, says the council’s Landscape Architect Phil Boulden.

“The water infiltration zone is positioned between the trees at least three metres away, encouraging the roots to grow sideways and producing healthier trees,” Phil says. “We have observed that the trees take up the water on the verge, which alleviates the risk of local saturation.”

The installation of the reuse systems presents an opportunity to plant new trees, further greening the region.

Greenery is benefitting from this system on Kangarilla Road in McLaren Flat, on Morton Road in Christie Downs, and on Alexander Kelly Drive in Noarlunga Centre. New inlets are being installed in Morphett Vale on Dalkeith Road, Argyle Avenue and Braemar Avenue, and in Happy Valley on Barcelona Drive.

“By collecting stormwater for tree irrigation purposes, we are slowing the flow of excess water into the pipe system,” Phil says. “The trees are absorbing some of the pollutants from the urban area that would otherwise be running out to the ocean.

“Healthier, happier trees are resulting in increased tree canopies. In turn, our city is cooled, contributing to the health and wellbeing of residents and saving energy resources.”

Council have also produced a pamphlet for residents that explains the benefits of the new stormwater reuse system, entitled Every drop counts.

Story credit: Onkaparinga Now City of Onkaparinga

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