Innovative irrigation

Article image - Innovative irrigation City of Onkaparinga Landscape Architect, Phil Boulden inspects the kerb inlet which reduces water runoff and produces healthier street trees.

Sections of the urban landscape of City of Onkaparinga, South Australia, 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, in McLaren Flat, and have proven to be cost effective and low maintenance.

City of Onkaparinga’s Landscape Architect, Phil Boulden, said the trees and plants in the street have flourished with the extra water.

“The water infiltration zone is positioned between the trees at least three metres away, encouraging the roots to grow sideways and producing healthier trees.

“We have observed that the trees take up the water on the verge, which alleviates the risk of local saturation.”

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

Greenery is benefitting from this system in a number of locations around the city and inlets are being installed at several new sites.

“By collecting stormwater for tree irrigation purposes, we are slowing the flow of excess water into the pipe system.

“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.”