Stormwater retention performance of tree integrated infiltration trenches designed for suburban streetscapes

• Published in: The Science of the total environment 2024-12, Vol.954, p.176634, Article 176634
• Main Authors: Hanley, Paul A., Livesley, Stephen J., Fletcher, Tim D., Grey, Vaughn, Szota, Christopher
• Format: Article
• Language: English
• Subjects: Peak flow reduction; Runoff retention; Stormwater control measure; Structural soil; Tree health; Urban forestry
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.176634

The volume of stormwater generated by streetscapes in cities is a primary driver of urban stream degradation. Large infiltration trenches can be integrated into streetscapes to potentially retain large volumes of runoff and increase growth rates of nearby trees. To test this, a field study was conducted where three structural soil infiltration trenches receiving runoff (12 m long, 0.6 m wide and 0.6 deep) were installed alongside a carpark in Melbourne, Australia, with sizing determined by space constraints in a typical streetscape. The three structural soil trenches had raised outflow drainage, which created internal water storage for runoff received from a carpark. To separate the effects on tree growth of i) the presence of structural soil from ii) passive irrigation into the structural soil, three structural soil trenches (6 m long, 0.6 m wide and 0.6 deep) not receiving runoff and without outflow drainage were also installed. Runoff capture, exfiltration, outflow and tree growth was monitored over 19 months. Only one system performed close to the design intent and retained 18 % of runoff, due to slow soil exfiltration rates (