Integrated Stormwater Treatment at an Auckland Commercial Development
Project Objective:
The client’s objective was to maximise land yield across a large shopping centre and adjoining carpark in Auckland, while meeting regulatory requirements and achieving robust water quality outcomes. Given the site’s commercial scale, space efficiency, and high-performance treatment were essential.
Stormwater Strategy:
To balance performance with spatial constraints, an integrated Green Infrastructure solution was selected. This approach delivered superior pollutant removal while aligning with modern, sustainable design standards.
Treatment Train Overview:
The site was divided into two primary catchments, each with a tailored system to address both gross pollutant removal and fine filtration.
Catchment 1 – 32,371 m²
Cascade Separator™ CS6 (pre-treatment / Gross Pollutant Trap)
125m² Filterra® Bioscape® (bioretention for fine pollutant removal)
Catchment 2 – 39,243 m²
Cascade Separator™ CS6 (pre-treatment / Gross Pollutant Trap)
150m² Filterra® Bioscape®
The Cascade Separator™ removes gross pollutants, sediments, and floatables upstream, while the Filterra® Bioscape®provides high-performance bioretention, consistently removing TSS, nutrients, metals, and hydrocarbons.
LittaTrap™ Deployment:
Key Outcomes:
Maintenance:
Filterra® Bioscape® is simple and low-cost to maintain, with a 6-monthly replacement for the mulch layer. This can be done by hand maintenance or by a vactor truck to suck up the mulch, and then a mulch blower to reapply the mulch.
Cascade Separator™ follows an inspect-to-maintain service, ensuring the system remains fully functional with minimal maintenance required between service intervals.
LittaTrap™ can be maintained by hand or by a vactor truck. Hand maintenance is simple; Lift the LittaTrap™, Tip out the LittaTrap™ into a rubbish bin and then simply replace the LittaTrap™ back into the drain.
Conclusion:
