Station Bay is a boutique residential subdivision just outside the Lake Tekapo township, developed by Covington Group. Stringent water quality requirements were set by ECAN for this high-profile development. The team at Davis Ogilvie, Timaru, were tasked with the stormwater management design for the 5.1-hectare first stage of the development.
Due to the proximity of the lake a green infrastructure solution was considered essential. Davis Ogilvie approached Stormwater360 to explore treatment options, and whether a Filterra® Bioscape would provide benefits over a conventional rain garden design. Stormwater360 worked together with all parties through design to installation to ensure the highest of quality standards throughout the whole process.
Treatment Performance
When comparing the Filterra® Bioscape to a conventional rain garden, the footprint can be minimised due to the high infiltration rate of the engineered media used.
This media is made in New Zealand, undergoing over 25 quality assurance tests to ensure quality and performance. The Filterra® media is approved for an infiltration rate of 2540mm/hr (can be designed up to 4445mm/hr), conventional rain gardens typically have an infiltration rate of approx. 300mm/hr.
With stringent water quality requirements set by ECAN for this development, effective stormwater treatment was vital to protect the pristine water of Lake Tekapo.
Stormwater360 delivered a truly outstanding solution for the protection of the local water environment
Jonathan Speedy - Development Manager, Station Bay, Covington Group
Biological treatment to remove contaminants
The designed Filterra® Bioscape footprint of 165m2 is approximately 1/8th of the size of the conventional system required to treat the same catchment area (rain garden footprint approx. 1,280m2). Minimising the footprint allowed for an additional 3 lots to be developed, and decreases the time and costs for maintenance.
Using pre-treatment upstream of a filtration device in a treatment train approach is considered best practice. A pre-treatment device will remove most of the coarser sediment and gross pollutants, ensuring the performance and maintenance frequencies of the filtration device are optimised. Two Cascade separator™ systems were used to provide upstream pretreatment for the Filterra® Bioscape.
The Cascade Separator™/Filterra® Bioscape treatment train should ensure this large development does not impact the pristine nature of Lake Tekapo.
