- SITE
- Sylvia Park, Sylvia Park commercial retail centre, Auckland, NZ New Zealand
- ENGINEERS
- SKM NZ
- CONTRACTORS
- Ross Reid Contractors
Design
Management of Storm water contamination at Sylvia’s park has been undertaken by a Treatment train approach using the Enviropod and Storm filter.
The Enviropod is a catch pit insert with a 200 micron screen. It is designed to sit in the catchpits screening out over 50% of the contaminant load before it reaches the stormfilter
The Stormfilter comprises of a vault holding numerous stormfilter cartridges. The stormfilter cartridge is a siphoned radial filter cartridge, filled with various types of filter media depending on the targeted contaminants
ZPG media is used in the Storm filter cartridge. ZPG is a combination of Zeolite perlite and Granular activated carbon. ZPG filter media was chosen because of its ability to absorb dissolved heavy metals and PAH, which are likely to occur on the site because of the high traffic loading.
The treatment train has been modelled in a design package called music (the model for urban stormwater improvement conceptualisation). This estimates a 91% removal of Total Suspended Solids. It is estimated that this media combination treatment train will remove over 40 - 60% of copper, lead and zinc, the principle heavy metals of concern.
Maintenance
With on-going maintenance responsibilities lying with site owners Kiwi Income Property Trust, maintenance cost and cleaning frequency were key design factors. The treatment-train approach greatly reduced the maintenance frequency of system. The treatment-train targets different contaminants with alternate devices. The EnviroPod targets gross pollutants and sediment, the StormFilter targets fine sediment and dissolved metals. The EnviroPod removes over 50% of the sediment before it reaches the StormFilter, preventing the ZPG media from clogging with sediment, prolonging the cation exchange properties of the media. Extensive research has been undertaken on the load capacity of each StormFilter cartridge, this allows Ingal to accurately estimate maintenance Frequencies. Maintenance frequency is largely influenced by surface area. The cartridge configuration of the StormFilter gives a verylarge surface area for filtration. The Sylvia Park StormFilter design had similar surface area than a conventional sand filter while having a ¼ of the overall plan foot print.