Media used in rapid bio-filtration devices have hydraulic conductivity rates exceeding 2,500 mm/hr. Stormwater360 New Zealand has partnered with Contech Engineered Solutions (USA) to produce a rapid bio-filtration medium using locally available materials. Current bio-filtration guidance limits the hydraulic conductivity of media to less than 300 mm/hr to support plant growth. Using a short-term plant trial (3 months) and 4 ongoing plant trials (>11 months) plant growth was assessed.
In total 99 plants were grown (26 different tree, shrub and grass species), of which 91 plants (92%) and 23 plant species (88%) successfully established and grew in the rapid filtration medium.