SUSTAINING PLANT LIFE IN HIGH HYDRAULIC CONDUCTIVITY MEDIA

Josh Daken, R&D Assistant, Julia Watson, R&D Engineer, Kevin Jonathan, Senior Engineer - Stormwater360

POSTER ABSTRACT

Media with high hydraulic conductivity is often considered unsuitable for plant life. This study focuses on sustaining plant life in high hydraulic conductivity given that the plants' role in biofiltration is to uptake pollutants and nutrients and rejuvenate the soil. Rapid filtration media with a hydraulic conductivity of 4445mm/hr exceeded the GD01 recommended rate of 500mm/hr for standard TP10 rain garden mix.

This research involved comparing growth rates and moisture retention of sets of plants in the rapid filtration media and the TP10 mix. Tap water and stormwater sourced from a local catchpit watered the plants biweekly to simulate natural weather in a controlled environment.

• The TP10 plants grew 18.25% over three months, with the rapid filtration media plants growing 5.29%. Both soils retained enough water to sustain stable plant growth, with only two of the eight initial plants showing decay: Carex Virgata in the rapid filtration media and Libertia Grandiflora in the TP10 mix.

Critically, the rapid filtration media required no weeding and little maintenance compared to the TP10 rain garden, which consistently grew large weeds.

Despite possessing a high hydraulic conductivity, plant life can grow and thrive in rapid filtration media with low maintenance, providing cost-saving, space reduction, and environmental conservation benefits.