Roadway Curb By-pass System

Analysis of stormwater contamination from roads clearly identifies high levels of dissolved pollutants including oil, petrol, metals, nutrients and sediment that are creating a cocktail that is more toxic than untreated sewage. This contamination is spilling into our rivers, creeks and oceans causing substantial environmental damage.

This roadway project in Sydney, Australia is an area of predominantly clay-based sub-soils and the bay into which the stormwater drains suffers from silting and pollution. The stormwater is treated at the source by the construction of a porous road shoulder consisting of grass cells and turf. The runoff filters through the grass cells and through the reactive filter media. From there, the runoff is collected in Atlantis drainage tanks that continue the purification process and divert the water into nearby retention tanks. This water is then directed to a balancing tank and used to irrigate a nearby landscape area.

Excess filtered runoff that can’t be stored in the retention tank will be stored in detention tanks and absorbed into the surrounding soils, if the soil permeability permits. Alternatively, purified water will be discharged into the local creek.

A major factor for this infiltration project was meeting engineering design requirements for suitable compaction of the filter medium to maintain the integrity of the road surface, while maintaining optimum infiltration rates.

The system incorporates the extensive use of Ecomedia and Infiltreat, which are infiltration media that are engineered to have effective physical and biological treatment properties. Three different reactive media formulas are used to suit the specific soil and water conductivity requirements of the particular site. The formulated media contains naturally occurring micro-organisms that biologically degrade and remediate toxic chemicals that are the result of daily urban and industrial activities.

Through this process, toxic chemicals are transformed into natural and non-toxic elements. The toxic chemicals treated include PCBS, PAHS, organo-phosphates, coal tars, pesticides and herbicides. These toxins are carcinogenic to humans and their accumulation in soils and waterways are a major health and environmental concern. Some heavy metals can also be biologically degraded using Ecomedia.

Click to see full-sized diagrams: