Resources

Contamination of freshwater resources and estuaries as a result of runoff from urban development in New Zealand is threatening aquatic life. Many of the pollutants associated with urban runoff are derived from motor vehicles, and territorial and regional authorities in New Zealand have identified stormwater management as a priority environmental issue in urban areas.

While sediment and associated contaminants in road runoff can be removed by a range of treatment devices, the removal of dissolved contaminants has proved to be far more challenging. Increasing attention is being paid to the use of various filter systems, such as relatively low-cost treatment wall systems, to reduce the dissolved contaminant load in road runoff. Treatment walls are permeable barriers that allow the passage of water while removing or breaking down pollutants by employing agents such as chelators, sorbents and microbes in the barrier material (media).

Landcare Research evaluated the effectiveness of various potential filtration media for the removal of contaminants from road runoff for Transfund New Zealand (Transfund) between July 1998 and June 2004. Laboratory studies were carried out over the first two years of the contract, with subsequent testing of the most promising medium in two pilot studies at sites identified in consultation with Transfund.

Keywords: contaminants, monitoring, road, road runoff, stormwater contaminants, traffic, treatment walls