The Hydrology and Hydrochemistry of an Artificial Turf Field: a longitudinal case study at Ellerslie, New Zealand

Abstract

This study aimed to investigate temporal change in toxic leaching from a newly-installed crumb rubber-based artificial turf field at Ellerslie Football Club in Auckland, New Zealand over a 28-month period. Rainfall and stormwater discharge at the site was monitored and an automatic sampler collected flowproportional samples during storm events. These were tested for a leachate suite of 15 heavy metals using standard ICP-MS analysis. Thirty-four storm events were sampled over the 28-month monitoring period. Metals were examined for temporal change and correlation was made between metals to assess relationships. Event mean concentration and mass first flush were calculated for all storm events. Two different flow pathways were observed, ‘runoff’ flow from infiltration through the artificial turf pitch and ‘washoff’ flow from infiltration excess and an adjacent concrete path. Washoff flow had higher peak flow rates and higher concentrations of metals suggesting the artificial turf field sub surface acted to filter contaminants and delay the rate of stormflow. In contrast to other studies of artificial turf fields copper was observed to be the main contaminant of concern, rather than zinc, with 87% of all samples exceeding ANZECC 80% thresholds for species survival. Three other metals, (aluminium, iron and zinc) were observed at concentrations that exceeded local guidelines for ecotoxicity for parts of the monitoring period. For the first three months both copper and zinc loads were comparable with heavily trafficked road surfaces (greater than 20,000 vehicles per day), which would result in the field being labelled a high contaminant generating activity under local government rules. Mass first flush results were metal and event specific. Applied at the scale of the monitoring period, following mass first flush methodologies, a ‘Land-Use First Flush’ can be observed for the artificial turf field as all metals exhibited a two to three order of magnitude decrease over time.