Appendix C: Gross Pollutent Generation and Treatment

Introduction

Gross pollutants form a significant part of the total amount of pollutants deposited in urban catchments in Australia. Allison et al. (1998) estimated that the total wet mass of gross pollutants deposited within Melbourne amounts to 60,000 tonnes annually. As well as reducing aesthetic values in the catchment, these pollutants play a significant role in disturbing physical habitats and degrading water quality within the waterway.

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Allison et al. (1998) sampled gross pollutants during storm events within an urban catchment in Coburg, which is a suburb of Melbourne. The catchment had an area of approximately 150 ha, with a mixture of land uses including, residential, commercial/residential and light industrial. The conclusions from this sampling indicated that:

As part of their study, Allison et al. (1998) collected data on the amount of gross pollutants collected during ten clean-outs of a CDS gross pollutant trap device in Melbourne. A total of 13 rainfall events occurred during the ten clean-outs of the CDS device. The device was located at the outlet to a 50 ha catchment in Coburg. As with the previous sampling, organic matter constituted the largest component of the gross pollutants collected in the CDS device.

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