Investigation into the performance of first flush systems for diesel engine based pollution on roof runoff

Abstract

[Abstract]: Ergon Energy has approximately 30 diesel power stations which generate electricity in isolated communities throughout Queensland. At most of these sites, rainwater tanks are located adjacent and provide water for domestic purposes to the workers’ camp. The water has long been suspected of contamination, although it has not previously been tested. The objective of this study is to assess the quality of the collected water and consider any health risks in accordance with the Australian Drinking Water Guidelines. Following initial testing, first flush devices were installed with the aim of measuring any improvement in water quality. The study considered 25 different metals, total petroleum hydrocarbons (reported in four different carbon fractions), heterotrophic plate count and Escherichia coli contamination in the water. The study also included testing for polycyclic aromatic hydrocarbons which were determined to be the most likely contaminant to cause failure to comply with Australian Drinking Water Guidelines at these sites. Twenty-three different polycyclic aromatic hydrocarbons were considered, both in the collected water and the dry buildup of contaminants on the roof. The study investigated the effects of variable parameters such as rainfall patterns, wind speed and direction, materials used in rainwater goods and detention time. The results clearly indicated that the stored water is unfit for domestic purposes and should not be consumed. Metals concentrations were the main cause of non-compliance with Australian Drinking Water Guidelines. In most cases the study was not able to clearly define whether these contaminants originate from diesel particulate matter. The first flush devices had little effect on harvested rainwater quality in comparison to other parameters. Further testing would be required to assess possible health risks if rainwater harvesting is to continue at these sites, however sufficient data does exist to warrant their removal.