Effective Monitoring and Assessment of Contaminants Impacting the Mid to Lower Yarra Catchments: A Temporal Scale Assessment
(2008 – 2010)
Melbourne Water invests around $60 million a year to protect and improve the health of Melbourne’s rivers and creeks. Among others, and in cooperation with EPA Victoria, one aim is to improve water quality conditions of Melbourne’s iconic River, the Yarra. As a first step towards water quality improvement, it was necessary to characterise pollution levels from stormwater discharges into the Yarra.
Indeed, characterising pollutant levels from urban stormwater drains during dry and wet weather periods is important for a number of reasons, including:
- assessing and improving WSUD treatment technologies;
- assessing the effects of stormwater runoff on downstream systems; and
- for modelling purposes.
However, in order to accurately characterise pollutant loads and concentrations, representative monitoring methodologies must be used. Indeed, the adequacy of some commonly used sampling methods (such as ‘grab sampling’) is dependent on a number of factors, including: the pollutant’s variability (both spatially and temporally), the frequency of sampling and the corresponding time period being characterised (i.e. daily, weekly, monthly or annual loads).
While EPA Victoria undertook a sampling program to assess the spatial variability of pollutants in the lower and Middle Yarra, this project investigated the temporal scale variability of pollutants entering the Yarra River:
The outlet pipes of nine urbanised catchments (3 residential, 3 industrial and 3 commercial) were monitored during both dry and wet weather periods. Analysis of results showed that most pollutant levels varied between catchments (i.e. from one catchment to another), temporally within catchments (i.e. from one sampling time to another at the same location) and temporally during wet weather events (i.e. pollutant concentrations vary over the hydrograph). This information contributed to an increased understanding of the temporal variability for bacterial, heavy metal and Total Petroleum Hydrocarbon contaminants leaving different drainage systems during dry and wet weather periods. The water quality results gathered during this study can also be used to help improve the sampling design of future bacterial and toxicant pollutant investigations.
McCarthy D.T., Bratieres K. and Lewis J.F. (2010) Effective monitoring and assessment of contaminants impacting the mid to lower Yarra catchments: a temporal scale assessment. Monash University, Australia. PDF (5.9 MB)
McCarthy D.T. (2010) Effective monitoring and assessment of pollution types and loads entering the drainage system from commercial areas. Monash University, Australia. PDF (1 MB)
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