Attachment 4 - Stormwater Managment Plan

The objective of this paper is to share data regarding wastewater discharges, as well
as contaminant levels in solid and liquid wastes. This report presents the overall
findings of several studies undertaken by ACWA and others and includes the results
of water quality testing of effluent of professional car washes and studies where
effluent from street car washing was collected.

Stormwater is the water that is collected in drains from street runoff carrying with it
a range of pollutants including sediments, pathogens, nutrients, hydrocarbons, heavy
metals and chemicals from various activities. These pollutants are deposited into
rivers, estuaries and bays with no treatment and significantly degrade river, estuary
and bay water quality and aquatic habitat.

The impacts of stormwater are cumulative in that thousands and thousands of
individual sources of pollution are combined to cause this contamination.

The information presented in this paper is a collection of the information in the
sources quoted at the end. The findings of these studies and the conclusions of this
paper show that waste wash water from residential car washing is a considerable
source of stormwater pollution. It also demonstrates that any single uncontrolled
residential car wash activity might be inconsequential with respect to its contribution
to the pollutant load being delivered to stormwater, however, when extrapolated
over an urban area for a year, the pollutant loading becomes very significant.

This paper gives an indication of the impact of home car washing across the whole of
Australia.

The critical pollutants are summarised as follows;

      Petroleum hydrocarbon waste: gasoline, diesel, and motor oil
      Total Organic Carbon
      Copper
      Lead
      Zinc
      Surfactants
      Suspended Solids


Often society has been slow to recognize the link between individual behaviours and
practices, and the detrimental impacts that they may have on our natural aquatic
resources. Home car washing is one of these. In some instances, car washing is
carried out on lawns, which allows for the infiltration of the wash water. However, in
most cases, it is performed on impervious surfaces where the wash water drains
directly into the stormwater system.


The following is a brief discussion concerning several of the crucial pollutants
detected, the calculated annual pollutant loading for Australia as a whole, with it’s
consequential impacts water quality. Notable in the ACWA studies is the impact of
reduced volume of car washing during drought restrictions so both drought and non
drought conditions are quoted. The volumes and concentrations shown here are as
they leave the car.



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