2002-2005 Coramba (NSW) Benzene
The primary action taken from the beginning of the issue was to protect the drinking water supply. After May 2002 low levels of benzene were detected in the drinking water supply which was consequently disconnected by the Coffs Harbour City Council in consultation with NSW Health. Tanker trucks transported over 6 million litres of drinking water from Red Hill Reservoir to Coramba over a period of 2 months.
The second key risk management strategy was establishing regular communication between agencies involved in the issue. Regular teleconferences and meetings were implemented to strengthen communication. The third main strategy was to maintain communication with residents and the general public. Coffs Harbour City Council created a webpage providing transparency to the issue by releasing information about test results and any new developments arising.
2002
On 12 June 2002 Council established a new water intake upstream from the contamination site. On 18 June 2002, 2.0µg/L benzene was detected in the newly established drinking water supply. Levels of 4.0 µg/L benzene were recorded on 24 June 2002. Water pumping was ceased and water carting commenced once more.
A successful pre-treatment drinking water plant was constructed, operating between August 2002 and January 2005. Water was treated by aeration and ‘activated carbon’ – charcoal treated with oxygen. The charcoal adsorbs (attachment by chemical attraction) odorous materials and other carbon-based impurities.
2005
In 2005 Coramba ceased sourcing and treating drinking water from the Orara River and established a connection to the Regional Water Supply from the Nymboida River. The Karangi Dam is connected to this supply as a reserve when the water quality of the Nymboida River is unsuitable for use.
The Coramba Fuel Contamination Interagency Community Working Party was created in December 2006 as a joint collaboration with the OEH (Office of Environment and Heritage), NSW Department of Health, Council, Premier’s Office and community members to work on ways to remediate the land.
Based on health considerations the concentration of benzene in drinking water should not
exceed 0.001 mg/L.
GENERAL DESCRIPTION
Benzene is a clear, colourless-to-yellow liquid and highly flammable aromatic hydrocarbon. It is presentin petroleum products such as motor fuels and solvents, and motor vehicle emissions constitute the mainsource of benzene in the environment. Benzene occurs naturally in crude oil and coal and is an additive and a by-product of oil-refining processes. It constitutes approximately 1-2% of unleaded gasoline by volume (US DHHS, 2011). Tobacco smoke is another significant source of exposure (WHO, 2010). It also occurs in natural gas and emissions from volcanoes and forest fires.
Human exposure to benzene occurs primarily through inhalation (WHO, 2010). When released to surface waters, benzene rapidly volatilises to the air (WHO, 2010). Benzene is not persistent in surface water or soil and either volatilises to air or is degraded by bacteria under aerobic conditions (WHO, 2010). For water contamination, benzene is therefore of most concern in groundwater. Benzene can also occur in foods and drinks as a product of the reaction between benzoate and ascorbic acid, and has been found in soft drinks in the UK at concentrations as high as 0.028 mg/L (FSA, 2006).
Benzene is also used widely as an industrial solvent by the chemical and pharmaceutical industries in theproduction of styrene/ethylbenzene, cumene/phenol and cyclohexane. The use of benzene as a solvent has been greatly reduced in recent years. Unlike other petroleum hydrocarbons such as ethylbenzene, toluene and xylene the odour threshold for
benzene is relatively high at 10 mg/L (WHO, 2003). ADWG 2011