Gas manufacturing plants, known as gasworks, used to produce town gas for heating, lighting and cooking. Gas was generated by heating coal. The resulting gas was captured, piped off and used as fuel.
Most NSW gasworks commenced operation in the late 1800s. With the introduction of alternative fuel sources, many began to be phased out in the 1960s. The last known operating gasworks in NSW was decommissioned in the mid-1980s.
The operation of gasworks throughout NSW has left a legacy of soil and groundwater contamination, in some cases extending to adjoining sites. The major contaminants include tars, oils, hydrocarbon sludges, spent oxide wastes, ash and ammoniacal recovery wastes. While many of these materials were recycled or reused, it was common for some to be buried on or near the gasworks site (for instance in underground tar wells, liquor wells, pipes and purifier beds) and not removed when the gasworks were decommissioned.
Some of these contaminants are carcinogenic to humans and toxic to aquatic ecosystems and so may pose a risk to human health and the environment. As a result, many former gasworks sites will require remediation before they will be suitable for sensitive land uses, such as housing.