Remediation work valued at approximately $100M is being undertaken by Thiess Services in Homebush Bay and at the ten hectare former Lednez/Union Carbide site on the Rhodes Peninsula, Sydney, NSW.
During the project, Thiess Services is closely consulting with State Government departments including the Department of Environment and Climate Change (DECC), the Department of Commerce, the Department of Health and the Department of Planning. Stringent health and environmental standards have been set for the project.
The former Lednez/Union Carbide site became contaminated as a result of its long-time use for chemical manufacturing, including the manufacture of pesticides. Lime and ash waste containing chemical residues was used to fill foreshore areas of the site and of the neighbouring site, owned at the time by the Allied Feeds company. As well as contaminating the land-based sites, this form of land reclamation resulted in contamination spreading into Homebush Bay. Consequently, sediment from the most contaminated areas of the bay is being removed as part of the Lednez/Union Carbide Project.
The principal contaminants of concern are dioxins, by-products of the chemical manufacturing process. Thiess Services’ work includes the staged excavation and classification of soil and sediment, treatment of contaminated material using a thermal method, and the re-instatement of material on site that meets the soil re-use criteria. The soil re-use criteria have been developed to protect both human health and the environment. A Site Auditor accredited by DECC approved the criteria.
The quantity of material to be excavated for the project is approximately 360,000 cubic metres (~540,000 tonnes) of soil from the dry land site and some 37,000 cubic metres (~46,500 tonnes) of sediment from Homebush Bay.
Removal of organic contaminants from the soil and sediment will be undertaken on site using a Directly Heated Thermal Desorption (DTD) unit. It is estimated that approximately 105,000 tonnes of material will require DTD treatment.
The State Government acquired the site in 1999 from the Lednez company (formerly the Union Carbide company). Once remediated, the site will provide a safe location for the development of public open space with direct access to the waterfront and private residential apartments.
Thiess Services established the site in May 2005 and excavation work commenced in December of that year. The project is scheduled for completion in July 2009.