Dutson Downs is located 20km south-east of Sale and consists of over 8,000 hectares of land. Dutson Downs was established in 1954 by the former Latrobe Valley Water and Sewerage Board (now Gippsland Water).
One of Gippsland Water's major wastewater and waste management assets is the Dutson Downs Resource Recovery Facility. The Resource Recovery Facility (RRF) consists of 3% of the land within Dutson Downs and is licensed by EPA to receive industrial wastes including those associated with water and wastewater services.
The waste management operations within the RRF include:
- liquid and sludge waste treatment and bioremediation;
- open windrow composting of biosolids;
- landfilling of oil contaminated sludges;
- emplacement of chromium contaminated tannery wastes in engineered landfill area;
- emplacement of asbestos in designated landfill area;
- fixation of oily sludges containing naturally occurring radioactive materials (NORMS);
- treatment and land filling of low level hydrocarbon and oil contaminated soils;
- industrial and domestic wastewater treatment.
The following provides a summary of these waste management activities at the RRF of Dutson Downs:
Industrial liquid waste treatment – bioremediation pond
All biodegradable liquid waste is delivered to the bioremediation pond for disposal. These wastes are transported in sealed road tankers and each load delivered to Dutson Downs is subject to an EPA transport permit.
The treatment system at the bioremediation pond is similar to the sewerage wastewater lagoons. The process of waste treatment includes biological digestion with the micro-organisms breaking down the organic matter to produce a stable sludge that settles to the bottom of the pond.
The bioremediation pond is lined with clay which has a permeability of 10-9 metres per second, which is deemed by the EPA as an adequate barrier to prevent liquids leaching away from the contained area.
On an annual basis, this pond treats 20,000 kilolitres of biodegradable liquid waste that the EPA classifies as prescribed waste . A majority of this organic waste (approximately 50%) is now proposed to be recovered and composted for reuse at the Soil and Organic Recycling Facility proposed by Gippsland Water at Dutson Downs.
Biosolids - composting
The solids and screenings from Gippsland Water's water and sewerage treatment plants are delivered to Dutson Downs for further treatment and disposal. Gippsland Water has been undertaking trials to compost this material using other organic waste such as sawdust and green wastes. This process includes windrow composting to encourage micro-organisms to devour the organic matter to produce an inert product. This may then be spread directly onto land as a soil conditioner.
Treatment plant sludge, called biosolids, is generated within Gippsland at a rate of 40 to 50 tonne per week. This material is now proposed to be composted by Gippsland Water's Soil and Organic Recycling Facility proposed at Dutson Downs.
Contaminated soil disposal
Soils contaminated with hydrocarbons and other organic contaminants are taken to Dutson Downs for disposal. Old petrol stations or industrial sites that are being remediated to allow the land to be used for other developments often require that contaminated soils are removed. Soils can become contaminated from spillages or from leakages from underground storage tanks.
These soils are currently treated at Dutson Downs using natural biological processes before being disposed to waste cells as a cover material. Gippsland Water is now proposing to treat these soils at the Soil and Organic Recycling Facility.
Chromium cells
Waste containing chromium salts are a by-product of the tannery process at leather tanneries. The residual material is transported to Dutson Downs for disposal in single, dedicated storage cells. Each cell has a compacted clay base, a bentonite clay geotextile liner and a plastic liner to ensure an adequate barrier between the cell and surrounding environment is provided to prevent leaching of water into the groundwater.
When full, the cell is capped with clay and the location is recorded via GPS on a site plan as a permanent record and a new cell is then constructed.
Hide and hair
Hide and hair is waste material trimmed off hides during the tanning process. Approximately 1,600 tonne per annum of tannery waste, which is mainly biodegradable, is disposed in a dedicated cell. As this material is bio-degradable it is of low risk to the environment and Gippsland Water is investigating how this material can be incorporated into composting.
Asbestos landfill site
Asbestos waste transported from industrial sites or from commercial contractors is taken to Dutson Downs for disposal in the asbestos cell which is clay-lined. Domestic asbestos is not received at this facility. The asbestos is transported in accordance with EPA transport requirements which includes being double wrapped in a heavy black plastic. The wrapped asbestos is placed in the cell and immediately covered with fill material to ensure no exposure to the environment.
This asbestos landfill also accepts synthetic mineral fibre (SMF) and ceramic based fibre which is handled and disposed of using similar methods to asbestos.
Oily sludges
Oily sludges are generated by ESSO from its offshore oil drilling operations. After initial treatment at ESSO, the wastewater is piped to Dutson Downs for further treatment and disposal. The sludge residuals are transported to Dutson Downs once a year over a period of a few months.
These sludges contain naturally occurring radioactive material (NORM) which are first treated in a fixation plant specifically designed for this purpose. At this stage the sludges are 'locked' into the supporting material of cement and lime to prevent them escaping. The final treated product is then buried in highly engineered landfill cells with multiple bentonite clay and high density polyethylene liners and leachate monitoring. |