Rural Wastewater Options
Recently, Tonkin Consulting oversaw the compliance and financial audits of all Community Wastewater Management Systems (CWMS) in South Australia, to provide a snapshot of future viable options for rural communities.
Community Wastewater Management Systems were introduced to South Australia in 1962 as a lower cost alternative to the conventional sewer.
Initially developed to manage the environmental harm caused by the disposal of primary sewage to land in a largely uncontrolled and unregulated environment, they were previously known as Common Effluent Drainage Schemes (CEDS) and then Septic Tank Effluent Disposal Schemes (STEDS).
Ten years later, the introduction of a State Government assistance program led to a rapid uptake of the schemes, particularly by regional local councils.
Each scheme generally consisted of gravity drains connecting allotment septic tanks to a central treatment facility, typically oxidation lagoons. Treated effluent was disposed of through discharge to adjacent water courses and evaporation. Settled solids needed to be pumped out of septic tanks on a regular basis, so pumping stations within the collection network were the only additional capital works apart from lagoons that had to be provided.
Once in place, the local council handled the operation and management, with the Local Government Association providing subsidy administration and assistance. Today around 130,000 mostly country South Australians are connected to a CWMS.
Current Practice
The recent audit work overseen by Tonkin Consulting, shows the CWMS concept has far from outlived its usefulness. New schemes, while still extremely cost effective, are becoming relatively sophisticated and now generally include wastewater treatment plants capable of providing effluent to a standard suitable for beneficial reuse – Mount Barker in the Adelaide Hills and Berri–Barmera are two such examples. It’s more than likely that all future schemes will need to include a reuse capability, with the treated effluent replacing potable water for irrigation and some industrial purposes.
Currently, any proposed new scheme is assessed on the basis of total cost of the asset, over its design life, and the whole-of-life cost to the community for a variety of collection alternatives, including sewer.
The future is about environmental as well as economic sustainability and that track will need to be followed if funding opportunities available at both State and Federal level are to be accessed.
Tonkin Consulting did much to pioneer the CWMS concept in SA. For more information contact Gerry Doyle, Team Leader of Tonkin Consulting’s Water Resources and Wastewater Group, phone 8273 3100. |
