Different treatment levels for systems requiring land application areas
There are generally four levels of treatment:
- primary treatment
- secondary treatment
- disinfected secondary treated
Wastewater treatment units providing primary treated effluent are only suitable for:
- in-ground application by soil absorption in trenches, mounds or evapo-transpiration absorption
- seepage beds and trenches.
Wastewater treatment units providing secondary treated effluent are suitable for:
- application to land by covered surface drip systems
- application to land by shallow subsurface drip systems.
Wastewater treatment units providing disinfected secondary treated effluent are suitable for:
- all of the above methods of application
- above ground application by spray irrigation.
Wastewater treatment units, treating greywater only, providing disinfected advanced secondary treatment quality, are suitable for:
- surface spray irrigation
- toilet flushing
- cold water used for washing clothes in a washing machine.
Waterless composting toilets (WCT) are an acceptable means of treating human excreta only. Treated waste from a WCT may be buried on-site where direct access is restricted and no root vegetables are grown.
All the above options for end users of the treated wastewater are subject to the consent and approval from the permit authority (council).
Manufacturers and suppliers procedures for systems
In Tasmania, on-site wastewater treatment units including but not limited to the technologies contained within the AS/NZS 1546 series, require accreditation with Consumer, Building and Occupational Services (CBOS). This information provides guidance for manufacturers, suppliers and/or agents on the process to be followed when seeking accreditation.
On-site wastewater management systems are regulated in Tasmania under the Building Act 2016.
The installations must be designed for the specific conditions of the site and in accordance with the National Construction Code (NCC). Installations must be designed and installed by Tasmanian licensed practitioners and approved through the Plumbing Permit process.
A treatment unit that is used in the design must be accredited by the Director of Building Control.
Step 1: Determine what type of technology the unit employs, for which accreditation is being sought. Determine which Australian/New Zealand Standard (AS/NZS 1546 series) would apply to it. If the technology employed in a unit does not meet one of the AS/NZS 1546 series Standards then a custom accreditation assessment will likely be required. Contact CBOS for more information. The maximum sizing for accredited units is 10 Equivalent Persons or (10EP) and this is for domestic wastewater as defined by AS 1546.3 0217. Contact a JAS-ANZ accredited conformity assessment body (CAB) to have the system assessed and tested for compliance.
Step 2: Obtain a certificate (including the testing report) from a JAS-ANZ (CAB) certifying that the unit has been tested and is compliant with the relevant Australian Standard and NCC. Once obtained, this CAB certificate is deemed acceptable evidence of compliance, providing that the testing has been completed in climatic conditions similar to Tasmania.
Step 3: Complete the CBOS application form and submit with the relevant application fee.
Step 4: CBOS will access the application:
- Are the climatic conditions under which the testing was completed relevant to Tasmania?
- Evidence of approvals or authorisation from other Australian states or territories
- How was the unit tested if there isn't an appropriate Australian Standard?
- The performance of the unit if approved in other jurisdictions
- Is the unit based on established technology or is it a totally new technology?
- Is satisfactory information provided for the ongoing, operation, maintenance and management of the unit, and
- Details of servicing and maintenance requirements and what skills and knowledge are required to service and maintain the unit.
Step 5: A successful application may be issued with a Certificate of Accreditation and will be subject to conditions of accreditation. These conditions are requirements that the unit must meet and continue to meet for the duration of the accreditation.
Step 6: A successful accreditation is for a period of five years (subject to conditions). The accreditation document will be uploaded onto the CBOS website within the appropriate category for the technology.
On-site wastewater management system designers
In Tasmania, on-site wastewater management system designers must be licensed with CBOS.
Licensees must be aware of the scope of that licence and any limitations that may apply always work within the scope of their licence.
Licensees should only use accredited on-site wastewater treatment units within their designs unless they are a unique product. A unique product is purpose built for a particular site and not offered for sale. The approvals for such products is at the discretion of the permit authority.
Minimising risk to public health
Effective performance and management of sewage minimises risks to public health and the environment. On-site wastewater management systems collect, contain, treat and assimilate and process wastewater, human excreta, or both, so that public health and environmental standards are achieved.
Performance and management requirements will vary depending on:
- the source of the wastewater or human excreta
- the method of treatment
- effluent quality required for the end uses of the treated water.
Managing on-site wastewater management systems in Tasmania
In Tasmania, the installation of on-site wastewater management systems is managed as follows:
- The Director of Building Control assesses the results of performance testing of each treatment technology. Where satisfied that the technology meets the appropriate standard, a Certificate of Accreditation will be issued (with conditions), allowing the system to be installed and used.
- The permit authority considers applications to install or alter on-site wastewater management systems. The permit authority needs to be satisfied that the proposed system is likely to be installed and used in accordance with the conditions of accreditation.
- Systems which are purpose built for a particular site and not offered for sale, do not require accreditation and are dealt with by the permit authority.