TAS Part C4 On-site liquid trade waste systems
Introduction to this Part
This Part sets out the requirements for the on-site treatment and disposal of liquid trade waste.
Performance Requirements
An on-site liquid trade waste system must ensure—
- the risks associated with the discharge of treated liquid trade waste to the environment are minimised; and
- surface water and ground water are not polluted; and
- soil productivity is maintained or enhanced.
Health, environment and amenity protection
- blockage and uncontrolled discharge: and
- the entry of foul air and gasses into buildings.
- the safe and hygienic transferal of waste; and
- safe access for clearing blockages.
Transferal of liquid trade waste
- have appropriate treatment and storage capacity for the volume of waste and frequency of disposal: and
- be of the appropriate size, strength and rigidity for the nature, flowrates, volume of wastes, by-products and residues which must be processed; and
- have vehicle access for collection of waste, where appropriate; and
- be of an appropriate structural strength for when pedestrian or vehicular traffic is likely; and
- be constructed from materials which are resistant to water and the expected waste that will be disposed.
- contamination of drinking water, soils, ground water and waterways; and
- foul air and gasses accumulating within or entering buildings; and
- uncontrolled discharge; and
- the unauthorised access by people; and
- the entry of stormwater to the sewerage system.
- cleaning, maintenance, measurement and performance sampling provisions to the requirements of the Authority having jurisdiction; and
- the identification of the manufacturer, model, serial number and capacity after installation.
- the receiving Network Utility Operator; or
- The Authority having jurisdiction for on-site wastewater management systems.
Applications
C4P3(2)(e) does not apply in cases where a contaminated stormwater discharge of limited volume is accepted by the Network Utility Operator.
Low risk liquid trade wastes can be described as those water-borne discharges, other than sewerage, that are classified by the Permit Authority as presenting a low risk to cause harm to the environment and on-site wastewater management systems. These discharges must be trapped and partially treated before being permitted to enter the on-site wastewater management system.
Trade waste products or installations may be used if they are considered low risk.
Design, construction and installation
Deemed-to-Satisfy Provisions
Performance Requirements C4P1 to C4P3 are satisfied by complying with C4D2 to C4D19.
Application
- the Network Utility Operator (where applicable); and
- occupational health and safety; and
- dangerous goods management; and
- environmental protection.
- be capable of discharging liquid trade waste at a quality set under a Consent to Discharge issued for that equipment or system by the Network Utility Operator; and
- the sanitary drainage system must comply with:
- AS/NZS 3500.2; and
- the Network Utility Operator's guidelines, insofar as the provisions relate to the system.
Explanatory information: Cross-volume considerations
Part B1 of NCC Volume One sets out requirements relevant to the excavation of pipework adjacent to a building and footings for the purpose of installing liquid trade waste systems in Class 2 to Class 9 buildings.
General requirements
Explanatory information
Examples of low-risk trade wastes are discharges from—
- food preparation in take-away shops, restaurants, hotels, motels and the like
- laboratories in education institutions such as schools and universities
- service stations, vehicle detailing and washing.
It is the role of the Permit Authority to determine whether trade waste discharge is high-risk or low-risk when installed in areas outside the jurisdiction of the Network Utility Operator.
Location
Trade waste appliances must be fitted with covers which can withstand vehicular or pedestrian traffic or other loads likely to be imposed on them and be easily removable by one person.
Covers
Trade waste appliances must be constructed from materials suitable for the characteristics of the liquid wastes likely to be discharged.
Materials
- DN 100 riser from a disconnector gully outside a building; or
- DN 50 vent from a disconnector gully at the outlet of a non-portable appliance inside a building; or
- DN 50 vent from a DN 80 trap riser at the outlet of a portable appliance, inside a building.
Explanatory information
Sizing of trade waste ventilation should take into consideration the expected discharge volumes and cooling requirements of the specific installation.
Ventilation
- DN 50 minimum for a portable appliance with hydraulic loading up to 5 fixture units; or
- DN 80 minimum for a portable appliance with hydraulic loading greater than 5 fixture units; or
- DN 100 minimum for all other appliances.
Exemptions
Installations outside C4D7(1) may be permitted by the Permit Authority.
Connections
- be constructed of mild steel plate, minimum 3 mm thick with 4 rows of 10 mm diameter holes at 25 mm centres: and
- be hot dipped galvanised after fabrication.
Explanatory information
See TAS Figure C4D8 for a typical silt pit.
Silt pits
- be constructed of mild steel plate, minimum 3 mm thick with 5 rows of 10 mm diameter holes at 25 mm centres; and
- be hot dipped galvanised after fabrication.
Explanatory information
See TAS Figure C4D9 for a typical silt trap.
Silt traps
- be constructed of mild steel wire with a minimum diameter of 2.5 mm woven to give 7 mm aperture widths on a 32 mm x 32 mm x 25 mm angle iron frame with mitred corners; or
- be constructed from minimum 3 mm thick mild steel plate, with 6 holes at 12 mm centres over the entire area of the basket; and
- be hot dipped galvanised after fabrication.
Explanatory information
See TAS Figure C4D10 for a typical straining pit.
Straining pits
- be constructed of mild steel wire with a minimum of 2.5 mm woven to give 7 mm aperture widths on a 32 mm x 32 mm x 25 mm angle iron frame with mitred corners with a top frame of welded angle iron; or
- be constructed from minimum 3 mm thick mild steel plate, with 6 mm holes at 12 mm centres over the entire area of the basket; and
- be hot dipped galvanised after fabrication.
Explanatory information
See TAS Figure C4D11 for a typical straining trap.
Straining traps
- mild steel plate; or
- other authorised material.
- minimum 100 mm concrete walls with a smooth internal finish; and
- have suitable reinforcing mesh within the concrete.
- be constructed of an authorised material; and
- provide adequate structural support.
Exemptions
Where the Permit Authority has not specified the capacity of a grease interceptor in accordance with C4D12(5), it must be—
- equivalent to the maximum hourly discharge; and
- no less than 250 litres below the outlet.
Explanatory information
- The contents of a grease interceptor may become slightly acidic. It is recommended that the internal concrete surfaces below the outlet level be provided with an acidic resistant lining.
- Where the grease interceptor is installed outside a building, consideration should be given to fitting airtight covers.
- See TAS Figure C4D12 for a typical grease interceptor for above ground installations.
Grease interceptors
- 6 mm unplasticised polyvinyl chloride (PVC-U); or
- 0.79 mm galvanised sheet steel; or
- 0.63 mm copper sheet; or
- 0.63 mm of 316 stainless steel; or
- Other authorised material.
- be extended to open air; and
- comply with AS/NZS 3500.2.
Exemptions
Where the Permit Authority has not specified the capacity of a grease interceptor in accordance with C4D13(1), it must be—
- equivalent to the maximum hourly discharge; and
- no less than 100 litres below the outlet.
Explanatory information
See TAS Figure C4D13 for a typical portable grease interceptor appliance.
Portable grease interceptor appliances
- two DN 100 vents in addition to the ventilation provided for the sanitary drainage system; or
- appropriate mechanical ventilation.
- a minimum of DN 50: and
- connected to the outlet of the grease trap chamber.
Explanatory information
See TAS Figure C4D14a and TAS Figure C4D14b for typical venting arrangement for grease trap chambers.
Venting of grease traps
Grease traps in multi-storey buildings must have a reflux valve installed between the outlet and connection to the sanitary plumbing system.
Explanatory information
See TAS Figure C4D15 for a typical installation of a grease trap in a multi-storey building.
Grease trap installation in multi-storey buildings
- 6 mm mild steel plate; or
- other authorised material.
- be extended to open air; and
- comply with AS/NZS 3500.2.
Exemptions
Where the Permit Authority has not specified the capacity of an oil and petrol interceptor in accordance with C4D16(1), it must be no less than 11400 litres, below the outlet.
Explanatory information
See TAS Figure C4D16 for a typical oil and petrol interceptor appliance.
Oil and petrol interceptors
- 6 mm PVC-U sheet; or
- 0.63 mm acid resistant stainless steel all welded construction; or
- other authorised acid and alkali resistant material.
- the diameter of the outlet pipe being at least one size larger than the inlet pipe (i.e. DN 65 inlet - DN 80 outlet); or
- where the inlet pipe is DN 100, the diameter of the outlet may be DN 100.
- enables ready access for maintenance and inspection; and
- provides ready access for fitting of the cement mortar test block; and
- enables ready access to the sampling valve; and
- provides ready access for replacement of the marble chips.
- be surrounded with concrete walls and base with a minimum thickness of 100 mm; and
- omit the 25 mm sampling valve; and
- have a minimum DN 100 outlet pipe located no deeper than 600 mm below surface level; and
- have the outlet pipe connected to a disconnector gully fitted with a loose fitting grate or screwed cap.
Exemptions
The requirements of C4D17(4) does not apply to existing systems.
The capacity of an acid neutralising tank as shown in Tas figure C4D17 is the minimum requirement of 27 litres between the marble chip level and the outlet level.
Explanatory information
See TAS Figure C4D17 for an acid neutralising tank.
Acid neutralising tanks
- 6 mm PVC-U sheet; or
- 0.63 mm acid resistant stainless steel all welded construction; or
- other authorised acid and alkali resistant material.
- DN 100 when the pipe inlet size is DN 100; or
- a minimum of one size larger than the inlet pipe.
- enables ready access for maintenance and inspection; and
- provides ready access for fitting of the cement mortar test block; and
- enables ready access to the sampling valve.
- be surrounded with concrete walls and base with a minimum thickness of 100 mm; and
- omit the 25 mm sampling valve; and
- have a minimum DN 100 outlet pipe located no deeper than 600 mm below surface level; and
- have the outlet pipe connected to a disconnector gully fitted with a loose fitting grate or screw cap.
Exemptions
The minimum capacity requirement of a typical mixing tank in accordance with C4D18(1) is 100 litres.
Explanatory information
See TAS Figure C4D18 for a typical mixing tank.
Consideration should be given to a mixing tank being provided with adequate structural support.
Mixing tanks
- 6 mm unplasticised polyvinyl chloride (PVC-U); or
- 0.79 mm galvanised sheet steel; or
- 0.63 mm copper sheet; or
- 0.63 mm 316 stainless steel; or
- other authorised acid and alkali resistant material.
- DN 100 when the outlet size is DN 100; or
- a minimum one size larger than the inlet pipe.
- be surrounded with concrete walls and base with a minimum thickness of 100 mm; and
- omit the 25 mm sampling valve; and
- have a minimum DN 100 outlet pipe located no deeper than 600 mm below surface level; and
- have the outlet pipe connected to a disconnector gully fitted with a loos fitting grate or screwed cap.
Exemptions
Where the Permit Authority has not specified the capacity of a settling tank in accordance with C4D19(1), it must be—
- equivalent to the maximum hourly discharge; and
- no less than 72 litres, below the outlet.
Explanatory information
See TAS Figure C4D19 for a typical settling tank.
Settling tanks