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The wastewater from mechanical workshops can contain contaminants such as fuels, solvents, heavy metals, battery acids, flammable substances, caustic cleaners, coolants, paints, fillers, grit and residue. If not properly managed, this wastewater can pollute our waterways, damage our sewer systems and wastewater treatment facilities and affect the health and safety of sewerage system workers.
You will need to determine what best suits your business. Outlined below are the options for the treatment and disposal of liquid wastewater generated by your business.
A dry process means the work area is not connected to sewer or stormwater systems and the workshop operates without a floor drain or wash bay. This method poses the least risk to the sewerage system and saves you the cost of complying with our minimum standards for pre-treatment.
The business must:
Any business where liquid waste is generated from a trade or manufacturing process and then released to a sewer system will be required to comply with our trade waste policy and trade waste plan. However, exemptions to requirements to have pre-treatment facilities and equipment may be given where wastewaters are collected onsite and not released to a sewer or stormwater system. This means that all wastewaters generated from wash bays or parts washing sinks within workshops or similar commercial activities are to be collected into appropriately sized holding tanks for collection and eventual disposal by an approved and licensed liquid waste transport business. No wastewaters are to be released or connected to a sewer system with the exception to that which is generated from an approved hand wash basin.
Once the wastewater is contained onsite in a holding tank and no connection or release is made to the sewer, it is no longer to be considered as a trade waste. It may instead be classed as a regulated waste under Environmental Protection legislation and may affect a current Environmental Licence (Environmentally Relevant Activity - ERA license) or require a business to obtain an ERA licence. Should you decide to implement an onsite system for collecting wastewater it is advisable that you make contact with our Environmental Health Branch to discuss any ERA licensing conditions or requirements that might apply to your operations.
The capacity of any holding tank will need to be carefully considered to ensure that it can be effectively serviced to meet the needs of your business. Other measures should also be implemented to ensure your obligation to prevent overflows or releases to stormwater or the environment is met (i.e. General Environmental Duty).
The storage of large amounts of regulated waste on-site may trigger a change in the material use of a premise from that which it has previously been approved. For further information regarding the storage of large amounts of regulated waste you are advised to contact the relevant administering authorities including; the Department of Environment and Resource Management (DERM), our Development Assessment and Environmental Health Branches.
Discharge to sewer means the work area is connected to sewer but not connected to stormwater systems. This method requires pre-treatment devices to be installed and compliance with discharge conditions. A pre-treatment device is required to reduce the quantities of silt, oil, grease, and petroleum hydrocarbons entering the sewer.
Obtain a trade waste approval which will allow all liquid waste generated by the business to be discharged to sewer provided all pre-treatment requirements are installed and sewer admission limits are maintained.
Liquid trade waste application form (online)
Trade waste liquid discharge - category 2 form (PDF for print)
Trade Waste Management Plan
2.54 Trade Waste Policy