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The most significant contamination of trade waste discharges from retail automotive businesses are fuel or oily hydrocarbons. Hydrocarbons cause toxic or flammable vapours in sewers, and oily residues which foul water level sensors and pump switches, potentially resulting in sewer overflows when pumps fail. Hydrocarbons can also interfere with biological treatment processes at wastewater treatment plants.

The second most significant contamination are suspended solids, which can accumulate in sewers and pump stations, contributing to odours and blockages

Permit Requirements

Retail Automotive Business requires a trade waste permit to discharge process wastewater to sewer. There is an annual charge for this permit.

Pre-treatment requirements

Pre-treatment is required to reduce these contaminants to acceptable levels. Suitable pre-treatment is a silt sump and an oily water separator such as a coalescing plate separator, vertical gravity separator or hydro cyclone. Oily water separators must be maintained in accordance with the manufacturer’s recommendations. Collected oil and sludge must be disposed of offsite, not discharged to sewer.

Single, double and triple interceptors are no longer acceptable as pre-treatment devices.

Only quick break detergents/degreasers are permitted in conjunction with those vehicle washing activities within the scope of the guideline. These detergents/degreasers temporarily emulsify oil/grease and suspend solids during cleaning but release this material soon afterwards. This allows the final pre-treatment device to operate effectively.

Coolant and radiator fluid

The discharge of coolant and radiator fluid to sewer is not permitted. These fluids should be collected and disposed of by a licensed liquid waste contractor.

Other prohibited discharges

Highly acidic or alkaline wastes, paints, sealants or other products must not be discharged to sewer.