Contaminated surface water

Directing stormwater, rainwater or groundwater to our wastewater system can overload it, causing overflows.

All customers must manage excess water on site by using bunding, stormwater drainage channels and roofing. 

What you need to know about discharging contaminated water

We understand it's not practical to roof an area in some circumstances and the contaminated run-off can't be directed to the site stormwater system.

In these situations, we may only permit the first 10 mm of rainfall collected in a first flush system to be discharged to sewer. You must have our written approval to discharge this first flush volume to sewer.

In all cases, the wastewater first flush volume must be treated to meet our acceptance standards before discharge.

We'll consider an application to discharge rainwater from contaminated open areas. However, you may need to provide:

  • evidence why the area can't be roofed to direct the rainwater to the site stormwater drainage system
  • a report from the EPA or local council confirming the run-off is contaminated and can't be directed to the site's stormwater drainage.
Our requirements differ depending on the size of the open area.
Open area < 50m2 Open area > 50 m2
  • Install an approved first flush system designed to capture the first 500 litres of rainfall and direct the rest to the stormwater drainage system

  • Install an approved first flush system designed to capture the first 10mm of rainfall and direct the rest to the stormwater drainage system

  • First flush volume to be pumped to sewer at a rate not exceeding 0.3 litres/second

  • Install an approved rainfall cut-off device and delay discharge of first flush volume to sewer for at least one hour after rain stops

or

  • Install a complete approved first flush system* in accordance with the manufacturer's specifications, designed to capture the first 10 mm of rainfall, or more if specified, and direct the rest to the stormwater drainage system

*Fox Environmental Systems FF600

We won't permit you to discharge groundwater or surface water collected during excavation and construction to our system. You must treat and discharge it to the site stormwater drainage system.

Talk to the NSW Environment Protection Authority or your local council about their requirements.

 

Typical set up for first flush system

Select the image to see a larger version.