Industrial stormwater discharges potentially contain hazardous pollutant volumes, loads, and characteristics that can overload downstream treatment structures.

Stormwater is any precipitation that flows off a hard surface such as a roof, driveway, forecourt, or road into a gutter, sump/catchpit, or waterway. Ideally, stormwater discharges should only consist of clean rainwater. Contaminated stormwater must be treated prior to discharge. Washwater, process wastewater, and other contaminated sources of industrial wastewater must be discharged along with sewage according to trade waste requirements

We monitor our waterways and audit industrial sites to ensure that only clean stormwater is discharged into the network and that good management practices are in place to reduce risks to our waterways.

A properly functioning drainage system will work so that: 

  • wastewater and trade waste go to the sewer
  • contaminated runoff is treated before going to the stormwater network, or it goes to the sewer
  • clean runoff is collected onsite and discharged to the stormwater network.

Consents and approval to discharge

We operate our stormwater network under resource consents granted by Environment Canterbury Regional Council (ECan)(external link), so we are responsible for elevated contamination in our rivers and streams. If you are planning a building or development that would use our stormwater network, we suggest you get advice on stormwater and your property early to take this into account in the design and consenting process.

If you have an existing industrial site, you may be audited to ensure that your site is operating with adequate controls and good management practices in place to mitigate your risks to our waterways. If no unavoidable and/or unacceptable risks to stormwater are found, your site will be issued an approval to continue discharging stormwater. If we suspect elevated contaminants in your stormwater discharge, we may collect samples and/or issue you a list of action items to reduce your risk.

If your site is an unacceptable risk to the environment, it may be excluded from our consent coverage in order for us to limit our liability. If that occurs, you will need to obtain a consent directly from ECan at your cost, or cease discharging into our network.

Good management practices

Industrial businesses can have numerous activities occurring onsite that generate a wide range of contaminants. Good management practices (GMP) can prevent and/or reduce stormwater pollution at the source, and they should be implemented wherever possible. These practices include utilising site layout tactically, housekeeping, checks and maintenance, spill control and safeguards, and employee training. At some sites, engineered treatment solutions may also be necessary to help manage stormwater quality and quantity.

Good management practices may be required to be implemented to achieve stormwater compliance at an Auditor’s discretion or when discharge trigger values are exceeded. There are resources available to guide you.

Non-compliance

Penalties may occur for non-compliant businesses in accordance with Resource Management Act enforcement measures such as:

  • an abatement notice
  • an infringement notice
  • an enforcement order
  • alternative environmental justice
  • prosecutions and formal legal action.

To report a spill, please call ECan’s Pollution Hotline on 0800 765 588. Pollution prevention guidance can also be obtained through ECan's website(external link) or phoning 03 365 3828.