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Stormwater and your business

Learn how you and your business can manage stormwater and help protect water quality by reporting and preventing spills and pollution.

Preventing pollution

Some of the ways your business can prevent water pollution include:

  • Comply with Mississauga’s Storm Sewer Use By-law at all times
  • Create a pollution prevention plan if your business involves any type of material that could cause a spill. The plan should detail all sources of pollution, their handling and all appropriate spill prevention techniques used
  • Create a spill response plan and regularly train your team in the event liquid materials or wastes spill on your property
  • Understand and maintain the private drainage system on your property
  • If your business handles liquid materials including wastes, follow applicable federal, provincial and municipal requirements and follow materials best management practices
  • Liquid wastes cannot be discharged into storm drains or the storm sewer system. Liquid storage should be stored as far away as possible from stormwater catch basin inlets.
  • Maintain appropriate and secure outside storage and secondary containment
  • Keep all catch basins clear of litter and debris and perform frequent inspections to contain and properly dispose polluted discharges before they enter a catch basin
  • Inspect, maintain and document any oil and grit separators (OGS) or other stormwater treatment facilities on your site

Reporting a spill at your business

If you or your company are responsible for a substance that has spilled, you must report it immediately according to Provincial law.

If a flammable, poisonous, corrosive or explosive material is spilled, it can be unsafe for people and the environment. Reporting spills immediately can help protect you from litigation, fines and expensive clean up costs.

City spill response and cleanup

When investigating a spill, the City identifies the source of the pollution by reviewing CCTV footage and City stormwater system maps, conducting dye tracing, taking samples and inspecting the area.

When a spill has occurred, the City cleans areas impacted by the spill and may pump large volumes of polluted water. This includes roads, pipes, downstream infrastructure and the creek channel. The responsible party will be billed for costs incurred during the clean-up process.

Managing stormwater

Contact a drainage professional for large and complex flood risk-reduction measures. A professional can customize these measures for your business.

Some measures on industrial, commercial and multi-residential properties, such as those below, may be eligible for a stormwater credit.

Construction, erosion and sediment control

Erosion and sediment control

Erosion is the loss of land or soil by water or wind. Soil that collects in or gets moved by water is called sediment. If you’re doing construction on your property, you may need an erosion and sediment control permit. For more information, review the Erosion and Sediment Control By-law.

Surface-water discharge during construction

Often during construction, there is a need to remove surface water from excavations to allow the construction of building foundations. When water must be removed, any sediment in the water must be removed prior to discharge into the stormwater system.

Contractors or property owners must ensure that the removal of clean water from excavations does not pose a nuisance to the neighbourhood from flooding or other impacts.

Deep excavations and dewatering

If you’re doing construction that requires the excavation of a deep underground structure, you must work with a consultant to determine if your project requires groundwater removal through dewatering. In that case, you’ll need to apply for temporary discharge approval.

Construction spills

If there’s a spill of sediment or other pollutants on your property during construction, report it to the Spills Action Centre at 1-800-268-6060.

Oil-grit separators

To protect water quality in our creeks that drain to Lake Ontario, the City requires that on-site stormwater treatment measures like oil and grit separators (OGS) are installed on industrial and commercial properties.

An OGS is an underground device that captures oil and sediments from stormwater and melted snow.

You must inspect and maintain them regularly, and keep maintenance records on-site. Learn more about how oil and grit separators work.

Green infrastructure

Water is a very valuable resource. There are many different ways to manage rainwater on a large property that can benefit the environment, and your business. Green infrastructure, also known as low-impact development, uses natural systems to capture, clean and filter stormwater and still reduce the risk of flooding. Some types of green infrastructure can also help to cool buildings and provide water for non-potable uses.

Greening Corporate Grounds program

Property owners can receive guidance on green infrastructure measures through Credit Valley Conservation’s Greening Corporate Grounds program. Through its services, you can identify stormwater management improvements that can qualify for a stormwater credit.

Large scale rainwater harvesting and collection

Rainwater harvesting works like collecting water in a rain barrel, but on a larger scale. Large properties use storage tanks or cisterns to collect, store and filter rainwater that runs off the roof or parking areas.

Bioretention facilities

Bioretention is the process of removing contaminants and sediment from stormwater runoff. Bioretention facilities are excavated areas that collect stormwater runoff, slowing down the water and allowing some of it to soak into the ground.

Bioretention facilities are not recommended to manage spills or if soils may be impacted by pollution.

Bioretention facilities might include native plants or special soil to help capture pollutants in the water. They’ll also have an overflow to help manage heavy rain.

Soakaway pits (dry wells), infiltration chambers and trenches

Soakaway pits, also known as soakaways or dry wells, are underground spaces, lined with landscape fabric, where rainwater collects and soaks slowly into the soil after a rain event.

Infiltration chambers are large, plastic, open-bottomed devices with perforated sides. They’re generally located beneath parking lots or other impervious areas.

Infiltration trenches are long, narrow trenches where water can slowly soak into the soil below.

Each of these methods temporarily store stormwater runoff and release it slowly into the ground. This can help cool the rainwater, trap sediments and slow the flow of water into the stormwater system which can reduce flooding and erosion.

Blue-green roofs

A green roof uses a variety of native plants to help absorb and transpire stormwater. It can also help with building cooling in the summer and insulation in the winter.

A blue roof collects stormwater which can be stored and reused for irrigation. Blue roofs can also help to cool buildings.