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Stormwater Management

What is Stormwater Runoff?
What is Stormwater Management?
Why is Stormwater Management Important?
What is Richmond Hill’s Role in Managing Stormwater?
Introducing the Stormwater Management Rate
Reduce your Runoff Footprint
The Future of Stormwater Management
Runoff from melting snow Stormwater Management Pond

What is Stormwater Runoff?
When an area is converted from a natural area to an urbanized area, the volume of water that runs off the land increases due to the addition of hard (impervious) surfaces. Depending on the season, stormwater comes from rain and from melting snow and flows into our storm sewers and storm ponds. From there, this water makes its way to local streams, rivers or lakes. Stormwater runoff is different from wastewater, which flows into sanitary sewers from household drains.

This diagram shows the change in the percentage of stormwater runoff and other parts of the water cycle as impervious surfaces increase. Higher percentages of impervious surfaces mean less water will seep into the ground or evaporate into the air and more stormwater runoff will flow to local streams, rivers and lakes.

Graphic showing the effects of imperviousness on runoff and infiltration

What is Stormwater Management?
Stormwater management involves storing and directing stormwater runoff in urbanized areas to control flooding, erosion and water quality. This practice protects communities, municipal infrastructure (like roads, sidewalks and trails) and local waterways. The objective of stormwater management is to slow the release of stormwater runoff into natural systems.

One way of managing stormwater runoff is through the use of stormwater ponds. Stormwater ponds can be ‘dry’- filling up during a storm, or ‘wet’- having a permanent pool of water. These ponds are designed to hold back stormwater and release it slowly to natural waterways. Wet ponds also allow sediment to settle to the bottom of the pond instead of traveling to a local stream. Stormwater management ponds are so well integrated into the landscape that to many people they appear to be natural ponds. However, they do require maintenance to keep them working properly, such as sediment removal or cleaning of catch basins. Sometimes older ponds need to be replaced with newer, more efficient designs.

Stormwater Infrastructure at Headwaters ParkWhy is Stormwater Management Important?
Without stormwater management, runoff from urbanized areas would flood communities and roads, cause stream erosion and destroy aquatic habitat. In August of 2005, the City of Toronto experienced a major storm event which resulted in the collapse of part of Finch Avenue. The storm was so intense that the Black Creek culvert under Finch Avenue was unable to handle the amount of runoff flowing through it.

More recently, the south end of Don Valley Parkway was flooded in May of 2013. The Don River overflowed its banks and spilled onto the DVP. This caused major delays for the morning commute. Runoff from this storm also caused basement flooding in many homes.

On July 8, 2013, a record breaking 126 mm of rainfall was recorded at Pearson International Airport within a 24 hour period. This was more rainfall than Hurricane Hazel in 1954. This extreme rainfall event cause the closure of highway ramps, parks, and offices, it flooded streets and basements and caused major electrical outages in certain parts of Toronto.

Lakes and local streams also suffer from runoff. Stormwater that rushes uncontrolled from urban pavements causes streams to rise faster and more dangerously than those in rural areas. The force of the water during rain events scours stream bottoms, erodes banks, harms fish habitat and increases pollutants such as phosphorus and heavy metals. Stormwater picks up dirt, oil, grease, road salt, fertilizers, pesticides and bacteria from urbanized areas. During its journey over pavements, stormwater also becomes warmer which is harmful to fish

Stormwater management is required to release runoff into natural waterways slowly, imitating the water cycle before urbanization. Stormwater ponds are also important because they provide an opportunity for sediment (and pollutants attached to the sediment) to become trapped in the pond bottom, rather than moving into the local streams.

What is Richmond Hill’s Role in Managing Stormwater?
Richmond Hill is responsible for planning adequate stormwater control for new communities, and to operate and maintain these systems. The municipality owns and operates more than 60 stormwater ponds, 440 kilometres of storm sewers and 13,500 catch basins and manages more than 150 kilometres of streams and rivers.

The municipality must ensure the stormwater system is operating in accordance with various acts, regulations and approvals provided by federal, provincial and local authorities including the Ontario Ministry of Environment and Toronto and Region Conservation Authority.

Recent Projects 
  • Pioneer Park Stormwater Management Project
  • Rumble Pond Adaptive Stormwater Infrastructure Project

    Stormwater Infrastructure at Mill PondIntroducing the Stormwater Management Rate
    The Stormwater Management Rate, beginning in October 2013, is a new charge that will appear on your water bill to provide dedicated funding for stormwater management in Richmond Hill. This rate is used to plan for long-term upkeep of the stormwater system. A similar rate is already being collected in other municipalities in the Greater Toronto Area and beyond, while others are currently looking for ways to implement a dedicated stormwater charge in order to provide a sustainable funding source similar to our water and wastewater systems. It is expected that more municipalities in Ontario will be moving to a dedicated stormwater rate in the future.

    Richmond Hill’s stormwater system (ponds, storm sewers, catch basins, etc.) requires ongoing maintenance, including periodic repair and replacement. Ponds, storm sewers and catch basins are more likely to perform poorly if they are not maintained properly. Planning for repair and replacement will help to avoid costly and inconvenient situations like washed-out roads and trails, stream erosion or flooding. This is a problem faced not only in Richmond Hill but in other municipalities across Canada.

    The Stormwater Management Rate will be phased in over approximately ten years, while working towards being a fully sustainable funding source. Since stormwater runs off both developed and undeveloped land, all residents and businesses will be charged the Stormwater Management Rate. The charge will appear on the water bill as “Stormwater Charge.” Residents who currently receive a quarterly water bill for their property will see the new charge appear on those bills starting October 2013. Businesses who currently receive a bi-monthly water bill for their property will see the charge appear on those bills starting November 2013. Residents and businesses who are not on Richmond Hill water will be billed annually for the stormwater management rate.

    For more information on the Stormwater Management Rate including annual charges and how the charge is applied to your water bill please visit the Water, Wastewater and Stormwater Billing and Collection Page. For your convenience the information is also available in Chinese [PDF], Russian [PDF], and Farsi [PDF].

    Reduce your Runoff Footprint
    Everyone can help reduce the amount of stormwater runoff. Try these tips to reduce your stormwater ‘footprint’, lower your water bill and conserve water:
    • Use a carwash instead of your driveway to wash your car. This will decrease the mixture of wash water and sediment entering storm sewers.
    • Clean up animal waste, grass clippings and fallen leaves from your property regularly.
    • Be careful to not over-fertilize your lawn as excess nutrients can enter the stormwater system.
    • Have your car fixed if it is leaking fluid. Oil and other vehicle fluids can be very harmful to fish and wildlife reliant on our streams, rivers and lakes.
    • Use rain barrels to capture roof runoff and use this water on your lawn and gardens.
    • Disconnect your roof downspout if it is connected to a storm sewer. You can either connect it to a rain barrel or have it directed onto your lawn. Use water from rain barrels to water your lawn or gardens.
    • Manage your use of road salt and sand in the winter. During snow melt periods, salt and sand will enter the storm sewer system and can have negative impacts downstream.
    • Dispose of household hazardous waste properly, not down a storm drain.
    • Choose plants that are drought tolerant and don’t need to be watered as often.
    • Check your sprinkler system for leaks and ensure you are only watering your lawn on days and times allowed. The best times to water your lawn and garden are in the early morning or late evening.

    The Future of Stormwater Management
    Green roof at Oak Ridges Community CentreOver the past 30 years, there has been a shift in the way stormwater is managed. It was first thought that stormwater needed to be removed from the site and sent to a watercourse as quickly as possible. The idea of using a treatment-train approach to stormwater management has been gaining momentum. What does treatment-train mean? It means that stormwater will be treated not at one location, but multiple locations. This approach begins at the source (e.g. on a commercial or residential property), through conveyance (e.g. storm sewer) and end-of-pipe (e.g. stormwater management pond) before being slowly released into the environment.

    Some types of alternative stormwater management controls are green roofs, bioswales and rainwater harvesting.

    A green roof is a roof planted with soil and vegetation. This allows rainwater to be captured on the roof, soaked up by the plants and transpired to the atmosphere. This also helps to filter any water not retained by the roof and increases biodiversity of the local natural environment.

    Bioswale in the parking lot at Oak Ridges Community CentreRoof runoff can also be captured by a cistern and used for irrigation or toilet flushing. This process, called rainwater harvesting, lowers the amount of runoff entering stormwater management ponds and helps decrease water consumption.

    Bioswales are designed to capture, treat and infiltrate runoff from small storms. They have been used as medians between parking lot aisles and along the road right-of-way. Part of the curb is cut away to allow runoff to flow into the bioswale.

    The Oak Ridges Community Centre is a perfect example of many of these innovative controls put into practice. Next time you visit the community centre look for the green roof and bioswales in the parking lots!

    Guidelines for Development
    Richmond Hill Stormwater Management Landscape Design Criteria & Implementation Guidelines [PDF]

    This document is to be used by developers and consultants and provides specific guidelines for landscaping in areas surrounding stormwater ponds. The goal of this document is to enhance the aesthetic quality of the pond area, integrate the pond with the community while increasing environmental sustainability, pond performance and public safety.

    Town of Richmond Hill Standards and Specifications Manual [PDF]

    The Standards and Specifications Manual provides developers and their consultants the design criteria for infrastructure such as storm and sanitary sewers and stormwater ponds.

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