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Stormwater and climate change adaptation

Climate change is expected to bring about more extreme weather events such as rain, snow, drought, heat waves and severe storms. The massive damage caused by Hurricane Sandy is a reminder that extreme weather is now a reality. Stormwater systems will be affected by the increased frequency and intensity of rainfall events. The higher volume of rainfall may exceed the capacity of stormwater entry points or cause sewer overflows, leading to infrastructure damage and impacting water quality. Stormwater systems may need to be upgraded to deal with the increased flow. There is an urgent need to understand and adapt to the many climatic changes that are expected to occur. Innovative stormwater management practices are an important part of climate change adaptation.

A recent report published by climate scientist, Dr. Gordon McBean, examines how weather patterns in Canada have changed in the past and how they are expected to change in the future. The report aims to provide decision makers with the information they need to better adapt public and private infrastructure to the realities of the changing climate. In the report, Dr. McBean states, “Both the historical and projected trends shown in the research point to the need for Canada to adapt now in order to minimize social and economic costs in the future.” Predictions made for Atlantic Canada in the report include a likely increase in hurricane and storm activity in the region with resulting storm surges. Freezing rain events will likely increase by 50 per cent in Newfoundland. Nova Scotia could see increases of about 20 per cent.

These extreme weather events have had already had huge environmental and economic impacts in Canada. In 2011, catastrophic events cost Canadian insurers roughly $1.7B and almost $1B in each of the two previous years. The majority of these insured losses were caused by extreme weather events, but smaller weather events also played a role in significant property damage for consumers (IBC). 

Climate change impacts all of us and we all have an important role in reducing the potential impacts of stormwater. Source control involves managing runoff on individual lots and relies on property owners and developers to implement practices to reduce the amount of runoff leaving a site. Installing a rain barrel, creating a rain garden, retaining green space and not using pesticides are a few small practices that will protect your home, increase the resiliency of our stormwater systems and improve our ability to adapt to climate change.

Urban Water and your Property

The following blog post was written by Mike Price, former general manager of Toronto Water and highly valued Ecology Action Centre volunteer. This  post provides a comprehensive overview on the issues and solutions related to incoming water on a property. A subsequent post will look at outgoing water, or drainage. Thanks for the great blog contribution, Mike! 

Downspout deco-chain (Photo: M. Price)

The water used on a typical urban lot comes from two directions. Down from the sky or out of a water pipe. Rainfall can be good, and sometimes hazardous, but we don’t make the best use of it. The water from your tap (potable) can be from several sources:

        - Private untreated supply from a well on the property

        - Municipal treated supply, from the tap, originates from surface water (lake or river) or ground water from wells

·        Current Issues regarding municipal water supplies

      -  Surface waters, lakes and rivers, can become contaminated from human activities. 

      -  The volume of supply from surface water in Canada is dwindling due in part to ‘climate change’, but also due to increased demand. 

      -  Ground water supplies are similarly impacted but depending on the depth of the well the ability to replenish is being negatively impacted by human intervention.

      -   A large amount of energy is used to treat and pump the municipal water to reservoirs and around the water distribution system. 

      -  During hot summer months up to 50% of the water supplied is used for external ground watering.

       - Throughout the year about 60% of the building water use is for flushing toilets

Recreational beach closure (Photo: M.Price)

. Current solutions for urban water providers and users

    Water providers (Province, Municipalities and/or water utilities)

  -   Prepare and implement Source Water Protection Plans

  -   Prepare and promote Water Efficiency Plans

  -   Actively seek out and repair water pipe leaks

  -   Eliminate unnecessary fire hydrant flushing

  -   Minimize energy used in the treatment and distribution of potable water

  -   Prepare and regulate Pollution Prevention Plans

  -   Prepare and implement Storm Water Management Plans

   -  Mitigate the impacts of Combined Sewer Overflows

   Water users (residential and ICI property owners)

 -  Minimize tap water use

     a)   Low flush toilets

     b)   Reduced volume shower and tap heads

     c)   Grey water re-use (for toilet flushing)

    d)   Use more drought resistant garden plants (called Xeriscaping)

    e)   Eco-gardening

     f)   Use timers on automatic sprinklers

 - Maximize rain water use

     a)   Rainwater harvesting

               1.   Downspout disconnection

               2.   Grade property to keep rainwater from running off the property

               3.   Use rain barrels for garden watering

               4.   Create specific areas for a rain garden

               5.   Minimize paved areas

Rain barrel installed at disconnected downspout  (Photo: M. Price)

Pain in the Drain

 This article was written by Heather Hunter and published in the Summer 2012 edition of 'Between the Issues', the Ecology Action Centre's quarterly publication. Thanks for covering this important topic, Heather. The full BTI can be downloaded here.

The last time you were caught in a downpour, jumping over sidewalk rivulets and trying not to get splashed by passing cars, perhaps your thoughts didn’t automatically jump to where does all this water go? What contaminants might be in it?  But stormwater, the rainwater and melted snow that runs off roads, lawns, roofs and other hard surfaces, is an area where some real environmental action is needed. Storm water often contains motor oil, gasoline, sediment, fertilizer and other contaminants which damage natural aquatic habitats.  Without proper stormwater management practices, serious environmental and economic consequences can occur such as erosion and loss of habitat.

Cameron Deacoff, an Environmental Performance Officer with the Halifax Regional Municipality, took some time to explain why we should be giving this issue some major consideration and steps that we can take at individual and municipal levels to improve our storm water management practices.

Why you should care about storm water management
On earth there is a finite amount of water.  Fortunately, water is efficiently conserved through the hydrological cycle – including the processes of evaporation, transpiration, condensation, precipitation, surface runoff & percolation. This natural water cycle is disrupted by human intervention.  In urban landscapes in particular, impervious surfaces such as roofs, roads and parking lots render the land unable to absorb water. Instead, stormwater runs over streets and sidewalks and along the way becomes polluted with oil, garbage, fertilizers, pesticides and other contaminants.  In fact, studies have shown that storm water conveys up to 600 pollutants, many of which may be harmful to both humans and the environment.  Unlike sewage wastewater, stormwater is often not treated before it enters our waterways.

While good stormwater management has always been important, it is now being seen as more of a “hot button” issue as people are gaining a better understanding of the impact on environments, including erosion, removal or destruction of fish and wildlife habitat, and pollution causing direct damage to fish and other aquatic organisms.  We are understanding that stormwater needs to be managed - efforts should be made to reduce contaminants in street run-off, and there should be some treatment before stormwater joins up with natural waterways.  In addition, there is an understanding that we should avoid directing stormwater into wastewater systems (i.e. sewers that handle wastewater from toilets, tubs, laundry etc) because wastewater systems are not designed to treat stormwater flows. During heavy rainfall events, treatment processes can fail as throughput exceeds the capacity of treatment facilities, resulting in untreated overflows. Other risks associated with poor stormwater management include flooding, basement backups, and associated property and financial losses.

The importance of stormwater management is not going to decline any time soon.  Cameron explains that aging infrastructure is making the issue more serious today. “Much of the infrastructure in the ground was put there several decades ago,” he says, “and maintenance and replacement needs are ramping up”. He adds that “climate change is also having an impact on the issue, because our weather patterns are changing, resulting in increasing volumes of precipitation, and increasing intensity of rainfall events. Winters have been milder, resulting in less storage of precipitation as snow and ice, making for shifting hydrological patterns for which stormwater management systems were neither designed nor constructed.”

What you can do
To enhance your individual stormwater management practices, Cameron provided the following tips:

• Retain as much natural land cover on your property as possible (i.e., do not cover the ground with asphalt, concrete, etc. unless necessary).
• Disconnect your downspouts (eaves troughs, foundation drains, sump pumps, etc.) from your house onto the surface of your property for drainage into the ground; or at least ensure that they are not connected to the wastewater sewer system.
• Store and manage waste materials properly so that they do not flow into storm sewers, swales, etc., during a storm. This includes covering dirt piles, removing litter and pet waste.
• Landscape your property with plants and other materials that are native to where you live. These have fewer needs for fertilizers and pesticides, which should be used sparingly if at all.
• Support fees for storm water management. These services benefit you and the environment.

At a municipal policy level, there are many steps that cities and towns in NS can be taking to improve stormwater management practices.  Some recommendations include:

• Having your town or city conduct a review of water-related issues within their jurisdictions, and those shared with neighbouring municipalities.
• Ensuring that municipal urban design & planning jointly consider water quality and water quantity along with land use and transportation.
• Devote some attention to retrofitting issues in older urban areas, not all towards improving development practices in new "greenfield" areas.

Some municipalities such as the City of Cambridge in Massachusetts and Victoria BC have begun implementing progressive by-laws to counter stormwater pollution.  In Cambridge, significant investments in catch basin cleaning, street sweeping, and urban forestry programs have been made.   

In Victoria, bylaws have been passed for businesses as well as construction and development sites. Businesses must be fitted with a “Storm Water Rehabilitation Unit”, which is a generic term for any system designed to remove targeted contaminants. In general, any system that removes solids such as gravel, sand and silt, and floating materials like oils and trash should be adequate. At construction sites, regulations prevent construction waste water from being directly joined to drainage systems or sewer systems, hazardous wastes are tightly controlled with spill plans in place, and after construction has finished the site must be cleaned up to prevent excess gravel, dirt and pollutants from entering natural waterways.

Stormwater management practices may vary across municipalities, and depending on existing infrastructure, different levels of investment may be required. However, the first step is to raise our level of awareness about this issue.   To reduce harm to our natural waterways, and our overall ecological footprint, stormwater management must become a permanent part of our “environmental consciousness”.

Thermal pollution

When we think of how stormwater impacts lakes, rivers and streams, we tend to think of sediment and other contaminants that degrade water quality. We rarely think of how elevated runoff temperatures, known as thermal pollution, can greatly alter the temperature regime of natural water bodies. On hot days, impervious surfaces, such as parking lots and roofs, absorb and emit heat.  When it rains, heated runoff that flows over these surfaces can potentially increase the temperature of receiving waters. Increased temperatures can negatively impact coldwater fish populations by interfering with spawning and migration patterns, decreasing dissolved oxygen levels and even resulting in fish kills.

Stormwater Best Management Practices have an effect on runoff temperature, and the University of New Hampshire's Stormwater Centre has been researching the effectiveness of various BMPs in regulating thermal pollution from stormwater runoff.

They found that surface systems, such as retention ponds, that are exposed to direct sunlight provide little no reduction of high runoff temperatures and can potentially increase already elevated summer runoff temperatures. Various infiltration and filtration systems were best able to moderate runoff temperatures by thermal exchange with cooler subsurface materials. Systems with a large subsurface area had the greatest ability to buffer runoff temperatures. The full report titled 'Examination of Thermal Impacts from Stormwater Best Management Practices' can be found here. 

Brook Trout. (Photo: Source)

Pioneer Park Stormwater Management Project

The Town of Richmond Hill, Ontario, created a stormwater management park to collect and treat runoff as well as provide flood and erosion protection to neighbouring communities. Originally built in the 1980's, Pioneer Park treated runoff from 26 ha of residential development. Redesigned in 2009/2010, the improved stormwater management park now provides water quality and quantity services to a 740 ha catchment area.

The park consists of a wet pond to treat runoff from everyday rain events, a dry pond to collect and treat runoff from major, intense rainfall events, an oil grit separator for pre-treatment and a channel for fish passage. This project was a 2010 winner of Insurance Bureau of Canada's Watershed Awards.

The completed stormwater management park. Photo: www.rmconstruction.ca

Under construction in 2010. Photo: www.rmconstruction.ca

Check out this great video to learn more about how Pioneer Park was created and the many environmental and economic benefits it provides to the Town of Richmond Hill. This video was provided by Insurance Bureau of Canada.

12,000 rain gardens

The Puget Sound region of Washington State is tackling water quality issues with a new campaign to install 12,000 rain gardens by 2016. Once completed, these rain gardens will soak up 160 million gallons of polluted stormwater runoff each year. This innovative campaign offers financial incentives and comprehensive educational materials to neighbourhoods as a way to encourage individuals to do their own part to reduce the amount of pollutants entering the environment while solving drainage problems around their own homes. By encouraging individuals to become neighbourhood champions and recruit others, entire neighbourhoods are coming together to learn about and install rain gardens.The campaign currently has 706 raingardens installed.

Check out the website to find some great resource materials and learn more about the program.

http://www.12000raingardens.org/index.phtml

Constructed wetlands

"S" shaped constructed wetland

At the headwaters of Frenchman's Creek in Dartmouth, a wetland was constructed to treat stormwater runoff from the adjacent sports fields and parking lot. The wetland has a serpentine shape and varying depths in order to maximize residence time of the runoff in the wetland. This allows for increased removal of nutrients and metals through plant uptake and adsorption. This stormwater treatment feature essentially acts as a kidney purifying the water. The runoff leaving this site now enters the natural environment at a much higher quality than it would if directly released without treatment. 

This wetland would require occasional maintenance to maximize function. Construction was done by Jeff Pinhey and Rob Leblanc in 2007. 

The marsh is predominantly vegetated with cattails

Stormwater Management at Dalhousie University

A group of students enrolled in “Campus as a Living Lab”, a course at Dalhousie University that aims to engage students in efforts to “green” the campus and surrounding areas, have delved into the world of stormwater management. Students, Bridgette DeCoste, Tiara Pettinger, Robyn Pirie, Nicole Power, Michelle Simone and Paul Westlund, chose two areas on campus, the Dunn parking lot and the Grad House, to focus their research. The intention was to create transferable stormwater management designs that could be implemented by homeowners who are interested in managing stormwater on their properties. The students created three levels of increasingly complex designs for both sites and investigated five different management approaches; vegetated swales, permeable pavement, rain gardens, rain barrels, and French drains. The students then presented their designs to experts in the field, as well as with facilities management staff at Dalhousie to determine the most feasible and cost-effective approach to stormwater management on the two sites.

Here are graphics of the third designs for each location

Dunn Parking lot - featuring permeable pavement and vegetated swales

  

Grad House- featuring french drain, rain barrels and rain gardens

Click here to read the full report

The most interesting part about this report for the Ecology Action Centre is the transferability of the designs. Because each component of their designs is featured individually as well as a part of the whole system, the report contains a wealth of information directly relatable to any homeowner who’s looking into taking on some of these retrofits on their own properties. The report also contains several appendices including tables with a complete breakdown of all the costs associated with these retrofits, and a list of water-loving plants native to Nova Scotia, for installation in the rain gardens.

Thanks to all the students for their excellent work.

Green roofs

Saint Mary's University research green roof

Green roofs are important stormwater management tools that reduce the volume of stormwater  leaving the site by capturing and retaining rainfall and returning precipitation to the atmosphere through evapotranspiration. They are ideal for improving stormwater management in urban areas as they make use of existing roof space. To learn more about green roofs, I spoke with a group of Saint Mary's University grad students who are researching green roof plant communities (thanks Steph, Amy and Tobi!). 


There are two types of green roofs - intensive and extensive. Intensive green roofs have deep soils which can support a wide variety of plant species, including larger shrubs and trees.  They are used for both aesthetic and functional purposes. Intensive roofs require maintenance and care, much like a typical home garden. Extensive green roofs use less soil (layer can range between 2 - 20cm)  which makes them much lighter, but also limits the variety of plants that can be grown in such shallow conditions. Grasses, mosses and sedum species are commonly used.  Extensive green roofs require little to no maintenance. Some roofs may need irrigation for the first year while the plants are establishing, but they can then be left entirely on their own. 


Green roofs can be installed in three ways. Soil can be brought to the roof top and placed on top of the required waterproofing, filtering and insulation layers then planted with selected vegetation. More typically, green roofs are installed as small modules or vegetation trays that contain soil, plants and a shallow gravel layer to ensure the contents are secure on windy rooftop conditions. A third option, known as pre-cultivated vegetation blankets, are composed of soil and vegetation mats that can simply be rolled out onto the rooftop. 

Green roof modules

Green roof layers including pre-cultivated vegetation blanket (www.xeroflor.ca)

Along with improving stormwater management, other benefits associated with green roofs include increasing the life time of roofs, creating urban wildlife habitat, improving energy efficiency of the building, improving air quality and reducing the urban heat island effect. 


The city of Toronto has introduced a Green Roof Bylaw that requires the construction of green roofs on all new buildings of a certain size. You can read more about Toronto's bylaw here.

Rain Gardens

Rain garden constructed by Clean Annapolis River Project (www.annapolisriver.ca)

Rain gardens are small, landscaped areas that capture, filter and infiltrate rainwater.  Rain gardens can create an attractive detention area where runoff can slowly soak into the ground, be taken up by plants and return to the atmosphere through evapotranspiration. Planted with water-tolerant native plants, rain gardens can become a beautiful and functional feature on your property.

Rain gardens allow at least 30% more water to infiltrate into the ground, compared to a conventional lawn (source). They can help recharge groundwater resources, reduce stormwater volumes and create habitat. Rain gardens are relatively easy and inexpensive to design and build. Just keep in mind a few important considerations when deciding where and how to install a rain garden on your property:

-Observe how stormwater naturally runs in your yard. Place the rain garden at a low point or elsewhere along the natural flow path.

- Maintain at least a 1% slope from the impervious surface to the garden. 

- Rain gardens should be located approximately 3 m away from a building to avoid drainage problems on your property.

-Clay soils don’t allow for proper drainage, therefore look for a place with soil that is sandy, gravelly, loam or a mix. If your soil has a high clay percentage, you can add sand, fine gravel and/or organic matter to improve permeability.

- The surface area of a rain garden should be 20-30% of the roof/parking lot area it drains.

- A general guideline for rain garden depth is 7.5 cm in soils with relatively low infiltration rates (i.e., loam) and up to 15 cm in soils with high infiltration rates (i.e., sandy or gravelly soils).

-  A downspout can empty directly into a rain garden. Just add some stones or a splash pad to prevent erosion.

Rain garden (Photo CMCH: bit.ly/dCOkur)

Some really helpful tips on installing and maintaining rain gardens can be found from the Canadian Mortgage and Housing Corporation's factsheet 'Improving Stormwater Management in Your Yard'.  

More great information on rain gardens, including a list of native, water-loving plants, can be on the Clean Annapolis River Project website. 

Do you have a photo of a rain garden or maintenance tips that you'd like to share? We'd love to see them! 

Beautiful! (Photo: www.atlantic.sierraclub.ca)