Rainwater and Stormwater Management at Home

A Cautionary Story for Home Owners: Preventative Steps for Storm and Rainwater Management

In this article, my primary concern is for owners who have recently complied with the City’s downspout disconnect program. They may think that because their downspouts are disconnected, that their property is now correctly and sufficiently drained.  However, this may not be the case, and further design and action may be required to achieve this.

In  2007, the City of Toronto’s free Downspout Disconnection Program ended, and a new Mandatory Downspout Disconnection Program commenced.  This required that all Toronto homeowners disconnect all downspouts by the end of 2009.

For many years, homeowners in urban areas such as Toronto, living in homes connected to stormwater lines, took it for granted that vast quantities roof-generated rain and snow melt water would conveniently collect in eavestroughs, and flow quickly through downspouts into the stormwater system.  This was, in fact, integral to the successful mechanical design of our housing stock when it was constructed.   Generally, homeowners could ignore the functioning of this system, unless moisture problems developed.  That is, until now.

It is now essential that owners familiarize themselves with the basic issues and some of the science of rainwater control, at least within the bounds of one’s own property.  It may not be as exciting as undertaking a new renovation, but poorly designed drainage control systems can eventually cause serious damage, and unless taken into consideration, can result in future expensive repairs that could easily undo all the good intentions of a beautiful interior renovation.

For those who do not understand the reasoning behind the City’s decision to disconnect downspouts, and who want to become more aware of the ecological benefits as well as a wider range of stormwater and sustainability issues, the City of Toronto has an excellent resource located at: http://www.riversides.org/rainguide/index.php This site also includes a “Do-It-Yourself” Downspout Disconnection Guide.

In contrast, homes in rural areas, or within smaller towns or municipalities that do not have stormwater infrastructure are not affected by this program, of course.  Homeowners in these areas have had no choice but to rely upon their own regular, pro-active observance of rainwater behaviour on their property, and over the years, likely have developed appropriate solutions to control surface runoff and drainage, thus minimizing potential damage to land and buildings on their property.

Where does all that water go?

To avoid property damage, urban owners must now become more acutely aware of the next critical step. Once the downspouts have been disconnected, all the snowmelt or rainwater collected by one’s roof is now directed to one of two places: either stormwater is allowed to infiltrate (soak into the ground), or it is stored for later use (a separate topic for a future article).

The focus of this article is on infiltration/distribution, as I believe this is the most likely source of potential problems around the home.   From personal observation, I’ve noticed that disconnected downspouts and their extensions are routinely dumped anywhere from 3’ to 10’ away from the original stormwater connection.  While this may appear to be correct, it is only by carefully observing rain water behaviour over time, and during periods of heavy rain or snow melt that one can actually determine whether the placement is, in fact, effective. As a proactive owner, consultant and designer, this is not only an area of personal interest, but one that I have studied.  However, (and this is completely understandable), not all owners are able to make this level of commitment, this level of detailed observation, and not all owners are physically capable of making the next necessary steps.

In my own case, I disconnected my stormlines, and used a 4” PVC pipe extension to the downspouts.  I prefer PVC over aluminum because it is extremely tough, will not crush or dent, and the large diameter and smooth interior finish allows roof debris (leaves, etc.) to flow with less likelihood of becoming blocked.  It is also inexpensive, comes with standard joint connections, and can easily be worked with simple tools.  Lastly, joints need not be permanently welded with adhesive to be effective, and this gives them the flexibility to be re-adjusted at any time, while still performing as needed.  PVC comes in two basic colours, black or white, so for style-conscious individuals this may be an issue.

At first, I extended the drain line approximately 10’ from the original storm connection.  I thought this would be sufficient, however after the first big storm, I was forced to add another 4’ accordion-type extension.  Even after careful placement, after the next storm, I realized that because of a subtle, barely visible dip in the front yard within 8 feet of my exterior walls, stormwater would tend to form a large pool about 3” deep, rather than drain away quickly, as I had expected.  With drainage, it may require more than a single step to get it 100% right.  This led me to add the final piece, an infiltration trench, across my front yard in order to achieve correct and positive drainage.

An infiltration trench is a surface drainage feature that directs stormwater flow into a trench filled with stones.  Trenches can be 30cm to 1m deep, 60cm to 1 m wide, and can be any length depending on the amount of water. They are sloped to direct water from one end to the other, and are used to direct water away from sensitive areas to another permeable surface or stormwater management system.

What are the Benefits?

• Simple, low cost and effective managing large amounts of stormwater on your property.
• Can be incorporated into existing landscaping.
• Ideal for major storm events as it both infiltrates and can convey water to other infiltration and storage systems.
• Work well with other stormwater management systems.

The main point of this story

If I had simply assumed that my first solution was correct, and not maintained a vigilant attitude, I could have experienced more severe water-related damage including deterioration of masonry and foundations, mould, decay and other moisture-related issues. My concern here is for owners who have now had City disconnects, and who assume that their property is now correctly and sufficiently drained.  This may not be the case, and further design and action may be required to achieve this. Carefully note the following disclaimer from the City, and their wise advice to engage a trained specialist for this type of service:

DISCLAIMER (from the City of Toronto)

The City cannot guarantee the accuracy or completeness of the information or its application to any particular property. Readers should where possible verify the information before acting on it. Where appropriate, professional advice and service should be sought from a knowledgeable and licensed contractor or civil engineer.

While we endeavour to provide accurate information, it is provided strictly “as is” and the City makes no representations or warranties as to the accuracy, reliability, completeness, currency, or suitability of the information provided. Readers relying on this information and this web site do so entirely at their own risk. In no event will the City of Toronto be liable to you or anyone else for any decision made or action taken by you or anyone else in reliance on this information. The City does not accept and specifically disclaims any and all liability for any injury, loss or damage whatsoever incurred as a result of the use of, reliance on, the information provided by the City and in no event will the City, its Councillors, officers, directors, employees or contractors be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit, including any property damage or loss or personal injury, associated with, resulting from or arising out of any use or misuse of this information.

A few Tips…

• Direct the stormwater to a storage device or a permeable surface like a lawn, garden or infiltration system.
• Do NOT direct stormwater onto another impermeable surface like a driveway, sidewalk or paved path where it will simply run off the surface and into the stormsewer.
• Direct flow away from your (and your neighbour’s) house foundation – approx. 1.5 meters away.
• Avoid creating soil erosion – use a splash pad Splash pads are pads, (pavers, bricks, etc.), placed beneath the outflow of a downspout to dissapate energy and stop erosion. so the strong current of water does not erode the soil.

Natural Drainage: Observe the natural drainage patterns on your property after a storm, including the paths where water runs, and where water pools. Choose a low point for your stormwater landscape solution, or a location somewhere along the natural flow path. If your yard is relatively flat and evenly drained, you can create a depression anywhere,

Vulnerable Areas: To avoid creating moisture problems, you will need to direct stormwater away from vulnerable areas, such as your house foundation or neighbouring homes. Direct stormwater at least 1.5m from the foundation of your house, and locate a stormwater management system at least 4 m from your house unless overflow is directed further (e.g. with a trench or swale).

Call Before You Dig: Before starting any excavation project, it is your responsibility to locate any underground utilities on your property. Most utilities can be reached by calling the free service Ontario One Call or 0N1Call at least one week prior to digging. Some utility providers are not participants in this free service and need to be contacted directly; check your utility bill for the Ontario1Call symbol or a contact number for excavation information.

Maintenance:

• The only maintenance required is to clean eavestroughs and downspouts twice annually to keep them clear of leaves and debris. Installing leaf guards and filters will make this easier, but will add to the initial costs.
• Replace downspouts, eavestroughs and crumpled pipes when needed to ensure clear flow.

Visit my website to learn more about residential construction project management at: 

http://housecallsprojectmanagement.com/