Thanks to Terry Warner who provided the following information to the Board meeting on 13 March 2019.
The winter of 2018/19 brought record snow accumulations to Ottawa. All that water means a lot of melt and runoff in spring. This brief article will speak to one area homeowner’s efforts to prevent surface water flood proofing.
We have lived in this house for nearly 20 years. Twice I have had water come into the finished basement. The previous owner replaced the drain tile and damp proofed the exterior of the foundation. After the first incident I made a serious effort to regrade the lawn to eliminate an obvious depression and to change the slope away from the wall.
In no particular order, here are my flood proofing suggestions.
My back of a cigarette pack calculations shows the recorded snowfall in Ottawa to date is about 280 cm = 110 inches or 10 feet. If the conversion snowfall to water ratio is about 10:1, there is about 10 inches of water per square inch. Or a cubic foot of water per square foot. There hasn’t been any significant melting since the fall, so most of that snow is still here. If even half of that evaporated or melted to ice, there is still 6” of water on top of every square inch. From shoveling the fallen snow in the yard, I found there is about 2’ of crusty, granular snow lying on a hard layer of ice on the ground. I estimate that layer to be about 4-6”. Until the top insulating snow is gone, that ice will be a factor. Fortunately I think it is also keeping the ground below from freezing too deeply, which will help absorb some of the runoff.
That runoff must go somewhere. Preferably not into anyone’s basement, and hopefully all of it into the storm sewer system. Every property has neighbors, and until the water gets all the way through the drainage system, the water will flow until it finds its own level. If your neighbors are big areas without many drainage ditches, expect more of that water on your property.
My house is in the middle of a long flat section of the street. It is one of the lowest houses on that stretch with an even lower spot in the backyard. Invariably, the 6 or 8 neighbors watch as a pond forms in our backyards. It sometimes lasts a couple weeks and has been known to attract ducks. During high water I run a submersible sump pump from the lowest part of my lawn and 1½” hoses forward to the street. I shop at Princess Auto off Hawthorne Road and I have not been disappointed with their version of industrial grade supplies.
To find the nearest storm drain consult this map.
This year, my second line of defence is sandbags all around the window wells. During the winter I found the big box home store had sold out of sand, at $5 per bag. Thinking to how the City prepares for floods, I found that the City has You-Fill bags and fresh sand available outside the Industrial Ave yard opposite the fire station.
A filled sandbag weighs 20kg. Expect to get tired. Never do it all in one shot. A round trip from the house to the Yard, fill a dozen bags and return took about an hour. I’ve made four trips so far. Working alone, I put the bag in a plastic bucket. It originally had dog biscuits and is about the size of a household waste paper basket. I cut the flat base and the first four inches off a broken orange traffic cone. It is a funnel and props the bag open. There is almost no spillage or wasted effort. My Lee Valley round nose shovel has ears on the blade and three shovelfuls will overfill one bag. Move the bag off the shoveling site, tie it with two wraps and half hitch, then into the vehicle. The advantage of two people filling is one person rests while the other works.
To build the wall, I cut 3’ wide strips of waterproof tarp as a membrane layer against the expected rising water. Build the wall on the membrane and tamp down the bags to fill in as many gaps as possible. Even four inches of rise will move flowing water away. But have enough bags on hand to raise any barriers that will be overtopped. I expect to have to shovel trenches down to the ice layer I mentioned and get the water closer to my pump.
Finally, don’t expect anyone to help you if you get into trouble. The City’s response after the tornado proves they talk a good line but really have very little ability to render assistance. If you need to call 911 or 311, its already too late.
Fluctuating temperatures are a good thing, except when my downspout drains have frozen. I one place there is a cone solid ice about 2 feet high. To get the water moving away, I picked up a long run of 4″ lay flat flexible hose and attached it to the most offending downspout. When the night temperatures go below freezing, I have a habit of lifting the hose to knee height so any standing water can run out. If everything freezes. I’ll dismantle that run and lug all 40′ into the basement to thaw. Water flows better than ice.
Some succinct preparation statements:
- Set aside work clothes, gloves, boots, and hat for fighting the run off. Just like on a farm, leave the muddy clothes at the door.
- I have been able to stay healthy so far but my tennis elbow has flared up from gripping tool handles too tightly. Also, my arms and upper body are sore from the extra physical effort. Lift with your legs and keep good back posture. You can’t afford to lose any able bodied workers.
- Use the correct tools correctly. I leave the plastic snow shovels for moving soft snow. I have steel shovels and a substantial ice chipper for ice and hard snow. I’ve rediscovered my fondness for square nose shovels. Short handles for digging, and long handles for scraping. Round nose shovels are for digging soil, and we’re not there yet.
- The only defense against flooding is to keep the city’s catch basins flowing – use a rake to clear any leaves and litter. (The voice of experience says, wear a raincoat and boots because passing vehicles will splash). Monitor for ponding in case the drain gets overwhelmed. If that happens go clear the next basin over. If that doesn’t work, go help your neighbor redirect any overflow!
- Let the warm sun melt the driveway and front sidewalk. I found dark traction sand works well to attract even more warmth to stubborn ice patches.
- Although the next idea seems extreme, there is an awful lot of snow to consider. Shovel walking paths across the lawn to encourage meltwater to flow into the natural micro relief under the hedge and out to street. If necessary use the snowblower and shovels. Grass regrows.
- Keep the downspouts flowing so the shingles don’t get ice damage. If the buried drain backs up, keep a few Robertson and Phillips self-tapping screws and screwdrivers handy to separate any of the joints if required.
- Redirect the downspouts as far away from foundation as possible. Aluminum components are really cheap – a ruined basement is really expensive. Downspouts come in standard lengths, angles and sizes. They are very easy to install with a hacksaw, and screws.
- Build a barrier across every possible entry point to a height at least one row higher than you think is necessary – this includes any grade level doorsills and any flush windows (i.e. the laundry room window off the side driveway). I took the drastic step of prying off a few deck boards to inspect a concealed basement window and was rudely surprised to see ice already damming almost level with the metal window well. Leave enough room behind the sandbag wall so any doors to open and not cut the bags. Expect surface runoff to find the lowest elevation all around the foundation.
- To build a sandbag wall, expose the lawn for about 2 ft. Lay a membrane of heavy gauge poly plastic sheet or tarp on top of the soil as a waterproofing layer extending forward. Expect there will be some leakage. Lay a tight row of sandbags lengthwise to reduce the numbers of small joints. A good sandbag is about 20kg, filled enough to leave enough neck to tie off but not under filled and wasteful. Smack the bags in place with a pick handle, shovel blade or sledge hammer head to compress the sand inside the bags but not so hard you burst the bags. Stagger the joints each row. (The voice of experience says, be prepared to seal any gaps with aerosol expanding foam.) Fold the membrane back onto the wall and weight the free edge.
- For pumping, think where to find the lowest spot of the lawn. Dig out around that site. If possible, snowblow and shovel a walking trench from the street to the lowest spot. You will have a smooth place for drain hoses, and a smooth surface to walk without turning an ankle. (Again, there’s that voice of experience.) Put the sump pump in a milk crate, and brace or bungee it so it won’t fall over. Connect your largest diameter drain hose to the pump and run out the hose without kinks. Run electricity to the pump over the snow and out of the water. Use a timer if the pump cannot be monitored continuously. Be prepared to repair or install hoses, clamps, couplings and other fittings according to conditions.
- When the melt and run off are done, take stock of what worked and what didn’t. Plan to repair or replace the tools and supplies you need. Stockpile them in a readily accessible place. (The voice of experience discovered a thick layer of ice had formed on a shed floor and immobilized some of the tools needed for this season.)