Friday, February 21, 2014

A Primer On Basement Flooding In Toronto

Basement flooding is one of the realities of living in Toronto.  There's three major problems here:

  • The houses are often built over the top of aquifers, flood-plains and other places with a naturally high water table.  This means the water rises until you find it coming up under the floor.
  • The infrastructure wasn't designed to handle what the city planners threw at it.  A perfect example is the street I currently live on.  The storm sewer was laid in the 1950s and it's plenty big enough to handle our street, but in the 1960s and 1970s when the city planners decided to pave over 100 acres of nearby fields to turn it into car parks and big box stores, that's 100 acres of storm water catchment with no ground to seep into.  The water runs into the drains, and those are connected to the storm sewers that run towards the lake.  On its way, it runs past our neighbourhood, which is also connected to the same sewers and so it barrels back up into people's basements.
  • The homeowners are at fault, for not fixing up eaves-troughs, downspouts, soil-grading, disconnecting weeping tile, etc.

As a home-owner, you end up having to play detective - trying to work out what combination of the above is causing your flooding.

The current house I live in, which was built in 1952, was purchased by me in 2011.  In 2012, we got flooded in our basement after 50mm of rain fell in one hour. That cost $26,000 to fix (thankfully, we had sewer backup and flood insurance!).  The main cause there was the city sewers backed up.  This was easy to fix going forward - install a back flow preventer.  In 2013, we had a storm where over 70mm of rain fell in one hour, and our flooding was reduced by 95%... the back flow preventers were doing their job.

The new problem we could see was whilst we solved the problem of back-flow, the water table would rise so fast it was breaching the basement floor.  Now it looked like we needed a sump pump to relieve the hydrostatic pressure (the pressure from the rising water table) by pumping out the water before it gets high enough to breach the basement concrete floor.  Thankfully, I already had a 1/2hp submersible pump, so I threw that down the hole where the back-flow preventer was - thus I had jury-rigged a sump pump to remove most of what had still entered, but we didn't need to call the insurance company.

The next issue was the downspouts and eaves-troughs.  I emptied those, got everything ship shape, and we survived another 50mm an hour downpour with just a little puddling.  However, I'd still not saved up enough for the sump pump. 

Then, I made a silly mistake...

My partner had ordered some eaves trough cleaning company from Groupon to come and empty everything in the autumn.  They got so overwhelmed it's now spring and they're still not coming for another month.  In the meantime, I didn't brave the cold and go up there myself.

So, we arrive at today, and where the eavestrough overflowed down the wall, we have another huge puddle in the basement.  Further, because I'd still not got the sump pump in, we had more puddles in the family room.

Whilst I couldn't fix the horses that have bolted, I could prevent one more catastrophe - the 3ft of snow round the house had to be dug up and shifted, so it's not melting against the foundation walls.  That appears to have relieved some of the downward flow to the puddles.

I'm now entertaining estimates for the sump pump, and come spring, will re-grade the soil where necessary.

The moral of the story is this:  I've got 99% less problems now, than I had when I first bought the house.  Further, most of the issues now are preventable.  Whilst the sump pump is expensive (they have to break through the basement floor, go down a good metre or more and install the well wall and drop in the pump, then go through the external wall and install a discharge pipe), the rest is free - it's just a case of taking the time and planning when to do preventative maintenance. 

A good 75% of today's issues in my basement could have been prevented for free, but I would have to have put in the effort last year, then moved some of the snow as soon as it fell.