Question
I live in New Brunswick, Canada and have a couple of drainage issues (only in the winter).  I live on a hill, the land is slightly higher (than my driveway and basement windows) on the back side of my home.   Snow will melt, and water runs onto the driveway (later to freeze on the driveway).  This ice will build up over the winter becoming a real pain.  Also, I have three basement windows close to grade.  When there is snow on the ground and we get a heavy rain, the snow collects and holds the water, raising the water enough that it comes into my finished basement through the closed windows.  We have installed window wells however I do not wish to bring them so high that we can not see out the window.  I believe I am going to rent a back hoe to make good trenches (to move the water to an area that will drain well) filled with 3/4" clear stone.  I think I would prefer to make a trench wider with more stone than to install piping that may clog later?  I am unsure if I should use fabric (thinking it may seal and prevent water propagation).  Also, it would be nice if I could place some soil and seed over the rock trench system as it is would look best.
 What I am wondering is will water freeze on top of the stone, soil, lawn system I propose to install, sealing off the drainage system from taking water away?  Do you have any other suggestions?  I would like to do this fix right the first time and am able to send a couple of pictures if you feel you could better advise.
Thank you in advance for your consideration.

Mark F

Answer
Hello,

I would suggest the idea of intercepting the water before it reaches the area. This can be done by ditch,swale,trench drains or catch basins.

Filter fabric can be omitted if the pitch of the pipe is steep enough to allow fine sediment to be flushed out. Otherwise it would probably be a good idea to use fabric. The soil behind the fabric will not cause clogging.

A rock filled french drain will carry less water because the rock displaces it and a such a french drain will clog as readily as a pipe,perhaps more so. Planting over it would also slow the water down and give the water time to soak into the drain. I think perhaps you would be better served by a drain with an open inlet such as a trench drain or catch basins.

French drains are not suited well for the collection of surface water and so of course are not suited to intercepting water from slopes,where the water is faster moving. Water movement through the gravel in the drain would be relatively slow. You need to remove the water at a fast rate before it can get to your driveway. The gravel in a french drain only serves as a retention area and as a slower conduit for water and the gravel can serve as bedding for the pipe. The water builds up and is retained in the gravel of the french drain and then is drained away at a faster rate by the perforated french drain pipe.

A french drain with soil cover will be even less efficient at intercepting surface flow then one where the gravel extends up to grade.

Any water frozen over the drainage devices is not moving. As it thaws out it will leak into the drainage device.

A berm or flood wall could also be a possibility but then a retention area to hold the water would have to be constructed behind the berm or wall. A french drain could possibly be used to drain such a retention area.

A pic would be helpful but none of this general advice will substitute for an analysis of the site and a plan. I would not proceed with construction until I was reasonably sure of a good solution. Good luck. Let me know if I can be of further help.

Mark Harshman


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