Will Ontario's Code allow a dry well where Ottawa groundwater sits high?

Ontario's Building Code permits a dry well for foundation drain discharge only where natural groundwater is below the bottom of the dry well, and the well is at least 5 m from the foundation (clause 9.14.5.3). If groundwater in your area sits high, that first condition cannot be met, and the Code does not allow a dry well.

What the Code requires instead

Where a dry well is ruled out, clause 9.14.5.1 says foundation drains must discharge to a sewer or a drainage ditch. The City of Ottawa says foundation drains in some older homes may be connected to the sanitary or combined sewer, and that foundation drains should not be connected to the sanitary sewer. Where gravity drainage to a sewer is not practical, clause 9.14.5.2 requires an automatic sump pump, with the pit at least 750 mm deep and at least 0.25 m² in area, covered with a child-resistant, airtight lid. The City advises discharging the sump pump to the ground at least 1.2 m from the foundation, or connecting it to the storm sewer.

The Code gives no number for what counts as "high" groundwater, and it gives no test a homeowner can run. Whether groundwater at a specific property is high enough to disqualify a dry well, and what the right discharge point is for that property, are things a contractor assesses by looking at the site, the soil and the existing drainage arrangement.

A few things worth asking any contractor who proposes a dry well or a sump discharge:

• What evidence do they have about groundwater depth at this property, and how does that satisfy clause 9.14.5.3?
• Where exactly will the discharge go, and how does that connect to the storm sewer or reach the surface?
• Who pulls the permit, given that drain tile replacement and plumbing alterations both require one from the City of Ottawa?

Because the discharge point for a sump pump or a foundation drain touches the plumbing system, ask whether a licensed plumber does or signs off the plumbing portion of the work.

Before any design work, ask the contractor to show in writing where the drains will discharge and which option in 9.14.5 that uses.