Drainage and Lot Grading Standards

Lot Grading Commmon Residential Lot Issues Residential Standards Commercial Standards

Lot Grading

Lot grading is the shaping of the ground to allow surface water runoff to flow away from buildings to a drainage path, usually toward a City right-of-way. Proper lot grading keeps surface water away from buildings for the benefit of the property owners.

All property owners are responsible for their own lot grading, which must protect buildings on their lot and not negatively impact adjacent properties.

Common Residential Lot Grading & Drainage Issues

Improper lot grading can cause poor surface drainage. Runoff from heavy rain or melting snow can result in standing water, flooding, foundation settlement or basement dampness.

Many issues can be resolved with open communication. All property owners have an equal interest in effective drainage of surface water. Remember that maintaining the grading area around your house and your property is your responsibility as a property owner. Be ready and prepare your house for the potential of flooding, even if it has never happened before. You can prepare for these storm or runoff events by employing the following strategies:

Checking your own grading and surface runoff.
- Ensure that there is proper slope away from the foundation, including the area under decks and steps.
- Keep all drainage swales and grading along the common lot line unobstructed and free draining. If you are unsure which way the water is supposed to be draining, you may request this information from the City of Steinbach Engineering Department via e-mail at engineering@steinbach.ca. If available, the lot grading plan that includes your property will be provided.
Add the final 4 inches of landscaping (e.g., topsoil, sod, or other decorative landscaping material) after rough grading (4 inches below design grade) of your lot has been approved by the City of Steinbach Engineering Department inspector.
Ensure window wells are installed and maintained where required. Window wells allow the ground adjacent to a window to be raised to achieve proper slope away from the foundation.
Clean your eaves troughs and downspouts regularly. Make sure downspout extensions are discharging surface water onto your own property. All roof downspouts shall be located in a manner such that they provide effective positive drainage away from the building. They shall discharge through a suitable elbow fitting onto a splash pad in order to carry run off away from the foundation.
Ensure your sump pump is discharging onto a splash pad as per By Law 1674 (View Sump Pump Discharge Information). Water from your sump pump should be allowed to infiltrate into the earth prior to exiting your property.
During snow melt, shovel snow away from the window wells, downspouts, and your house foundation, within your private property, to provide a path for surface water to follow towards a City right-of-way or rear yard swale.
Any driveway on a lot shall have a minimum grade of 2% and a maximum grade of 6% and shall be constructed in a manner such that it will not inhibit water runoff away from the building.
Talk to your neighbours to work out solutions because they may not realize there is a problem.
- If you need help to initiate a conversation and collaborative solution with your neighbour, you can contact the City of Steinbach Engineering Department at engineering@steinbach.ca for suggestions.
Contact a professional landscaper or lot grading contractor to complete a drainage inspection of your property. These companies can survey your property and determine if your property is in compliance.

Residential Lot Grading Standards

Minimum Lot Grading Slopes

Rear-to-front drainage

The rear lot line is the high point on the lot.
Surface water on the property is drained to side yard swales.
Side yard swales must be a minimum of 2% slope to the front.

Split drainage to a back lane

The highest elevation is set near the midpoint on the property.
Surface drainage then flows to the street and to the rear lot line and onto the lane.
Side yard swales must be a minimum of 2% slope to the front and rear.

Split drainage to a rear yard swale

The highest elevation is set near the midpoint on the property.
Surface drainage then flows to the street and to the rear lot line and onto a rear yard swale.
Side yard swales must be a minimum of 2% slope to the front and rear.
It is very important to maintain elevations according to the lot grading plan along rear yard swales. Any change of elevation will affect not only the owner but also their neighbours.

Side Yard Swale Improvements

In many of the older sections of the City, pre-existing drainage problems exist. These problems can become more obvious when older lots are re-developed (commonly referred to as infill development).

Infill development creates an opportunity for neighbouring owners to consider the existing state of their grading and take steps to improve the surface drainage on their own property. In many cases, a common property swale can be made in conjunction with any infill development. Whether the drainage issue has existed for many years or will become more obvious as a result of infill development, there are options to correct these issues. The suggested improvement process is as follows:

The first step is to communicate with your neighbour to begin the discussion of drainage improvements.
Next, you should examine your own grading and understand any changes needed to ensure that surface runoff is directed away from your buildings. Your neighbour should do the same.
You should then evaluate the existing drainage pattern and discharge locations with your neighbour to determine the best place for water to flow out of downspouts or sump discharge splash pads.
You may need to create or improve the swale between the properties. A shared swale on the common property line (Detail A, below) is the preferred choice. If the neighbouring property owner is not cooperative, a separate, internal swale within the lot (Detail B, below) is sometimes required to solve a drainage problem. Installation of the retaining wall ensures that any surface water originating on your property does not affect or damage the neighbouring property.

Rear Yard Swales

These swales are required so neighboring properties may properly drain their storm water runoff. Rear yard swales are shown on the approved lot grading plan and must be maintained by the property owner.

Swales must be unobstructed and free draining.

Trees should not be planted in rear yard swales.
Fences must be installed so as to not obstruct the bottom 150mm (6 inches) to allow water to flow underneath.
Rear yard swales may not be enclosed by installing a pipe.

Commercial Lot Grading Standards

Any property that is being newly developed or any existing developed property that is being expanded, added to, etc. will be required, as part of the Building Permit requirements, to submit an engineered lot grading and site servicing plan indicating geodetic building elevations, lot elevations, and typical drainage patterns. Also required will be engineered storm runoff calculations ensuring that the City’s storm runoff guidelines are met.

Engineering Consultants

Engineering companies must pre-qualify to work on commercial lot grading and site servicing plans submitted to the City of Steinbach. Engineering companies that are not pre-qualified but who wish to submit plans must provide an application to work, in writing, and include the following information:

A company profile including a company description, staff expertise, and examples of similarly completed work complete with references.
A brief summary of understanding City of Steinbach commercial lot grading requirements.
A brief summary of the project scope of work.

If, in the City’s opinion, the company appears qualified to complete the work, the company will be permitted to complete the work on a probationary basis.

To obtain the list of pre-qualified companies and any other information related to this process you may e-mail engineering@steinbach.ca.

Stormwater Management Policy

Roof and surface drainage from these lots shall be controlled in a manner satisfactory to the City in order that the maximum rate of run-off into the City's storm system shall be not greater than if these lots had been developed as residential properties (i.e. the average residential lot has an imperviousness of 35%). All Rational Formula runoff calculations are to be based on a 2 year storm event, with "t" (time) = 15 minutes and "i" (intensity) - 2.63 in./hr. Surface type coefficients shall be as follows: 0.10 for landscaped or grass; 0.50 for gravel; and 0.90 for asphalt or concrete pavement or building areas. While the allowable total runoff from a site will be restricted to a 2-year storm event with an average site impervious value of 0.35, the storage areas (if required) for this site shall be sized to handle the volume accumulated from a 25-year storm event (5.01 in./hr. for 15 min.).