Infill development often presents unique challenges when building in a mature neighbourhood.
When applying for an infill development permit you must include a proposed lot grading plan if an approved lot grading plan does not already exist.
Lot grading plans must be approved by the City before starting construction of any buildings, additions to buildings, or alterations of surface drainage. See sections 4(1) of Drainage Bylaw 18903, and 14.10 of Zoning Bylaw 12800.
When formulating your lot grading design plans, working with adjoining property owners could minimize costs associated with stormwater control. Create a lot grading plan that defines how your lot will convey surface runoff to a City right-of-way without flowing into adjacent private properties.
- Confirm the site servicing requirements for roof drainage and subsurface water drainage. Contact EPCOR Infill Water and Sewer Servicing at 780-496-5444 or email firstname.lastname@example.org for information relative to an existing storm service and for options to dispose of subsurface water from the foundation drainage system.
- Swales must be designed to provide a minimum slope of 1.5% for surface runoff. Swale design must begin with the elevation of the final drain point at the sidewalk, curb, or paved lane when locating critical high points and calculating slopes. A minimum depth of 10 cm and a minimum width of 15 cm is required. Also, the design must provide an elevation difference of 15 cm between the lowest opening (entrance door or window well) and the bottom of the drainage swale.
- Internal drainage swales are required for locations where a common property swale cannot be constructed due to existing grading or unapproved grading on an abutting property. Minimum slope of 1.5%, a minimum depth of 10 cm and a width of 15 cm is required.
- Retaining walls must be constructed to support any elevation difference between a developing property and an adjacent private property (Detail B). Retaining walls must be constructed of concrete (with a curb or trough) or of pressure-treated timbers with a minimum of 10 cm x 15 cm (4" x 6") and must project below the existing ground elevation of an adjacent property. Retaining walls must be self-supporting. Permeable walls require a permanent moisture barrier.
- Common property swales (Detail A) are possible where common adjacent properties are suitably graded. For example, when there is an existing approved infill development or when adjacent property owners collaborate to create a common property swale by undertaking grading improvements on their properties.
- Plan the demolition and reconstruction processes to ensure interim control of surface drainage during all phases of the redevelopment project including creating internal drainage swales and controlling roof, downspouts and sump pump discharge. Directing or allowing surface runoff to flow onto adjacent private property is a bylaw violation.
- During construction, internal drainage swales are required to ensure interim control of surface runoff. Directing surface runoff onto abutting private property may be a bylaw violation.
It is the owner's responsibility to maintain the lot grading and ensure it meets the requirements of the Drainage Bylaw and the lot grading guidelines. For more information, please refer to lot grading inspections pamphlet.
Site inspections and grading approvals can be arranged by submitting a lot grading certificate to the City by:
- Email to: email@example.com, or
- Mail to:
2nd Floor, Edmonton Tower
10111 104 Avenue NW
Edmonton, AB, T5J 0J4