Infill development often presents unique challenges that require specific attention. An application for an infill development permit must be accompanied by a proposed Lot Grading Plan. For any property where a Subdivision Design Grade Plan does not exist, it will be the responsibility of the applicant to work with an Alberta Land Surveyor to develop a Lot Grading Plan that illustrates both existing and proposed grades.
Grading for infill developments must be configured to move surface runoff to the abutting public sidewalk, road and/or rear lane. This can be achieved with the development of an internal swale (located entirely within your property) or a shared swale (in cooperation with the adjacent property owner). Swales must be designed to provide a minimum slope of 1.5% for surface runoff.
The optimal goal here is to handle your drainage entirely within your property without negatively impacting any of the adjacent lands. The development of common property swales and internal swales for infill developments are often the most cost-effective method and most popular choice as the water is being handled within the property and directed toward the sidewalk, road and or lane.
Common property swales (Detail A) are possible where abutting properties are suitably graded (i.e. an existing approved infill development) or where abutting property owners collaborate to create common property swale by undertaking grading improvements on both properties.
Internal swales (Detail B) are required for locations where a common property swale cannot be constructed due to unapproved grading on an abutting property.
When the use of swales has been included in the design, the lot grading plan must show locations, slopes, and cross section details for the swales.
Detail A Detail B
Properties Abutting Infill Development
For properties with no approved Lot Grading Plan, including properties abutting infill developments, it is highly recommended that all property owners establish and maintain surface grades and elevations adjacent to buildings in such a way that the water drains 1) away from buildings, and 2) toward a Town right-of-way (road, lane, sidewalk, etc.)
Regrading and Landscaping in Mature Neighborhoods
Regrading to alter the flow of surface runoff on premises must be illustrated in an approved Lot Grading Plan. Therefore, consulting with abutting property owners is a critical step when considering any grade changes or downspout location changes that affect surface runoff management between neighboring lots. Changes to a downspout or sump pump discharge location that directs surface runoff onto an abutting private property may be a bylaw violation.