The Eastern Subwatersheds Stormwater Management Retrofit Study is one of 17 projects in the City's Ottawa River Action Plan (ORAP).
What are the Eastern Subwatersheds?
The Eastern Subwatersheds cover an area of about 150 square kilometres in the east end of the City of Ottawa. A subwatershed is defined as all of the lands that drain to a particular creek. In this case, the Eastern Subwatersheds are made up of all of the lands that drain to Taylor Creek, Bilberry Creek, Voyageur Creek and Green's Creek and an area that drains directly to the Ottawa River known as the Queenswood catchments. This area is roughly bounded by Trim Road to the east, the Greenbelt to the south, Conroy Road to the west and the Ottawa River to the north.
Study Area: Eastern Subwatersheds
Why is a Retrofit Plan required for the Eastern Subwatersheds?
Much of the urbanized area within the Eastern Subwatersheds was developed with little or no stormwater management. When it rains in these areas, stormwater runs off roofs, roads and parking lots, is conveyed in storm sewers and discharged uncontrolled to the local creeks, or directly into the Ottawa River. Uncontrolled stormwater carries a host of pollutants and leads to large volumes of runoff and higher peak flows in streams. This affects water quality, increases erosion, degrades fish habitat, threatens infrastructure, and contributes to closures at Petrie Island Beach.
ORAP identified the Eastern Subwatersheds as a priority area to address these impacts of uncontrolled storm water runoff. The Retrofit Study will identify a long-term plan to:
- Improve water quality in the local Creeks and the Ottawa River
- Reduce flooding and erosion in the Creeks
- Improve the health of the Creeks
- Contribute to reduced closures at Petrie Island Beach.
What are the Retrofit Study's objectives?
The objectives *of the study are to:
- Reduce flood risk to public health and safety and to property along the Creek** corridors
- Reduce erosion impacts in the Creek corridors that are detrimental to property, infrastructure and stream habitat
- Re-establish a more natural hydrologic cycle for the Eastern Subwatersheds
- Improve water quality in the Creeks and the Ottawa River by reducing the impact of stormwater runoff
- Reduce the impacts of stormwater runoff on Petrie Island Beach
- Protect, enhance or rehabilitate natural features and functions along the Creek corridors
- Increase public awareness about stormwater management and public involvement
* Note: the numbering is for convenience and does not indicate priority.
** The Creeks referenced include Bilberry, Voyageur, and Taylor Creeks and the urbanized tributaries of Green's Creek (MacEwan Creek, Cyrville Drain and Mather Award Drain).
How is the Retrofit Study being carried out?
The Retrofit Study is being conducted as a Master Plan under the Municipal Class Environmental Assessment (EA) process. It will look at how different stormwater management measures can be retrofitted into existing communities.
The Study will:
- Define a range of retrofit scenarios (different combinations and amounts of the measures described below)
- Evaluate how well they meet the study objectives
- Identify a Preferred Retrofit Plan for the Eastern Subwatersheds.
What stormwater management measures will be considered?
SWM measures are classified by where they are located within the storm drainage system and include:
Lot level: These measures are located at the source of runoff, that is, on the lot. They reduce the amount of rainfall that runs off and prevent pollutants from being carried off the lot. Lot level measures are considered to be the first line of protection in maintaining or restoring the health of a watershed. Though each lot may be relatively small in size, the use of lot level measures on many properties can combine to provide a cumulative benefit.
Typical lot level measures include: rain barrels or cisterns that harvest rainfall for later use on the property; rain gardens and other absorbent landscaping measures that capture and infiltrate runoff; green roofs, and the use of various permeable materials for the construction of driveways and parking lots.
Conveyance measures follow lot level measures. These measures collect and accumulate runoff from individual lots and transport it to the drainage system's outlet, usually the closest creek or river. Conveyance measures include drainage ditches, swales, storm sewers and the road allowance. Conveyance retrofits include perforated or leaky pipes and curb extensions or bump-outs, that treat and absorb runoff via the use of soils and plantings called bioretention.
Next in line are End-of pipe measures, located at the end of the storm sewer system, where it outlets to the nearest creek or river. End-of-pipe measures are larger scale facilities that receive the accumulated runoff collected by the conveyance system. They provide treatment to improve the quality of runoff before it is discharged and can also store the runoff to avoid flooding impacts. End-of-pipe measures include constructed ponds and wetlands.
Stream rehabilitation measures: At times it may be necessary to consider in-stream measures that improve the stream's ability to withstand urbanized flows while at the same time maintaining its natural features and functions. Such measures can include re-building sections of the stream, creating off-line pools for floodplain storage, and cutting down banks to re-connect an eroded channel with its floodplain. While the intent is to avoid hardening the stream as much as possible, this is sometimes unavoidable if infrastructure or property is threatened by on-going erosion.
Oil and Grit Separator
All of these types of measures will be considered in the preparation of the SWM Retrofit Plan.
How can you get involved?
For more information about the Retrofit Study, please watch the video on this website and review the other information provided. Let us know what you think by providing your comments. If you have any other questions or would like your name added to the Study's mailing list please contact Laurent Jolliet.