Mill Creek Roper Pond sustains and enhances the natural environment while providing flood management

Aerial view of Mill Creek Roper Pond

During major storms, the City of Edmonton’s Argyll Tunnel, a major stormwater sewer that
discharges to the North Saskatchewan River, can become overloaded and cause flooding in the Mill Creek drainage basin. The City sought a sustainable stormwater management
solution to address potential flooding, and retained Associated Engineering to develop the
design, oversee construction, and provide overall project management.

The Mill Creek drainage basin covers an area of about 10,000 hectares in central and southeastern Edmonton and the County of Strathcona. About 25% of the area has been developed, most of which is commercial and industrial.

Working with the City, Associated Engineering developed a stormwater management pond and wetlands to reduce surcharging on the tunnel, reduce flooding potential, improve stormwater quality of the discharge to the North Saskatchewan River, and enhance the natural environment.

The site selected for Mill Creek Roper Pond was an industrial area along Mill Creek that, over the years, had become overrun by abandoned and rundown buildings, farmhouse, and barns, as well as industrial and domestic waste. Thus, a major site clean up was required.

Removing debris and contaminated soils from the area was the first step in restoring the ecological balance of the area. In total, 6,500 tonnes of general waste, concrete, and steel and 5,600 tonnes of contaminated soil were removed from the area. As soil conservation was a critical component of the ecological restoration, all useable soils were salvaged and reused.

Mill Creek Roper Pond provides storage for a 1 in 100 year storm event and controls the release of stormwater downstream. The wetlands improve the water quality of the stormwater discharged to Mill Creek and the North Saskatchewan River. The dual cell wetland design incorporates deep pool inlets and outlets for removing sediments and contaminants such as hydrocarbons and heavy metals. Natural vegetation in the low marsh area provides filtering to further improve the water quality.
A treed area in the middle of the pond was left to create an island refuge for wildlife, which presently is the nesting home for a red-tail hawk. Habitats were created to attract new wildlife and waterfowl to the area. Other habitat enhancements include bat boxes, birdhouses, and dragonfly boulder perches.

A trail system was constructed around the pond for light recreational use, including walking, jogging, and cycling. The trails were set back from the natural areas to minimize impact on wildlife and habitat. Along the trail, nature view points, seating, and interpretive signage were constructed to provide public education on the natural environment, stormwater management, wetlands, and ecological restoration. The information on the signage was based on the public school science curriculum to encourage public school tours, as well as use of the facility by people who work and live in the area. The City hopes that through this process, they will encourage environmental stewardship.

Herb Kuehne, P.Eng., Project Manager, states, “Mill Creek Roper Pond provides a naturalized wetland area for waterfowl nesting, birds, and wildlife, serves as a multi-use recreational facility, improves the quality of stormwater, and reduces the risk of flooding overloading the storm tunnel downstream. The work helps to restore the ecological balance in the Mill Creek ravine and provides benefits to the community for years to come.”

This project received the Consulting Engineers of Alberta’s 2007 Award of Excellence for sustainable design, and an award of Merit for Community Development. Congratulations to the project team!

Alberta Highway Design and Construction Team