From Sewage Lagoon to Wetland Nature Preserve

A treatment plant expansion and upgrade includes a constructed wetland that doubles as a community nature study resource.
From Sewage Lagoon to Wetland Nature Preserve
The wetland ponds are surrounded by hundreds of young trees and shrubs, and about 20 strategically placed white spruce and white pine saplings will grow into a windbreak.

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A sewage lagoon being converted into a wetland and nature preserve at the Grand Bend Area Wastewater Treatment Facility in southern Ontario has solved treatment capacity and budget problems while gaining widespread recognition for its sustainable design.

The new 0.65 mgd facility was the first wastewater treatment project in the world to be certified under the Envision Sustainable Infrastructure rating system, sponsored by the Institute for Sustainable Infrastructure (ISI). It is also the first Envision-verified project in Canada.

Fitting the budget

Located on the shore of Lake Huron, the Grand Bend facility is jointly owned by the municipalities of Lambton Shores and South Huron, and is operated by Operations Management International. The original four-cell sewage lagoon facility was built in 1979 with a rated capacity of 0.5 mgd. By 2008, population growth and increasing septic system failures were causing effluent discharges that adversely affected surface and groundwater quality.

To solve the capacity problem, the communities in 2008 began design and contracting of a new tertiary-level treatment plant, but major budget overruns forced a stop to that project and brought alternatives into the picture.

“In 2012, the municipalities decided to abandon the originally designed sewage treatment facility because of the high capital cost and find a more affordable design,” says Brent Kittmer, director of community services for Lambton Shores. In 2013, they chose the Ontario-based design firm Stantec for its design plan to convert one of the four lagoons into an extended aeration mechanical treatment facility for biological nutrient removal with a constructed wetland and nature preserve.

Abundant plantings

This year more than 2,600 plants and shrubs were planted on the 31-acre converted lagoon site. Two wetland ponds are joined by a spillway lined with riprap. The ponds are surrounded by 200 shrubs, such as service berry, bottom bush, swamp rose and dogwood, plus 200 deciduous whips, such as sugar and silver maple, tulip tree, aspen, cherry, oak and basswood. Twenty strategically placed white spruce and white pine saplings provide a windscreen.

Along the shore and on the water of the kidney-shaped ponds are 2,170 native plants, including Canada anemone, Canada blue aster, sedge and Canada blue joint. Floating species like water lily and clumps of broad-leaf pondweed complement emergent plants that include water plantain, spike rush, wild calla and bull rush. Occasional clusters of boulders break the waterline, and sunken logs are placed in each pond at irregular intervals. A deep-water refuge of more than 12 feet has been excavated in each pond.

A berm of topsoil and gravel creates a turtle habitat along a portion of one shore. Turtle-basking logs and rootwad are nearby in the water. Half a dozen pits and topsoil mounds, a tall-grass prairie habitat, and high and low marsh areas dot the surrounding area.

Near the edge and along the perimeter of the wetland will be a gravel-surfaced hiking trail. A picnic area and a gravel parking area will be near the trailhead. Also planned are interpretive signage and a stone seating area at a learning center near the edge of the wetland. The public will be invited to tour and visit the wetlands.

Cooperative venture

Gary Deonarine, Stantec project manager, says the willingness of Lambton Shores and South Huron to include sustainable solutions enabled the design team to provide a wetland and nature preserve. “Through enhancement of local habitat geared toward native species, we hope to encourage the public and educational programs to enjoy this feature and become more environmentally conscious and understanding of infrastructure in their communities,” he says.

Stantec used the ISI Envision framework during the design to integrate sustainable features. The system sets a framework for planning, designing, evaluating and rating infrastructure projects against the needs and values of the community. It evaluates the economic, social and environmental costs and benefits of all types and sizes of projects, helping owners, designers and policymakers undertake consistent, objective and holistic planning.

Key sustainable features include the constructed wetland and a flexible design that makes the facility responsive to changing wastewater flows. The project also received sustainability credit for low construction and operating costs gained through efficiency, construction of the project within the original facility’s footprint to save nearby prime farmland, and creation of trails and interpretive signage.

During design, horticultural and conservation groups were engaged for their ideas on what the wetland should look like. Those groups helped with the planting phase. Says Kittmer, “We were thrilled about the wetland component of our project because it provided other opportunities for collaboration with community groups, which is a key part of our organizational culture.”



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