Navigating Ontario’s future

In Canada, the province of Ontario faces significant challenges in maintaining water quality and quantity as it grapples with stressors such as climate change, intensified urbanisation and population growth.

For the town of New Tecumseth, which borders Lake St. Clair, achieving a reduction in phosphorus levels has been a key part of protecting the local watershed.

The town owns and operates three Wastewater Treatment Plants (WWTPs) to provide sewage services to the serviced areas in the community, including the Tottenham WWTP.

Challenge

Increasingly, traditional approaches to address water quality issues by providing advanced levels of wastewater treatment are resulting in only marginal water quality improvement but with significant increases in negative sustainability impacts. This is the case for the Tottenham WWTP, which is undergoing an upgrade.

According to Heather Brewer, Engineer, “It is emerging that as the level of wastewater treatment approaches the practical limit of technology for phosphorus removal, watershed protection requires alternative measures to address comparatively significant phosphorus loads from other sources, such as urban stormwater and rural non-point sources.

“Control of these other sources may be outside the traditional regulatory framework governing the wastewater treatment facility, and innovative approaches are needed to implement a functional watershed protection program.”

Solution

The new Tottenham WWTP is designed for an annual average day flow capacity of 4,082 m3/d (144,150 feet3/d) and is located in what was one of four pre-existing lagoons. It includes a range of features, including screening and vortex grit removal, extended aeration process, two-stage tertiary treatment, chemical addition for enhanced phosphorus removal and pH control, ultraviolet disinfection, aerobic digestion for sludge stabilisation, odour control system and biosolids utilisation on agricultural land.

Based on a detailed Water Quality Impact Assessment by XCG Consultants Ltd, the phosphorus loading to Beeton Creek from the Tottenham WWTP was not to exceed 65 kg/year.

While the new Tottenham WWTP will produce an annual TP loading of 104 kg/year (229 pounds/year) at its rated capacity, the implementation of a total phosphorus offsets program will achieve an equivalent annual reduction of TP loading into the watershed to be credited on a 2:1 ratio, and rural best management phosphorus offsets to be credited on a 4:1 ratio.

The phosphorus load offset potential from the improvement of existing stormwater management facilities in the Beeton Creek watershed was estimated at approximately 30 kg/year (66 pounds/year).

Outcomes

By entering into a partnership with the local Conservation Authority (CA), the town leveraged directives to address the unregulated watershed loading sources with measures as needed to provide wastewater servicing based on an advanced tertiary treatment facility.

To achieve this, the town combined a new limit of technology tertiary wastewater treatment facility with a phosphorus offset program.

Heather concludes, “With accelerated eutrophication of certain rivers and inland lakes in Canada attributed to phosphorous loading from human activities, this integrated watershed protection approach is one of the first of its kind to be approved in Ontario by the Ministry of the Environment and Climate Change (MOECC).

“It provides a successful example to municipalities located in other phosphorus stressed watersheds in this jurisdiction and elsewhere.”