By Heather Brewer, Ben Samuell, George Godin, and Emil Rafanan
A new wastewater treatment facility capable of achieving an effluent yearly average phosphorus concentration of 0.07 mg/l, is being built by the Town of New Tecumseth to serve the community of Tottenham. This effluent concentration is considered to be the current limit of technology in wastewater treatment, as achievable by two-stage tertiary treatment.
New Tecumseth in southwestern Ontario, is an amalgamated municipality including the towns of Alliston, Tottenham and Beeton, as well as the surrounding rural area of Tecumseth Township. In 2010, the Town completed an Addendum to the 2005 Class Environmental Assessment, to review the preferred alternative for wastewater servicing. The 2010 Addendum identified replacement of the existing Tottenham wastewater treatment plant with a new limit of technology treatment facility, discharging to Beeton Creek.
Recognizing that the allowable phosphorus loading limit for this receiver would require a concentration less than achievable by a limit of technology facility, a non-point source control program has been accepted by the Ontario Ministry of the Environment to reduce loading from other sources. This is to achieve no net increase in overall phosphorus loading to the receiver. Non-point source load reductions include a mix of urban stormwater system retrofits and rural best management practices.
The wastewater treatment facility
The new Tottenham WWTP is designed for an annual average flow capacity of 4,082 m3/day, providing adequate capacity for growth in Tottenham to at least 2031. The new treatment facilities are located in what was one of four pre-existing lagoons. This allows the plant to be completed before the majority of the existing facilities are decommissioned. The new facility includes:
- Screening (6 mm) and vortex grit removal in a headworks building.
- Extended aeration process, consisting of bioreactors with fine pore diffusers and secondary clarification.
- Two-stage tertiary treatment using ballasted clarification (complete with 6 mm perforated plate tertiary screening) and shallow-bed sand filtration. This is all located in a new administration/tertiary building.
- Chemical addition for enhanced phosphorus removal and pH control.
- UV disinfection.
- Aerobic digestion for sludge stabilization.
- Odour control system.
- Biosolids utilization on agricultural land.
Infrastructure from the existing facility, which will be reused, includes two lagoons for temporary storage of flows exceeding peak day tertiary treatment design capacity, a lagoon for biosolids storage during winter periods, and the existing outfall to Beeton Creek.