Mount Brydges Wastewater Treatment Facility major improvements to the existing process to address compliance and operation & maintenance issues

Proponent

The Corporation of the Municipality of Strathroy-Caradoc
52 Frank Street
Strathroy-Caradoc, Ontario
N7G 1T8

Site location

Mount Brydges Wastewater Treatment Plant
22416 Mill Road
Township of Strathroy-Caradoc, County of Middlesex
N0Lnbsp;1W0

The Ministry received an application from The Corporation of the Municipality of Strathroy-Caradoc (the Proponent), for Mount Brydges Wastewater Treatment Facility (WWTF) major improvements to the existing process to address compliance and operation & maintenance issues.

An Environmental Compliance Approval (ECA) number 7788-8BJRL8 with a rated capacity of 825 cubic metres per day was issued to the Proponent on January 26, 2011, for Mount Brydges WWTF, for the treatment of sanitary sewage and disposal of effluent to a municipally-owned dry ditch which runs to the Vermeersch Drain located in the Upper Thames River watershed. When the Ministry Director issued a new ECA Number 5977-CPKPGM for the interim flow equalization tank on December 20, 2023, the original ECA Number 7788-8BJRL8 was revoked and replaced with the new ECA Number 5977-CPKPGM. The improvements being proposed by this application (Reference Number 7675-CN5RZ8), if approved, will amend the new ECA Number 5977-CPKPGM.

Current facility description

The Mount Brydges Wastewater Treatment Facility (WWTF), situated at 22416 Mill Road, provides wastewater treatment services for the Municipality of Strathroy-Caradoc, Ontario servicing the Mount Brydges Area. The Mount Brydges WWTF is currently rated at 825 cubic metres per day and treats sanitary sewage generated by the community of Mount Brydges. The current WWTF operates with a rotating biological contactor (RBC) process and currently has an Average Daily Flow (ADF) of approximately 300 cubic metres per day (To see Existing Site Layout, refer to supporting materials Figure 1).

Project need and process improvement objectives identified by the proponent

Mount Brydges WWTF has historically struggled with performance and effluent compliance, particularly with total ammonia nitrogen (TAN) and total suspended solids (TSS), as specified by the Ministry of the Environment, Conservation and Parks (MECP). Frequent mechanical failures of the RBCs’ mechanism, lack of pretreatment, and process treatment sensitivity to seasonal flow and loading fluctuations are major causes of recurring non-compliance of the WWTF historically. These operational challenges also significantly limit the WWTF capacity below its current rated capacity of 825 cubic metres per day. In summary, the poor performance of the existing process treatment system can be attributed to:

• Continuous moving of heavy mechanical equipment (discs and shafts) leading to frequent maintenance/repair shut-downs due to wear and tear.
• Sensitivity of attached growth process to temperature and loading fluctuations.
• Prolonged response time of attached biomass to adjust to maintenance/repair shut-downs and re-starts.
• Lack of preliminary treatment (screening and grit removal) contributing to wear and tear for downstream equipment.
• Lack of RBC system redundancy and robustness.

The process improvement objectives are as follows:

• Improve resiliency of the WWTF to consistently in compliance with the effluent limits and objective requirements per the ECA.
• Reduce operation and maintenance requirements and mitigate frequent maintenance/repair shut-downs due to equipment wear and tear.
• Improve sludge quality through pre-treatment process via removal of screenings and grit.
• Improve odour control at the facility.

Proposed facility process improvement upgrades

The existing spare concrete tank (kept empty on site as a ‘future’ RBC tank) is being converted to a flow equalization system to address the compliance issues in the interim solution. An ECA Number 5977-CPKPGM for the interim flow equalization tank was issued on December 20, 2023.

The Municipality intends to perform major improvements to the existing process to achieve long-term operational efficiency and resiliency of the WWTF to consistently meet the Ministry effluent requirements and reclaim its current rated capacity of 825 cubic metres per day.  

The proposed long term solution process upgrade, if approved, will amend the ECA Number 5977-CPKPGM and is within the approved rated capacity of 825 cubic metres per day, which includes the following upgrades (To see Proposed Process Improvements Site Layout, refer to supporting materials Figure 2) to achieve the process improvement objectives listed above:

• Addition of a headworks building to provide preliminary treatment such as screening and grit removal;
• Addition of an active carbon absorber odour control system to mitigate odourous air generated as part of the treatment process;
• Conversion of the existing RBC tanks (three in total) to extended aeration system (to improve process treatment and operation resiliency;
• Replacing existing return activated sludge (RAS) pumps (Qty: 4) to RAS/ waste activated sludge (WAS) pumps with piping and automated valves;
• Installation of a new scum collector system in the secondary clarifiers to improve scum collection and downstream process treatment such as filtration and disinfection;
• Installation of a new sludge holding tank for temporary storage of sludge at the WWTF before hauling off-site, thereby reducing the frequency and noise of sludge hauling trucks going to and from the WWTF.