To view the sewer cleaning and inspection program click here.

The Wastewater Treatment Plant operates two aerated lagoons with mechanical pre-screening. Generally, the plant relies on naturally occurring bacteria to perform the task of treating the influent, which we help along with aeration, mixing and occasionally the addition of some chemicals. The existing plant was built in the 70s and has undergone numerous upgrades specifically intended to alleviate concerns with odour and treatment effectiveness.

Odour has been an issue on and off for at least twenty years, predominately in the Spring and Summer months when temperatures increase and atmospheric conditions cause evening inversions. The odours are prominent when anaerobic digestion (without oxygen) is occurring. There are many factors influencing why this occurs (see bottom of post for a list) and why residents are encountering odours, and addressing the problem has proved difficult. One of the challenges is that measuring the success of a change in process or operations can take over two weeks to realize, due to the size of the ponds, by which time the climatic or other conditions may have changed, rendering the validation of the change difficult or impossible. One thing we do know for sure is that aeration and mixing are necessary components and generally our operational changes have been around improving these factors.

• Conversion to fine bubble aeration
• Desludging the first pond
• Addition of ferric chloride dosing at Downie Lift Station
• Inlet Works odour control project
• Periodic dosing the first pond with granular nitrate
• Periodic addition of beneficial bacteria in first pond
• Eliminating some anaerobic waste streams
• Installing mixers in first pond
• Improvements in airflow/cooling in the blower room to increase air output.
• Additional aeration work underway in 2017.

This work has been conducted with advice and design from qualified professional engineers who are experts in the field of sewer treatment and with input from our operators, who are trained in accordance with the Provincial Environmental Operators Certification Program (EOCP) and are working hard to ensure the plant operates as efficiently and odour-free as possible. Municipal Sewer Treatment is regulated by the Ministry of Environment, and generally the permit conditions are based on effluent quality, what is discharged to the river. Previous measurements of the odour have shown that it has been far below any health risk levels.

Inflow

• Biological Oxygen Demand (BOD)
• Total suspended solids
• pH, too acidic can cause anaerobic digestion.
• Total flow
• Temperature
• Grease
• Treatment inhibitors/toxicity

Pond

• Aeration of the pond (Dissolved Oxygen)
• Mixing - Seasonal turn over. It is quite common for aerated lagoons to smell for a week or so in spring and fall.
• Temperature
• warmer temperatures leads to higher treatment rates, requiring more oxygen.
• lower temperatures inhibits treatment, causing sludge build up, which can turn over causing odours when air temperatures increase.

Environment

• Wind and airflow
• Diurnal and seasonal patterns
• Temperature
• Proximity to dwellings