Town of Osoyoos Sewer Odour Issues

Town of Osoyoos Sewer Odour Issues

Town Council and staff are aware of odour issues again this year from the wastewater treatment plant by the golf course and associated wastewater system in the community. We take these odour issues seriously, and understand the frustration that residents feel as this issue remains unresolved and seems to recur each year. Wastewater treatment and disposal are complex matters and the Town can’t simply change operating procedures or buy an additive that will resolve the situation despite claims that could be done and the problem would be resolved.

The Town has budgeted for system improvements in its Financial Plan designed to improve the treatment and disposal of wastewater and address odour concerns including the recently completed Main Wastewater Pumping Station (MWWPS) at a cost of approximately $5M. The new MWWPS includes screening capacity designed to remove solids and other discarded materials often found in wastewater before pumping effluent to the sewage lagoons for treatment. This will reduce the accumulation of sludge in the lagoons and improve bacteriological processes that treat wastewater. The Town will likely need to de-sludge the sewage lagoons again in the near future now that the MWWPS is online to improve system operation.

The Town has recently completed works to improve aeration to the treatment plant, hoping that it would improve dissolved oxygen levels in the ponds; oxygen is key in the support of the biological processes. The Town has budgeted for an Operational Assessment of the lagoons in 2020 to review and improve operational processes as well as potential capital improvements to access the treatment process.

Why does the Wastewater Treatment Plant smell so bad at certain times of year?

The odour concerns seem to be worst during periods of hot weather and when the Town experiences its seasonal peak visitation in the summer months. The wastewater treatment system receives inflows in the summer that are far greater than the amount usually received during non-peak months. The treatment system is designed to receive these additional flows, but the treatment process needs to adjust and this takes time. Odours are further exacerbated by the higher temperatures due to a rise in water temperature.

There are many factors influencing why this occurs and why residents experience issues with offensive odours. Addressing this problem has proven difficult and despite it being a concern for many years a final solution has not been identified. The size of the ponds, variation in volumes and composition of inflows as well as climatic conditions makes it difficult to predict when the odour issues might arise but generally it is worst when the weather is hot. While offensive, these odours do not present a risk to public health.

How does the Wastewater Treatment Plant work?

The wastewater treatment plant operates with aerated lagoons and now with mechanical pre-screening at the MWWPS. The plant operates with naturally occurring bacteria to perform the task of treating the influent, which is enhanced by aeration, mixing and occasionally the addition of some chemicals. Once treatment is complete, the treated effluent is then chlorinated and used to irrigate the Osoyoos Golf Club and West Bench sports fields, with any excess being disposed of to the ground south of Desert Park racetrack. The Town operates monitoring wells to ensure that wastewater disposal does not negatively impact ground water supplies or Osoyoos Lake. In 2020 the Town has budgeted for the installation of two new groundwater monitoring wells.

The Town continues to obtain advice and design solutions from qualified professional engineers who are experts in the field of wastewater treatment and disposal. The Town’s operators are trained in accordance with the Provincial Environmental Operators Certification Program (EOCP) and work hard to ensure the plant operates as efficiently and odour-free as possible. Municipal wastewater treatment and disposal is regulated by the Provincial Environmental Management Act and subject to permit conditions that dictate effluent quality and disposal methods.

Some factors that influence odours:

Inflow

• Wastewater collection system piping and manholes
• Wastewater pumping stations
• 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.
• Air Temperature
• Warmer temperatures leads to higher treatment rates, requiring more oxygen.
• Lower temperatures inhibits treatment, causing sludge build up, which can turn over (seasonally) causing odours when air temperatures increase.

Environment

• Disposal method
• Wind and airflow
• Time of day and seasonal patterns
• Temperature
• Proximity to dwellings

Contact Information

Operational Services
250.495.6213
pubworks@osoyoos.ca