Re: Searchmont Ski Resort –…

Re: Searchmont Ski Resort – Proposed Wastewater Treatment Plant (WWTP) – Submission to the Environmental Registry of Ontario

To the Ministry of the Environment, Conservation and Parks,

I am submitting this comment in response to the proposed wastewater treatment plant (WWTP) for the Searchmont Ski Resort. These concerns are based on a summary of findings from an independent wastewater treatment expert who reviewed the design brief.

Buoyancy Control and the Need for Watertight Construction

The design appropriately includes anchoring of the lift station and tanks to protect against buoyancy, which is necessary given the shallow groundwater conditions at the site. However, the expert review noted that watertightness of all buried tanks and piping is equally important and is not addressed in the design brief.

If tanks, joints, or piping are not fully sealed, groundwater infiltration can enter the system, which can:

·        significantly increase hydraulic loading on the treatment plant

·        reduce treatment performance

·        compromise SBR cycle timing

·        increase sludge production

·        reduce the effectiveness of tertiary filtration and UV disinfection

Even though MECP does not typically regulate construction‑level details such as sealing methods, excess infiltration is an operational and performance risk that can directly affect the plant’s ability to meet its effluent limits. Given the shallow groundwater table at this site, watertight construction is essential to prevent inflow and infiltration from overwhelming the system.

I respectfully request that MECP require the proponent to:

1.      Address watertightness of all buried tanks and piping in the detailed design.

2.      Demonstrate that the system is protected against infiltration, especially during periods of high groundwater.

These steps are necessary to ensure the WWTP can operate reliably and maintain compliance under real‑world site conditions.

2)      Winter Temperatures, Insulation, and Biological Treatment Performance

The design brief does not mention insulation of tanks or process components, aside from noting in the Napier‑Reid documentation that insulation is excluded from their scope.

Insulation is an important consideration for maintaining wastewater temperatures within the biological treatment system. Colder temperatures slow down biological processes, including BOD removal and nitrification, which could affect the plant’s ability to meet effluent limits—particularly ammonia.

Physical and chemical processes associated with solids removal and phosphorus removal are generally less sensitive to cold temperatures, provided that equipment is protected from freezing. However, the biological processes in the SBRs are temperature‑dependent, and maintaining adequate wastewater temperature is essential for consistent performance.

The expert review noted that Napier‑Reid’s design calculations do consider both winter and summer conditions, including biological treatment performance at wastewater temperatures as low as 5°C. If the tanks are buried and insulated, achieving a winter wastewater temperature of approximately 5°C is reasonable, and the modelling appears to appropriately account for the process implications of winter conditions.

However, because insulation is not described in the design brief, it is unclear how the proponent intends to maintain the temperatures assumed in the modelling. Without insulation or equivalent construction measures, actual winter temperatures could fall below the design basis, potentially compromising biological treatment performance.

I respectfully request that MECP require the proponent to:

Clarify how wastewater temperatures will be maintained to match the assumptions used in the Napier‑Reid design calculations. Confirm whether insulation or other thermal protection measures will be included in the detailed design of buried tanks and process components. Demonstrate that the plant can reliably achieve the required biological treatment performance under realistic winter operating conditions.

These steps are necessary to ensure that the winter temperature assumptions used in the design are achievable and that the plant will perform as intended throughout the year.