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.
The expert concluded that while the proposed treatment technology is commonly used in Ontario and can perform well, several important design assumptions appear to be incomplete or underestimated. These issues could / would affect the plant’s ability to reliably meet its effluent limits and protect the sensitive receiving watercourse.
Below is a summary of our understanding of the key concerns the expert identified and the considerations and calls to action we are asking the MECP to consider carefully:
1) Concerns About Underestimated Influent Strength and Commercial Wastewater Impacts
The Design Brief describes the influent as “typical domestic wastewater.” However, based on the concentrations presented in Table 5 of the report, the proposed influent characteristics align more closely with weak to medium strength domestic sewage according to standard wastewater literature. The report does not explain whether these values were derived from actual monitoring at the existing facility or whether they are purely assumed. This lack of clarity is concerning given the nature of the proposed development.
A significant portion of the projected wastewater flow—approximately half—will originate from commercial uses, including restaurants and a conference centre. These types of facilities are well documented to produce wastewater with substantially higher concentrations of:
• Total Suspended Solids (TSS)
• Biochemical Oxygen Demand (BOD)
• Total Kjeldahl Nitrogen (TKN)
• Total Phosphorus (TP)
• Fats, Oils, and Grease (FOG)

Commercial restaurant wastewater can have BOD concentrations in the several hundreds to thousands of mg/L, depending on food type, cooking practices, dishwashing procedures, and grease management. In contrast, the design basis used in the report assumes an influent BOD of only 110 mg/L, which is typical of weak domestic sewage and does not reflect the expected contribution from commercial kitchens.
The expert review concluded that the influent concentrations used by the proponent and NapierReid are likely underestimated for a facility with this level of commercial activity. If 50% of the daily flow originates from restaurants and food service operations, all influent design concentrations (BOD, TSS, TKN, TP, FOG) should be reevaluated and increased to reflect the higher strength wastewater expected from these sources.
Underestimating influent strength has direct implications for:
• Nitrification performance and the ability to meet ammonia limits
• Aeration requirements and blower sizing
• Alkalinity demand
• Sludge production rates
• SBR cycle timing and tank sizing
• Tertiary filtration loading
• Overall treatment reliability

If actual TKN concentrations are higher than assumed, the plant may not achieve the required ammonia removal, and the treatment equipment may be undersized for realworld conditions.
Given the sensitivity of the receiving watercourse and the importance of accurate influent characterization, I respectfully request that MECP require the proponent to:
1. Clarify the basis for the influent concentrations used in the design (measured data vs. assumptions).
2. Reassess influent strength to account for the substantial contribution from restaurants and commercial kitchens.
3. Demonstrate that the treatment system is adequately sized for realistic BOD, TSS, TKN, TP, and FOG concentrations.

These steps are necessary to ensure the WWTP is designed to handle the actual wastewater characteristics expected from the proposed development.
2) Peak Flows May Be Higher Than the Design Assumes
The design uses a peaking factor of 2.0, but existing data from the resort shows peaks closer to 2.0–2.4, especially on weekends and holidays.
Without flow equalization, underestimating peak flows could lead to hydraulic overloading and reduced treatment performance during busy periods.
The design proposes an average daily flow (ADF) of 180 m³/day and a peak daily flow of 360 m³/day, which represents a peaking factor of 2.0. For a resort facility with highly variable occupancy — including weekends, holidays, and seasonal surges — a peaking factor of 2.0 appears low. Resorts typically experience sharp, shortduration spikes in water use, and the expert review noted that a higher peaking factor would be more realistic for this type of facility.
Based on the existing flow data already collected by the proponent, the actual peaking factor appears to range from approximately 2.0 to 2.4. This means the design is using the lowest end of the observed range, rather than the upper end that would provide a margin of safety. Underestimating peak flows can lead to hydraulic overloading of the SBRs, reduced settling performance, increased solids carryover to filtration, and reduced UV disinfection effectiveness.
Given the sensitivity of the receiving river and the importance of accurate design flows, I request that MECP require the proponent to justify the selected peaking factor and demonstrate that the plant can reliably handle peak flows at the upper end of the observed range (2.4), not just the minimum value.
3) Concerns About Design Flows, OBC Values, and Flow Monitoring
The proposed design flows in Table 3 of the Kresin Design Brief reference the Ontario Building Code (OBC) as the basis for flow generation rates. While the OBC values used for the restaurant and conference room components appear accurate, it is not clear where the value of 225 L/bed for the hotel component was derived. This is not an OBC value. Under the OBC, the applicable design flows are:
• 500 L/person for a resort hotel
• 250 L/room for a regular hotel/motel

The design brief does not explain why a nonOBC value (225 L/bed) was selected, nor does it justify why a lower value is appropriate for this facility. This is a significant concern because OBC values represent peak or maximum day flows, not average day flows. Since the proposed design does not include any upfront flow equalization, the accuracy of both the average and peak design flows becomes critical to ensuring the plant can reliably handle realworld peak conditions.
If the development is phased, detailed flow monitoring will be essential to verify actual average and peak flows. This is normally a standard ECA condition requiring the owner to track and report daily flow values. However, the design brief does not specify how daily flows will be measured.
The NapierReid package appears to include a flow meter as part of the tertiary treatment equipment, but this meter is located after the treatment process. A posttreatment flow meter does not represent the true influent entering the plant from the resort and therefore cannot be used to verify whether influent assumptions were correct or whether peak flows are being exceeded.
To ensure accurate flow tracking, the proponent should install a flow meter on the raw/influent sewage pumping station, where all wastewater first enters the system. If such a meter is already included in the lift station package, it is not clearly shown in the available drawings, and it would not typically be included unless explicitly specified.
Given the sensitivity of the receiving watercourse and the importance of accurate design flows, I request that MECP require the proponent to:
1. Justify the use of 225 L/bed and explain why OBCspecified values were not used.
2. Demonstrate that the design flows adequately capture peak conditions, especially in the absence of equalization.
3. Include influent flow monitoring at the raw sewage pumping station to ensure accurate tracking of actual flows entering the plant.

These steps are necessary to ensure the design is protective, robust, and based on defensible flow assumptions.
4) Technology Is Proven, but Performance Depends on Accurate Design Inputs and Proper Operation
From a highlevel perspective, the proposed treatment technologies are wellestablished and capable of meeting the effluent targets if the design assumptions are accurate. Sequencing Batch Reactors (SBRs) are a reliable and proven biological process for BOD removal and nitrification, and NapierReid has a long track record of successfully implementing this technology over the past 25 years.
However, the expert review emphasized that the ultimate performance of the plant will depend heavily on the accuracy of the design flow and influent quality assumptions. As noted in earlier comments, several influent parameters—particularly BOD, TSS, and TKN—appear to be underestimated given the significant contribution of wastewater from restaurants and commercial kitchens. If the plant receives higher or different influent strength than what the design is based on, the system may experience difficulty meeting its effluent limits, especially for ammonia.
In addition, the expert noted that plant operations will play a major role in performance. The way the facility is operated and maintained by the owner and their contracted wastewater operator will directly influence effluent quality. Even proven technologies can underperform if influent assumptions are incorrect or if operational oversight is insufficient.
Given these factors, I request that MECP require the proponent to:
1. Reassess influent flow and loading assumptions to ensure the design basis reflects realistic conditions for a resort with substantial commercial wastewater contributions.
2. Demonstrate that the treatment system is adequately sized to handle higherstrength influent if actual conditions exceed the assumed values.
3. Provide an operations and monitoring plan that ensures the system will be properly managed to achieve consistent performance.