Wastewater System - Tillsonburg

The County maintains a diverse portfolio of assets that are required to provide the community of Tillsonburg with the safe collection and treatment of wastewater. The Tillsonburg Wastewater Treatment Plant (WWTP) provides wastewater treatment for residential, commercial, industrial and institutional users in the Town of Tillsonburg.

The wastewater collection network transports waste to the WWTP for treatment. The wastewater collection network consists of a mix of gravity mains, and forcemains. Wastewater flows by gravity wherever possible or using sewage pumping stations (SPS) where changing elevations require. Other specialized structures such as maintenance holes, valve vaults, meter stations, diversion structures and siphons are required to convey wastewater to the WWTP.

Inventory

The replacement cost valuation for the linear assets in this portfolio are based on current tender prices, where available. The replacement cost valuation for wastewater vertical is based on the latest information available, which includes current replacement costs, insurance valuations, inflation, and valuations from studies and assessments completed in prior years. Quantity changes are attributed to refinements and updates made to the inventory, ensuring more accurate and current data.

Condition

The percentage of assets in poor or critical condition has increased from 15% as reported in the 2024 AMP to 17%. The percentage of assets in good or excellent condition has decreased from 50% as reported in the 2024 AMP to 48%. As assets continue to age their condition rating will decline until lifecycle strategies are triggered and completed.

Key Performance

The wastewater network collects and treats wastewater from homes, businesses, institutions, and industry. Wastewater travels through the sanitary sewer system to the WWTP for treatment. It is intended that all wastewater assets will be maintained, rehabilitated, and replaced to perform the same function and manage the same capacity as they are currently designed to do.

Proposed Levels of Service Review

Information on scenarios reviewed is contained within the AMP document. As the system’s reserve balance and proposed funding under all scenarios are sufficient to fund the short-term needs, the average expected condition of the portfolio is the same under all scenarios for nearly 40 years, which aligns with the 2025 Budget Survey responses where 67% of respondents indicated that the service level related to municipal water and wastewater services in Tillsonburg should be maintained.

Based on the analysis, staff are recommending Scenario D. The proposed level of service target is to fund the system at 60% of overall lifecycle needs. The use of PVC pipes for linear started becoming popular in the 1970’s; their useful life of 90 years is theoretical as this material has not been in use long enough to confirm the lifespan. Staff also identified an improvement area in 2024, to look at the lifecycle strategies for process assets as it may be beneficial in the long-term to incorporate various strategies and not anticipate a run-to-failure strategy on some of these assets. Once incorporated this may result in reductions to the annual investment required, as such staff feel it is not prudent to target the fully funded scenario at this time.

Funding Gap Analysis

Planned Investment Level
An estimated inflationary rate is not included in the planned investment shown in the table below as the 2025 investment level exceeds the proposed investment recommended. Although interest rates are declining, the reserve balance will continue to earn interest and contribute to the planned investment for this portfolio. 

Proposed Investment Change
As the 2025 investment level exceeds the proposed level identified, staff are proposing a one-time reduction to the annual contribution to reserve of $300,000 for 2026, which would result in a reduction in the monthly fixed charge for the average residential user of approximately $3.21 or $38.52 annually. It is important to note that the capital contribution to reserve is only one factor in determining the rates required to support the system’s capital and operating requirements, and the overall rate requirements are determined through each budget process. Although the proposed reduction for 2026 would still result in the annual contributions exceeding the target level, the annual inflationary increases are not anticipated to be required over the 10-year period.

Comparison of required investment to proposed investment (millions)