Condition Assessment of Regional Distribution Reservoirs – Winnipeg, MB

Potable water reservoirs are a key component of many potable water supply networks across Canada. As per The 2019 Canada Infrastructure Report Card, approximately 72% of existing publicly owned water reservoirs were constructed prior to 1999 (minimum of 24 years old); approximately 26% of existing water reservoirs were constructed between 1940-1969 (54-73 years old) and approximately 7% of existing water reservoirs were constructed prior to 1940 (minimum 73 years old). Approximately 33% of the existing reservoirs are in fair, poor, very poor, or in unknown condition; approximately 41% are reported to be in good condition.

As evidenced by Canada’s Infrastructure Report Card, there is a significant inventory of reservoir structures that will be requiring some form of major intervention (rehabilitation or complete replacement) in the near future. From the owner’s strategic asset management perspective, condition assessments are fundamental exercises undertaken to establish the current condition of a reservoir, to gauge its remaining useful service life, and to establish capital and maintenance strategies to maximize the service life of the structure. Condition assessment results inform the owner’s prioritization of capital and maintenance resources and establish high-level budget forecasts used in financial planning.

Project Background and Objective

The City of Winnipeg’s potable water infrastructure consists of a complex system that delivers water from Shoal Lake, located at the Manitoba/Ontario border, to customers via a 135 km away via a gravity fed aqueduct. The aqueduct supplies the Deacon Reservoirs, the City’s four main raw water storage reservoirs cells. From Deacon, the water is treated and supplied to three regional water distribution reservoirs strategically located throughout the city. These reservoirs are the MacLean Reservoirs (205 million litre [ML] capacity, constructed in 1962), McPhillips Reservoir (227 ML, 1974) and Wilkes North and South Reservoirs (140 & 112 ML, 1980 & 1997). Considering the critical nature of these regional reservoirs to the City’s water distribution system, their advancing age and condition, and the substantial total replacement cost, the City of Winnipeg Water and Waste Department (WWD) engaged Dillon to provide consulting engineering services for the condition assessment of its regional reservoirs (with the exception of the Wilkes North Reservoir which was assessed and rehabilitated by Dillon in the last 15-years) to provide recommendations to extend the service lives of these critical assets by fifty (50) years.

Scope of Work

In order to develop relevant asset management strategies to extend the respective service life of each reservoir by 50-years, a detailed condition assessment of each reservoir was first completed, generally consisting of:

• An undrained boat-based inspection to examine the reservoir roof soffit, column tops, bearings (where applicable), joints, and other miscellaneous structure components located above the typical operating water level
• A drained-cell inspection to examine the remainder of the reservoir structure below the operating water level
• A CCTV inspection of all accessible piping infrastructure servicing the reservoir
• A leakage assessment to identify possible sources of known water leakage and to approximate the rate of leakage from the structure
• A building envelope inspection to confirm the condition of the existing building envelope
• An inspection of the interior and exterior of the access building, valve chambers, and emergency escape/ventilation hatches (where applicable)
• An exterior inspection to generally inspect the facility grounds.

Once the condition of each reservoir was understood, any immediate maintenance needs (for purposes of addressing life-safety or critical operational issues) were identified and communicated, the remaining useful service life of the asset was estimated, various asset management strategies were developed and assessed through an economic (life-cycle and capital cost) and weighted criteria (price per point) analyses. Ultimately, the preferred asset management strategy over the remaining service life of each reservoir was determined and communicated through a comprehensive condition assessment report.

Health & Safety

Reservoir structures have unique health and safety (H&S) considerations beyond those applicable to many other infrastructure assets. Although the structures are likely very large, they are usually considered confined spaces with very limited access, egress, and natural ventilation. Additionally, the type of inspection–boat-based and/or drained-cell presents other activity specific hazards such as working above water and the obvious slips, trips, and falls.

During boat inspection, all staff were equipped with floatation survival suits due to the water depth and temperature below. Finally, the Winnipeg Fire and Paramedic Services (WFPS) Technical Rescue Task Force unit was invited to each reservoir site prior to commencing inspections to review the site’s H&S plan and to obtain a first-hand understanding of that respective reservoir’s site layout and constraints in the event that they were called out for an emergency.

Acknowledgements

Dillon was the prime consultant on this assignment completing all scope of work with the exception of the building envelope assessment which was completed by Dillon’s Subconsultant, Crosier Kilgour & Partners (CKP)—CKP directly retained Saber Industries Inc. to carry out excavations to expose the reservoir’s building envelope, as well as Flynn Canada Ltd. to carry out building envelope repairs following destructive testing. Uni-Jet Industrial Pipe Ltd. supported Dillon’s reservoir piping infrastructure assessment by completing CCTV inspections. Finally, the City WWD’s staff were critical team members that were highly involved throughout the project.

Awards

• Award of Merit, Association of Consulting Engineering Companies Manitoba, 2025

Project Details

Project Partner: City of Winnipeg
Business Unit: Community Planning & Infrastructure
Service Offering: Treatment and Pumping