The best laid plans… not a pipe dream
By Kalpna Solanki CPHI(C) BSc MBA and Mike Squire AScT
Installation of the High Density Polyethylene (HDPE) primary and secondary water supply mains through Beban Park
Earlier this year, the EOCP published an article on the catastrophic failure of a manhole in Squamish, this time, we’re looking at what went wrong in Nanaimo.
In the 1981s, a major watermain was installed in Nanaimo using high pressure concrete pipe (Hyprescon) that was expected to have a lifespan of approximately 80 years, yet it failed prematurely, and it failed catastrophically.
When the Hyprescon pipe failed on a Friday evening, 3 April 2020, 22 million liters of water were lost. This resulted in three reservoirs being completely drained, and leaving a hospital as well as thousands of people without water. It took a few hours to isolate the main, but a temporary repair was completed, and the hospital and residents had water service restored by early Sunday morning.
There was a significant amount of water on Bowen Road. However, it could have been worse, a lot worse had the break occurred at a very busy intersection uphill from a shopping mall. In addition, if there had been a fire during this time, firefighting capabilities would have been greatly compromised. The repair and damage to a few businesses amounted to approximately $250,000.
When it comes to water, the system is as good as the weakest link. So, although the drinking water in Nanaimo comes from a stellar water treatment system at the South Fork Water Treatment facility, if the water supply system is deficient, the quality and quantity of the water supply could be jeopardized.
A systematic review of the pipe revealed other signs of future leaks and structural failures, and the consequences of additional failures would be severe. To manage the risk, several measures were taken:
- An emergency water supply shutdown procedure for the Hyprescon pipe section was implemented;
- The 2021-2025 Capital Plan was reprioritized, and the Midtown Water Supply Project was introduced;
- Other major water supply capital projects were deferred in an effort to make way for the Midtown Water Supply Project and balance the water supply budget within the City’s Financial Plan.
The Millstone River crossing is prepared
The initial upgrades to replace the Hyprescon pipe were estimated to cost $23.5 million, however, due to a volatile construction market, and the addition of a secondary supply for redundancy, the final cost is expected to be closer to $55 million.
After a thorough water supply routing study through the middle of the City, it was determined that the best option would be to parallel the Nanaimo Parkway and avoid other corridors with congested underground utilities and major infrastructure.
It was also found that the water supply through the middle of the City had little redundancy and was at risk in other areas crossing the Nanaimo Parkway and Buttertubs Marsh. From this review, it was determined that a secondary water supply main would be required for future growth and provide further capacity and resiliency to the water supply system in the midtown region.
The Midtown Water Supply Project will construct two large-diameter water pipelines to replace the aging and undersized current infrastructure that transmits potable drinking water to the central and northern areas of the City. This project will enhance the existing water supply network, build resiliency within the core of the City, and provide a dedicated water supply main to the Nanaimo Regional General Hospital.
The proposed new Primary Transmission watermain will deliver potable treated water from a connection point at College Drive near the Nanaimo Parkway to the Labieux Road pump station, will remove the need for the Labieux Pump Station, and make way for a future hydropower regeneration facility. The proposed Secondary Transmission watermain will provide redundancy and deliver potable treated water along Bowen Road from Pryde Avenue to East Wellington Road, along East Wellington to the Nanaimo Parkway, then the watermain will have the same alignment as the new Primary watermain to the Labieux Road pump station.
The project will be completed in two phases:
Phase 1 (purple circle) will build a new Secondary transmission watermain that will deliver potable treated water from the Pryde Avenue pump station to the Labieux Road pump station. The northern half of the new Primary water supply main shall also be built in Phase 1 of the project. Upgrades of the City’s distribution watermains and pressure reducing stations will also be constructed as part of Phase 1 in the East Wellington Road/ Bowen Road/James Way area of the City. This phase is currently under construction within two City construction projects, the Midtown Water Supply Upgrades Project and the Midtown Gateway Project. The Midtown Gateway Project is transforming a legacy brownfield site impacted by past industrial activity into a revitalized neighbourhood gateway.
This phase (pink rectangle), will complete the construction of the Primary water supply main along the east side of the Nanaimo Parkway from East Wellington Road to College Drive Reservoirs.
Some unique features of the Midtown Water Supply project:
- Depending on the location of the water supply main, three types of material are being used:
- a. Kubota ductile iron pipe, also known as hazard pipe, is being used in marsh areas with unfavourable soils and a stream crossing. These pipes have flexible expansion joints to allow for seismic resilience. Although these pipes are more expensive, they provided a $ 900,000 savings compared to the conventional support piles and caps to traverse the marsh areas.
- b. High Density Polyethylene Pipe (HDPE) solid wall pressure pipe in two wall thicknesses (DR11 and DR13). What is unique about this pipe is that two sections are heated to 230°C (450°F) for 45 minutes, they are then held together for approximately 25 minutes, and the two sections are then ‘fused’ together. The heating and fusing machine is on tracks, can be moved along as needed, and can even be used within a trench. HDPE pipe was chosen for its cost effectiveness, delivery, and seismic stability.
- c. Conventional welded steel pipe and coatings were used in high-pressure areas exceeding 200 psi.
- d. Other features, such as an urban trail network on top of the new mains in several areas allow connection of the City’s multiple-use pathways through the midtown area that will promote livability and active transportation.
- Once the new primary main is commissioned and in service, slip-lining construction using the old Hyprescon concrete pipe on Bowen Road will provide the remainder connection for the secondary main to Pryde Avenue and a new dedicated service to Nanaimo Regional General Hospital. Using this construction methodology will avoid costly surface restoration and additional traffic disruptions.
3. This project required a great deal of collaboration between various City departments as well as a provincial ministry. To name a few:
- a. City of Nanaimo Parks, Recreation and Culture
- b. City of Nanaimo Public Works and Engineering
- c. City of Nanaimo Strategic Initiatives
- d. City of Nanaimo Communications
- e. BC Ministry of Transportation and Infrastructure
- f. School District 68
- g. Vancouver Island University
- h. Nanaimo Regional General Hospital
4. In an effort to expedite the project at the start of the COVID pandemic, Koers and Associates Engineering Ltd. was engaged through a Request for Proposals process and tasked with reviewing the City’s proposed water supply routing options and advancing the design to a 50 % stage. After the 50% design completion, the project went out for construction procurement using a Negotiated Request for Proposal. Knappett Industries Ltd. was selected as the top-rated proponent and worked collaboratively with Koers and the City to develop constructability enhancements and value design cost savings. Overall, with the owner, engineer, and contractor all working together, they were able to save over 5 million dollars and provide a timely schedule to address the current risk to the City’s water supply through the midtown region.
The project is expected to be complete in the fall of 2024.
Learn more about this important project by visiting: www.nanaimo.ca/goto/ MidtownGateway