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Water Today Title February 21, 2024

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  North America’s Largest Siphon-Powered Membrane Water Treatment Plant Reduces Costs, Energy Consumption & Protects The Environment

“By taking advantage of the hydraulic pressure in the water supply from the South Fork Dam impoundment and the steep topography of the plant site, the plant uses a siphon to suction water through a submerged membrane filtration treatment process, eliminating mechanical pumping, significantly reducing energy, reducing the building footprint, capital and operating costs.” -- Mike Squire, AScT, Manager Water Resources, City of Nanaimo

The City of Nanaimo’s South Fork Water Treatment Plant is strategically located midway
between the South Fork Dam and the City’s boundary to take advantage of the gravity system and avoid costly pumping.

Interview with Mike Squire, Manager, Water Resources The City of Nanaimo

By Suzanne Forcese

WT: What is the source of Nanaimo’s drinking water? How many people are served?

Squire: The South Nanaimo River Watershed is the drinking water source for approximately 100,000 residents of the City of Nanaimo. The City also supplies water to South West Extension, Snuneymuxw First Nation Reserves, the District of Lantzville, emergency/temporary supply for North Cedar Improvement District, and Nanaimo Forest Products (Harmac).

The source of this high-quality water was established in the early 1930s when the South Fork Dam was constructed. 

The City owns and operates two dams within the watershed that store water to ensure consistency of supply throughout the year and release water to maintain the environmental health of the river. 

The higher dam, Jump Creek, impounds approximately 17 million cubic meters of water and provides active storage, meaning that the level fluctuates over the course of the year.

The lower dam, South Fork, impounds approximately 2 million cubic meters of water. The City’s intake is at the South Fork Dam and the water level at the dam is maintained to provide a consistent supply pressure to the South Fork Water Treatment Plant.

WT: The South Fork WTP is state-of-the-art technology. Please describe how unique the system is and the technology itself.

Squire: The plant provides screening, flocculation, and chemical mixing, two-stage membrane ultrafiltration, ultraviolet (UV) disinfection and chlorination. It has been operating since December 2015.

Siphoning water through membranes makes it very energy efficient, providing a saving of over $70,000 per year in power costs. The two stages of filtration recover more than 96% of the water that passes through the plant making it very highly efficient.

Almost all the waste from the treatment process is handled onsite – the liquid waste is discharged to the engineered wetlands, and the solid waste (sludge) is used as topsoil.

Treated water from the South Fork WTP is fed into a clear well which provides contact time for disinfection and available balancing storage to the City’s water supply system. 

From there, potable water flows to the City into our Energy Recovery Facility which generates revenue daily by selling electricity back to BC Hydro as the reservoir fills up with potable water.

The energy produced is enough to power 40-60 homes and helps offset the electrical power consumption of the South Fork Water Treatment Plant.

WT:  And this is an award-winning Plant. Tell us about that.

Squire: We received an award for Engineering Excellence in 2017 through the Association of Consulting Engineering Companies of British Columbia. This was a recommendation from a Value Engineering exercise involving the owner, contractors, and engineers by taking advantage of the hydraulic pressure in the water supply from the South Fork Dam impoundment and the steep topography of the plant site.

The plant uses a siphon to suction water through the submerged membrane filtration treatment process.

The siphon eliminates mechanical pumping, the typical approach to most treatment plants, significantly reducing energy use.

Using a siphon also reduces the building footprint, capital operating and maintenance costs.

The South Fork plant is the largest siphon-powered membrane treatment plant in North America.

The two-stage membrane filtration process also increased plant efficiency and reduces drinking water production costs. 

A constructed wetland treats waste streams from the water treatment process, eliminating the need for onsite mechanical waste treatment equipment or conveying wastes to a distant waste treatment facility.

From the City’s perspective, this aligns with the visions of the City Plan Nanaimo ReImagined  and Council's green initiatives.

From our environmental operator’s perspective, it achieves the goal of providing healthy and safe drinking water while reducing the impact to the environment.

WT: What challenges do you face and what mitigation strategies are in place?

Squire: Climate Change is expected to result in more annual total precipitation for the watershed, with more precipitation occurring in the winter and less in the summer. Earlier snowmelt, hotter, drier summers, and an increased population will reduce the available supply of water while increasing the demand for water.

These factors will necessitate careful monitoring and control of the release of water from the dam for fish habitat. 

However, the existing reservoir storage capacity is expected to serve the City’s needs beyond 2061.

The City’s management of the water system and low levels of water loss will need to be maintained at current levels. With this, the City has plans to build a more resilient water supply system

by including the following:

  • Demand Management through continued Water Conservation practices
  • Promote individual efforts to conserve water through the replacement of inefficient fixtures
  • Reduction of discretionary outdoor use will also be necessary to allow water to be used more productively for vegetable gardening to increase food security
  • Updating Emergency Preparedness Plans and Water Supply Emergency Plans
  • Continued development of a secondary source of water supply and emergency water supply for the City
  • Building additional above-ground reservoir storage
  • Building redundancy within the water supply system
  • Increased efficiency in how the City controls the dam and manages the release of water is recommended to meet the future needs of the community and increase the City’s ability to maintain healthy environmental flows and fall pulse releases of water for the salmon run in the South Nanaimo River (given the anticipated drier and warmer summers that are expected with our changing climate)
  • Seismic upgrades to the South Fork Dam intake and construction of a redundant siphon intake

WT: Are spills and crimes a concern?

Squire: Our watershed is restricted access and protected. Access is strictly limited to safeguard our water supply from human contamination and other pollutants. Since the watershed is privately owned, a partnership between the City and Mosaic Forest Products was formed to protect the source and quality of our water.

WT: You have touched on the salmon run. Please elaborate on the ecosystems and their protection.

Squire: Water from the Jump Creek/ South Fork Dam System is required both to meet fisheries requirements and to supply drinking water to the City. Watercourses like rivers and streams require water to flow through them to sustain aquatic ecosystems and the human livelihoods and well-being that depend on these ecosystems.

For the South Nanaimo River, the primary water management environmental goal is the enhancement of flows to meet fisheries requirements during July, August, September, and October while continuing to meet municipal supply needs.

The City is responsible for the environmental flow release downstream of the South Fork Dam, which is a minimum of 1.0 cubic meters (about the volume of a large refrigerator) per second annually, which equates to 66% more than the annual consumption for potable water. 

In addition to the consistent environmental flows required year-round, pulse releases of 3.9 million cubic meters are required to trigger spawning in early September and early October to help with moving the rearing salmon upstream and away from harm.

WT: Please tell us about your Outreach and Education programs.

Squire: We have partnered with the Regional District of Nanaimo’s Drinking Water and Watershed Protection Program

that promotes environmental awareness and is tasked with helping protect the region’s water resources. This program outreaches to the general community via media, and social events, and provides additional watershed education through tours of the watershed and Southfork Treatment Plant to primary grade students and the public on Earth Day and World Water Day.

The City also participates with other community groups and Vancouver Island University to provide water resources information and tours. On average we have 6-12 tours per year in the watershed and through the Southfork Water Treatment Plant.

WT: A career in the industry. Many cities in Canada and the US are experiencing a shortage of qualified operators. Is this an issue for you?

Squire: It has been difficult to attract Level 3 Water Treatment Operators as there are only a select few in the province to pull from. There are more than double the amount of Level 2 operators than Level 3 in the province.

The next step to obtaining a Level 3 Water Treatment requires additional Direct Responsible Charge (DRC) time, training, and experience. However, there is a lack of proper succession programs and higher classifications of treatment plant facility to support this need.

We are currently working with the Union to become an employer of choice and provide succession planning and hiring of operators that can be mentored by our more experienced senior operators.

The purpose is for employee retention and attraction and for us to have a formal succession plan that satisfies the Environmental Operators Program (EOCP). For us, it is the only thing that the City does that is regulated by the Local Health Authority and it is important that we ensure our operators are formally certified.

WT: What are the advantages of a career in the industry? What are you personally most proud of?

Squire: Providing safe, clean, and healthy drinking water to the community and protecting the environment makes me proud.

It has been rewarding to be proactive in planning, designing, building, and operating water resources infrastructure for the City -- now and into the future.

All of us on the team are proud that residents and businesses in the community have access to safe water. We are committed to ensuring this is readily available for generations.

 Here is a plug from our famous poster boy! Jaymie Miller

WT: Please leave us with one last drop.

Squire: At the turn of a tap, we receive one of the world’s most precious resources. Next time you turn on the tap think about how water is essential to life, our health, our environment, and our growing community!