As part of significant upgrades to its drinking water supply system, the City of Nanaimo constructed a new reinforced concrete storage reservoir. Commissioned in 2015, the new Reservoir No.1 replaced a 100-year old open-air raw water reservoir in order to receive treated water from its new membrane filtration plant. The City’s main water supply is from the Jump Creek Reservoir, which is at higher elevation than the water treatment plant and Reservoir No. 1. The upgraded water supply system takes advantage of the area’s topography and hydraulics, since the elevation difference allows water to reach the treatment plant and subsequently ReservoirNo.1 without using pumps. Reservoir No.1 is 110 meters below the elevation of the new water treatment plant so there is a significant amount of potential energy available.
Gravity systems such as this one usually use control valves and pressure reducing valves (PRVs) to manage flow and dissipate excess pressure, which is potential energy that is typically wasted. The City of Nanaimo system uses hydroelectric turbines instead of PRVs to dissipate excess energy while filling the reservoir, and recovers it in the form of electricity to be sold to the grid through a 20-year Electricity Purchase Agreement under BC Hydro’s Standing Offer Program.
Collaboration contributed to the success of this project. The City’s Mayor and Council showed strong leadership and had a vision of a sustainable community. During the project’s development and implementation, Council continued to be supportive and enthusiastic due to the innovative technology and direction towards energy resiliency.
BC Hydro was also a valuable partner for the project. In addition to purchasing the electricity, BC Hydro provided guidance during the early phases of the project while the City undertook feasibility studies and project design.
The City was primed for this project because staff previously considered recovering wasted energy at the old reservoir, and conducted a feasibility study to respond to a BC Hydro call for power in 2001. While unsuccessful, it meant that the City had a better understanding of the technology and was ready when the right opportunity presented itself, at rates that are more favourable.
In the three years since commissioning, operations staff have optimized the energy recovery facility to generate higher revenue without compromising service delivery, primarily by running the turbines during peak periods. Revenue has increased steadily since 2015, even though water consumption has decreased.
This successful project has opened the door to future projects. Council is enthusiastic to explore further opportunities and staff have an improved understanding of the technology. The “water experts” are now also “energy experts”.
Typical boxy water and sewer infrastructure buildings are nothing to show off; however, the striking wood building of Reservoir No.1, in a beautiful setting, shows off the infrastructure within and is a destination for the public and a source of pride for the City and community.
Reduces energy use by 750 to 1,000 MWh per year, which is enough to power about 60 – 80 City of Nanaimo residences
Energy recovery will lower the waterworks department’s total GHG production to 9 tonnes CO2e, a reduction of over 60%
Since the energy recovery facility and new reservoir began operation in 2014, the City of Nanaimo has generated between $70,000 and $100,000 in extra annual revenue by selling energy to BC Hydro
Project payback is under 10 years and project operation is 50 years.
Created short-term design and construction jobs
New facility ensures continued access to safe drinking water
Contributes to community sustainability by increasing the cost efficiency of the water supply system
New reservoir offers provision of fire protection between Chase River and Departure Bay as well as emergency storage
Total project cost:
$7.68 million from the Gas Tax Fund
$3.5 million covered by the City Water Fund