Naramata's Energy Efficient Water Treatment
Naramata is an unincorporated community in the Regional District of Okanagan / Similkameen (RDOS). It has approximately 900 households and 450 hectares of irrigated agricultural lands. Water is taken from two creeks (Robinson and Naramata) and a lake then chlorinated and treated. The system is owned and operated by the RDOS.The existing distribution system services 782 domestic connections and 450 hectares of irrigation with a maximum daily usage of 31 million litres (eight million gallons). Eighty-six percent of the water is used for irrigation. Meeting these consumption needs is challenging, given that:
- no source alone provides enough water to meet domestic and agricultural needs;
- storage reservoirs don’t provide enough capacity; and
- existing pumps and piping don’t provide the required flow to meet peak demands.
In 2004 public health Officials worried about the quality of water coming from the creeks and provided to community members. A new treatment facility was required, and treating lake water was recognized as the optimal public health decision.
“We used an interactive review with staff and public via the Naramata Water Advisory Committee - a committee made up of local residents,” explained past Engineering Services Manager, Andrew Reeder “There is no policy set for this, it’s just good practice.”
Geothermal heat exchanger
Reeder recognized that energy could be saved by using a heat exchanger to tap the latent heat of treated water. This water could be used to heat the facility in winter months, and cool it in summer months. Now the exchanger has been installed, Reeder was proud to report that, “100% of the water that goes through the exchanger is utilized and treated and consumed.”
When the RDOS looked at ways to build the Naramata water treatment plant the water operations staff found a better way to pump water. Typically water is pumped from below to the top of the reservoir so the water cascades down to the users. Instead the RDOS made a ‘mid-level resevoir’ and converted that into a treatment plant. The water is pumped from there. The result is less energy used by not moving more water than necessary. By building the treatment plant mid-level, water is only pumped to the zones that need it resulting in huge energy savings.
At the new treatment facility the water is exposed to high intensity Ultra-Violet (UV) rays. These rays deactivate harmful viruses and organisms. The UV system doesn’t use chemicals and is energy efficient.
Initially, the RDOS issued an RFP to look at energy efficiency as well as the initial capital costs of the UV equipment itself. They used a life cycle cost analysis to pick the UV equipment. They chose Wedeco equipment – which cost the most to purchase, but was cheaper to install and had the lowest energy consumption. The pay back time will be about two years.
As a result, the tender process required the contractor to use the UV equipment. An Novation Agreement (a special type of agreement between the RDOS, the engineering consultant and the supplier of the UV equipment) was drafted which married the vendor of the UV equipment with the contractor so they became responsible for the equipment and its warranty.
Progressive Split of Water System
The replacement of the original pipe was required during the upgrades. In exploring this process, the RDOS recognized the opportunity to decouple their irrigation and municipal water systems. 86% of water treated to drinking quality was being used wastefully for irrigation. Treating and pumping this water from the Lake to fields wasted energy, and required chemical use.
Through a life-cycle-cost analysis the Region was able to see the long-term benefits of replacing older pipes with two new pipes while using the same trench. Using two pipes instead of one is called 'twinning' or 'duelling'.
The Region determined what pipes needed to be replaced first and what new pipes would give the greatest savings. An Asset Management Plan helped determine the timing of the pipe replacements and duelling of the irrigation and domestic pipelines.
The RDOS will continue to split the pipes over the next 40 years. Once twinning is complete one pipe will be used to pump the potable water supply from the treatment plant. The other pipe will be fed by the upland creek source and not require pumping, this saves on pumping costs. Eventually, all residential homes will receive treated water while agricultural land will receive untreated upland creek water. This creek water pipe will reduce pumping costs because it is gravity-fed through creek irrigation.
Another innovation on-site is generation of their own chlorine. This will not only eliminate spill risks but a side result is to elliminat having to ship chlorine from far away.
Naramata was careful to work with good analysis and assessment information right from the start.FundingNaramata is collecting a tax to split the water system. The Improvements project was financed by Provincial Federal grants.
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