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Sunday, Nov 10, 2019

Eden Valley Water Treatment Plant upgrades help to meet current drinking water guidelines and increase capacity

Eden Valley WTP Exterior

Approximately 30 kilometres west of the Village of Longview, AB on Highway 40 lies the community of Eden Valley, part of the Bearspaw First Nation and a member of the Stoney Nakoda Nation. The community has a population of about 800, and receives its drinking water from the Highwood River. Water is treated in a direct filtration facility which was built in 2005. A water distribution system serves about half of the community, with the remaining residents receiving water transported by trucks and delivered to household cisterns.

In 2016, a feasibility study of the Eden Valley water system recommended expansion of the existing system to include a new raw water reservoir and a new treatment train at the existing water treatment plant to provide redundancy and to meet the future needs of the community for a 20-year horizon. Indigenous Services Canada provided funding to move forward with the $8 million project.

New UV Treatment

Project Manager, Andrew Robertshaw, says, “Historical growth rates for the community were used to develop population projections for the 20-year horizon, resulting in an assumed annual growth rate of 2.4% and a design population of 1,257. Water demands were projected based on an average water consumption rate of 314 litres per capita per day, using a maximum day demand peaking factor of 2.5 times the average daily demand.”

New Raw Water Storage Reservoir

A raw water storage reservoir was needed to store raw water off-stream from the Highwood River during periods of high turbidity. The project team determined 90 days of storage would be sufficient, resulting in the need for 44,000 cubic metres of additional raw water storage to supplement the existing raw water storage pond with 6,100 cubic metres of available storage capacity. In 2018, the new aerated raw water reservoir was constructed near the water treatment plant. 

The design capacity of the treatment system needed to meet the maximum day demand with one redundant filter. The existing direct filtration treatment system has two filters. Also, the surface water treatment system was designed to achieve a minimum disinfection to achieve 5.5 log reduction of Giardia and Cryptosporidium oocysts and 4 log reduction of viruses.

The system was designed to achieve the treatment requirements using a treatment process comprising direct filtration, ultraviolet (UV) disinfection, and chlorine disinfection. The existing system included direct filtration and chlorine disinfection, so only UV disinfection was needed to meet the proposed treatment requirements. 

New Treatment Train

To achieve the required treatment capacity for the 20-year horizon, a new treatment train was added, comprising two filters. Process Engineer, Anne Bridgman, says, “With the addition of the new treatment train, the duty capacity of the system was increased from 468 cubic metres per day to 1,256 cubic metres per day (based on one redundant filter).” A new building was added to the existing water treatment plant to house the new treatment train, as well as a chemical storage room, emergency shower, and washroom. 

The water distribution upgrades improve fire protection for the community

The upgrades to the water distribution system included new service connections to six residences and the gas station; 270 metres of 150 millimetre watermain; 1,865 metres of 200 millimetre watermain; and 14 fire hydrants. The upgrades increase hydrant coverage for fire protection in the community; include installation of manholes that can accommodate strap-on water meters in key locations to locate significant water losses; and expand the distribution system toward the long-term objective of connecting all residents in the community. The improvements to the water distribution were completed in Fall 2018 and Spring 2019.