AWARD OF EXCELLENCE / WATER RESOURCES Exshaw Municipal Water System
October 1, 2013
By ISL Engineering and Land Services
Juror Comments: “We appreciated this project because it has changed the quality of life in an existing town with the use of local resources.”
Juror Comments: “We appreciated this project because it has changed the quality of life in an existing town with the use of local resources.”
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ISL Engineering and Land Services designed and implemented a complete municipal water system to replace private water wells in Exshaw, a hamlet of 360 people in the Municipal District of Bighorn, east of Banff, Alberta.
The new water system consists of a low-tech, low maintenance water treatment process that also has a low lifecycle cost. It will provide safe treated water to the community for the next 25-plus years, serving 1,200 people at its full development.
A distribution system was also designed and installed within the existing community’s infrastructure to supply the treated water to the community, and for firefighting.
New aquifer water
source had complications
Given Alberta Environment’s regulations, ISL had to find a water source that is not connected to surface water for the new system. The engineers identified the Calgary Deep Aquifer (the pre-ice age river bed of the Bow River) as a suitable source. The raw water is considered high quality, but has elevated levels of iron and manganese, which resulted in turbidity and aesthetic concerns. In addition, the aquifer was found to be contaminated with iron-reducing bacteria and sulphate-reducing bacteria, with the latter producing hydrogen sulphide as a toxic waste product.
These combined characteristics meant the water could not be effectively treated using existing technologies, so ISL investigated alternatives, aiming for low capital cost and ease of maintenance.
ISL identified a water treatment technology based upon traditional slow-sand filtration, using its natural effectiveness, but adapted to address its typical inadequacies. For example, the filter maintenance was simplified to minimize downtime by not requiring the physical removal and replacement of the filter media. These enhancements also allowed higher filter loadings, reduced the backwash cleaning frequency and operator input, and also enabled the system to function on demand.
The treatment system treats the complex source water effectively, while the enhancements make it relatively easy to operate and maintain. It also uses less energy and costs less to run than other treatments.
Robust, modular and simple to operate
The treatment system is robust enough to handle variations in the quality of the source water, while the modular structure of the filter equipment means that it can easily be increased in size to double its capacity.
The annual energy consumption of the water treatment is less than 6,000 kWh, compared to the 40,000 kWh estimated for more conventional technologies. And with monthly (rather than daily backwash) as the norm, the treatment process produces less than one-tenth the volume of wastewater compared to other treatment processes.
The process uses off-the-shelf equipment that can be operated by the municipality’s existing Level 1 operators.Chemical inputs were reduced to just the one required by regulators for disinfection: sodium hypochlorite. The chemical is generic, readily available and doesn’t require special handling.
A water distribution system was also provided in the community, which required relocating utilities and constructing water mains across roads, highways, rail tracks, creeks and floodplains, all within environmentally sensitive areas.
Households and industries in Exshaw now have a safe, secure potable water supply. The system also provides fire protection. Just two months after completion, firefighters used the supply to tackle a big fire at a local landfill. cce
Project name:
Exshaw Municipal Water System, Alberta
Owner:
Municipal District of Bighorn No. 8
Award-winning firm/prime consultant:
ISL Engineering and
Land Services, Calgary (Josua le Roux, P.Eng.; Fadi Maalouf, P.Eng.; Michael Dobbin, RET; James Hanley, P.Eng.; Abhishek Garg, P.Eng.; Jose Zapote, P.Eng.; Wes Stambaugh, P.Eng.; Yanina Goyhman, CET; Ronald Loeppky, C.Tech; Michael Mullin, CET)
Other key players:
Oasis Filter (process); Tronnes Surveys
(survey); Levelton Engineering (geotechnical); Colleaux
Engineering (electrical, instrumentation, process control);
DJA Engineering (electrical).
