Arrow Creek Water Treatment Plant
Building the Arrow Creek water treatment plant in Erickson, southeastern British Columbia helped end a decade-long dispute that had thrust the community into the national spotlight.
The dispute began after the 1985 and 1990 outbreaks of giardiasis from Arrow Creek, the water source for 7,000 users. Despite these disease outbreaks, local officials steadfastly opposed adding chemicals — particularly chlorine — to treat the water. A well-organized political action group fought tooth and nail to avoid treatment, even though samples routinely showed fecal and other contamination.
Following the Walkerton tragedy in May 2000, the B.C. Government stepped in and hired CH2M Hill to help resolve Erickson’s water dispute. The engineering challenge was to address the seemingly contradictory goals of protecting public health while respecting the community’s wish to avoid using chemicals to treat the water. This was an extremely difficult problem. The project also involved repairs to the water intake, and it had to be done in a sustainable, environmentally friendly manner — all within a project budget of $9.9 million.
To find a solution, CH2M Hill worked closely with the province and a focus group of about 25 community representatives and health officials. In this way the engineers could fully understand all the critical issues and establish a solid foundation for gaining acceptance of the recommended approach.
Ultrafiltration and ultraviolet treatment
CH2M Hill recommended a combination of simple, relatively new processes that require no chemicals — membrane filtration (ultrafiltration) and ultraviolet (UV) disinfection.
To maintain the quality of water in the distribution system after treatment, the consulting engineers initially recommended that a trace amount of chlorine be added to the treated water as it passes through the distribution system to consumers’ taps.
The community representatives remained uncomfortable even with the undetectable trace of 0.2 parts per million of chlorine. So CH2M Hill researched and developed an option that involved no chlorine in the distribution system at all. To the engineers’ knowledge, this combination of approaches is a “first” in Canada.
Safeguards for the no-chlorine distribution system
Operating a distribution system without a chlorine residual meant the system had to have a high level of integrity. The Ministry of Health approved a trial of the ‘no-chlorine’ option provided that (1) all water receives ultrafiltration and UV disinfection, and (2) improvements are made to ensure the distribution system is made completely safe from contamination.
The Ministry of Health conditions required:
* the distribution system to be flushed and cleaned, and confirmed to be clean and free of pathogens prior to the start of the trial;
* the existing, open treated water reservoir to be covered or replaced with an enclosed steel or concrete reservoir.
* backflow prevention devices to be installed on approximately 75% of the existing Erickson customer connections to reduce the risk of backflow contamination;
* regular monitoring to be performed on water in the distribution system;
* an emergency response plan to be in place to protect public health, including a standby chlorine system capable of providing immediate residual disinfection of the water if necessary.
In a community referendum, residents voted overwhelmingly (78%) in favour of accepting the proposed solution.
A low ecological footprint
The sustainability of the Arrow Creek project can be measured on several levels. Because it delivers treated drinking water without the use of chemicals, the plant has no need to transport chemicals or dispose of chemical by-products. The design minimizes energy use through energy-efficient heating and lighting, variable speed pumps, and the supply of water to the distribution system by gravity. The fully automated, low-maintenance water treatment process typically requires only two hours per day of operator attention.
Incorporating a fish ladder into the intake improvements eliminated the barrier to fish passage and resolved an historic concern of the Department of Fisheries and Oceans.
Creating the right “fit” of technology for society
The Arrow Creek project is an example of how the engineer’s role is expanding from providing a technical response, to leading the “fit” of technology into society. Engineers now realize their role requires addressing the context of the project as well as providing a technically elegant solution.
CH2M Hill was responsible for all aspects of engineering, from conception to start-up. This included project management using the firm’s proprietary project delivery system. The project was completed on time, and for $9.3 million, $600,000 under budget. Contract extras were less than 1%, well below industry norms of 5% for similar construction.
The plant can process 30 million litres per day, and has been in service since October 2005, providing water that fully meets all Canadian drinking water guidelines. After a decade of having to boil their water, Erickson residents can now trust the local tap water.
Project name: Arrow Creek Water Treatment Plant
Award-winning firm: CH2M HILL, Burnaby, B.C. – prime consultant, process, structural, electrical engineering, architecture (Lawrence Benjamin, P.Eng., Dino Kruger, P.Eng., Larry Llewellyn, P.Eng.)
Owner: Regional District of Central Kootenay
Supplier: Trojan Technologies