Challenge

Since 1930, the city of Revelstoke has been distributing untreated Greeley Creek water as its primary source for drinking water. In 1995, the city experienced a disease outbreak from the tainted water supply. The Ministry of Health identified several cases of giardiasis and cryptosporidiosis. Detailed sampling and investigation revealed the diseases were waterborne, originating with animals in the Greeley Creek Watershed. 

As an interim safety measure, Revelstoke started chlorinating the water supply. However, the community did not support long term use of chlorine as a primary disinfectant, and chlorination only would not have met the provincial Ministry of Health standards for potable water.

A Community Water Advisory Committee was appointed to identify options and to conduct an open process, encouraging two-way communication to inform and listen to residents. In February 1998, the city council unanimously accepted the Committee’s recommendation to build the 4.5 MGD membrane treatment plant. 

Solution

After a detailed analysis of the submitted tenders, the consulting engineering firm of Dayton & Knight, Ltd. recommended the MEMCOR® Continuous Microfiltration system (CMF). This decision was based upon:

• Competitive evaluation of capital costs
• Life cycle
• Operating costs
• Membrane replacement costs
• Technical ability

In April 2000, a compact, modular microfiltration system was installed, allowing for easy expansion in the future.

Results

The completely automated CMF system is monitored and operated from the city’s downtown office, eliminating the need for a full-time plant operator and reducing operating costs. 

The system also allows comprehensive analysis of turbidity levels and system integrity. In-situ instrumentation performs testing on both filtrate water quality and operational diagnostics for the maintenance of the system. 

Since the completion of the CMF membrane plant, Revelstoke only uses chlorine as a secondary disinfectant to provide a ‘disinfection residual’ in the distribution lines to prevent bacterial re-growth. This allowed the chlorine to be reduced to non-tastable levels of .2 to .3 ppm.