Drayton Valley Wastewater Inflow/Infiltration Study

Drayton Valley, AB

ISL was retained by the Town of Drayton Valley to manage a sewer flow monitoring program conducted by SFE Global and study the results to determine the extent of wet weather inflow and infiltration (I/I) problems in the Town’s wastewater collection system.

Flow Monitoring

Flow monitoring was conducted through the 2014 season at eight locations in the wastewater collection system and through the UV facility at the treatment plant. The results of the 2014 monitoring indicated very high levels of inflow/infiltration and extended periods of high flows, despite experiencing only small rain events.

Resulting Risks

The conclusion was that there remains a high risk of basement backup and a risk of exceeding plant treatment capacity during moderate to large storm events.


The depth and velocity sewer monitoring data indicated many periods in which either the depth or velocity were fouled, providing faulty data. Since fouling is a common problem with sewer flow monitoring, ISL recommended more frequent inspections for future sewer monitoring and ongoing flor monitoring at the treatment plant.


ISL made recommendations for upgrades to the municipal system, private systems and the servicing standards for new developments. ISL recommended that the upgrades to private systems be made through a public outreach program and the provision of funding support.

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