South Fork Water Treatment Plant

The City of Nanaimo’s new South Fork Water Treatment Plant is an exception, and a model for sustainability. The City of Nanaimo engaged Associated Engineering to complete pilot testing of treatment options, and provide preliminary design, detailed design and construction services for the preferred option, membrane filtration.

Taking advantage of the hydraulic pressure in the water supply from the South Fork Dam impoundment and the steep topography of the plant site, Associated Engineering’s design team conceived the idea of using a siphon to suction water through the submerged membrane filtration treatment process.  The siphon eliminates mechanical pumping, the typical approach for most treatment plants, significantly reducing energy use.  Using a siphon to draw water through the filters also reduces the building footprint, and capital and operating and maintenance costs. Treating 116 million litres of water per day, the South Fork plant is the largest siphon-powered membrane treatment plant in North America.