The green water spotted running into Willows Beach this week was an environmentally safe tracing dye, said David Brozuk, Oak Bay superintendent of public works.
“It’s basically to see if there’s a cross connection from a sewer service into a storm service,” Brozuck said. “We don’t want any sewage to get into our outfalls, then into the ocean.”
Generally, there are two types of lines. One handles household sewage, while the other handles naturally occurring wastewater such as rainwater or gardening water. The naturally occurring runoff can go directly through sewer outfalls into the ocean, but crews need to monitor to make sure that there’s no cross-contamination with any potentially toxic sewage. The municipality frequently tests lines and trenches when a house is undergoing renovations or upgrading its sewer system.
“Older houses have storm and sewer lines in the same trench. After 60 to 70 years the sewer and storm line seals start to disintegrate or wear away, which can cause the sewage to enter the storm line that would put in into the ocean,” Brozuck explained.
According to Brozuck, the municipality conducts between 150 and 200 such tests every year. Usually, the discoloured water washes away in a few hours, though dry weather can sometimes cause it to linger. The tests are mandated by the CRD and paid for by Oak Bay. Brozuck estimated that each test costs approximately $200, meaning the municipality spends around $35,000 conducting tracing tests yearly.