Sewage lagoon odour returns as cooler weather causes mxing

EAGLE STAFF

With cooler weather arriving, a foul odour from the town’s sewage lagoon recently returned, drifting across town when winds blew from the west or northwest.

Public works superintendent Bob Bors explained the measures staff have taken to minimize the smell while responding to a question from Greg Carlson during the Oct. 6 council meeting.

Lagoon contents “start to mix” when night-time temperatures drop, Bors said. As the liquid moves, “it’s bringing the anaerobic bacteria to the surface and that’s breaking down sludge and creating an HS (hydrogen sulphide) gas,” the source of the odour, he explained.

Staff added sodium nitrate to the wastewater to produce oxygen, but it was “only half a dose,” using up the town’s supply. Bors said he was having difficulty obtaining more 50-pound bags, though a liquid alternative is available.

A full dose of sodium nitrate, added at the lift station in St. Andrews Park, is about 51 bags spread over two days, he said. “We’ll slowly pour half of that in, let that flush through the system and get pumped out, then the next day, we’ll add the other half,” Bors explained.

When the lagoon turns brown instead of its usual emerald green, it signals the need to create oxygen by adding sodium nitrate, he said.

“Typically, you don’t have as many smells as early as we’ve had this year, but we’ve had some cool nights and still some hot days, so that water’s constantly mixing,” Bors said.

The town usually releases sewage into Eagle Creek in the spring and fall, but “now we’re only draining once a year,” he said. “Last year, we drained before harvest, but this year, with the harvest completion date uncertain, we held on, so we’re doing a late fall drain. For us, a spring drain would be better because it blends in with the spring runoff, and we get a lot better test results downstream.”

Bors said he still needs to speak with golf course officials to see if they want to use sewage for irrigation in the spring, though the course must follow regulations if it does. He hopes to have some available for the course if needed in summer.

The lagoon is nearly full, so some wastewater must be released this fall. He is waiting for one field to be harvested before proceeding. “Without special permission, we can’t drain past Nov. 1,” Bors noted.

Meanwhile, one stack at the water treatment plant requires rebuilding. Staff are waiting for an inspection company to visit so workers can “open up one stack for testing.” He hopes they can “tear it apart and rebuild it while they’re here and take some of the metal rings back for analysis,” Bors said.