The City of Calgary has provided new insights into the sewage discharge incident

The City of Calgary has provided new insights into the sewage discharge incident from last week, revealing details leading up to its detection by water crews on March 28.

While an exact volume cannot be determined, General Manager of Operational Services Doug Morgan mentioned that over the past week, the total missing sewage is estimated to exceed 100 million liters. "Our records indicate that on March 19, we received approximately 7 million liters less wastewater than usual. As the days progressed, a continual decrease in wastewater received became evident. By Thursday and Friday of last week, we estimate daily receipts were about 52 million liters below expectations," Morgan informed reporters on Monday. He emphasized that although the city regrets any wastewater entering the Bow River, the discharge at the leak site near the Bonnybrook Wastewater Treatment Plant constituted less than 1.5 percent of the river's total flow for this time of year. "Models and similar incidents in other cities suggest that the material would have diluted rapidly, thus lessening downstream impacts," he added. As of Monday morning, a strong sewage odor lingered near the Ogden Boat Launch, close to the location of the wastewater pipe break. Morgan noted that the city is conducting water tests every four hours, but it may take some time for the odor to dissipate from the riverbank water. Testing results indicated a significant decrease in E. coli levels since the weekend.

Alberta Health Services has not issued a boil water advisory nor does it plan to, according to Morgan. "We advise people to avoid the river for now, but there is currently no advisory from health authorities," Morgan stated. The pipe that ruptured last week is an 850-millimeter steel pipe that has been in place since 1972. It is part of a system comprising two active and one redundant wastewater pipe leading to the Bonnybrook wastewater treatment plant beneath the Bow River. Morgan confirmed that an investigation into the cause of the break is underway, though the age of the pipe was not considered a contributing factor, as it was expected to have a lifespan of 75 to 100 years. "We are initiating the investigation, ensuring that safety is a priority.

Given the active work site and significant water volumes, the process will take as long as needed to ensure safety. Crews are currently on-site assessing how to safely access the pipe for inspection," he said. "I assure you, we will provide updates as more information becomes available." Morgan remarked that such a pipe break is uncommon, noting that the City of Calgary has not experienced a similar incident with sewage under the Bow River in recent history. "Unlike drinking water distribution systems, the wastewater system operates on gravity, resulting in lower pressure within the pipes, which makes breaks less likely for several reasons," he explained. "While regular maintenance is conducted, it's not typical industry practice to routinely inspect pipes like this one. Records indicate that this particular pipe hasn't been inspected in the past 15 years, and until we determine the cause of the failure, it's uncertain if an inspection would have identified potential issues." Mayor Jyoti Gondek reassured Calgarians that their drinking water remains safe and that the leak does not pose a serious health risk to river users. She highlighted that the challenge of aging infrastructure is not unique to Calgary, as cities like Atlanta and Denver in the U.S., along with Winnipeg and Quebec City in Canada, face similar issues. "We're not alone in this regard. This is a legacy challenge that has persisted for decades. Maintenance and infrastructure investments have frequently been postponed or deemed too costly, prioritizing short-term goals at the expense of essential infrastructure, which can lead to severe consequences," she noted.

"I have spoken with leaders at both provincial and federal levels about the necessity for collaboration and funding to assist cities in maintaining and upgrading infrastructure. However, it is crucial that these discussions translate into tangible actions. No single entity can shoulder this responsibility alone." By Aryn Toombs.