Posted On: Friday, October 1, 2021
The Town’s wastewater and stormwater sewers are nominally separated systems and Town staff suspect that pumping station capacity was exceeded due to inflow and infiltration through unauthorized connections or other breaches in the wastewater system. A thorough investigation into the causes of this event is being conducted.
The rainfall event caused sewer back-ups in the Craigleith area, but no untreated wastewater was released into Georgian Bay during the weather event. “Events such as this have very serious repercussions for residents who may be affected”, stated Alar Soever, Mayor of The Blue Mountains. “We should not have seen the volumes we received in our wastewater system, which indicates we had excessive inflow and infiltration. While we have an active program to address inflow and infiltration, we had not seen significant infiltration issues previously in this part of our system.”
On Tuesday, September 21st, Town wastewater operators proactively prepared for the forecasted heavy rainfall by emptying and increasing storage capacity at both the Treatment Plant and at the lagoon ponds. In addition, both forcemains were opened at the Craigleith Wastewater Treatment Plant, allowing the pumping station to reach its 180 litres per second firm capacity.
During standard operation throughout the fall season, the pumping station typically handles a flow between 10 to 35 litres per second. However, due to the excessive rainfall, by 3:30pm, the flow had reached 225 litres per second, far higher than the station’s capacity. Shortly after 6:00pm, the on-call operator responded to a high-level alert at the Craigleith Pumping Station. The alarm was followed by a second alarm, indicating that a pump had failed. The pump failure was caused by a short circuit. The operator contacted the Town’s electrical support contractor, who immediately responded to fix the issue. At 7:44pm, a second pump failed due to motor overload. Working with the electrical support contractor, repairs were made and both pumps were restarted and operational throughout the night with flows between 200 and 240 litres per second until rainfall subsided and typical operations resumed. Staff remained at the station overnight to closely monitor the operations of both pumps.
To reduce stress on the pumping station, Town staff called in Region of Huronia Environmental Services to start hauling wastewater from the lift station directly to the Treatment Plant. During this time, the Town received calls from residents in the Craigleith area reporting sewage backups. Town staff have been in contact with affected residents. A homeowner may choose to submit a claim for damages. More information on how to submit a claim can be found on the Town’s website at https://www.thebluemountains.ca/risk-management.cfm.
The rain event was unusual with 138mm of rainfall occurring over 30 hours in the collection area of Craigleith Wastewater Treatment Plant. This led to the increased pressures on the system. The Grey Sauble Conservation Authority reviewed the nearby rainfall data and determined it to be close to a 100-year storm event.
Inflow and infiltration is suspected to have had a major impact on system capacity. Unauthorized connections to the wastewater system via downspouts or sump pumps can overwhelm the Municipality’s sanitary sewer infrastructure. It also leads to substantial amounts of clean water entering the sanitary sewer, which requires unnecessary treatment at the Wastewater Treatment Plant. The Town currently monitors inflow and infiltration through sewer cameras and will be implementing smoke and dye testing in the future.
The Town would like to remind residents that in the event of a wastewater emergency, wastewater operations staff can be reached 24/7 by calling (705) 446-5041. The after-hours emergency line connects residents directly to an on-call wastewater operator.
For more information, please contact:
Allison Kershaw
Town of The Blue Mountains
Manager of Water and Wastewater Services
(519) 599-3131 ext. 226
Location: The Gallery - Blue Mountains Public Library - 173 Bruce Street S, Thornbury
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