News : 2003 News Releases - City of Winnipeg

2003 News Releases

City releases independent review of sewage plant failure

WINNIPEG - JANUARY 17, 2003 - An independent review of the flooding at the North End Water Pollution Control Centre has concluded that “the event did not result through negligence” but that “the flooding was a result of inadequate operating and maintenance procedures.”

The report, authored by Associated Engineering (B.C.) Ltd. and released today by the City of Winnipeg, contains 13 recommendations for improving plant design and operation and maintenance procedures.

On September 16, 2002 at about 1:15 p.m. a mechanical failure shut down the North End Water Pollution Control Centre, one of three sewage treatment plants in the city. Staff had been doing routine maintenance on one of six pumps in a pump well. They believed the valve to the pump was closed but not properly seated. When they loosened an inspection plate it blew off the pump flooding the pump rooms. The flow could not be contained and by 5:00 p.m. that day untreated wastewater began draining into the Red River. The plant was shut down for 57 hours until two pumps were put back into operation and the normal treatment of sewage was restored.

“Council was very concerned with the potential environmental impact of this event,” said Councillor John Angus, Chairperson, Standing Policy Committee on Public Works. “We believed that an independent review was the best way to gain an impartial perspective into the cause of the accident and to receive expert opinion on how to prevent this kind of event from ever happening again.”

“This report provides the public with an independent appraisal of not only what happened on September16, but also what needs to be done to ensure that our wastewater facilities operate efficiently and that we clearly understand our areas of vulnerability,” said Gail Stephens, Chief Administrative Officer.

The independent report commends staff for their exemplary response to the incident and also concludes that, “the event of September 16 did not result through negligence. Procedures carried out by staff were done with the best intentions and according to the training and direction provided to them.

The event was influenced by a mechanical failure. However, the flooding of the pump wells was not directly caused by the valve failure. The flooding was a result of inadequate operating procedures, documentation and training, and inadequate maintenance procedures.”

The report recommends five design changes to the facility in order to reduce the chances of future flooding incidents and to isolate certain areas for safe maintenance work. The major recommendation includes the installation of sluice gates at the entrance to the areas where the pumps operate in order to stop the flow of sewage into the plant during routine maintenance or an emergency. The report also notes that several metal components in the plant are seriously corroded which could prevent the pumps and suction valves from operating properly.

The report’s eight operation and maintenance recommendations include: conducting a plant-wide risk assessment of equipment conditions, developing safe job procedures, providing options for managing and mitigating risks, and preparing an emergency response plan.

“The Water and Waste department concurs with all of the recommendations in the independent report,” said Stephens. “In fact many of the recommendations match those from the department’s own internal review. The 2003 Capital budget contains a proposed $750,000 for a risk assessment analysis of all three wastewater plants and the department is already moving ahead on implementing many of the job analyses and work practice procedures recommended in the independent review.”

Approximately 427,000 cubic metres of untreated wastewater flowed into the Red River during the 57 hours that the plant was shut down. Water quality tests conducted by Manitoba Conservation at several points on the river revealed that oxygen levels in the water remained within acceptable limits to support aquatic life. Tests indicated that the spill should not have resulted in any direct toxicity to aquatic life. The wastewater flow was estimated at 1-1.5% of the river’s total volume flow in September of 2002.

Please see the attached reports below.

Fact Sheet
Chronology of Events
Report on the Shutdown of the North End Water Pollution Control Centre
September 16, 2002

The North End Water Pollution Control Centre, 2230 Main Street, opened in 1937 and processes raw sewage from the north and central areas of the city, including about 370,000 residents. It is one of three sewage treatment plants in the city and processes approximately 70 per cent of the city’s wastewater. Treated wastewater from this plant flows into the river.
On Monday, September 16, 2002, at about 1:15 pm, a failure shut down the North End Water Pollution Control Centre.
Because of the failure, by 5:00 pm that day, untreated sewage began draining from the plant into the Red River at a rate of 185,000 cubic metres per day, or 1-1.5% of the river’s flow. The river flow in September 2002 was approximately double the seasonal norm.
Staff had been doing routine maintenance work on one of six pumps in a pump well. Staff believed that the large valve which controls water flow through the pump was closed, but not properly seated. Staff loosened a 12 inch diameter inspection plate which surprisingly blew off the pump allowing sewage to flow into the pump well.
One worker was thrown back by the water pressure but still tried to replace the 90 pound inspection plate against the force of the water. The workers attempted to stop the flow but were forced to abandon the pump wells when the sewage was 3 feet deep.
Because all three pump wells are interconnected, all six pumps were flooded causing the plant to be shut down.
Notification of the plant closure was quickly provided on the afternoon of September 16 to Manitoba Conservation, Winnipeg Regional Health Authority, City of Selkirk, Municipality of St. Andrews, and Environment Canada.
First of daily media releases was issued at 5:38 pm on September 16. It was first estimated that it would take at least a week to get the plant back into operation.
A commercial diver reattached the inspection plate to the pump, and staff then began pumping out and hosing down the three wells which each contained 33 feet of sewage.

Once the wells were drained, staff worked around the clock to remove the pumps one by one and send them out to be cleaned, dried and serviced.
The next day, September 17, media were provided access to the facility and that day and throughout the week, were provided interviews with Barry McBride, Director of Water and Waste.
On September 17, booms were placed on the Red River at eight outfalls to contain and remove any floating debris from the discharge.
On September 17 the Water and Waste department began daily monitoring of water quality at 13 locations along the river. Tests for dissolved oxygen were taken since sufficient levels of dissolved oxygen are required to support aquatic life. All oxygen levels remained within Manitoba Water Quality Standards.
On September 19, at 12:01 a.m., a first pump was put back into service. At 1:30 a.m., a second pump was up and running. With both pumps operating at full capacity, water treatment resumed, and by 5:16 a.m., the plant was fully in operation and raw sewage ceased to flow into the river.
The plant was shut down for 57 hours. During that time, approximately 427,000 cubic metres of untreated wastewater was discharged into the river.
On September 24th, City Council instructed the Chief Administrative Officer to retain an independent engineering firm to conduct an impartial review of the incident to determine the cause of the accident and to make recommendations to prevent similar accidents occurring in the future.
On Tuesday, November 19th the faulty valve was removed and inspected. It was found that a 42” section of valve guide was missing from one side of the housing which caused the valve wedge to offset while being closed and had become stuck open by 13.5 inches. It is still not known what caused the portion of the guide to break off.
On Friday, January 17, 2003 the City of Winnipeg released the Council requested independent report and the Water and Waste department released their own internal report on the event with recommendations on how to avoid future incidents.

Final Summary Report (pdf, 1374kb)

Report on the shutdown of the North End Water Pollution Control Centre on September 16, 2002 (pdf, 2179kb)

Last update: 07.07.2005

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