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.
Final Summary Report (pdf, 1374kb)
Last update: 07.07.2005
* Top of Page