Skip to content. Accessibility info.
Joint Session Receives Positive Update on the Halifax Wastewater Treatment Facility
(Tuesday, June 30, 2009) – Earlier today, in a joint in-camera session of HRM Regional Council and the Halifax Water Board of Commissioners, staff presented the findings of the forensic audit conducted into the January 14th malfunction at the Halifax wastewater treatment facility (WWTF). Staff also delivered positive news on a proposed interim measure to divert dry weather flows to the Halifax facility.
The report, which focuses on cause, provides more detail into the events that took place on the morning of January 14th.
As has been previously released, the main utility power feed from Nova Scotia Power Inc. was lost in the early hours of the morning. The two generators came on and power to the plant was restored.
To summarize briefly, the interim report reveals that during operation of the facility, one of the generators overloaded when three pumps fed from that generator came into operation. The resulting overload caused the generator to shut down to protect itself from damage.
This shutdown inhibited the electrical controls of certain components of the facility. This resulted in the five-pump system shutting down and could not be restarted. In addition, the emergency shutdown circuit failed to close the inlet gate. This caused the wet well area to flood quickly with approximately 60 feet of wastewater. Investigators from consulting firm CH2M HILL stated that no intervention by the operator could have changed the sequence of events.
CH2M HILL will continue its overall system review looking into all aspects of the wastewater collection system as well as the Halifax, Dartmouth & Herring Cove WWTFs. Where necessary, design modifications will be implemented to ensure the safety, reliability and integrity of the full system.
In the meantime, the recovery effort is well underway. Crews are on-site and working on an initiative that could see dry weather flows diverted to the WWTF, screened and discharged through the existing Halifax WWTF outfall pipe, approximately one kilometre into the harbour.
This initiative is being attempted as an interim measure only and many technical/engineering challenges need to be overcome to make this possible.
This temporary diversion of dry weather flows, which should be in place in two months, will be done concurrently with plant restoration and not delay any final recovery of the plant. While this measure is moving ahead, crews will continue to work to fully restore the Halifax WWTF for spring 2010.
Halifax Water staff is also looking at further measures to reduce and hopefully eliminate odours that have occurred in isolated areas as a result of the WWTF shutdown. Recent tests with a small scale ozone generator proved very successful at reducing odours. Two larger units are on order and should be operating within two weeks. Halifax Water will continue to address odour concerns as they are identified.
Five new wastewater pumps are being ordered at an installed cost of approximately $2 million with reimbursement from the insurer. These pumps are the largest single equipment replacement cost and have the longest lead time for delivery, six months.
HRM and Halifax Water continue to work closely with the project partners.
Staff continue to work with CH2M Hill to enhance the design and operation to reduce the risk of flood reoccurrence. Restoring the Halifax WWTF to full operation and implementing improvements as required and protecting the investment of residents remain our key objectives.
The next Harbour Solutions update will come to Council by August 11th. In addition, Council has agreed to be subject to recall from its scheduled summer break if required.
Visit http://www.halifax.ca/HWWTF/index.html for more information on the Harbour Solutions Project.
- 30 -
Mayor Peter Kelly
Halifax Regional Water Commission