According to regional staff, the exceedance, measured July 20, was due to an external electrical power trip, as well as the following recovery procedures.
The exceedance was over the four-hour rolling average limit for carbon monoxide.
The CO limit for is set at 40 milligrams per cubic metre, as set out in the DYEC’s environmental compliance approval.
The CO levels measured during the exceedance were 55 milligrams per cubic metre in boiler number two while it was being taken offline.
All other emissions measured at the centre were in compliance at the time of the exceedance.
Both of the centre’s boilers were shut down afterwards.
Boiler number one was back online July 21, and Boiler number two was back online the next day.
The Ministry of Environment, Conservation and Parks Spills Action Centre was informed of the exceedance by the region. Emissions monitoring data can be found at www.durhamyorkwaste.ca.