By Graeme McNaughton/The Oshawa Express
Durham’s garbage will once again be burning at both boilers at the Durham York Energy Centre.
According to Cliff Curtis, the region’s works commissioner, the Ministry of Environment and Climate Change gave its approval to Covanta, the incinerator’s operator, to go ahead with the second phase of its abatement plan to get Boiler No. 1 up and running again on Friday, Aug 5.
The boiler was taken offline at the end of May after stack tests found it was emitting more than 13 times the allowed amount of dioxins and furans.
According to Health Canada, dioxins and furans are a byproduct of incineration processes, and can accumulate in biological tissues. The federal entity also says that while humans and animals are all exposed to the two compounds, exposure in higher concentrations can lead to serious health problems.
Curtis says the boiler, initially started with natural gas on Aug. 5 to bring it up to the appropriate temperature, should once again by running on 100 per cent waste. From here, the incinerator will go through at least a week, but possibly several, of tests to see how things are burning.
“Then they take a detailed look at the operating conditions, so they’ll try different loads and different burn rates and that sort of thing to get a feel for how it’s reacting, and why we got the unexpected results with the last test,” he says.
“Then after that, they run a diagnostic test program, and once we’re through that period, then we do the actual stack test.”
Curtis says there will be diagnostic stack tests in mid- to late-September, with the stack test for compliance coming in November or December.
While the cause behind the exceedance has not been proved 100 per cent, Curtis says the incinerator needs to be running so that tests can be done to ensure they have found the culprit.
“We’ve identified some suspects, but we won’t be able to say definitively until we actually test it under operating conditions – that’s why we had to get it operating again,” he says.
“It’s like when your car is making a funny noise. You can’t diagnose it unless the motor’s running. So we had to restart (the incinerator) and find out what the real problem was.”
While Curtis would not go into specifics as to what the suspect issues are, he did say that part of the investigation was to determine what was different between the failing Boiler No. 1 and Boiler No. 2, which passed its stack test.
“The big mystery, of course, is why unit one failed and unit two, which is extremely similar, passed. That didn’t make much sense, so we took a look at what could possibly be different between the two units,” he says.
“Some of it has to do with some of the maintenance that took place while the unit was down before restarting for the stack test on unit one. So we want to make sure nothing was damaged. The proof’s going to be when we do a test on a run.”
According to a June technical memo, HDR, a consultant to the Region on the incinerator profile, is of the opinion that a series of events on the week of May 9 – the week that stack testing took place – contributed to the exceedance of dioxins and furans.
According to the report, the hopper that collects ash at the second and third pass of Boiler No. 1 become filled with fly ash, either within the hopper or at the discharge valve, resulting in high ash levels.
The boiler was shut down on May 5 due to a plugged feed chute, during which time Covanta chose to clean out the ash in the second and third pass hopper using explosive charges.
In its report, HDR says that some of the fly ash from the plugged hopper may have gotten into the flue gas stream and carried to the back end of the boiler and into the air pollution control system. The explosive charges may have also led to other deposits in the boiler tubes being knocked loose. It was these higher levels of ash that may have contributed to the higher dioxin and furan levels, according to the report.
If the September stack test goes well, the incinerator will continue to operate. However, things get more complicated should it fail again.
“Then we’ve got a big problem. We’d have to consult with the Ministry of the Environment and Climate Change on how to proceed,” Curtis says.
“We cannot operate out of compliance, so if we’re not in compliance, we’ll have to take a pause like what we did with the latest test and try to find out what caused the problems before we continue to operate.
“Durham and York are as interested as everyone else in making sure that this plant operates properly.”