Roof of city’s composter beyond repair: report

Similar systems elsewhere suffering same fate: Henderson

The roof of Edmonton’s once world-class composter is so rotten it will either have to be kept for short-term summer use only or demolished, according to a city update released Thursday.

Officials investigated running glycol lines in the roof and using waste heat from the composter to melt snow, or simply keeping extra staff on standby to shovel off the heavy load before it could cause a structural collapse. They even looked at building a new shelter around the old building, or simply adding extra steel supports.

But it’s not worth it. The old system is finished, the update said.

Since the composter shut down last October, all of Edmonton’s household garbage has been heading to the landfill.

“There’s still a chance we can use (the composter) this summer,” said Ward 8 Coun. Ben Henderson, a member of council’s utility committee, which is scheduled to review the issue next Monday.

But this is the risk of being first, he said.

“This was really early composter technology. We were one of the first to put this kind of thing into place at this kind of size ... Other people that built composters around the same time are having these same issues.”

Edmonton’s composter was built in the late 1990s by TransAlta and, at that time, ranked as the largest co-composter in North America. The composting and waste facility started operating in 2000 in a complex roughly the size of eight football fields.

The aeration hall building, where the roof is not at risk of collapse, covers more than the size of three football fields.

Inside, the facility used to accept all of the waste homeowners threw out in the regular trash.

The large, non-compostable items were filtered out, then the organic waste was left to decompose by keeping the humidity and temperature high, and stirring it to introduce oxygen.

The process was incredibly smelly, produced a poor-quality compost contaminated with heavy metals, and had a corrosive effect on the building ’s steel structure.

The poor state of the roof took city officials by surprise and it’s still not clear exactly why.

Both waste management and infrastructure officials declined to comment Thursday.

Edmonton has a second composter that is supposed to open this spring, behind schedule. It uses a different process — one using bacteria to break down garbage without the presence of oxygen.

It will generate methane in a controlled environment, which can then be harvested for use at the Edmonton Waste Management Centre.

But the new composter was planned just to add capacity, not to replace the old one.

That’s why deciding what to do with grass clippings and yard waste is urgent, said Henderson. If those are going to keep going in the trash, Edmonton will need to rebuild the composter at roughly the same size, even if that capacity is only needed for a few weeks a year.

If grass clippings can be left in the yard, and leaf or yard waste picked up separately, the new composter can be much smaller. The yard waste can be simply composted outdoors at the waste management centre. Then all Edmonton has to deal with is a small amount of leftover kitchen scraps.