Two towns in Manitoba have sworn off deep-shaft sewage treatment plants, similar to the one Dawson City plans to build.
Last week, Ketza Construction Corp.‘s $16-million bid to build a more conventional lagoon-style system was turned down for technical reasons.
Instead, a BC-based company is to be awarded a government contract for $25 million.
Corix Utilities is proposing a deep-shaft system, where sewage is stored in underground tanks.
There are only a few of them in operation.
One is in Virden, Manitoba, which has a population of just over 3,000.
“Our system is definitely not working for us,” said Virden’s manager of works and utilities Cornie Peters.
“It is in the process of being replaced.
“We are going to go with more conventional (sewage) treatment.”
Virden’s deep-shaft system, which was installed in the late 1970s, only worked for a few years, he said.
“For the past 10 years it’s been nothing but struggles.”
The new technology seemed like a good idea at the time, added Peters.
“And we thought it might be a little cheaper.”
But it just can’t meet Canada’s waste-effluent standards.
“It’s way over,” said Peters.
The total fecal chloroform count should be around 30, he said. Virden’s is at 9,000.
The total suspended solids count is even worse.
The average is 40 to 60, said Peters.
“We’re at 110,000.”
Virden’s deep-shaft system can’t even remove nitrates and phosphates, found in dish soaps, he said.
“This system is incapable of it.”
Portage la Prairie also installed a deep-shaft system in the late 1970s.
But the Manitoba city has already replaced it.
“Our waste load was too much for it, so we decided to go with a more conventional system,” said Portage la Prairie director of operations Kelly Braden.
Portage la Prairie has a high level of agricultural and industrial waste, he added.
“So it was not the right type of system for us.”
Deep-shaft sewage treatment uses oxygen to break down sewage held in underground tanks that can be more than 100-metres deep.
“One selling point is its compact size—most systems are big concrete tanks,” said Braden.
“Another is that, with a high concentration of oxygen, there is a higher rate of decomposition,” he said.
“In theory, it should be cheaper, because it’s using less electricity than open-tank systems.”
Homer, Alaska, has been operating a deep-shaft system since 1991.
Last year, it cost the town $524,000 in operations and maintenance.
That’s up from the previous year, which was $511,000.
“It works very well,” said Homer utility supervisor Jim Hobbs.
“It meets out fecal and total suspended solids (standards) easily.”
Alaska’s waste-effluent standards are not as rigid as Canada’s.
Homer’s standards are based on a 30-miligram-per-litre-per-month ration.
Canada’s are set at 25.
“It’s a balancing act to meet the requirements but not spend too much money on chemicals,” said Hobbs.
A Canadian company installed the system, he added, citing Deep Shaft Technologies Inc.
“But that technology has changed hands,” said Hobbs.
“I can’t comment on the new company.”
Noram took over Deep Shaft Technologies in 1998.
The Vancouver company has been commissioned by Corix to build Dawson’s new deep-shaft, sewage treatment system.
“I’m not overly familiar with the technology,” said Corix general manager Graeme Bethel, discussing deep-shaft systems in a previous interview.
Noram has a lot more experience internationally than it does in Canada, he added.
Bethel recommended calling Noram for details.
Several calls to Noram have not been returned.
Contact Genesee Keevil at
gkeevil@yukon-news.com