The Yukon government has finished an initial design scheme for Dawson’s court-ordered secondary sewage lagoon system.
And it is smaller than was originally expected.
In an interview Wednesday, program manager Kriss Sarson said the $14-million project will require two sewage lagoons, not three, as was originally anticipated.
“That will substantially reduce the footprint — by 60-to-70 per cent — in that ballpark,” he said.
The need for a holding cell, that can hold Dawson’s primary sewage for 60 days, is not required because the effluent is very weak, he said.
Two cells, with 15-day holding times, will be sufficient to treat the sewage, which will be collected and piped from Callison, then returned to town, before being released into the Yukon River through the current force main at the screening plant.
The final size of the lagoons, first anticipated to be 275 metres by 400 metres, will also depend on whether they are constructed below grade or slightly above grade.
The pilot plan does not anticipate heating the sewage in the pipelines between Dawson and Callison, said Sarson.
Quest Engineering Group from Whitehorse has created the pilot plan.
“It appears we can get it out and get it back without freezing being an issue,” he said.
The annual operation and maintenance cost for running the system is projected at approximately $320,000.
But Sarson cautioned that the number is not finalized because the project is still in design mode.
A lagoon system is the best option for Dawson because of operation costs and technical simplicity, he said.
Operating a mechanical-sequencing batch reactor plant would cost the town upwards of $600,000 a year.
Also, operating such a system requires a “class four” sewage system worker, and no such person is currently employed in the Yukon.
“The issues of trying to attract and retain an operator from the South — it’s difficult to achieve that,” he said, noting it takes “years” to attain this certification.
“Not having a trained operator puts the system at risk.”
Acquiring parts and skilled labour from Edmonton — in the event of a breakdown — is also expensive, he said.
So the lagoon is the best option, despite the need of a pipeline to move the sewage several kilometres to and from town, he said.
“It has a snowball effect, the more complicated the system, the more resources that are required.
“When you look at people versus financial resources, the area lagoon is a better match.”
The town of Dawson staff trained to manage the screening plant could also manage the lagoons with no additional certification required, he said.
Dawson’s sewage effluent is too weak to be treated effectively by a sequencing batch reactor, which relies on bacteria eating the sewage.
“You need a high microbial population, which requires a good food source. Dawson’s effluent is very weak in the winter. How do you keep you bugs active? It just increases the complexity. ”
The court has ordered the system to be in place by December 31, 2008.
However, the government will be hard-pressed to meet this deadline, said Sarson.
“That’s what we are striving for, but without the design completed, there could be some hiccups.”
One of these hiccups is ongoing negotiations with landholders in Callison who have claims to the areas where the government wants to build the lagoons.
Sarson maintains continuing negotiations with one miner who controls claims at the south edge of Callison.
Sarson would not go into detail about those discussions.
“With any negotiations of that nature, it wouldn’t be appropriate to go into detail; I wouldn’t want to affect the integrity of the negotiations,” he said.
“We are dealing with the conflicting land uses.”
Sarson said he had expected the process to be difficult.
“From day one, it’s been NIMBY, not in my back yard; that’s expected,” he said.
“Most people, when they choose to live or locate a business, didn’t anticipate to have a sewage lagoon as a neighbour.
“The government will balance the needs and concerns of the area residents with regulatory requirements.
“Without belittling anybody’s concerns, it may not be possible to make everybody happy.”
Once the site is established and the design concept finalized, the next major hurdle will be obtaining regulatory permission for the project from the Yukon Environment and Socio-Economic Assessment Board, which has an office in Dawson.
Moving the project through Yukon’s deep bureaucracy will be time-consuming, he said.
“You can’t force-feed it. You have stay with it consistently and keep it going and try to move it through.”
Sarson will provide the latest information, including site updates, at the March 21st advisory committee meeting in Dawson.