Reaching full capacity in the city's long-term sewage pond is forcing the municipality to seek a 45-day extension from Oct. 31 to Dec. 15 on discharging treated sewage.

Last week, the city applied to the Yukon Environmental and Socio-economic Act Board (YESAB) for an environmental review.

It did so after the Yukon Territory Water Board ruled that it needs a YESAB decision document before it can decide on changing the discharge period under the water licence.

The documents filed to the YESAB by Wayne Tuck, the city's engineering and environmental services manager, note the city is seeking the extension to discharge as much treated sewage as possible using its Pot Hole Lake to provide additional treatment.

"The water levels within the long-term storage pond have reached supply full levels due to a combination of factors which include a limited time period to discharge, diminished ability of Pot Hole Lake to exfiltrate, as well as unseasonable high precipitation and water levels which resulted in flooding within the Southern Lakes region in 2007," notes the YESAB application.

A May 8 letter from Tuck to the water board on the extension application also points to vandalism of the pipe at Pot Hole Lake in August 2007 as a factor in the high water levels of the long-term storage pond at the sewage lagoon.

The YESAB application notes water levels at the long-term pond are now encroaching on the recommended space needed between the water and the land.

"Extension of the discharge period is required to ensure that the long-term storage lagoon will not over top the eathern berms," the application reads.

Since June, the city has been discharging the treated sewage from the long-term pond to Pot Hole Lake and West Lake under an order of the water resources inspector.

That will end on July 31, when the current water licence kicks in. The practice is also seeing treated effluent discharged into Pot Hole Lake.

The approval to begin discharging into Pot Hole Lake a couple of months early has been extremely beneficial, Tuck said this morning.

"That's going to help significantly," he said.

No physical changes would have to be made to Pot Hole Lake if the extension application is approved, it's noted in the YESAB application.

While the long-term plan will see additional effluent discharged into the Yukon River, which is permitted under the current water licence, the city hasn't had the technology to do so.

"The city currently does not have an outfall into the Yukon River which will allow for direct discharge into the river," the application reads.

"The city now has funding for its construction, and the city is requesting bids for its construction. The detail(ed) design and construction plan must be submitted to the water board prior to its construction, which is planned for 2009."

Tuck said the $2.5-million budget for the project is coming out of the funding the city has received from the federal gas tax pot.

While the treatment facility, Pot Hole Lake and most of the proposed piping that will allow for Yukon River discharge will all be on city-owned land, the outfall piping and diffuser will be in the river under a licence of occupation that would be issued by the territorial government.

Under a section detailing the potential environmental and socio-economic impacts, it's argued that if the extension doesn't proceed, there could be a failure of the long-term storage pond's earth berms and damage to the nearby area.

By extending the discharge period, the area surrounding the treatment facility would be protected by preventing overtopping and structural failure of the berms, which would see the city not able to meet the requirements under the water licence.

It would also mean more treatment for the sewage with the use of the aquifer and a reduced need to discharge treated sewage directly into the river, the application reads.

While the long-term plan will see the construction of a system into the river, Tuck stressed the city's aim is to continue using Pot Hole Lake as much as possible in an effort to avoid direct discharge into the river.

As for when the city expects to hear from the YESAB to then go back to the water board, Tuck doesn't have any set timelines, noting he's hopeful responses will be fairly quick with the Oct. 31 deadline.

Karen Baltgailis, the Yukon Conservation Society's executive director, said this morning the society will be looking into the application and potential environmental impacts.