Soil troubles push sewer project back

Latest in list of issues with Coxwell bypass

Completion date on the Coxwell sewer trunk has now been moved to November after the project hit yet another delay as crews struggle to seal the new bypass pipe 42 meters below ground.

Unstable soil conditions at the O’Connor Drive and Coxwell Boulevard shaft has stymied contractors’ attempts to grout around the new 500-metre bypass pipe and the main Coxwell line for a third time.

“We’ve hit a pocket of pressurized water right at the point where we are exposing the old existing sewer,” said Lou Di Gironimo, head of Toronto Water.

After a series of delays, the $40-million project seemed to be nearing its end earlier this year when construction workers discovered groundwater and began the process of de-watering the exit shaft — the end point of the new bypass pipe.

Efforts to build the bypass have been underway since early 2009, shortly after crews discovered a 60-metre long crack at the northern part of the Coxwell pipe, at Barbara Crescent.

Local residents have expressed frustration at the ongoing delays.

The Coxwell sewer trunk carries waste from one-third of Toronto homes into the Ashbridges Bay treatment plant.

Once the pipe are successfully sealed, crews can move onto the final stage of the project: cutting into the existing sewer and inserting a flume to divert sewage flow through the bypass, which travels around the damaged portion of the sewer trunk from Taylor Massey Creek to Coxwell and O’Connor.

The project has been plagued by delays, including mechanical breakdowns, the removal of an abandoned sewage pumping station and a work stoppage after the Ministry of Labour ordered an access ladder be built near the exit shaft.

Initial reports indicate they have made some headway with a new grout material, Di Gironimo said in mid-August.

A May report also outlined the contingency plan in the event of a collapse of the sewer trunk, including the creation of an emergency makeshift treatment site in the Keating Channel.

Di Gironimo said it’s important contractors get the project right.

“The delays are partly because we are encountering difficult soil conditions but we’re also proceeding very, very cautiously,” he said.

“We can’t afford to get it wrong.”

About this article:

By: Karolyn Coorsh
Posted: Aug 24 2012 12:59 pm
Filed in: NEWS
Edition: Toronto