Plans are moving ahead to build a new $8 million sewer line to replace an unstable one in the Gatchell area.
The trunk sanitary sewer main, known as the Gatchell Outfall Sewer, failed in 2007, forcing the city to make emergency repairs to maintain sewer service in the area, which includes Gatchell and a portion of Copper Street. A less severe slippage took place in 2013, again forcing emergency repairs.
“It was determined that permanent repairs to replace the failed section of sewer in place would be extremely complex and costly and subject to risks of future slope failure,” a report that went to the operations committee Monday said.
Wendi Mannerow, a city water/wastewater engineer, told the committee that replacing the sewer with a rock tunnel is the recommended solution for the long-term.
“It's removing the pipe from a high-risk area,” Mannerow said.
It's a crucial sewer line connection, she said, because it leads into the wastewater treatment plant on Kelley Lake Road, location of the $63 million biosolids plant.
“All of the sewage in Sudbury comes through this tunnel,” Mannerow said.
A Class B environmental assessment is currently being done, part of the long process preparing for construction of the rock tunnel, scheduled for 2018-2019. The environmental assessment should be completed in April of this year.
“The EA is the first step in the process,” she said.
A detailed design of the tunnel should be completed by the end of next year. The plan is to reroute the tunnel away from its current location by the walking trail along Junction Creek to connect with an existing rock tunnel near the wastewater treatment plant on Kelly Lake Road.
Two public input sessions have been held -- one in 2010 and another in January of this year. While the cost is estimated to be $8 million, $1.9 million has already been put aside, leaving $6.1 million left to finance.