Driller Mike breaks through on Bellwood tunnel

The tunnel is only the third large construction project in the USA to use the Construction Manager at Risk (CMAR) structure. The PC Construction/HJ Russell JV carried out this role. The designer was JP2, a JV of Stantec, PRAD Group, and River 2 Tap. TBM operation was subcontracted to the Atkinson/Technique JV.

The TBM launched from the Bellwood Quarry site in October 2016 despite challenging working conditions including summer temperatures hitting 43 degrees Celsius and 100 percent humidity.

“I’m proud of our team. They had obstacles and challenges and challenging ground, but they stuck together and didn’t give up, and they were successful. There was great leadership and supervision all around,” said Larry Weslowski, Tunnel Superintendent for the PC Russell JV.

“The guys built everything per the specs to help with scheduling. It was a challenge but there was no negativity during the process.”

Hard granitic rock challenged the 19-inch disc cutters from the outset. “There was ground so hard that it would take eight hours to go 1.5 m. It was between 117 and 310 MPa UCS. The beginning of the job was tough,” said Weslowski, but he added that once the learning curve had been overcome “they started breaking project records left and right towards the end. We got a best day of 38.4m. Rates just kept increasing.”

With tunneling complete, the USD 300M project for the City of Atlanta’s Department of Watershed Management is on track to meet its scheduled overall completion date of September 2019. The project will turn the inactive Bellwood quarry into a 9.1 billion litre raw water storage facility connecting with the Chattahoochee River and various water treatment facilities.