Drilling of a 2.2-mile sewer tunnel under Rhode Island is finally complete. What comes next?
PAWTUCKET – In a huge burrow deep beneath the east bank of the Seekonk River on Thursday morning, heavy blocks of stone came crashing down as a giant machine chewed through the last stretch of bedrock to complete a 2.2-mile-long tunnel aimed at keeping the waters of Narragansett Bay clean.
With its cutter head rotating relentlessly, the tunnel boring machine has been working around the clock for a year and a half, grinding through 25 millimeters of rock face each minute to carve out the 30-foot diameter tunnel that will capture stormwater and sewage before they can reach the Seekonk River and then the Bay.
The work has been painstaking and incremental, but in the end it wrapped up sooner than anticipated.
“They were a little bit ahead of where we thought they would be,” said Jamie Samons, spokeswoman for the Narragansett Bay Commission, operator of the biggest wastewater treatment system in Rhode Island.