 So earlier this year, workers finished boring a 2.2-mile tunnel under the east bank of the Seekonk River. The work took more than a year and a half of nonstop tunnel boring. The tunnel is 30 feet in diameter, built to capture the stormwater and sewage before it reaches the river and Narragansett Bay. Rhode Island's sewage system gets easily overwhelmed when we get storms because, well, the system is old.