 The tunnel is 30 feet in diameter, built to capture the stormwater and sewage from the city before it reaches the river and the Narragansett Bay. Rhode Island's sewage system gets easily overwhelmed when we get big storms. You know that. You know it all too well. The tunnel will take that excess stormwater so that it can be treated. But the thing is, the tunnel won't be ready until 2026. Now, why is this important? Well, because, again, talking about our sewage system, it's a very old system.