Norwich – Norwich Public Utilities and sewer construction contractors got a close-up look Monday at how their predecessors more than 100 years ago ran sewage and storm water collection lines beneath the downtown  streets.

A five-man crew Monday started what is expected to be a weeklong project to replace a section of a fieldstone box that runs along Bath Street and Broadway, serving as the main sewer and storm water conveyance system for the past 110 years. The fieldstone box – part mortared together and part dry-fitted, like a neat stonewall -- is topped with large, flat stones that cover the culvert.

The fieldstone culvert at the corner of Bath and Broadway had started to collapse, causing a sinkhole to form beneath a sidewalk patio to the right side of the United Congregational Church.

Bill Dewey, construction general foreman for NPU, said the $100,000 project calls for running a 30-inch diameter new plastic pipe inside the stone culvert, connecting it to a steel pipe that was installed along Bath Street in the 1980s.

The steel pipe abruptly ends near the intersection, where the stone framework has remained in use since then. Dewey said crews hope to leave much of the stonework in place, pulling off only the top stones to lay the new pipe.

The work is expected to take all this week, weather permitting.

“If it rains, we’ll have to shut down, because it will fill up with water,” Dewey said.

The Chestnut Street intersection in front of City Hall will remain closed throughout the project. NPU officials had expected to close Bath Street that also leads to City Hall, but NPU spokesman Chris Riley said Monday it looks like one lane of Bath Street can remain open. The gaping 10-foot hole with protective metal framing will be fenced in overnight for security, Dewey said.

This project only will replace a 90-foot section of the stone culvert, Dewey said. The stone culvert network will remain in operation in many sections of downtown for the foreseeable future. At the end of the 90-foot section where the new plastic pipe will lay, the combined water and sewer system will continue in the stone system.

One stone culvert runs from Mohegan Park all the way into the downtown, he said. In some places, steel pipes have replaced the stone, and in others, concrete was used to line the stone culvert to prevent leaks, Dewey said.

“There’s a huge stone culvert down there,” Dewey said, pointing down Bath Street toward Franklin Square.

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