WILLISTON — Even as the first snowflakes of the year fell in the Champlain Valley Thursday, it was easy for any observer to note the progress construction crews have made on Phase I of the Addison Rutland Natural Gas Project, a 41-mile natural gas pipeline from Colchester to Middlebury and Vergennes.
A tour hosted by Vermont Gas Systems officials shuttled reporters to different sites around Chittenden County where workers are digging trenches and laying pipe.
After Vermont Gas secured the final environmental permits it needed, crews broke ground in June. They’ll continue until the ground freezes for the winter, which, given the freezing temperatures forecast for this week, could come soon.
In that five-month time span, company spokesman Steve Wark said crews have laid about five miles of pipe at several sites in Essex, Williston and Colchester. Wark added that the completed work to date includes some of the most difficult, including steep, rocky terrain and a span underneath the Winooski River.
Crews are building meter and regulation stations in both New Haven and Middlebury, but will not begin trenching in Addison County until the spring.
Project manager Charlie Pughe said about 100 laborers work on the site on any given day, six days a week.
Depending on the terrain, crews can lay between 300 and 600 feet of pipe each day.
PROJECT MANAGER CHARLIE Pughe at a construction site in Williston.
In sensitive areas such as waterways, road intersections and wetlands, crews employ a technique called horizontal directional drilling (HDD) instead of trenching. In this process, the pipe is snaked underground (or underwater) between two bored holes.
Pughe said HDD costs about three times as much as the trenching method, but is more sensitive to nearby soil.
Vermonters make up many of the laborers on site, but much of the actual pipe laying is done by out-of-state firms that specialize in building pipelines. Pughe said that while it may look simple, building a pipeline is an exacting process that involves huge pieces of pipe.
“You can’t just hire a plumbing firm to build your pipeline,” Pughe explained. “There is no margin for error.”
In most areas, the pipeline will be buried three feet underground. In agricultural fields, the standard depth is four feet, and in other areas such as roadways and wetlands the pipe is laid deeper still.
In some areas, the pipe has already been laid and covered with soil that has since sprouted grass. After crews remove erosion fencing, there is no visible evidence that a pipeline has been laid there, except for yellow plastic markers placed along the route.
In most cases, Wark said Vermont Gas tried to place the pipeline within a 50-foot right of way, meaning on each side of the line there is at least 25 feet to a road or structure. But in some cases, Wark said this was not possible. In Essex, for example, part of the pipeline runs within 15 feet of the roadway.
THE PIPELINE SNAKES through the ground in Essex.
Pugh said several different inspectors are on site daily to ensure that construction meets all applicable safety standards.
“When they’re out there, there’s a welding inspector checking all the welds, and there’s an X-ray crew that checks as well,” Pugh said.
There are other inspectors as well, such as utility inspectors that oversee construction and backfilling of trenches, coating inspectors who check the joints along the pipe, and the state gas inspector who checks that the project meets state and federal regulations.
“The Department of Public Service has a full-time inspector that they hired,” Pugh said. “We agreed to that as part of the process, and that’s a cost that the department is billing back to Vermont Gas.”
When it’s all said and done, 220,000 feet of 12-inch steel pipe will be in the ground. Vermont Gas hopes to complete the project late next year.