The old-fashioned methods will protect the land and river nearby.
The sound of chainsaws will echo through a quiet Bloomington neighborhood for the next two months as workers from CenterPoint Energy clear trees and other vegetation in a right-of-way over a high-pressure natural gas main.
The work above and below the Minnesota River bluffs was carefully planned with city and U.S. Fish and Wildlife Service officials because of its proximity to the river and the fact that the utility easement cuts through the Minnesota Valley National Wildlife Refuge. Instead of bulldozing the site, trees will be cut down one-by-one with chainsaws, leaving the wood behind to prevent erosion and provide habitat for wildlife.
"It's been a very collaborative process," said Gerry Shimek, a biologist and specialist with the refuge. "They understand where we're coming from and the importance of the refuge."
CenterPoint spokeswoman Rebecca Virden said clearing vegetation along the path of the gas pipeline is part of routine maintenance. But such projects have gained new attention since a natural gas pipeline exploded last fall in San Bruno, Calif., killing eight people and destroying 38 homes.
Virden said the work will aid the utility in doing visual inspections on site and patrolling the easement area with "sniffer trucks" that check for gas leaks.
The work covers about a quarter-mile strip of CenterPoint's 60-foot-wide pipeline easement from the river north to near Spring Valley Circle in the southeast corner of Bloomington. The slope from the river up to the bluff is dramatic, Shimek said, making it a challenge to work on. The spot also is crossed by a refuge walking trail along the bluff. "We realized that with fragile soils and steep slopes, they couldn't use mechanical means [to clear vegetation]," Shimek said.
"This will be done the old-fashioned way, by guys running up and down slopes with chainsaws, clearing trees one at a time."
The work is being done while the ground is frozen to minimize disturbance of the soil. CenterPoint normally would grind and remove tree stumps, but on this project trees will be cut off at ground level and roots will be left intact to gradually rot while holding the soil in place. The felled trees will be cut up into eight-foot lengths, and the wood will be left at the site. Shimek said much of it will be placed perpendicular to the slope to create "slope breakers" that prevent rain water from rushing down the bluff.
Though CenterPoint could clearcut its entire 60-foot easement, the utility is trying to minimize the project's impact on the land by clearing the site 40 feet wide near the river and 15 feet wide up on the bluff. Homeowners who live within about 200 feet of the project have been notified about the work, and Virden said about six or seven homes are near the site.
There are no endangered plants or highly sensitive animal habitats in the area being cleared, and the refuge trail is being protected, said Charlie Blair, the refuge manager. Cutting around the trail will be done early on weekday mornings, when there are not a lot of people in the area.
Clearcutting on the site should be completed by mid-March. Shimek said seeding on the site likely will be with grassy native plants that help stabilize the soil but won't impede utility trucks and workers who need to get to the site later.
Mary Jane Smetanka • 612-673-7380