T has plan to maintain Back Bay buildings
$3m well system to elevate levels of ground water
By Peter Schworm, Globe Staff | April 21, 2008
The Massachusetts Bay Transportation Authority plans to build a $3 million well system along the Southwest Corridor in an effort to elevate low ground water levels that threaten the structural integrity of Back Bay buildings.
The agency, whose train tunnels are a major cause of the damaging ground water shortage, has pledged to replenish the water table around Back Bay Station to keep buildings' wooden foundations submerged. Buildings on man-made land in the South End, Back Bay, and lower Beacon Hill are supported on wood pilings that rot and crack if they dry out, a condition that, left untreated, can lead to collapse.
Leaks in underground structures, such as subways and tunnels, have drawn water away from the soil, while an overall increase in development has reduced the amount of rainwater that seeps back into the ground.
The planned well network will include a cutoff wall to prevent leaks and to help maintain water levels.
Gordon Richardson, who heads the Citywide Emergency Groundwater Task Force, an advocacy group, said the authority's plan marks a significant advance. He commended the T's general manager, Daniel Grabauskas.
"There's no question they are making a good effort here," he said. "Under Grabauskas's leadership, the MBTA has done an about-face on the ground water issue."
Leaks in MBTA tunnels in the Back Bay and the Storrow Drive underpass are major contributors to low water levels in the area, Richardson said.
In the past several months, the MBTA has completed recharge wells in the area to boost ground water supplies, Richardson said. The new recharge system, which agency officials anticipate will be operational toward the end of 2010, will reuse water from an agency pumping station, located on Follen Street, as a primary source.
Richardson said the group is pushing for state legislation that would require state agencies and private developers to make sure underground structures are watertight and do not pose a risk to many of the city's historic buildings.
"Everything from Trinity Church to the bridges across the turnpike, to all buildings built in the Back Bay before 1920, it's all on wooden pilings," he said. "And wooden pilings have to be kept wet."
Ground water depletion jeopardizes structures built on man-made, filled land in Boston that rely on water to solidify their foundations.
About half of Boston is built on land that was originally water or marsh, he said.
For years, neighbors and advocates' pleas for water system improvements went unheeded, Richardson said.
But, in the past two years, city and state officials have given the problem higher priority.
"There have been a series of quiet successes," Richardson said. "There's been progress on a lot of fronts."
Representatives from city and state agencies and neighborhood groups have worked with the MBTA to address the ground water issue.
In a statement, Grabauskas praised the collaborative effort as "teamwork at its best."
"Their work has ensured that a viable solution will become reality," he said.
