With groundwater at Beacon and Dartmouth streets reaching an alarmingly low level, the Neighborhood Association of the Back Bay (NABB) sponsored a workshop at the French Cultural Center Wednesday to address residential groundwater issues in the neighborhood.
The discussion included speakers Elliot Laffer and Christian Simonelli, executive director and technical and recharge coordinator of the Boston Groundwater Trust, respectively, along with the city’s new chief of Environment and Energy Brian Swett and John Sullivan, chief engineer of the Boston Water and Sewer Commission (BWSC).
Sullivan said leaks in underground tunnels, including transit and sewer connections, are often to blame for lowered groundwater levels, but the cause of the depletion at Beacon and Dartmouth streets remains unknown.
“It happened in a sudden way,” Laffer added. “In one month, the level dropped from a 5-foot elevation to 3 or 3½ feet and stayed down.”
As for a possible solution, Sullivan said, “It might be cheaper for us to find a way to bring water in, rather than patch [the leak].”
To residents who fear the foundations of their homes might fall prey to receding groundwater levels, Laffer advised contacting a geotechnical engineer, but he said digging a test pit at a cost of $5,000 to $10,000 is the sole surefire way to assess the situation.
“The fact is you don’t know you have a problem until you have a problem,” Laffer said. “The only way to know for sure is to dig a test pit and take a look.”
And more than 80 years after the costly method was used to repair the foundation of the main Boston Public Library building in Copley Square at a cost of $250,000, underpinning remains the only reliable remedy for repairing compromised pilings.
“It’s expensive because it’s miserable, difficult handwork,” Laffer said of the technique.
Visit the Boston Groundwater Trust online at www.bostongroundwater.org to access the latest data from observation wells and other information.