Monitoring wells detected unprecedented high temperatures in the groundwater in Boston’s Leather District, prompting resident fears of damage to building foundations. Photo by Steve Adams | Banker & Tradesman Staff
Piping hot tap water emerging from his cold-water faucets was a red flag that something unusual was occurring in the neighborhood where Robert Qua bought a condominium in 2019.
Since 2021, Qua and his neighbors at 717 Atlantic Ave. in Boston’s Leather District have been searching for the heat source. They noticed that the snow melted on one side of the street during winter storms. Occasionally, boiling water appeared to be bubbling out of manhole covers. Monitoring wells maintained by the Boston Groundwater Trust beneath the sidewalk measured temperatures up to 158 degrees, Qua said.
“My overriding concern is: Here you have water that we’ve measured up to 158 degrees for a few years now,” he said. “What is that doing to the pilings that support all of the buildings in this neighborhood?”
Qua contacted the Boston Groundwater Trust, a nonprofit agency that’s responsible for monitoring subsurface conditions through a network of 812 wells.
Typically, groundwater temperatures range from 50 to 60 degrees, said Christian Simonelli, the group’s executive director.
“The groundwater level was stable but the temperature [on Atlantic Avenue] was off the charts: 140 to 150 degrees, which was the highest we had ever seen in any well,” he said.
The Leather District problem has been studied by parties that have a stake in the subsurface infrastructure, including the Boston Water and Sewer Commission and Vicinity Energy, which operates a 24-inch steam pipe that runs down Atlantic Avenue from its nearby plant on Kneeland Street.
In the meantime, Qua and his neighbors are pressing officials for a permanent solution to protect their real estate investments.
In searching for causes of the groundwater changes, Qua said the “800-pound gorilla in the room” is potential effects from developer Hines’ 51-story South Station Tower, which began construction in 2020.
The tower foundation required excavation to 150 feet, according to an Engineering News-Record report, and is located across the street from the 711 Atlantic Ave. condos. Hines did not respond to a message seeking comment.
A Surprising Cause of Cracking Foundations
After large portions of downtown Boston were filled to expand the Shawmut peninsula in the 1800s, many buildings rose on wooden pilings sunk into the fill.
In the 1980s, catastrophic damage to some Beacon Hill townhouses’ foundations revealed that a drop in groundwater levels was to blame. The wooden pilings had become exposed to the air, enabling bacteria to eat away at the supports. Studies blamed leaks into cracked sewer pipes for draining the groundwater table.
The Boston Groundwater Trust was created in 1986 to collect data and work with utilities and developers on strategies to maintain ideal subsurface conditions.
Since then, Boston has largely stabilized groundwater levels, Simonelli said. The trust checks groundwater levels in 812 monitoring wells, most of them six to eight times annually, to identify problem spots and plan fixes.
Boston also regulates new buildings in the filled areas of the city to ensure that they don’t diminish groundwater levels.
Article 32 of the zoning code regulates development in the Groundwater Conservation Overlay District. Among its requirements: New buildings must include groundwater recharge systems that capture precipitation from impervious lot areas, including roofs, and funnel the rainwater back into the ground.
“There are hotspots we continue to look at in conjunction with city and state agencies, and they are slated for repairs to fix sewers and manholes that may have inundation,” Simonelli said. “But overall, of the 812 wells, there’s only a small percentage below the threshold where we want them to be.”
Risks and Rewards of Below-Grade Heat
But now, researchers have identified another threat to building foundations in major cities.
Since 2019, Northwestern University professor Alessandro Rotta Loria has been monitoring subsurface temperatures in Chicago’s Loop through 150 sensors, and recorded temperatures up to 110 degrees.
“We can postulate that a number of operational issues in buildings might have been exacerbated,” Rotta Loria said, mentioning excessive settlement as an example. The effects on individual properties vary widely depending upon the distance to heat sources and building characteristics such as depth of foundations and building materials, he said.
“It’s an endemic consequence of the built environment: as soon as we build something, some heat is going to be trapped at the surface and some can be trapped below the surface,” he said.
Excessive heat can be addressed by adding insulation to heat sources such as steam pipes, he said. Or it can be recycled for use by ground-source pumps, which are gaining acceptance as an alternative to fossil fuel-based heating systems.
Steve Adams
Search for Permanent Solution
Crews from the Boston Water and Sewer Commission have inspected the 717 Atlantic Ave. condo building without finding any defects, Qua said. Vicinity Energy has performed periodic excavation on Atlantic Avenue and installed temporary pumps to remove excess groundwater, he said.
“Every time the pump fails, it doesn’t take a day or two and we notice the water out of our taps starts getting warmer,” he said. “There is definitely a cycle.”
Boston Water and Sewer Commission officials were not available for comment. Vicinity Energy did not make an executive available for an interview, but provided a prepared statement that it is committed to working with the city, Groundwater Trust and residents on a solution.
“The neighborhood has changed significantly in the last several years as a result of multiple construction projects and preliminary findings suggest that construction in the area may have influenced the underground water table resulting in intermittent changes in water temperature. To help alleviate the issue, we have already installed advanced monitoring, dewatering equipment, engaged engineering experts, and are collaborating with the city,” the statement said.
