Special to the Sun
As part of Boston Groundwater Trust’s 40th anniversary year, Christian Simonelli, the BGwT’s executive director, led more than 35 guests on a walking tour of lower Beacon Hill on Saturday, June 20.
“The neighborhood’s familiar brick row houses and historic streets provided the perfect setting for a deeper look at something most people never see: the groundwater that helps protect many of Boston’s buildings from below,” said Simonelli.
Over the course of an hour, tour participants explored the history of the ‘Flat of Beacon Hill,’ including how parts of the neighborhood and nearby portions of the Public Garden were created by filling in former tidelands. That history helps explain why so many buildings in this area depend on wood-pile foundations driven into the filled land and capped with granite blocks, said Simonelli.
“Those wood piles can remain strong for generations—but only if they remain submerged. When groundwater drops below the tops of the piles, exposure to air can allow decay to begin,” added Simonelli. “Maintaining groundwater levels is therefore essential to protecting tens of millions of dollars’ worth of some of Boston’s most renowned real estate. It’s our core mission at the Trust.”
The tour also included a reminder of what can happen when groundwater levels drop. On Dec. 18, 1986, residents of an Otis Place home were jolted awake before dawn by what they feared was an earthquake. In reality, one side of the house had suddenly settled after lowered groundwater levels caused the wood piles beneath it to decay.
The incident made headlines, including the memorable ‘Beacon Hill’s Cracking Up,’ and remains a powerful example of why groundwater monitoring matters in Boston’s filled-land neighborhoods.
The tour concluded outside the Church of the Advent, where participants watched a groundwater reading on Brimmer Street. The demonstration showed how a monitoring well is opened, how a probe attached to a measuring tape is lowered into the well, and how the probe signals when it reaches water.
“It was a simple but revealing look at the daily work behind the Trust’s monitoring program,” said Simonelli. “Our field engineer performs this kind of measurement dozens of times each workday across Boston’s filled lands.”
Simonelli extended BGwT’s gratitude to tour guests, who included Rep. Jay Livingstone and Beacon Hill Civic Association Executive Director Patricia Tully.
BGwT’s next groundwater neighborhood tour focuses on Back Bay and is scheduled for Saturday, July 18, at 11 a.m., beginning on the steps of Trinity Church in Copley Square. To R.S.V.P. for the July 18 walking tour and learn more about BGwT, visit bostongroundwater.org.