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Old stone culvert causing sinkholes once part of Jaffrey’s sewer system

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. Staff photo by Nicholas Handy

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—

  • Jaffrey's Department of Public Works determined Thursday that an old stone culvert is causing the sinkholes in the Jaffrey Public Library lawn and driveway. July 26, 2018 Staff photo by Nicholas Handy—



Monadnock Ledger-Transcript
Thursday, July 26, 2018 4:48PM

An old stone culvert has been ruled the cause of sinkholes in the Jaffrey Public Library lawn and driveway. 

The Department of Public Works found the culvert Thursday afternoon after a crew cut up the pavement around one of the sinkholes.

Digging up of the dirt revealed a gap between two large stone slabs. The gap is where one of the sinkholes appeared. 

“There is no imminent danger to the public,” Jaffrey DPW Director Randy Heglin said. “It’s a small culvert, it doesn’t appear to be more than 12 inches deep.”

Two potholes – one about 10 inches wide and four feet deep and another about two feet wide and two feet deep – were discovered by Library Director Julie Perrin on Saturday, prompting the library to close the driveway indefinitely.

About a half dozen small sinkholes were later discovered in the lawn, causing segments of the lawn to also be closed to the public. 

The part of Saturday’s Riverfest that was scheduled to be held on the library lawn was moved to the Jaffrey Civic Center lawn due to the sinkholes. 

The gap appeared after mortar or small rocks between the two stone slabs eroded or broke away over time, Heglin said. 

There is likely a blockage or plug in the culvert, Heglin said, which has caused water to build up and wash away some of the dirt underneath the pavement, leading to the sinkholes.

It was previously unknown if the sinkholes in the driveway and the lawn were connected, but Heglin said all the sinkholes seem to follow the path of the culvert. 

Heglin previously searched town records – including a map from 1924 – and found no evidence of the culvert. Heglin declined to speculate how old the culvert was.

Heglin said Monday he had received an email from an old town employee, who said the culvert was once connected to the town’s sewer system.

It is believed that the culvert was disconnected in the 1980s, and that it runs across the length of the Jaffrey library property. 

It has not yet been decided whether the culvert will be dug out or filled in, Heglin said. 

Heglin said this type of failure in such a culvert is not uncommon as he has seen it about 50 times in his 30-plus year career.

This is the first time he has found such a culvert in Jaffrey, however.

 Nicholas Handy can be reached at 924-7172 ext. 235 or nhandy@ledgertranscript.com. He is also on Twitter @nhandyMLT.