LEBANON — Aiming to diversify the city’s municipal water supply, officials are considering construction of a well that would provide residents with a secondary source.
Currently the city relies fully on water from the Mascoma River. In a search for a redundant source, geologists of Wright-Pierce Engineers, the firm tapped by the city to explore well locations, identified a potential site near the city’s wastewater treatment plant. Tests at the site, which sits at a confluence point between the Connecticut and Mascoma Rivers and on top of ideal bedrock, identified a particularly powerful groundwater flow.
“It’s really quite a bit of water,” Greg Smith, one of the owners of Wright-Pierce, said in a presentation to the City Council last week. “What that provides is a massive drought-proof scenario, with water coming in at both sides from these two rivers.”
The Upper Valley, like the rest of New England, has had an unusually dry summer. Scientists predict such events could become more frequent as climate change continues.
The Department of Public Works is planning to request adding a budget item of around $175,000 to the city’s Capital Improvement Plan in hopes of doing a more rigorous pump test, and to have a better understanding of the site’s capacity by digging a wider well.
“Without the larger-diameter well, we really don’t know what the yield will be,” Assistant Director of Public Works Jay Cairelli said to the City Council. “But it seems right now that it could be a completely redundant source or even higher-yielding source for us.”
Operating with a single-source municipal water supply, as Lebanon has for decades, leaves the city more vulnerable to fluctuations that it has little or no control over.
“In the 1950s, a tanker truck rolled over in the Mascoma and contaminated it, and the city’s water wasn’t able to be consumed for some time,” City Manager Shaun Mulholland told the City Council at its Aug. 17 meeting. “That’s all it takes for it to do that, and it actually happened.”
Climate change has increased the risk to the water supply by leaving the city dependent on erratic, unpredictable rainfall. Lebanon is currently under voluntary water restrictions. Further, the flow of the Mascoma River is controlled by a private dam that the city itself has no authority over, making the river all the more unreliable.
“That’s not ideal, especially in drought times,” Smith said. ”We need to adapt to changes in weather patterns.”
Currently the city runs its water source at around 1500 gallons per minute. The potential well is testing at around 1600 gallons per minute. Additionally, at the wastewater treatment plant, water from the Mascoma River is filtered through 3 feet of manufactured sand.
“At this new site, you’d be running through at least 150 feet of sand,” Smith said. “You basically have a huge natural filter, with massive filtration potential.”
Higher capacity and natural filtration aren’t the only advantages of the potential well site.
“Generally speaking, surface water treatment plants are much more expensive to operate than groundwater sources,” Smith said in an interview. “This would be a less expensive operation, with less expensive maintenance, by far.”
The site is set to undergo significant testing work in the next year. It would be even longer before the newly sourced water was flowing through city pipes.
“Permit through construction, and then depending on treatment, this project is probably on the order of four to five years to get the source online,” Smith said.
The council will receive another presentation from Wright-Pierce hydrologists on Oct. 19, and the issue will likely resurface again in December during appropriations votes for the 2023 budget.
Frances Mize is a Report for America corps member. She can be reached at 603-727-3242 or fmize@vnews.com.