Lyndon Flood Mitigation Study Evaluates Solutions, Sanborn Bridge Project Called Into Question

Paul Hayes phayes@littletonrecord.com Staff Writer Aug 4, 2024 Updated 19 hrs ago

 

 

LYNDON — Efforts to restore the Sanborn Covered Bridge could be undone as part of flood mitigation efforts.

The Hazard Mitigation Committee on Tuesday heard a preliminary report on 14 potential flood fixes for downtown Lyndon from SLR International, a Waterbury-based engineering firm.

The report showed that removing the Sanborn Covered Bridge and 2-6 feet of fill from its southern approach would reduce the greatest flood along the Passumpsic River.

Doing so would reduce flood impacts at the Route 5/114/122 intersection by a foot during a 500-year storm and a half foot during a 10-year storm, and at the adjacent mobile home part by .6 feet during a 500-year storm and .3 feet during a 10-year storm.

For reference, downtown Lyndon (July 10) and east Lyndon (July 27) each experienced 500-year floods in the past month.

However, bridge removal would undo the ongoing $2.2 million renovation of the Sanborn Covered Bridge and the creation of a park on the south approach.

Planning Commission Chair Holly Taylor suggested the project be put on hold, pending further study of the flood mitigation option.

Marty Feltus, Chair of the Hazard Mitigation Committee, agreed.

“I would say that’s a valid observation,” Feltus said. “That is interesting information and perhaps the persons that are involved in that project do need to stop and think about that to determine if that’s something that we want to put on hold.”

SLR International also suggested that an option not included in their report, the removal of Lyndon Electric Department’s Vail Dam hydro-power facility, be studied further.

Based on current data, dam removal could reduce flood levels on Broad Street by a foot or more in the event of large floods.

“This is the type of project I think folks were interested in,” said SLR engineer Jessica Louisos. “The next step would be a feasibility study and extra data collections.”

SLR’s report showed that other options were less impactful, such as raising the Route 5/114/122 intersection, floodplain restoration at the former highway garage site, and Center Street culvert improvements and property buyouts.

The Select Board, Town Administrator Justin Smith, Lyndon Electric Department General Manager Jon Elwell, and other key town officials could not attend Tuesday’s presentation because of a catastrophic flooding event in east Lyndon that same day.

Feltus noted that, “the devastating flooding we saw on July 30 in the East Lyndon area is a totally different issue and does not fit in the scope of this project regarding the Passumpsic River basin. Unfortunately, different strategies will have to be employed to react to that situation and prepare for the future.”

The Hazard Mitigation Committee expects to meet again the week of Aug. 19, in hopes of narrowing the list of options down to “two or three” choices, which would undergo a full cost-benefit analysis.

SLR will make a final presentation on the cost-benefit analysis in the fall, and the Hazard Mitigation Committee intends to use the information to apply for additional grant funding to implement one or more options.

They will submit a pre-application for the next funding round, due Aug. 30.

To review SLR International’s preliminary study or watch the presentation, see links below.

SLR International’s preliminary study: www.lyndonvt.org/wp-content/uploads/2024/07/Flood-Presentation-for-07_30_24-Meeting.pdf

Study presentation video: https://nvda.net/recordings/July30SLR.mp4

The Hazard Mitigation Committee is accepting public input on the study. Questions and comments can be emailed to Feltus at martyfeltus@gmail.com.

STUDY BACKGROUND

In November, the Hazard Mitigation Committee launched a 12-month grant-funded scoping study.

Waterbury-based engineering firm SLR International was contracted to perform the scoping study, which will take a comprehensive look at downtown flood hazards and create a ranked list of fixes, with recommendations and cost estimates.

Flood mitigation has become a pressing concern as major storms occur with increased frequency in Vermont.

Members of SLR International’s scoping study team said so-called “100-year floods” have grown 20 to 40 percent larger since the 1970s.

The scoping study will include hydraulic studies, cost estimates, taxpayer impacts, funding options, impact analysis, cost-benefit analysis, long-term maintenance requirements and more.

Explaining the project’s purpose, SLR International said, “Lyndonville has a long history of flooding as it sits in a low-lying area in the Passumpsic River watershed where tributaries, main-stem rivers, roads, and buildings all co-exist in the floodplain.”

“This Vermont Village is not alone in developing a plan for action following past flooding. Right now the City of Montpelier is asking similar questions following damaging floods in July – How can we avoid and reduce future flood damages?”

The scoping study is funded by a $75,000 subgrant from the State of Vermont under the Flood Resilient Communities Fund.

With completed scoping studies in hand, municipalities can seek further grant funding for project implementation.

For more information on Lyndon flood analysis and mitigation efforts visit https://www.lyndonvt.org/?page_id=692.