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Lamoille County Planning Commission

 

Jeffersonville/Cambridge Flood Resiliency Project

The Village of Jeffersonville (located within the Town of Cambridge) worked with the Lamoille County Planning Commission (LCPC) to develop its first Hazard Mitigation Plan. As part of the development of this Plan, LCPC and the Village contracted with an engineering firm to develop a model of flood hazards in the Village. Funds were available to implement two of the alternatives that had the greatest potential to reduce flood levels in the Village. The Town of Cambridge applied for Community Development Block Grant Disaster Relief Funds to implement these alternatives. 

Route 15 Bypass Culverts

The flood modeling identified enlargement of two culverts under Route 15 as having a significant benefit to reduce flooding. Further engineering analysis was conducted to refine the size, length, and processes needed to undertake implementation. Two culverts were selected to improve flow conveyance from the flood chute to the Lamoille River based on their location and proximity to infrastructure.

Culvert #1: A new 3’0” diameter culvert was installed next to an existing 18-inch corrugated metal pipe located on the upstream (northwest) edge of the Route 15/Route 108 roundabout, and a 4-foot diameter circular pipe was installed under the G.W. Tatro Construction driveway. The land approaching the culvert inlet was lowered to direct flood waters in the “flood chute” to enter the culvert rather than flow into the Village.

 

Culvert #2: An 18-inch metal pipe in disrepair was replaced with a large box culvert 2-feet deep by 13-feet wide. Additional improvements included lowering the first trail embankment along the flow path downstream of the highway and shortening the existing culvert, lowering the existing swale between the two trail crossings along the flow path, and installing an 18’ culvert under the second trail crossing along the flow path.

Grading and excavation related to installation of the culverts resulted in movement and/or removal of ~100 cubic yards of material. 

 

Cambridge Greenway/Railroad Bridge

 

Based on the flood modeling study the Cambridge Greenway/Railroad Bridge over the Brewster River was significantly undersized. The old bridge had a span of 52 feet and a low chord elevation of 454.1’ For reference, this is below the 100-year flood elevation (460.57’) and the 10-year flood elevation (457.43'). As a result, the bridge was impacted by flood waters on an almost annual basis. 

The bridge was replaced with an adequately sized and proportioned bridge. The project involved removing the existing abutments and minor floodplain restoration in the vicinity of the abutments ~0.4 acres to a depth of ~7.5 feet.