Natural Material Bank Stabilization along the Magalloway River and NH Route 16 using a Ballasted Tree Revetment
Jessica Louisos, PE, MS
Roy Schiff, PE, PhD
SLR Consulting
Waterbury, VT
This project included stabilizing the riverbank along the Magalloway River and relocating a failed portion of NH Route 16 in Errol. A key challenge of the project was to use natural materials so that the bank would return to a vegetated state with good habitat and matching surrounding conditions in the Umbagog National Wildlife Refuge. SLR collaborated with McFarland Johnson (MJ) on an alternatives analysis to repair the failed roadway and bank. A naturalistic bank stabilization approach was selected as stone was deemed to be likely too heavy for underlying soft soils and sheeting was not desired due to poor habitat and site aesthetics. The preferred alternative selected was a novel ballasted tree revetment to stabilize the bank and create a base for overlying soil and plantings.
J.P. Sicard (JPS) was the successful bidder on the NHDOT project. SLR worked with JPS to complete the final design for the tree revetment as part of the construction contract. We performed stability calculations following methods developed by the US Forest Service. We prepared a design plan to illustrate the plan and section of the proposed tree revetment. JPS successfully built the project in 2021. This project provides value to the engineering profession as it used a novel approach to a common problem – bank erosion.
Being located in the Umbagog National Wildlife Refuge where recreation is abundant, this project serves as a public awareness campaign for naturalistic bank stabilization approaches. Many people inquired about the project during site assessment and construction. With a lot of boating and fishing in the area, the site will be viewed by many over the years as revegetation progresses. The logs near the bottom of the stabilized bank provide good fish habitat during moderate and high water levels.
This approach is growing in popularity in the Unites States, and we now have an example of a successful installation in New Hampshire to build on. If bank revegetation, fish habitat enhancement, and natural site aesthetics are high on the list of project objectives, the ballasted tree revetment can be used in place of common riprap.
About Jessica Louisos, PE
Jessica is a Senior Water Resources Engineer with SLR International Corporation, specializing in flood resiliency, aquatic organism passage, stormwater planning and design, flood mitigation, and restoration of rivers, floodplains, and habitat. Jessica’s water resource work helps communities be more resilient to hazards and our river systems function more naturally. She completes project work and teaches courses on reducing our river – road conflicts.
Jessica graduated from the University of Vermont, having received a BS in Civil and Environmental Engineering in 2004 and a MS in Environmental Engineering in 2006. She currently serves as Treasurer for the Vermont Section of WTS, Government Relations Chair of the Vermont Section of the American Society of Civil Engineers, and Chair of the South Burlington Planning Commission. She received the Vermont Young Engineer of the Year Award in 2013. She loves creating pottery, sewing, and reading by the woodstove. And anything outside including swimming, hiking, skiing, canoeing, and camping with her husband and dog Ginger.
https://www.linkedin.com/in/jessica-louisos/
About Roy Schiff
Coming Soon