Pursuant to Executive Order: 11988 (Floodplain Management) and 11990: (Wetlands) and the Federal Emergency Management Agency’s(FEMA) implementing regulations at Title 44 of the Code of Federal Regulations Part 9, FEMA hereby provides final notice of its decision to provide Pre-Disaster Mitigation program funding for an action located in a floodplain and wetland. Funding would be provided through Vermont Emergency Management to Vermont State University for the Glen Brook Dam Partial Removal Project.
The proposed action is located at the Vermont State University’s Castleton, VT campus. The purpose of the project would be to reduce the hazards associated with the potential breach of the dam impounding Glen Brook Pond, which is currently assigned a Significant Hazard Potential classification by the Vermont Dam Safety Program. Partial removal of the dam would reduce the Dam Safety Program classification to that of Minimal Hazard and reduce the potential risk to human life and property, owner liability, and long-term costs for the University.
The proposed scope of work would be to reduce the height of the concrete spillway by 2 to 3.5 vertical feet over the full length of the spillway, which would reduce the dam’s height to within 1-foot of the rip rap currently buttressing the downstream slope of the dam. In doing so, the total volume of the impoundment would be reduced to approximately 330,000 cubic feet of combined water and sediment, and the surface area of the impoundment would be reduced from approximately 2.2-acres to 1-acre while allowing the majority of the sediment currently impounded by the dam to remain in place. The project would also involve decommissioning the low-level outlet in-place by filling it with flowable fill and removing the valve stem, removing invasive knotweed, spreading sediment removed from the impoundment, and planting native upland and wetland vegetation in areas disturbed and converted from pond.
The project is within a mapped special flood hazard area (1% annual flood chance) (A Zone); however, based upon hydrologic and hydraulic study completed during project design, the project is not anticipated to affect flood elevations or areas inundated during flood events. Portions of the project would occur within a delineated wetland, and the reduction of the impoundment area would affect wetland areas; however, impacts to wetlands above the impoundment would be expected to be limited by the presence of upstream beaver dams.
Additionally, aquatic organism passage would be expected to improve.
The project must occur in a floodplain and wetland due to the location of the dam. Alternative solutions were considered including no action, repair or modification of the dam, and full removal. The proposed action was selected as the alternative that achieved the project purpose of reducing the hazards of potential dam failure while minimizing project costs. Grant conditions will require compliance with all federal, state, and local laws, including coordination with the local floodplain administrator.
Map requests and comments about this project and potential floodplain and wetland impacts should be submitted within 15 days of the date of this publication to: Christian Paske, Environmental Protection Specialist Federal Emergency Management Agency, Cambridge, MA Christian.Paske@fema.dhs.gov; 202.704.1027
