Redesigned Culvert Improves Hydrology & Habitat
Our firm assisted the New Hampshire Department of Transportation with field assessment, engineering design, and permitting for the replacement of a failing 84-inch culvert beneath Route 150 in Kensington. The existing culvert was rated poorly for structural condition, aquatic organism passage, and geomorphic compatibility. Services included wetland delineation, geomorphic assessment, sediment and channel geometry analysis, and hydrologic and hydraulic modeling using HydroCAD and HEC-RAS. An alternatives analysis was completed with cost estimates, and a four-sided precast box culvert was selected as the preferred option to balance constructability and financial constraints.
Our team prepared permit-level plans using NHDOT standards and coordinated a Standard Dredge and Fill Wetlands Permit application for joint review by NHDES and the U.S. Army Corps of Engineers. The new culvert was designed to enhance hydraulic and geomorphic function and to improve aquatic organism passage for species such as eastern brook trout and American eel.
