During the significant rain event of October 8-10, 2005, the existing corrugated metal pipe arch culvert beneath White Birch Point Road became surcharged and eventually the backwater associated with the storm surge from the outfall of Gregg Lake caused a total breach of the roadway embankment and dry laid stone headwalls, leaving a gorge where the roadway had been. This stream crossing is the only access for the residents on White Birch Point.
QCC performed a hydraulic study and determined that the culvert size was severely deficient. QCC studied several mitigation alternatives and recommended that an 18-foot span, precast concrete rigid frame replacement bridge structure be constructed on a new alignment downstream of the existing pipe to allow for local use of the existing road during construction, as well as to accommodate proper hydraulic discharge from the Gregg Lake Dam spillway located approximately 80-feet upstream.
This project was funded by the Town of Antrim, the Federal Emergency Management Agency (FEMA) and the NHDOT Municipally-Managed Bridge Aid Program.