New London Culvert Repair

New Hampshire law classifies a 10 foot clear span culvert as a bridge. Bridges that are “deficient”-- in poor condition, with weight restrictions or with poor construction--are known as red-listed. According to Richard Lee, Public Works Director in New London, his town had a 10 foot culvert that was red-listed as “the culvert needed replacement because the bottom had rusted through.”

The New Hampshire Department of Transportation’s (NHDOT) Bridge Aid Program allows a municipality to receive up to 80% reimbursement using state funds for the cost of design and construction of a bridge rehabilitation or replacement project. Richard completed an application for the NH Bridge Aid Program and funds were set side for the New London culvert in 2005.

As luck would have it, the NHDOT had a culvert to repair down-stream of Richard’s. The NHDOT Bridge Repair Crew contacted Richard and offered to fix his culvert while working on their own. It was easy for the NHDOT to repair Richard’s bridge while doing their own since they only had to mobilize and demobilize once for both culverts.

Richard’s luck continued as the NHDOT had Bridge Aid money available in 2003 and offered to fund Richard’s culvert repair.

To repair the deficient culvert, the NHDOT built a coffer dam and ran the water through the damaged culvert through smaller pipes. They cleaned the culvert, installed rebar, built forms around the culvert bottom, and then filled the forms with concrete. The whole process took about two months.

The town of New London is quite pleased with the result. It saved money, had their culvert repaired ahead of schedule, and kept the road opened during the repair. According to Richard it is an “ingenious way to fix a culvert without tearing it out of the ground.”

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