Weirs Beach Boardwalk Rehabilitation

Laconia, New Hampshire

A severe flood event washed out 120 ft of the boardwalk, undermined the adjacent scenic railroad track, and caused the boardwalk embankment slope to fail. The original boardwalk was constructed in 1848 as a passenger platform for New England tourists arriving by train to Lake Winnipesaukee.

The City retained DuBois & King to design the repair for the damaged Weirs Beach Boardwalk section and to design upgrades and improvements to the entire 960 ft boardwalk to protect against future surface and high groundwater impacts after soil borings indicated that the entire boardwalk and railroad embankment was unstable.

DuBois & King engineered a design sufficient to handle the live load of the railroad that could be built during winter conditions within funding limits and schedule constraints. The design and construction was completed within 7 months, during winter conditions, and within the $1.13 million budget.

The design addressed the unstable slope, high ground water potential during flooding events, and provided a Cooper E-80 live loading for the railroad with sheet piling retaining walls with deadman anchors. The new underdrain/closed drainage system directs stormwater to a 200 ft treatment swale/retaining wall to create water quality improvements. Design features included new railings, stairways, crosswalks, and lighting. Reduced project cost by salvaging steel from the damaged boardwalk, utilizing recycled composite decking material, and specifying light fixtures that minimize light pollution.

Improved boardwalk is an economic centerpiece providing a safe link between the City beach, City docks, railroad station, restaurants, businesses, and shops.