Floodwaters are receding after a Christmas day deluge of rain and snowmelt inundated the Main Street Bridge project worksite in Peterborough, and the damage to the bridge reconstruction project is less than expected, Peterborough officials say.
Local first responders and employees of construction firm Beck and Bellucci hurried to the scene midday Friday after a surge of water flooded the temporary cofferdams and threatened equipment. Beck and Bellucci staff were able to remove equipment that could have posed a hazard on Friday, Fire Chief Ed Walker said, including a heater and propane tanks that were bobbing in the water and a pricey industrial generator sitting on a midstream platform; the generator was removed by crane upon the crew’s arrival Friday afternoon. The pedestrian bridge connecting Main Street to Route 202 was closed briefly over fears for its integrity before reopening on Saturday.
“Considering how it looked on Christmas day, we’re actually in relatively good shape,” Assistant to the Town Administration Ali Kreutz said on Monday. The project’s engineering firm, Hoyle and Tanner, determined that floodwaters undermined Route 202 during an assessment on Saturday, Kreutz said. Weaver Brothers Construction was at work making emergency repairs to stabilize the area and keep water out, she said, and Beck and Bellucci contractors were removing debris from their worksite as the water level dropped, until it reached a point they could start pumping out the cofferdams. DPW Assistant Director Seth MacLean said that no further undermining was expected as of Monday, and that the costs associated with the necessary repairs were likely to be negligible. Associated costs would not fall to Peterborough, Kreutz said.
Although Peterborough administrators said construction crews made no preparations for flooding in advance of the Friday storm because the United States Geological Service water level predictions hadn’t accounted for snowmelt, and that the drought conditions in the summer and fall meant that a heavy load of wood debris that hadn’t been pushed down the river earlier surged up on Friday, slowing the water and raising the levels, the predictive model did accurately predict the amount water levels ultimately rose, Walker said: the peak just happened several hours before the model predicted it to, due to warmer-than-anticipated temperatures and other factors.
“The gauge pretty clearly indicated that they would get a… three-foot increase in water level,” over baseline flows prior to the storm, he said. Walker confirmed that no equipment appeared to have been removed prior to the holiday. A representative from Beck and Bellucci could not be reached by press time on Monday for comment.
Water levels peaked Friday afternoon before receding, Walker said. The USGS gauge of the Contoocook River in Peterborough recorded water flow rates between 80 and 100 cubic feet per second (cfs) in the days through Christmas Eve, before rocketing up in the wee hours of Dec 25 to peak at about 1600 cfs, before slowly tapering down. As of Monday morning, levels hovered around 400 cfs. The 50-year median daily level for this time of year is closer to 100 cfs, according to the gauge.