Bridge estimate: faster, cheaper than expected

CORNWALL — Fewer than two dozen people came to a special town meeting Saturday evening (Oct. 8) at Cornwall Consolidated School, where a plan to replace the Lower River Road bridge took the final step needed for construction to begin.The single-lane bridge over Mill Brook, at its confluence with the Housatonic River just upstream of the Covered Bridge, was partially destroyed on Aug. 28 by Tropical Storm Irene. Debris and boulders that were pushed down the brook in torrential rain undermined a footing and washed out an abutment on one end. The bridge is the only access to four homes on that side of the dead-end road. Another concern is that the fire hydrant for West Cornwall, which pulls water from the river, is on the far side of the bridge, blocking its use for most of the village. A state of emergency has remained in effect. Fire hoses have been run down Lower River Road to the stranded homes as a precaution, since fire equipment has no access. There was one dissenting vote to the proposed appropriation of up to $450,000 toward the project. It is now estimated that the work will cost as much as $600,000. Rather than change the agenda, an additional appropriation will be sought at the annual town meeting Oct. 28.The Federal Emergency Management Agency (FEMA) had already approved a plan submitted just two days earlier. FEMA officials confirmed the agency would reimburse for 75 percent of costs. All needed state and federal approvals are in hand.Most of the questions residents brought to the meeting were answered during a presentation by First Selectman Gordon Ridgway, who provided a greatly changed scenario for construction than what had been previously suggested by a consulting engineer.Four pre-qualified contractors were brought in to inspect the difficult site, given 45 pages of information and asked to submit design and construction bids. Eliminating a separate design phase was a time-saving measure aimed at getting the new bridge done before winter. What was submitted Oct. 6 by Mohawk Northeast Inc., based in Plantsville, Conn., was what appears to be a significantly better, cheaper and faster approach. Their bid of $497,000 was by far the lowest. The two closest were for $600,000 and $677,000. But it was the plan that really sold the low bid. Test borings showed the stream bed is deep with boulders and cobbles. That would make it very difficult to drive in the large sheet pilings deemed necessary there for a bridge that could stand up to significant scouring. Instead, Mohawk will drill a dozen 40- to 45-foot deep holes down to bedrock, then drive in iron pipes and fill them with concrete, creating a foundation of “mini-piles” that is expected to last at least 100 years. Engineer David Battista said Vermont lost many bridges to the storm, offering a bigger picture of bridge design. The ones that survived were on pilings.The new plan also eliminates weeks of noise caused by banging in sheet pilings. It requires no coffer dams to divert stream flow. Instead of a Dec. 10 completion date, as estimated by Battista, Mohawk submitted a work flow sheet that will have the bridge in by Nov. 14.The financial picture was laid out by Ridgway. Costs in addition to the $497,000 for construction include $40,000 for engineering, $10,000 for a survey, $15,000 for test boring, $10,000 to Roger Kane for project management and an estimated $15,000 bonus.The latter is a $500 per day incentive, either a bonus payment or penalty, based on a Dec. 10 completion deadline. This is the same company that rebuilt the Covered Bridge 10 years ago, finishing a 10-day project in four. It was noted the Mohawk engineer on the project attended Cornwall Consolidated School.Final cost to the town is expected to be about $130,000. The capital projects account currently has a $70,000 balance.It seems amazing that the bridge survived for about a century built on piles of stone. But Battista explained earlier in the process that in flood situations, the Housatonic typically rises first, creating a backwater that slows the downhill rush of Mill Brook, which drains a huge watershed of Cream Hill and Cream Hill Lake.Over the years, culverts under four bridges upstream have been enlarged, sending greater volumes of water downstream. It makes no sense that the smallest opening is the last one. The Lower River Road bridge regularly becomes engulfed in water.While FEMA would not normally approve a design upgrade, they were able to be convinced that rebuilding this bridge to its original size would not meet current design standards for flow. It will remain 12 feet wide (one lane) but will be lengthened from 16 to 25 feet. Because there is little town-owned land there, guardrails will not extend beyond the length of the bridge. The rails will be timber — an added cost that everyone seemed to support for aesthetic reasons. The bridge is an important part of tourism in West Cornwall, being the optimum spot for taking photos of the historic Covered Bridge.