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2008_08-28 The Newtown Bee
DOT Considering New Housatonic River Bridge Downriver of Stevenson Dam By Andrew Gorosko
STEVENSON — In view of changing economic conditions, plus bridge constructability issues, the state Department of Transportation (DOT) is now considering building a new, less costly, Route 34 bridge across the Housatonic River downriver of the hydroelectric Stevenson Dam, instead of constructing a new span upriver of the dam, as has been in the planning stages for more than decade.
The DOT's complex existing plans to construct a new bridge about 250 feet upriver of Stevenson Dam in the Lake Zoar section of the river has long been under review by the state Department of Environmental Protection (DEP).
The site upriver of the dam proposed for a new bridge would require the installation of steel-reinforced concrete bridge pylons extending downward through 60 feet of water and also downward through 30-foot-thick river sediments to reach anchoring points in bedrock. The riverine sediments are contaminated with polychlorinated biphenyls (PCB's), mercury, and lead, thus complicating sediment control during bridge construction. Floating cranes would be needed to construct a bridge upriver of the dam.
PCBs, or polychlorinated biphenyls, are toxic, odorless, colorless chemical compounds that lie in Housatonic River sediments. In the past, PCBs were dumped into the river at a General Electric factory in Pittsfield, Mass., and have traveled downstream.
The new bridge would replace the existing deteriorating bridge atop Stevenson Dam, which links Monroe to Oxford. That bridge was built in 1919.
The 1,250-foot-long concrete dam creates the 11-mile-long impoundment upriver of the dam known as Lake Zoar, which is heavily used for recreation. In light of the existing bridge's deficiencies, the span was closed to traffic for two weeks in August 2005 to allow major bridge repairs to be made. The DOT considers the bridge to be functionally obsolete and needing replacement. The bridge is inspected annually.
Many Newtowners travel on the Route 34 bridge atop Stevenson Dam on their travels to and from New Haven.
Civil engineer Thomas Harley, who is the DOT's supervisor for consultant-designed projects, said this week that the Route 34 bridge planned for the area upriver of the dam is about 75 percent into its design phase.
But in view of changing circumstances, the DOT is now considering whether it would be wiser to construct a new bridge downriver of the dam, he said. Such a bridge might be constructed about 1,000 feet to 2,000 feet downriver of the dam, in an area where the river is much narrower and much shallower than it is in the Lake Zoar area upriver of the dam, he said.
It might be possible to construct a downriver bridge without any pylons being extended into the river, Mr Harley said.
The presence of PCB's in river sediments would not be as large an environmental issue for a downriver bridge as it would be for a bridge constructed upriver of Stevenson Dam, he said.
"We're broadening our set of options" in terms of what would make for the best location for a new bridge across the river, he said.
Although a bridge downriver of the dam would be a much shorter span than a bridge upriver of the dam, a downriver bridge would require longer bridge approaches, he noted. Construction work would include creating a terrace along a valley wall where a roadway would be placed.
Mr Harley estimated that a downriver bridge would cost much less money to build than an upriver bridge, reflecting a possible price of $45 million, compared to $60 million for an upriver bridge. Such projects typically have an 80 percent federal/20 percent state cost split.
Multiple issues have led the DOT to consider constructing a new Route 34 bridge downriver of Stevenson Dam, rather than upriver of it, Mr Harley said. Those include cost factors, environmental concerns, constructability issues, and public acceptance, he said. The availability of funds for such construction projects has become an issue in the face of rapidly rising construction costs, Mr Harley said.
"The whole idea is to put together a reasonable [bridge construction] plan with the money we have," he said, noting escalating construction costs.
Mr Harley said the DOT hopes to conduct a public informational meeting before the end of this year about the various options for constructing a new Route 34 bridge across the Housatonic River.
Such a session has not yet been scheduled. Previous public meetings on constructing a new Route 34 bridge were held at Masuk High School in Monroe in May 2002 and in March 1998.