DOT to outline bridge blasting plans at town workshop
Specifications for demolition of the old Jamestown Bridge were filed late last week by Cashman Equipment Company of Boston. The details are being reviewed by the state Department of Transportation for a presentation to the public tentatively set for March 22.
The DOT expects to complete its review by tomorrow and confirm the date and details of making the information public. The Boston marine specialty company, which won the bid to take down the bridge for $19.5 million and salvage rights, has been working on the bridge's dismantling since mid-January, after spending four months preparing for the task and assembling a project village of several office and supply trailers, heavy construction equipment, and one barge crane.
"It's coming down like Tinker Toys," one worker said.
Townspeople are facing two concerns about the work: reverberations from the blast that might affect nearby homes that the DOT and Cashman will monitor extensively, and traffic on the new Jamestown Bridge that parallels the old bridge, with 220 feet between the two nearly 7,000-foot spans.
Details of the actual demolition have been limited so far to reports that a series of low-grade explosives would be used to separate iron beams for removal. Sections of the bridge will be dropped into the bay for removal later, and the concrete rubble will be dumped at three ocean locations to become artificial reefs.
Some 1,650 feet of the western end of the old bridge is not part of the demolition plan, pending decisions about its development as a fishing pier. The location for the pier, left where it is or to be relocated, is yet to be decided.
The work starts in earnest, an exact schedule for detonations will be posted, and traffic will be disrupted for about half an hour at a time, between 10 a.m. and 2 p.m. on weekdays. Details about the blasts and about the traffic plan will be the focus of the public session now being planned.
The Cashman contract said that it notifies the DOT, which in turn is responsible for notifying all local, state, and federal publicsafety personnel about the schedule at least two weeks before any bridge closings. In addition, each closing must be posted at the DOT's transporation management center 48 hours before each blast, according to the contract
The contract also says that the bridge demolition must be by "non-scattering methods." Use of wrecking balls will not be allowed, but in addition to explosives, hydraulic hammers, breakers, and comparable tools will be used.
A total of 18 portable "road work" trailers have been in place about a month now in preparation for electronically updating traffic conditions on the new bridge during blasting on the old bridge.
The dismantling of the old bridge started in January with removal of large steel plates from the middle of the bridge, working outward with removal of roadway plates continuing for the full width of the bridge, making it impassable. Construction vehicles were using the old bridge occasionally as they prepared the bridge for the dismantling. The old bridge has been closed to vehicular traffic since 1992.
The plates are being removed by barge or truck for stockpiling and for delivery directly to buyers, based on Cashman's arrangements for the approximately 6,000 tons of steel in the bridge.
An estimated 24,000 cubic yards of concrete debris is involved. The Cashman contract specifies that all debris more than one foot in size will be removed from the floor of the Narragansett Bay, which the bridge spans.
Cashman specializes in marine construction and rental and sales of marine equipment. It is one of the largest barge companies in North America. The company is operated by James Cashman, third-generation owner of the equipment company that deals with inland and offshore construction, as well as project cargo services. The firm also operates Cashman Scrap and Salvage.