Since the old Hulton Bridge spanning Oakmont and Harmar was imploded, its curved steel trusses, still intact, have been sticking out of the Allegheny River.
Not for long, though, as those remnants should be gone by the end of this week, according to a PennDOT contractor.
Brayman Construction, the main contractor, has been hauling pieces of the steel superstructure out the Allegheny River since the Jan. 26 implosion as part of the $66 million bridge replacement project.
There was an estimated 2,200 tons of steel dropped into the river.
Once it's removed, Karlene Durso, project engineer for Brayman, said the contractor has to remove the stone piers and a small section of the bridge on the Harmar side, above the Norfolk-Southern rail lines.
The demolition of the 107-year-old lavender span has been a series of steps.
As planned, the implosion sheared off the bridge structure just above its piers, dropping it straight into the river.
The contractor's first order of business was to clear 300 feet of the river's navigation channel within 72 hours of the implosion. The Coast Guard closed down the river at the bridge to boat traffic during that 72-hour window.
“Brayman did an excellent job in having that navigation channel cleared,” said Allen Edris, the regulatory project manager for the Army Corps of Engineers, Pittsburgh district.
Mother Nature could have complicated salvage activities just after the implosion when ice started to back up against the partially submerged bridge, Edris said.
“But it warmed up, and the ice went away,” hesaid.
The Corps conducted a sonar-like scan of the river bottom 300 feet upstream and 100 feet downstream of the bridge to document its pre-implosion condition. Edris took another survey three days after the implosion on Jan. 29 to ensure the channel was clear and safe for boats. The Coast Guard then opened up the river to traffic.
The Corps plans to survey the bottom again when Brayman removes the stone bridge piers.
The contractor is expected to remove the bridge piers about 4 feet below river bottom, Edris said.
Crews will fill the river bottom depressions from the piers with rocks, likely limestone.
“The placing of those rocks will speed up the recovery of the river, allowing the substrate to fill in voids and have readily available habitat for fish and mussels,” he said.
Harmar's bald eagles
In addition to surveying the river, the Audubon Society of Western Pennsylvania has been monitoring the bald eagles nesting near the bridge above Route 28 in Harmar.
PennDOT contracted with Audubon to document any effects of the implosion on nesting activity.
Audubon watchers confirmed the birds were at their Harmar nest later in the day after the implosion. The birds have since been mating and were recently seen again at the nest Thursday morning.
The bridge replacement project started in September 2013.
A single-lane restriction on the new four-lane bridge will be lifted when crews complete a wall construction on the Oakmont side in early May, according to PennDOT.
Mary Ann Thomas is a Tribune-Review staff writer. She can be reached at 724-226-4691 or mthomas@tribweb.com.
