By BRADEN LAMMERS
> SOUTHERN INDIANA —
Metal was submerged under the murky waters of the Ohio River on Thursday and drilled into the river bed. And by today, the first casings will be in place — which will be filled with concrete — to begin forming the piers for a new bridge.
It’s all part of the foundation of the new Interstate 65 bridge that will carry northbound traffic across the Ohio River from Louisville to Jeffersonville. But planners said it will likely be a year before the ongoing foundation work appears above water. Once those piers are complete and towers are constructed, structural steel will be put in place and begin to form the bridge.
Joel Halterman, project manager with Walsh Design Build Team for the new Interstate 65 bridge, gave an overview of the project from atop the Big Four Pedestrian Bridge on Thursday, where preparation work on the Kentucky and Indiana shorelines stands out.
However, when construction begins, the efforts will not be easily visible from either the Big Four Bridge or either riverfront.
“You won’t see very much at all,” Halterman said. “The drilling is all inside of the casing. There’s no borings or blastings.”
He said the most local residents will hear will be the beeping from a crane.
The process to drill and install the foundation of the bridge involves a template that is placed into the water; then 31-foot-long and 12-foot-diameter metal casings are placed inside the template. Once the casings are in the proper location, a 30-foot-deep hole is drilled into the rock at the bottom of the river.
Four shafts will be drilled, two under each tower, which will be connected by a footer. The individual footers, with two shafts each, are then connected to each other and make up a single pier. The first casings and shafts that will be put in place for the bridge piers will be near the Indiana shore — what planners call tower five. Once the shafts are dug, rebar, or metal framing, will be placed into the hole and then concrete is poured into the frame.
Halterman explained that when concrete is pumped into the hole that has been dug, it pushes the water up and out of the casing. Then it will take about a week for the concrete to cure.
The process will be repeated in the Ohio River moving toward the Kentucky shoreline. In all, the bridge will include nine piers — four on land and five in the water.
Halterman said the construction timeline will be about eight weeks for the footings, it will take about nine months total for the towers to be completed and steel erection will begin next year, 280 feet above the water.
Before all of the work began on the bridge piers, a series of explosions in late May tested the durability and depth of a test shaft planners had designed. Walsh Construction Project Manager Max Rowland said the pier in the test, known as a lateral Statnamic load test, performed better than expected. For the construction crews on-site, it determined how deep they would have to dig.
“Once we found out how strong it was, that did impact the design — how far we would ultimately need to drill into it,” Halterman said of the bedrock.
And as construction crews move along, if inconsistencies are found under the river, it may change design plans.
“Most likely it would impact how far we would go into it,” Halterman said. “Inspectors will be with us at all times to examine the bedrock is the same that [crews] are drilling into.”