Officials outlined road traffic plans for the morning of the implosion — tentatively scheduled March 17 — as well as how boat traffic will be affected.
The blast will cause the exposed metal frame, or truss, under the deck of the old bridge to fall straight down and into Lake Marble Falls, officials said.
The deck, or roadway of the bridge, is currently being demolished and should be completely cleared off the structure by the end of the week.
No asbestos was detected in the old bridge; however, tests did show some lead paint on the bridge. TxDOT is removing the lead paint in areas where the explosive charges will be placed.
Officials said the blast and the truss falling into the lake below should not cause large dust clouds to rise into the air or large waves in the lake.
After the blast, the truss will be lifted out of the water to be recycled. TxDOT officials said the area near the bridge should be closed to boat traffic for about 24 hours to allow time to clear the lake before the implosion and then remove the debris. Vehicle traffic on the highway near the bridge is expected to be stopped for 10-30 minutes for the blast.
Concerns about the blast’s effect on the new bridge and the city’s drinking water also were answered.
“Any debris that might blow into the (new) bridge shouldn’t be of sufficient force to damage anything,” Hiemke said. “There’s really no concern to damaging the new structure.”
Blast monitors, or devices that detect the shockwave from the blast, will be placed around the bridge to determine the shock on land caused by the implosion.
Hiemke said TxDOT and Archer Western officials will perform pre-blast checks on buildings near the bridge. Anyone worried the blast from the implosion could cause structural damage can contact TxDOT or Marble Falls City Manager Ralph Hendricks to make a claim.
Hendricks said people who want to view the implosion are welcome to come to Lakeside Park, 306 Buena Vista. Members of the Burnet County Sheriff’s Office and the Marble Falls Police Department will be on patrol the morning of the implosion to ensure foot and traffic safety near the bridge as well as around private property.
A 1,000-foot zone also will be cleared on both sides of the water from the bridge and will be patrolled by six boats.
After the debris is cleared from the area, officials said construction of the second structure should begin in April. Demolishing the bridge without implosion would take 60-90 days longer. Currently, TxDOT anticipates the second structure to be completed in the fall of 2014.