Caltrans has secured the final of several permits necessary to demolish the largest pier of the old eastern span of the Bay Bridge using nearly 400 small explosives, a Bay Bridge spokeswoman said Thursday.
The U.S. Army Corps of Engineers signed off on the planned implosion of Pier E3 on Wednesday night and the demolition is scheduled to happen on the morning of Nov. 7, Bay Bridge spokeswoman Leah Robinson-Leach said.
The implosion is expected to last only six seconds and pull the concrete debris from the destroyed pier down into its own buried cavities. A "bubble curtain" of compressed air will contain the blast.
The Bay Bridge will need to be closed for up to 15 minutes that morning. California Highway Patrol officers will be on hand to stop traffic on the bridge and keep any boaters out of the area.
Caltrans has touted the implosion as the best solution for both the environment and the demolition project's budget. Mechanically removing the pier would take months and require building a dam around it, significantly disrupting area wildlife, according to project engineers.
If it works on Pier E3, Caltrans may seek future permits to demolish the remaining 21 smaller piers the same way. Pier E3 is the largest -- a 268-foot chunk of concrete buried 165 feet in the soft bay mud. It has already been partially dismantled in preparation for the implosion.
Caltrans has had to contend with a number of environmental concerns in planning the implosion, mainly the possible impact on area mammals like seals, sea lions and porpoises. Monitors will be keeping close watch to make sure no mammals wander into the area.
If any animals are spotted, the blast will be postponed. The timing was crucial as it was chosen to be when the fewest marine mammals would be in the area of the pier.
Environmental watchdog group Baykeeper has raised concerns about whether the bubble curtain can in fact contain the concrete debris and prevent it from polluting the bay. They have said they will be closely watching November's implosion.
Caltrans has been securing permits for months. The project required sign-off by the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, the state Department of Fish and Wildlife, and the National Oceanic and Atmospheric Administration, among other agencies.