In six seconds, a section of the old Bay Bridge will be gone.
The implosion of Pier E3, the equivalent of a five-story building weighing 20 million pounds, is scheduled for Saturday at 6:45 a.m. If the weather doesn't cooperate, the short blast will be pushed to 1 p.m.
The public will not really get a chance to watch the implosion, or rather 600 different charges, up close and personal, mostly because the entire ordeal will be underwater.
"This is not like Las Vegas," bridge spokeswoman Leah Robinson-Leach said, "where you see an implosion and there's a huge visual. This is not a tourist attraction. It's a demolition."
Some people still want to get as close as they can, and have set up "Old Bay Bridge Blow Up Watch Party" Facebook sites. The plan seems to be to arrive at California Avenue and Avenue N on Treasure Island before the sun comes up.
Environmentalists have been worried about how the blast will affect the wildlife, and a Caltrans official acknowledged to the Chronicle that 1,500 smelt will likely be killed. Still, the plan calls for a blast mat to contain dust, a bubble curtain to absorb shock and protect as many plants and marine animals as possible, and there's a hollow structure laid on the bay floor to collect debris.
Scientists will be looking to make sure that two birds, the endangered least tern and the protected brown pelican, are not in harm's way. If either is diving within 500 feet of the pier, the implosion could be delayed while monitors point lasers sound off air horns to shoo the birds clear of the demolition. Caltrans hopes harbor seals and sea lions will be deterred by buoys that make noice.
Bay Bridge traffic will be held for about 15 minutes to prevent potential distraction to drivers, and BART trains will be held temporarily outside of the Transbay Tube, meaning there could be slight delays.
When the bridge is imploded, the public will have no access to viewpoints on the eastern side of Yerba Buena Island, and the bike path will be closed to the public starting at 6 p.m. on Friday until after at least 10 a.m. on Saturday.
The Bay Bridge demolition began in September 2013 and is scheduled to be completed in 2018. Caltrans must still remove 21 more piers.