Coffer dam or dynamite? That's the question before Caltrans engineers as they ponder how to remove the East Span's largest concrete support structure in the fastest, safest, and most cost-effective way possible.

First, work with environmental experts to schedule a time of year when the fewest birds, fish, and animals are likely to be around. In this case, that would be November 2015.

Instead of one huge explosion, Toll Bridge Program Chief Engineer Brian Maroney explains in the video below, deploy hundreds of small charges simultaneously. The structure comes down in 6 seconds, cranes on barges remove the debris, and you're out of there in a fraction of the time a coffer dam would require.

There's still some time to decide.

The first phase of demolition, removing the 80-year-old structure's half-mile cantilever truss, was completed on June 12. Next step: dismantling the truss spans that stretch east of the cantilever to Oakland.