[Pedestrian]

Originally Posted by Busy Bee

^Wow... I had no idea it had those kinds of issues... Yikes...

It not only had that but the utility lines travel in the causeway ramp down from the Bay Bridge and those all broke in 1989.

Treasure Island sinking into Bay
Rachel Gordon, OF THE EXAMINER STAFF
July 27, 1995
Updated: Feb. 7, 2012 9:07 p.m.

It's not going down as fast as the Titanic, but it's slipping into the Bay at a steady pace, according to a study for the San Francisco Redevelopment Agency. That raises the possibility that as much as half the island could be put off-limits to development when the Navy leaves in 1997.

At its creation in 1939 for the World's Fair, Treasure Island stood 14 feet above sea level; today it's at 9 feet, thanks, in part, to the 1989 Loma Prieta earthquake.

If another big quake hits, the 404-acre landfill may ooze into the Bay even faster, unless the crumbling dikes and levees surrounding the island are shored up or replaced before then. The scenario is outlined in a new seismic study of the island commissioned by the Redevelopment Agency.

"If there were an earthquake, there'd be lateral spreading - the island would move, split apart," said Larry Florin, director of project development for the Redevelopment Agency.

But with the right amount of money and engineering ingenuity, the island - or at least part of it - can be saved, city officials say. The estimated cost to fix up the island's riprap frame: $69 million to $500 million, depending on the extent of the work . . . .

"The real news out of this report is that we're considering stabilizing a smaller portion of the island," said Gloria Root, chairwoman of the Treasure Island Citizens Reuse Committee.

In the short run, she said, the dikes and levees could be strengthened to protect perhaps half the island. In the longer run, she said, when more money becomes available and the will is there, the rest could be shored up.

What isn't protected, she said, could be converted to parkland or other recreational uses that don't require buildings . . . .

During the Loma Prieta earthquake, the dikes and levees - a series of boulders and rocks intended to keep the Bay out and the landfill from drifting away - sustained significant damage.

Treasure Island, which had been slowly eroding even without the earth shaking, fell between 6 inches and 2 feet closer to sea level in 1989, depending on the location, Root said.

https://www.sfgate.com/news/article/...ay-3139267.php

One assumes quite a bit of bolstering is being done as part of the construction now ongoing. I watched the Navy build a new medical clinic after 1989 and they "densified" the soil with tons and tons of rock. The new construction must involve pilings and bolstering the island perimeter. But Mother Nature has a way of winning these fights.