Actually, something else is causing the seals to fail on the bearings and master bearing. The sampling pipe was the original theory but it could not account for the damage being done.
FTFA “Contractors are not entirely sure what’s happening to the seals. They’re letting sand in, which is not good,” said Matt Preedy, deputy Highway 99 administrator for the state Department of Transportation (DOT). “Either you’ve got gaps somewhere, or you’ve got cracks in the seals.”
Basically, our water front soil make up is not ideal. Much of the Seattle water front is fill dirt from various late 19th century and early 20th century projects around Seattle. Much of the path Bertha is taking underground is lined with caissons to keep the liquid dirt at bay.