UP will handle this - probably just going to require a lot of monitoring / tactical response for a while, maybe years. And unless the mudpot decides to stop and park under the corridor (it's definitely under the weight distribution triangle already), pace it's going it will be on the other side of the tracks before too long.

Good news is it's surface feature / has a tell-tale. It could always become a giant sinkhole, but hasn't exhibited that flavor as yet. That's probably the most dangerous factor - how great of a squishy area it becomes. But also possible this is the first of a series of propagations from a somewhat static source.

More puzzling issue with UP is the dedication they've shown to keeping the Cascade line as an step-investment worthy / critical route in their system. Finance dept. must like the route, seems every few years it will provide an unscheduled challenge to the new generation of Omaha RR engineers..