Missoula levees can show signs of compromise if “dirty” boils found

Posted at 6:18 PM, May 20, 2018
and last updated 2018-05-20 20:18:31-04

MISSOULA – Sandbags and levees have helped keep parts of Missoula County as dry as possible through this flood season.

But something undermining these efforts is the break down of levees through dirty boils — tunnels of water that form through levees and show up as a bubbling hole on the other side.

Water passing through a levee that looks “clean” is fine but if a boil shows dirt or sand moving through it that could be a sign the integrity of the levee is in question.

While you cant just plug the hole in the levee, you can use proper sandbag techniques to stop the flow of material through the levee.

"The sandbag ring levee is intended to raise the water level around the boil to a point where it somewhat equalizes the pressure and then when it has less energy it can’t move the soil particles," Curtis Miller from the Army Corps of Engineers said. 

"You want it to still flow water cause it’s relieving that pressure but you don’t want it to have so much energy it moves soil," he added.

The US Corps of Engineers has examples available to view on their website.