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

Posted at 4:34 PM, May 21, 2018
and last updated 2018-07-05 14:55:25-04

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.

Reporting by Connor McCauley for MTN News

MISSOULA – Authorities say they’re temporarily modifying their flood evacuation order along the Clark Fork River to allow homeowners access to their property.

Affected residents can return to their homes and will not need to check in and out at roadblocks. However, homeowners are still being told not to re-inhabit their property or start recovery efforts.

Although the river is now seeing lower water levels, authorities stress that the flooding emergency is not over and river levels are expected to rise again within the next several days.

Residents should not plan to stay in their homes overnight and should stay alert of any changes to ensure safety. Road patrols are still assigned to the affected flood area and roadblocks will be re-established as conditions warrant.

Approximately 65 homes in Missoula County are still under evacuation orders.

Meanwhile, the Missoula City-County Public Health will provide a free immunization clinic from 1 p.m. to 4 p.m. on Wednesday for all residents affected by flooding and volunteers who have helped with flood-relief efforts. The location of the mobile clinic will be announced in the near future, according to a news release.

Authorities say that water levels on the Clark Fork River above Missoula continue to see a downward trend, with current levels dipping into minor flood stage for the first time since the morning of May 7.

Current forecasts predict levels will start to rise Monday and Tuesday, with the river reaching moderate flood stage again Tuesday evening. The river is currently predicted to crest at 12.05 feet around midnight on Saturday.

Although the Clark Fork River is not currently predicted to reach major flood stage this week, authorities are stressing that conditions can change quickly and that snowpack levels still remain high. Several homes in the evacuation area still have high water.

East of Missoula, the US Army Corps. of Engineers is continuing to work in the Turah area to make a repair to the Turah levee, which was experiencing some erosion. Heavy equipment will be working in the area and repairs are expected to take at least a week.

Utility companies are also in the area as there are several buried and overhead utilities near the levee.

The Clark Fork River from the Reserve Street Bridge to Kona Bridge remains closed until further notice, due to dangers caused by downed power lines in the river and high water levels full of hazardous debris. The closure applies to all water-based recreation, including, but not limited to: wading, swimming, fishing, floating, boating.

A flood information line at (406) 258-INFO is still being staffed from 9 a.m. to 1:30 p.m. Callers will hear an updated recording after hours. All residents in flooded areas are being urged to sign up for Smart 911 alerts to receive emergency notifications.

Reporting by Mark Thorsell for MTN News

A modified evacuation order remains in effect for the following areas:

  • Tower Street, north of 3rd Street
  • Kehrwald Drive
  • Channel Drive
  • Nancy Lou Drive
  • Keck Street and Stone Street – north of Flamingo Drive
  • Schmidt Road
  • Off Mullan Road
  • South Harpers Bridge Road
  • Hamel Road
  • Under the Reserve Street Bridge

Road Closures:

  • Tower Street closed to all traffic, north of 3rd Street
  • Nancy Lou Drive closed to all traffic
  • Stone Street north of Flamingo Drive closed to all traffic
  • Schmidt Road closed to all traffic
  • Harpers Bridge Road closed to all traffic
  • Hamel Road closed to all traffic
  • Short Street (and connectors) open to local traffic only
  • Preston Street (and connectors) open to local traffic only
  • Hiberta Street north of 3rd Street open to local traffic only
  • Stonybrook Drive open to local traffic only
  • River Road west of Reserve open to local traffic only