Permafrost Thaw and Related Flooding

Observation by Carol Oliver:

There's been a lot of permafrost melt along roads and homes; we hope an engineer from ANTHC can bring a camera up to look at underground lines before winter really sets in. Freeze ups can/maybe affect whole town.

Comments from LEO Editors:

We have received posts from other communities this month about thaw-related impacts, including roads and burial sites in Brevig Mission. A review of long-term weather data from the National Weather Service office in Nome shows that this year has been both the second-warmest and wettest since records began in 1900 (see graph). The combination presents a perfect scenario for thawing. This observation has been shared with engineering and environmental health with Norton Sounds Health Corporation and ANTHC. One important question is whether the thawing has exposed any pipes or resulted in any evidence of water or wastewater system leaks. This would imply that there may be an urgent problem. Any photos that could be provided of the thaw areas would be helpful. Mike Brubaker

Racheal Lee with Norton Sound Health Corporation writes: (10-18-2019)

I talked with our RMW, Luke Smith, about it…no specific information to share about extent of issue though.

Brad Blackstone with ANTHC writes: (11-6-2019)

Jesstin Patterson, an ARUC engineer from ANTHC, was in Golovin today working on a project to install a wastewater line from a home to the main. During the visit, he was able to converse with the local operator about issues in the water/wastewater system due to the permafrost thawing. The operator discussed an incident in which settling had pulled apart a service line from a saddle connecting to the main; the saddle then filled with sand and caused a backup into the home. This issue was taken care of; however, future monitoring of the area for additional issues and settling will be necessary. If funding becomes available, it may be prudent to inspect possible affected service lines with a sewer camera. Full inspection of the gravity main in that section would require digging up the line for visual inspection. The operator did not know of any other water or wastewater issues that have been caused by this settling. A more in-depth analysis of this problem may be necessary if further issues persist.

John Warren with ANTHC writes: (11-6-2019)

When a service saddle is used on a main, it is extremely important to compact the soils under the service saddle before it is installed. If this does not happen properly or if the materials are frozen, a void will form under the saddle due to consolidation of the supporting soils and the weight of soils above the saddle push the saddle down into the void causing the saddle to rotate on the main. This creates a lip at the connection point to the main causing waste to accumulate and eventually plug the service line. During cold weather construction it is impossible to compact the frozen soils. This is the reason we recommend sanitary wyes or tees and do not recommend the use of saddles for new construction in cold climates. In my opinion this is likely a construction issue and not a climate change issue.