Settlement of Water Treatment Plant and Numerous Areas in Community

Observation by John Monville:

The water treatment plant (WTP) foundation is settling as are many areas around town, including utility lines, several manholes, and numerous areas under/around homes. I know that the settling WTP foundation has been looked at previously and that a cooling system has been put into place. I was wondering if a precious deformation benchmark has been established to determine if the settling is continuing and to quantify the amount, if any, of the settlement is continuing.

It looks like there is no project currently in SDS (sanitation deficiency system) to address the settlement at the water treatment plant or its structural integrity. As the new PM for Noatak, I am looking into anything that has been documented in the past and want to make sure that the settlement of the foundation is properly documented moving forward to assist with funding. Other than the “CCH_AR_062011_Climate-Change-in-Noatak.pdf” that was attached do you know of any documentation of the WTP settlement?

Brian Menghini with ANTHC writes:

Thanks for passing this on. It’s been a while since I’ve been to Noatak, and my primary focus was the installation of the lift station. I viisted the WTP in 2017 and 2018. The operator Paul Walton showed me the settling in the WTP and the cracked floor while I was there, but that’s about it. I don’t have anything to add to the report other than what’s been said. I remember that 2 lift stations were rehabilitated. I don’t believe any active cooling was implemented."

Mike Brubaker with ANTHC writes:

We worked with Maniilaq, Northwest Arctic Borough, and Noatak to do a climate change assessment in 2010 (attached). Similar issues were raised at that time, and based on the observation and recent reports from Paul Walton, the problems are continuing. The water plant in 2010 had a foundation crack that was causing stress to pipe fittings (see related post). The source was thought to be thawing soil caused by heated lines and the warmer ambient temperatures in the area. A time lapse video was made of the plant by the water operators to try and see if any changes in the building were visible. The video is available at this link.

The condition with the water plant was described in the 2010 report as follows:

Since 2003, the floor in the northeast corner of the water plant has settled by approximately 4 inches and the water supply/return manifolds have settled between four and six inches. The primary cause of foundation failure appears to be caused by the waste heat supply and return lines. Unless the factors causing the thawing are addressed, settlement of the water plant foundation could ultimately result in failure of the building structure. ANTHC is currently developing measures that will help prevent thawing and will restore the structural integrity of the building.

As a result of the assessment, the Noatak Traditional Council developed a resolution requesting funding to address the foundation problems. These projects and others for the water plant were developed. ANTHC Engineering can provide more background on specific measures, the project, and any benchmarks that may have been created. It should be noted that University of Alaska Fairbanks (UAF) Permafrost Laboratory has been monitoring soil temperatures in Noatak for years. As stated in the 2010 climate change assessment report,

There is one soil temperature gauge in Noatak installed by Dr. Kenji Yoshikawa of UAF. For the period of June 1, 2008, to May 31, 2009, the mean annual ground temperature at a depth of -5.5 meters was 30.182°F. Soil temperatures are projected to increase over the next 30 years, but longer-term monitoring will be necessary to determine specific temperature conditions and trends for Noatak.

Updated data have been requested from the Permafrost Laboratory at UAF. This observation has been shared with tribal and city staff in Noatak, engineering and project management staff at ANTHC, and the Maniilaq Association Environmental Health Department.

Comment by John Warren (12-23-19):

When I was there in 2011, it appeared to me that the thaw issues were associated with the glycol heat add lines entering the building. The thawing/settlement appeared to be the greatest where the waste heat lines entered the building and then radiated out from that location. I drew a contour map of the floor slab that shows this settlement clearly (see document attached). I speculated at the time that heat from the lines might have caused the degradation of the permafrost or that a glycol leak might have occurred at that location sometime in the past. As I recall, they installed an active cooling system on the affected side of the building and then insulated the area in an attempt to stabilize the bank. If the permafrost degradation was caused by a glycol leak, this repair would slow but likely not stop the degradation.

Comment by John Warren: (12-30-19):

The historic information that we have provides data on differential movement of the floor system. I think we need to take some shots inside the building and compare that against the historic record. Differential settlement appears to be the problem of immediate concern. A benchmark will tell us if the whole site is sinking. The well head would probably be the best and most stable benchmark near the WTP. I am sure that we have historic elevation data on both the well and WTP. It would be very interesting to check this. Base elevations are usually set and documented in the as-builts for each structure. We should always be able to check for movement relative to the original construction. I believe that thaw is now accelerating so movement will occur quicker and with greater magnitude as time goes on. This is what I have been observing. The degradation in Quinhagak (for example) started out slowly about 15 years ago but seems to be accelerating as building movement is becoming more pronounced more quickly. I was thinking that we can use an automatic self-leveling laser to monitor for differential movement and level within a building. That should work really well for a plant like Noatak because it is fairly wide open. This is something the operator or RMW could do with a tape measure. It would not be defensible as far as funding requests go, though. A five-year interval for monitoring seems reasonable. I believe the well and the TBM set by the state at the airport in Noatak are probably the only two things in the community that we can rely on as being stable.