‘Sinkhole’ actually WWII underground water tank


The Commonwealth Utilities Corp. isn’t ruling out the possibility that the recent 5.8-magnitude earthquake played a role in the sudden collapse of the water tank in Sadog Tasi that was initially thought was a sinkhole. (CONTRIBUTED PHOTO)

What was believed to have been a geological sinkhole at one of the Commonwealth Utilities Corp.’s wastewater plants turned out to be an underground structure that collapsed, according to CUC.

In a brief conversation with CUC executive director Gary Camacho, he said after working with various engineering teams, CUC was able to determine what exactly the “sinkhole” was and it turned out to be an underground water tank dating back to World War II that collapsed.

However, Camacho said now that CUC has a better understanding, CUC isn’t ruling out the possibility that the recent 5.8-magnitude earthquake played a role in the sudden collapse of the water tank.

“We have a better understanding of it now. I would imagine the earthquake played a role in this because the integrity of the structure was fine for a long period of time. I think between deterioration and seismic activity, the combination may have triggered the collapse,” he said.

Meanwhile in an official press release from CUC, the agency contracted engineering teams and had them conduct a preliminary condition assessment using unmanned aerial vehicles (UAVs) which helped determine what the “sinkhole” actually was.

“Yesterday, CUC issued a notification regarding a sinkhole that formed at the Sadog Tasi Wastewater Treatment Plant. Since the initial report, CUC and contracted engineering teams and conducted a preliminary condition assessment using unmanned aerial vehicles (UAVs) and determined that the depression formed at the Sadog Tasi site was not the result of a geological sinkhole, but was caused by the structural collapse of a portion of a World War II-era underground water storage tank,” the press release stated

The metal tank, which sported a concrete roof, was approximately 130 feet in diameter and was filled with 3 million gallons of clear water, CUC stated.

Investigation found that a partial roof collapse occurred near the center of the tank which resulted in soil entering into the underground structure.

“While the cause of the roof failure is still under investigation, it is known that an earthquake impacted the region hours before the collapse,” the press release noted.

CUC has temporarily relocated all impacted staff to alternative operating areas as a result of the incident to ensure their safety and continues to provide uninterrupted power, water and wastewater services to its customers.

“The Sadog Tasi Wastewater Treatment process systems have not been impacted by the event and the facility has maintained uninterrupted operations,” CUC states.

In addition, structural and geotechnical engineering specialists will be conducting additional assessments to develop interim and permanent remediation action plans while ensuring the safety of CUC customers and staff.

“This is a developing situation. Corrections and updates to this event will be issued as new information becomes available,” said CUC.

Kimberly Bautista Esmores | Reporter
Kimberly Bautista Esmores has covered a wide range of news beats, including the community, housing, crime, and more. She now covers sports for the Saipan Tribune. Contact her at kimberly_bautista@saipantribune.com.

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