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Seoul gov't to establish new monitoring system in response to sinkhole incidents

Published: 23 Apr. 2025, 17:05 Updated: 23 Apr. 2025, 18:12

A large sinkhole in Gangdong District, eastern Seoul, on March 24 [YONHAP]

The Seoul Metropolitan Government will deploy a new underground monitoring system capable of detecting ground subsidence up to 20 meters (65.6 feet) below the surface in response to a series of recent sinkhole incidents.

The new system, aimed at strengthening preventive measures, addresses the limitations of current ground penetrating radar (GPR) technology, which can only scan about 2 meters deep. The city also plans to double its annual budget for sewer maintenance, increasing it from 200 billion won ($140.4 million) to 400 billion won.

City officials announced the new underground space management plan on Wednesday, a comprehensive strategy designed to prevent both small-scale subsidence and major ground collapses near excavation sites.

At the heart of the plan is the installation of a new "ground subsidence monitoring network" at key construction sites. The system uses pillar-type sensors embedded into the ground to monitor changes in soil movement caused by subsidence, extending as deep as 20 meters.

Seoul is the first local government in Korea to implement this technology. The first installation will be at a site on Subway Line No. 9 in Myeongil-dong, Gangdong District, eastern Seoul, adjacent to the site of a subsidence incident in March.

The city will also accelerate the replacement of water and sewage pipes that are more than 30 years old — a major cause of subsidence. It currently refurbishes about 100 kilometers (62 miles) of sewer lines each year at a cost of 200 billion won. Under the new plan, it aims to double that to 200 kilometers per year with an annual budget of 400 billion won.

Seoul will also expand its use of GPR equipment and personnel for excavation site safety inspections. With an investment of 1.5 billion won, the city will acquire three additional vehicle-mounted GPR systems, increasing its fleet from four to seven units.

A sinkhole in Busan on April 14 [JOONGANG ILBO]

To enhance transparency, the city will release the results of recent GPR safety inspections at five major rail construction sites totaling 49.3 kilometers (30.6 miles), including the Yeongdong-daero underground development project, as well as at 50 additional sites designated by local districts.

Seoul also plans to publish updates on ground subsidence reports from citizens and the city’s corresponding responses. Additionally, it will develop and release a “soil property map” centered on large-scale excavation zones.

Preventive measures are also being stepped up. Safety inspections at excavation and tunnel sites deeper than 10 meters will now be conducted monthly, rather than just once a year. To manage underground spaces more systematically, the city will establish a new department dedicated to underground safety.

Meanwhile, Seoul Mayor Oh Se-hoon visited the Yeongdong-daero development site in Gangnam District on Wednesday to inspect the progress of the project and its safety management protocols.

“Innovative management of underground spaces and construction sites is essential for ensuring citizen safety,” Mayor Oh said. “We will make strategic and comprehensive investments in underground infrastructure such as sewer and water systems to protect the city from sinkholes.”

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.
BY LEE SOO-KI [[email protected]]