Seoul gov't vows proactive measures to prevent sinkholes

The Seoul Metropolitan Government on Wednesday said it would implement pre-emptive safety measures to prevent sinkholes. The measure came six days after a sinkhole injured two people in Yeonhui-dong in western Seoul, last Thursday.

First responders control the site where a sinkhole appeared in Yeonhui-dong, western Seoul, last Thursday. [YONHAP]

The Seoul Metropolitan Government on Wednesday said it would implement pre-emptive safety measures to prevent sinkholes.

The measure came six days after a sinkhole injured two people after it abruptly swallowed a passing vehicle in Yeonhui-dong, Seodaemun District in western Seoul, last Thursday.

While the cause of the sinkhole has not yet been identified, the city government suggested that the flow of groundwater, subsurface infrastructure such as gas pipes and nearby construction work may have impacted the road subsidence. It noted that the area is a filled-in ground with strong groundwater flow.

The city assessed that soil loss under the road surface might have triggered the pavement deterioration, according to a press release on Wednesday. The city government said it did not find direct evidence substantiating the claim that construction at a nearby rainwater pump station destabilized the soil and caused the sinkhole.

Additional geotechnical surveys and ground drilling will be conducted to identify the exact cause of the sinkhole.

The city also promised a full investigation of all underground infrastructure and equipment in the Yeonhui-dong neighborhood by September and a special inspection of the nearby construction site.

All water, sewage, gas pipes and tubes containing telecommunication wires buried under Seongsan-ro between Yeonhui interchange and Sacheon Bridge will be subject to the safety inspection.

An officer from the Seoul Metropolitan Government conducts an inspection of subsurface stability in central Seoul on Tuesday. [NEWS1]

All water pipes installed 30 years ago or earlier — which account for 3,074 kilometers (1,910 miles) of the total 13,350 kilometers of water pipes in the capital — will be repaired by 2040. Approximately 62.5 kilometers of pipes will be fixed this year.

The city will also use endoscopic cameras to examine sewage pipes 30 years or older. Some 441 kilometers of sewage pipes will reach 30 years in use this year, the city government said.

The Seoul Metropolitan Government will enhance the precision of ground-penetrating radar (GPR) technology, which can detect subsurface voids up to a depth of two meters. The current accuracy ranges between 80 and 90 percent.

The city said it will introduce additional technology to detect symptoms appearing in the deep subsurface to reduce blind spots in the current underground safety monitoring system.

Yoo Chang-soo, Seoul’s second vice mayor for administrative affairs, promised the city would make every effort to provide a safe road environment and asked people to proactively report road inconveniences to the police or Dasan Call Center 120.

BY LEE SOO-JUNG [lee.soojung1@joongang.co.kr]