There was a sudden sinkhole on the sidewalk nearby the subway line 1 YeongDae Hospital Station. There have been already three or more ground subsidences since 2016, with a great concern among residents as the exact cause of the sinkhole has not been identified.
On the 20th of last month, 30cm-deep sinkhole was found on the sidewalk between Yeongdae Hospital Station Exit 2 and Youngdae Hospital Crossroad. The citizen who witnessed it said, “I am worried that it might cause safety issues since old people could get hurt as it is nearby the ventilation window”, reporting to Nam-gu office. The Nam-gu office had emergency repairs of the sinkhole, but some broken sidewalk blocks were witnessed all over the 130-meter-long way.
This is where the ground subsidence report has been received continuously for two years. When the first ground subsidence was reported last March 2016, the ward office concluded that the old sewer pipe of the public sauna was a cause and replaced the old sewer pipe. However, the ground subsidence report was followed in the same place this year. The ground subsidence report was received on the 12th of last month, and the report was received again on 20th. Seon-ae Choi (57), who operates a restaurant in the neighborhood said, “I walk on the road every day, and often saw the road fixed. I am greatly concerned that it might cause more accidents as there is a ventilation hole nearby.”
The Nam-gu office has not found the exact cause other than the old sewer. Even though Korea Infrastructure Safety Authority conducted the subsidence safety exploration with penetrating radar (GPR) all over Daegu area last year, it found no other cause than the partial ground subsidence. As a result, the ward office conducted drilling to confirm the exact cause of the subsidence on July 30th of last month.
Nam-gu office Construction Disaster Prevention officials said, “After drilling the ground, the household waste pipes connected to the sewage pipe were in a bad condition and took them out, filling up the spot with the soil. We assume that the ground subsidence occurred due to corrosion from the unused and old sewage pipes.” Young-mok Park, Yeungnam University Construction Engineering Professor, said “Once the underground sewage pipe gets old, the leak can occur and cause ground subsidence due to soil erosion. The exact cause should be clarified if there was any failure of soil stabilization or erosion from the old sewage pipes.”