Line 9 sinkhole tragedy... ”Strong concern” already four years ago = South Korea

A large sinkhole occurred at an intersection in Myeongil-dong, Gangdong-gu, Seoul, South Korea, and a motorcyclist who fell into the hole was found dead. This accident occurred four years ago.
According to JTBC and The Fact on the 26th, one of the causes of the sinkhole accident was the construction of the subway line 9 extension.
It was confirmed that there were concerns about sinkholes during the previous environmental impact assessment. According to the Seoul Metropolitan Government's Urban Infrastructure Headquarters' "4-stage Environmental Impact Assessment for Urban Railroad Line 9" in June 2021,
Four out of nine members of the Environmental Impact Assessment Council expressed concerns about groundwater leakage and land subsidence. The extension of subway line 9 is being managed by the Seoul Metropolitan Government's Urban Infrastructure Headquarters and is scheduled to be completed in 2023.
It will connect Seoul Gangdong-gu Central Hospital to the Godeok Gangil 1st District. It will have four stations, including one transfer station, and is scheduled to be completed in 2028. The total length will be 4,124 km.
The first section is 1,348 km long, the second section is 1,290 km long, and the third section is 1,486 km long. The first section where the accident occurred is the end point of the Central Patient Hospital.
The Korean Tunnel Society also expressed concerns. In April 2021, when the Line 9 extension work was ordered, the Korean Tunnel Environment Society sent a letter to the city of Seoul.
"Be careful as the route on level 4 is close to the underground tunnel on the Gangdong-gu-Gangdong section of the Sejong Expressway in Seoul." The route on level 4 is where the sinkhole occurred.
The society explained, "During the construction of the underground tunnel for the expressway, subsidence and damage to buildings were discovered at that point," and "the construction of Route 9, which is being carried out on the same route,
"We cannot help but be concerned about the situation," he said. Before work on the Line 9 extension began, the Seoul Metropolitan Government only responded to the association's concerns by saying that it would "take them into consideration."
When the interview began, Seoul City said, "We have told the construction company to reflect the Society's official statement in the design." Seoul City has said that this is just a general assessment of the environmental impact assessment,
The city maintains that no abnormalities were found in the measurements taken during construction. A city official said, "Every environmental impact assessment you look at has something to do with the groundwater level." He added, "There is no way that the groundwater level would have risen that much during the construction process.
"Nothing was found and the ground was reinforced using a multi-stage steel pipe grouting method," he said, explaining, "Measuring instruments installed inside and outside the tunnel also showed no abnormalities."