More than 30% of the sewage pipes buried in Seoul have been in place for over 50 years, as of the 15th. In the past five years, 40% of the sinkhole incidents that occurred domestically were caused by damaged sewage pipes.
According to the 'status of sewage pipes' submitted by Jin Seon-mi, a member of the Democratic Party, as of December 2023, out of 10,866 kilometers of sewage pipes in Seoul, 6,028 kilometers (55.5%) have been in place for over 30 years. Generally, pipes older than 30 years are classified as aging sewage pipes.
Additionally, the ratio of sewage pipes that are over 50 years old is 30.4% (3,300 kilometers).
Among the autonomous districts of Seoul, Jongno District has the highest ratio of aging sewage pipes. The ratio of sewage pipes over 30 years old is 66.3%, while those over 50 years old is 53.5%.
Following this, the areas with a high percentage of sewage pipes buried for over 50 years are Yongsan District (48.5%), Seongbuk District (47.7%), Yeongdeungpo District (45.7%), and Mapo District (45.4%). For pipes over 30 years old, the highest percentages are in Dobong District (66.2%), Yongsan District (65.2%), Yeongdeungpo District (63.6%), and Seocho District (63.2%).
Aging sewage pipes are one of the main causes of sinkholes. Water leaking through holes and cracked seams in old pipes washes away the soil underground, creating spaces where the ground can settle.
According to the Ministry of Land, Infrastructure and Transport, 394 of the 867 sinkhole incidents in the past five years (45.5%) were caused by damage to sewage pipes. This accounted for the largest portion of the causes of sinkholes.
The remaining causes of sinkholes include inadequate compaction (18.0%), poor excavation work (9.8%), damage to other buried objects (7.0%), and damage to water supply pipes (4.8%).
Jin Seon-mi noted, "We cannot leave the safety of the roads that citizens use for commuting to chance," and called for the government and local governments to transparently disclose safety-related information and to quickly establish measures to prevent recurrence, such as the maintenance of sewage pipes.