At approximately 4 p.m. on September 8, a mixture of mud and water surged to the surface during tunnel boring activities with TBM No. 2 at tunnel ring 816, located about 1,224 meters from Station S09 - Kim Ma and 15 meters below ground level.

The incident occurred during construction under Package CP03 of the pilot metro line project from Nhon to Hanoi Station.

“Throughout the tunnel boring process, the project has maintained 24/7 on-site monitoring. When the mud eruption was detected, the project owner, supervision consultants, contractor, and local authorities promptly arrived on-site to coordinate response efforts,” the Hanoi Urban Railway Management Board stated.

The project mobilized 30 personnel, five vacuum trucks, and specialized equipment including sandbags and other materials to contain the affected area. Cleanup and environmental sanitation efforts were immediately initiated, and constant monitoring of TBM operations was maintained.

As of 7:40 p.m. the same day, the mud flow had ceased. However, recovery and remediation efforts are still ongoing.

The board also confirmed that temporary accommodations are being provided for affected households in alley No. 7, Giang Van Minh Street, along with financial support for the business that had to suspend operations.

Lee Young Kyeong, Deputy Project Director and representative of the HGU contractor consortium responsible for Package CP03, publicly apologized to residents for the inconvenience caused by the mud spill.

Preliminary assessments indicate that the incident was due to complex geological conditions in the tunnel area, including loosely compacted fill layers, old unused water wells, and decommissioned drainage pipes that created pathways for mud and water to reach the surface.

According to the project board, technical parameters have since been adjusted to align with actual site conditions and to ensure continued safe construction, under the supervision of both the project owner and consultancy teams.

N. Huyen