Nearly a day after the incident, tunneling slurry from the Nhon – Hanoi Station metro project continues to overflow into Alley 7, Giang Van Minh Street (Ba Dinh District).

On the morning of February 21, dozens of workers and suction trucks were deployed to Alley 7 to clean up the leaked slurry from the underground metro construction.

Speaking with VietNamNet, a representative from the Hanoi Metropolitan Railway Management Board (MRB), the project’s investor, stated that they have decided to reduce the speed of the metro tunneling machine to assess the cause and impact of the incident.

"By slowing down the tunneling machine, the pressure will decrease, preventing further slurry from rising to the surface," the MRB representative explained.

This morning, MRB and metro tunneling experts held a meeting to carefully evaluate the effects of the slurry overflow on the surface.

Residents affected by the incident

Alley 7 on Giang Văn Minh Street is home to more than 30 households. Prior to the incident, 15 households had temporarily relocated, and three households - those most directly affected by the tunnel construction - had already handed over their properties to the investor.

At around 3:00 PM on February 20, residents of Alley 7 noticed large amounts of mud and slurry seeping through storm drains and immediately reported it to local authorities.

The affected area is part of the underground section of Hanoi Metro Line 3, which is currently under construction.

Upon detecting the issue, MRB, in coordination with the Hyundai & Ghella contractor consortium and the supervising consultant, quickly implemented technical measures to manage the situation and ensure safety and environmental hygiene.

By 9:00 PM on February 20, response teams had deployed six suction trucks, two street-cleaning vehicles, and over 100 workers to contain and clean up the overflow.

According to MRB, the slurry may have surfaced due to the presence of old wells or abandoned drainage pipes underground, creating unintended pathways for the tunnel-boring machine’s materials to escape to the surface.

As part of the project’s standard procedures, consultants and contractors had conducted prior surveys along the metro route before beginning tunnel excavation.

Quang Phong