"Stream" of mud suddenly erupts in the middle of a residential area in Hanoi's inner city

(NLDO)- Authorities believe that mud and soil overflowing from drainage manholes in Hanoi is due to the construction of the underground section of urban railway No. 3, Nhon - Hanoi station section.

On the evening of February 20, a representative of the People's Committee of Ba Dinh District (Hanoi) said that at around 3:00 p.m. the same day, a mixture of bentonite solution from exploratory boreholes appeared on the road surface and drainage ditches in lane 7 Giang Van Minh (Kim Ma Ward, Ba Dinh District). This is an area within the underground section of urban railway line No. 3, the Nhon - Hanoi Railway Station section, which is under construction.

Mud sprays from the drains. Photo: Trung Nguyen

According to records, at around 6:30 p.m., a lot of mud and dirt overflowed from the drainage manholes. Dozens of employees, contractor workers, machinery, and sludge suction trucks were mobilized to fix the problem.

Authorities initially determined that the cause was due to pressure when the underground drilling machine from station S9 to station S10 of urban railway line No. 3 drilled through this area.

A representative of Ba Dinh district said that immediately after discovering the incident, the district assigned relevant units to coordinate with the investor (Hanoi Urban Railway Management Board - MRB) to urgently inspect and fix the problem. The investor mobilized 4 vacuum cleaners and 100 workers to focus on checking and cleaning the environment to ensure environmental hygiene and people's daily life.

According to the representative of the People's Committee of Ba Dinh district, the bad phenomena that may affect underground drilling construction have also been warned to the people by the district and the investor since 2024. The district and ward have mobilized people to temporarily reside during the construction period.

Mud sprayed in many places in the alley. Photo: Trung Nguyen

According to information from MRB, during the excavation process with the TBM1 excavator, a phenomenon of tunneling additives spraying onto the ground surface occurred in the area of ​​lane 7 Giang Van Minh. After inspection, the investor MRB, together with the consultant and contractor, inspected the site and initially determined that the cause could be due to the existence of old wells or drainage pipes underground that created a path for the tunneling additives to flow to the ground surface (these old wells and drainage pipes are no longer in use).

According to the project process, before the tunnel construction, the consultant and contractor conducted a survey of the works along the route. However, due to the change of ownership of the works over time, many information were not fully provided, so it was inevitable that there was still a lack of data on underground works such as water wells, residential wells, or geological survey boreholes from previous projects that were not filled.

Vehicles and workers were mobilized to handle the incident. Photo: Trung Nguyen

During the drilling process, tunneling additives are sprayed under pressure to stabilize the soil in front of the excavation face. When encountering open holes such as water wells or boreholes, the tunneling additives will flow up to the ground surface through these voids.

MRB said the phenomenon only occurred for a short time and ended immediately after the TBM drilled through and installed the tunnel lining. This is a common phenomenon during the construction of urban tunneling projects.

Immediately after discovering the incident, the investor directed the consultant and contractor to urgently mobilize equipment and human resources to fix it according to the project's process, including cleaning the drilled mortar and cleaning the surface of the grouted area, ensuring safety and environmental hygiene in its original state.

Urban railway project No. 3, Nhon - Hanoi station section is 12.5 km long, with 8 elevated stations and 4 underground stations. Of which, the elevated section Nhon - Cau Giay is 8.5 km long (in commercial operation), the underground section Cau Giay - Hanoi station is 4 km long.

The project started in 2009 and was scheduled to be completed in 2015, but the schedule was delayed many times and is expected to be completed in 2027.

Source: https://nld.com.vn/suoi-bun-dat-bat-ngo-phun-trao-giua-khu-dan-cu-noi-do-ha-noi-196250220194303731.htm