Representatives of the Hanoi Urban Railway Management Board (MRB) have just discussed with the press about the cause of the incident where tunneling additives were sprayed onto the ground, spilling all over the alley during the construction of the underground section of the Nhon - Hanoi Railway Station metro line.

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On the morning of February 21, mud was still spraying onto the ground in lane 7, Giang Van Minh street. Photo: Quang Phong

The incident occurred on the afternoon of February 20, during the excavation of TBM1, a phenomenon occurred where tunneling additives were sprayed onto the ground. Accordingly, the tunneling additives were sprayed from the drainage box in the area of ​​lane 7 Giang Van Minh, Kim Ma.

Upon receiving the news, the Hanoi Urban Railway Management Board (MRB), the investor, together with consultant Systra, contractor Huyndai - Ghella and local authorities (Kim Ma Ward) were present to inspect the scene to coordinate handling according to the situation, activating the response plan.

Up to now, the parties have determined that one of the causes of the above incident is that underground there are old drilled water wells or old drainage pipes that are no longer in use, creating a path for tunnel drilling additives to flow to the surface.

This person further explained that this phenomenon only occurs for a short time and ends immediately after the TBM drills through and installs the tunnel lining. This is a common phenomenon during the construction of urban tunneling projects using TBMs using Earth Pressure Balancing (EPB) technology.

Regarding the solution, the investor has directed the consultant and contractor to urgently mobilize 6 mud suction trucks, 2 road cleaning trucks and 100 workers to clean up the drilled mortar and clean the surface of the area where the mortar was sprayed; monitor and stay on site to monitor developments, take timely response measures, and ensure safety and environmental sanitation.

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Mr. Sergei Papin, Chief Tunnel Engineer of Systra Consulting (France). Photo: MRB

“The material sprayed onto the ground is a mixture of mud, water and tunneling additives. The tunneling additives are completely harmless, environmentally friendly, meet European standards and have undergone strict project inspection and approval,” said Sergei Papin, Chief Tunneling Engineer at Systra Consulting (France).

Mr. Salvatore La Valle, Head of TBM Engineering Team, shared: “Construction in underground conditions always has many unpredictable risks, especially with the weak geological conditions in Hanoi.

Although the project has conducted thorough surveys along the route and worked specifically with local residents and authorities where the tunnel passes to collect data, in reality there is still incomplete information because household owners have changed and houses have been rebuilt many times.

However, we confirm that the buildings on the tunnel are continuously monitored and are all within safe limits. This phenomenon may continue to occur if underground holes are not detected and thoroughly handled. However, we have developed a response plan for this situation in advance and are making efforts to speed up the handling process to ensure environmental sanitation and people's lives," said Mr. Salvatore La Valle.

Affected people will be compensated.

Sending his apologies for the inconveniences during the construction process, Mr. Nguyen Ba Son, Deputy Head of the Hanoi Urban Railway Management Board, hopes to receive sympathy and cooperation from people in the affected area.

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Mr. Nguyen Ba Son, Deputy Head of Hanoi Urban Railway Management Board. Photo: MRB

Mr. Son also affirmed that the project always puts safety first, has been strictly implementing solutions and measures to ensure safety during construction, complying with the project's technical standards and current legal regulations.

“The Hanoi Urban Railway Management Board has directed the consultant and contractor to continue to survey, assess the causes and propose solutions to minimize the occurrence of similar situations as well as the impact on the people. The project will be responsible for fully compensating for any damages, if any,” said Mr. Son.