At 4:00 p.m. on February 20, while drilling the tunnel using a TBM1 excavator, a phenomenon of tunnel excavation assistants sprayed on the ground in the area of lane 7 Giang Van Minh, Kim Ma occurred.
After the inspection, MrB and the consultant and contractor inspected the site, the cause was determined to be that there were still water wells or old drainage culverts underground that had created a path for the tunnel borers to overflow to the ground (these old wells and culverts are no longer in use).
According to Mr. Sergei Papin - Head of the Systra Consulting Tunnel Engineering, the material sprayed on the ground is a mixture of mud, water and tunnel digging additives. In which, tunnel excavation additives are completely harmless, environmentally friendly, meet European standards and have undergone strict inspections and approvals of the Project.
