Construction works by Delhi Metro was not only poor in the elevated stretch of high-speed airport Metro express line but also in the underground tunnels.
This was confirmed during the last meeting of ministry of urban development on August 8.
Delhi Metro Rail Corporation (DMRC) has taken moral responsibility for the poor construction in the tunnel.
Last month, heavy seepage in the tunnel of the Airport line's underground section was noticed at several places between New Delhi and Shivaji Stadium stations and also near Aerocity Metro station.
On July 21, Sudhir Krishna, secretary, ministry of urban development, had visited the tunnel and expressed concern over the seepage that could endanger and may cause the earth above the tunnel to cave in.DMRC, which had initially described the seepage as normal and said it had nothing to do with construction works, has finally admitted to faults in the tunnel's waterproofing.
"All attempts are being made to reduce leakages in the tunnel but it would not be possible to achieve 100% results," said Jitendra Tyagi, director (works), DMRC.
A recent survey by New Delhi Municipal Corporation (NDMC) on the damaged stretch also revealed that there is no seepage in the length where the tunnel has been constructed with tunnel boring machine.
In a letter to Krishna on August 1, NDMC chairperson Archna Arora wrote, "Seepage has been observed only where tunnel has been constructed through cut and cover method."
"The seepage in the tunneled portion is not a new development," said an official of Delhi Airport Metro Express Pvt Ltd (DAMEPL), the concessionaire company.