Inflow Remediation – Vakola Marochi Tunnel, Mumbai, India

Mumbai, India,
2009 to 2010

Mumbai, India

Heavy inflow of water was occurring in an 11.850 km long tunnel being constructed 40 metres below grade by Hindustan Construction Co. Ltd. through a water bearing rock formation.

In order to pour the concrete liner under severe flow conditions, (3,500 litres/minute in the worst sector), a complex system with liners, sleeve pipes and drainage pipes was first installed to channel the inflow.  It facilitated the pouring of a high quality concrete without it being washed out.  After the concrete gained adequate strength, the diversion pipes and sleeve pipes were grouted to ensure a perfect contact between the rock and the formation.  The stable, balanced cement based grout also penetrated the rock formation surrounding the tunnel.

In the cold joint between the sections of tunnel, injectable tubes were attached which were subsequently acid washed and grouted with a water reactive, flexible, polyurethane grout.

ECO’s role as the grouting engineer and designer was to:

  • Prepare the design and Method Statement to facilitate the installation of the concrete liner, under extreme flow conditions without wash-out of the concrete.
  • Design all the grouting systems and grout formulations
  • Provide hands-on training of the Contractor’s Staff on-site