Friday, March 20, 2009

Namma Metro to go underground in July

Namma Metro to go underground in July

Before tunnelling work starts, engineers have to close all open wells and borewells

Aarthi R | TNN

Bangalore: Tunnelling work for Namma Metro Project will start in July. Right now, engineers have to find the right way through ‘restricted zone’ and close all open wells and borewells. Some of these obstacles are bound to come along the tunnel path.
Nearly 70 open wells and 47 borewells — owned by the government, private agencies and residents — were identified along the north-south and east-west corridors in a survey by Torsteel Research Foundation.
The Bangalore Urban district commissioner’s office had notified them in January this year, calling for objections. “The objections we got are now being evaluated. A committee has been formed to look into the matter and decide compensation packages as well,” a Bangalore Metro Rail Corporation (BMRC) spokesperson told TOI.
Tenders for the work on closing these water sources have been called for, and is expected to be finalized by Marchend. The actual work is likely to begin by mid-April.
The structure proposed by BMRC will have two tunnels each — along the north-south (NS) and east-west (EW) metro rail lines. The diameter will be 5.5 metres running for 4 km. The tunnels will be separated by 5 metres with a depth of 12 metres.
Mending borewells and open wells along the tunnel path was recommended to minimize the impact of the ‘Earth Pressure Balance’ tunnel boring machine. The presence of any such water sources may damage the machine or the water itself may be contaminated.
The mines and geology department recommended that a restricted zone around the tunnel be set up. Accordingly, 30 metres on either side of the central line along the tunnel will be out of bounds for building or borewell activities. This is to insulate the tunnel from disturbances.


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