HCC repairs water supply tunnel ahead of schedule
Hindustan Construction Company (HCC) has today completed the repair and restoration of the damaged Malad water supply tunnel well ahead of its scheduled date of completion of the project. With this, the drinking water supply to the western suburbs of Mumbai can be restored to normalcy in the coming days.
The Brihanmumbai Corporation (BMC) had urgently sought ingenious technical solutions from a variety of experts in the field and finally awarded this complex and hazardous project to HCC on 20th April 2010. Planned as a 55 day project, the repair of the Malad water supply tunnel has been completed in 30 days, with work undertaken round the clock.
This has not only helped restore the much sought normal water supply to Mumbaikars but also prevented the further loss of 5 million litres/day (equivalent to about 500 tankers of potable water everyday).
The tunnel was damaged due to an illegal bore well construction in the Liberty Garden area in Malad, about two months back which had disrupted the supply of drinking water being supplied to Malad and its surrounding areas.
Speaking on the occasion, Vinayak Deshpande, President and COO, Hindustan Construction Company, said, "The challenge here was to conceptualize and plan the most appropriate methodology of the task entrusted to HCC in order to restore the damaged tunnel to its original condition.
We deployed overseas technicians and even imported critical sophisticated equipment and materials to provide world-class engineering rescue operations for completing this job. With the perfect amalgamation of latest German technology, Belgium technicians and experienced HCC engineers we could complete this challenging task way ahead of schedule. It shall be our continuous endeavor to give world class, performing infrastructure to people, with international quality and ahead of schedule."
Since the damaged water supply tunnel is about 80 meters below the ground, it was not possible to assess the extent of damage nor conduct repair work from above ground level. Even though water supply had been stopped to the effected portion but the water which had gushed out was seeping back in the tunnel and was a threat to the foundations of near by high raise buildings.
Professional trained divers had to be deployed and lowered into the tunnel to assess the extent of the damage and the expected working conditions that would prevail while conducting the underground repair activities. This enabled the team to identify the safety measures that would be required to ensure the safety of our engineers.
Technical experts from Belgium were also brought in to engage with the HCC think tank in order to meticulously plan the methodology required to carry out the task and adhere to the project deadline.
The repair work was carried out by accessing both ends of the bore well shaft that damaged the tunnel. This entire shaft was filled with special sealing material using a sophisticated chemical injection system brought from Germany and Belgium.
The damaged tunnel area was then accessed from a shaft located in the BMC premises around 700 meters away. HCC had taken extra precautions for the safety of their engineers by deploying life sustaining arrangements inside the tunnel area which included fire fighting systems, proper ventilation systems, emergency oxygen supply systems, special lighting and a custom built trolley to carry heavy equipment inside the tunnel.
Oxygen levels were monitored on a continuous basis for the entire duration of the underground work that was carried out. HCC’s tunneling experience is well known in the industry and the company has tackled the toughest terrain, ranging from the geologically complex Himalayas to the soft soil of West Bengal.
The total length of tunneling work executed by HCC is over 160 kms with projects ranging from water supply, irrigation, sewerage, transportation and power generation. HCC has unrivalled expertise in large dia tunneling works where precision of work and quality of concrete used are vital factors. Few of the major land mark projects involving complex tunneling commissioned by HCC are:
• Tala HEPP(Hydro Electric Power Project): With HRT(Head Race Tunnel) of 6.80m diameter, 7,110 m long and modified horseshoe section
• Nathpa Jhankri HEPP: The longest tunnel in India with a span of 11.332 km long circular concrete lined HRT of 10.15m finished diameter
• Chamera HEPP: Used New Austrian Tunneling Method for the tunnel
• Yamuna HEPP: First major underground powerhouse built in the Himalayan region
• IIIA Water Supply Project: Two full face rock Tunnel Boring Machine’s were used in the boring of 3.60m diameter wide 12km long tunnel
• Ghatkopar High level Tunnel: A 2.74km long sewage tunnel with finished diameter of 2.5m, construction using shield Tunnel Boring Machine’s and lined with precast concrete segments.