Innovations

Adopting Trenchless Technology for Delhi Trunk Sewers

For many years, the conventional method for construction of sanitary sewers to collect wastewater has been trenching or open-cut excavation. New methods of obtaining geotechnical data and the development of new equipment have resulted in the adoption of innovative trenchless (no-dig) approaches involving earth boring, pipe jacking or micro-tunneling techniques with a minimum or no surface excavation. This new construction method results in social costs being reduced to a nominal amount compared to the open-cut methods. Such technology is being applied to the Delhi Trunk Sewer Programme under YAP-II.

The existing and vital Ring Road trunk sewer in Delhi is suffering from major settlements, leaking joints, ground water infiltration, siltation and structural deterioration. This will be totally rehabilitated adopting trenchless technology construction methods to:

1. Restore the sunken stretches of the sewer and improve the hydraulic gradient.
2. Restore the leaking joints and make them watertight to withstand the high ground water table and arrest the loss of soil supporting the pipe.
3. Enhance the structural capacity of the deteriorated sewer and extend its life span.
4. Protect the sewer from further hydrogen sulphide (H2S) related corrosion attack.
5. Provide abrasion resistance to withstand the sewers from damage due to carryover of silt, debris etc.
6. Improve the overall hydraulic flow in the sewer lines by improving the gradients and reducing frictional resistance.

Also, the new trunk sewer alignments on Bela Road and Wazirabad Road in Delhi pass through congested areas in close proximity to both elevated and underground Delhi Metro ways, buried utilities and busy roads. It has been planned that a major portion of the new sewers will be constructed by microtunnelling, a trenchless technology technique.

On December 14, 2005 a highly successful workshop was held in Delhi involving several internationally renowned participants organized by the Project Management Consultant (PMC) on the subject of “YAP-II and Beyond: A Workshop on Dissemination of Trenchless Technology in India” with the purpose of sharing the information with the experts worldwide on adoption of Trenchless Technology in the YAP-II programme in Delhi.

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