Calcutta’s Victorian-age sewer rehabilitation dissected

Recently, Dr. Ayanangshu Dey PhD CEng FICE and ICE Calcutta (Kolkata) representative presented two lectures on the restoration of Calcutta’s Victorian-age sewers.

Calcutta’s Sewer Rehabilitation.
Calcutta’s Sewer Rehabilitation.

Calcutta's Victorian brick sewer system was developed during the golden age of brick sewer construction in the mid-19th century, at the same time as Sir Joseph Bazalgette's development for London's sewerage system. The basic sewerage and drainage system was probably the first of its kind in Asia. It has served for more than a century before starting to show signs of distress such as structural failures, collapses and extreme siltation – culminating in water logging problems.

In 2007 the Kolkata Municipal Corporation (KMC) embarked on an ambitious project to rehabilitate, its oldest section, more than 130 years old. Dr Dey explained the long-term issues addressed in the project: retention of discharge capacities of sewers, regaining their structural integrity, reduction in water logging, protection against corrosion, future cleaning and maintenance, and socio-environmental aspects.

Adoption of trenchless technology made execution of such a logistically complex sewer rehabilitation works possible in one of the most heavily congested urban areas in the world, he said. The project cost c. £32m (Aus$ 55m) with the sewers re-commissioned in 2011 – one of the most successful brick-sewer rehabilitation projects using glass-reinforced plastic (GRP) 'slip-lining' technology in the world.

Talks were attended by practising engineers affiliated to Engineers Australia and ICE members, among others. They were organised by Engineers Australia's Sydney Division, ICE Australia's NSW Local Association (at Chatswood) and ICE Australia's Queensland Local Association, Brisbane.