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Colombo’s crumbling sewers causing road cave-ins
View(s):By Ishu Bandara
Colombo’s ageing underground sewage system has been identified as the main factor behind the recent road collapses and sinkholes in the city.
The two road failures leading into Colombo caused severe traffic jams between Model Farm Road Junction and D.S. Senanayake Junction in Borella on August 20 and 27.
These busy roads are used by thousands of people daily, and diversions through Baseline Road and Cotta Road led to long delays. The collapses disrupted office travel, bus services, and daily activities, showing how easily life in Colombo can be slowed by road failures.
The sinkhole in Borella. Pic by Akila Jayawardene
When the Sunday Times asked about these incidents, Deputy Municipal Commissioner (Engineering Services) A.D.S. Rohana said: “A major factor in the recent collapses is the bursting of old force mains (iron pipes). The rehabilitation of the Borella pumping station introduced larger, more powerful pumps, leading to higher flow through these old lines and causing them to burst. While some pumping stations have been rehabilitated, comprehensive rehabilitation of the entire network of force mains was not included in previous projects due to budget constraints. As a result, old, unrehabilitated pipes are now under increased pressure from upgraded pumping systems.”
He explained: “The sewage system in Colombo, built more than 120 years ago, is now badly deteriorating. At the time, planners understood the need for a strong sewage network and modelled it on advanced systems like London’s, but after independence this vision was neglected. The system uses clay pipes for gravity lines and iron pipes for force mains. Over time, the clay pipes have cracked and leaked due to ground settlement, while the iron pipes often burst under pressure. Recent upgrades to pumping stations, such as installing bigger pumps at Borella, have made the problem worse by pushing more flow into these weak old pipes. Natural disasters over the decades have also further damaged the system, leaving it fragile and unreliable.”
As learned by the Sunday Times, the situation highlights an urgent need to rehabilitate Colombo’s underground infrastructure to prevent further incidents.
In March 2024, a sinkhole appeared on Galle Road near the W.A. Silva Mawatha Junction in Wellawatte, disrupting traffic and underscoring the risks posed by the city’s fragile underground system. Similar to the recent incidents in Borella, these events show that such accidents can happen at any time and in any part of Colombo.
When asked about preventive measures, Deputy Commissioner Rohana said: “Identifying sinkholes before they occur presents a major challenge. While road depressions can sometimes act as warning signs, many collapses happen abruptly. Current SCADA systems can monitor pumping stations but cannot detect underground faults in road lines. More advanced technology, such as the ‘smart ball’ device that travels through pipes to detect weaknesses using acoustic and vibration data, could help. However, its high cost, reliance on imported expertise, and the need for guaranteed repair funding limit its proactive use.”
Deputy Commissioner Rohana said: “The CMC does not collect enough taxes to cover the high costs of repairs and upgrades. Many people who use the city every day are commuters who do not pay local taxes, while many residents live in underserved settlements, contributing minimal revenue.
“Although everyone agrees that the whole system needs rebuilding, finding enough money has always been a big problem. For example, a loan from the Asian Development Bank in 2017 to fix pump stations was delayed by the COVID-19 crisis, and some work had to be finished with local funds. In another case, it took 20 years to get funds to repair a force main in Wellawatte that collapsed in 2004. On top of this, sewage projects often get less attention because they are hidden underground and not as visible to the public.”
According to him, the CMC faces severe financial limitations in undertaking the massive task of overhauling the entire sewerage network. While some support has been received from Asian Development Bank and the Government for specific repairs and pumping station rehabilitation, comprehensive, long-term funding for the entire network is still lacking.
As a result, only “spot repairs” are carried out when failures occur, rather than a full overhaul.
The situation highlights an ageing sewerage system that cannot meet the city’s growing demands. CMC officials stress that only significant investment to modernie the system can prevent further collapses and safeguard Colombo’s residents.
| Work crews avoid safety gear Recent road collapses in Colombo, particularly in the Borella area, on August 20 and 27 between Model Farm Road Junction and D.S. Senanayake Junction, caused severe traffic jams, while also raising concerns about worker safety. The Sunday Times observed that Colombo Municipal Council (CMC) repair crews have already stabilised the affected areas and completed repairs to prevent further damage. However, municipal workers are often seen working without safety gear, such as boots, helmets, or protective suits, despite being exposed to hazardous environments, including waste-filled trenches and unstable roadbeds. When the Sunday Times asked about workers not wearing safety equipment, Deputy Municipal Commissioner (Engineering Services) A.D.S. Rohana said: “Yes, I agree. Most workers involved in repairing these collapsed sections often operate without adequate safety gear. We provide them with boots, helmets, and appropriate protective suits, but they report discomfort in wearing boots in wet conditions. Water seeps into gumboots when working in sewage-filled trenches, making it more difficult to work than without them.” Worker behaviours are difficult to change. Some choose not to wear uniforms. In certain work areas, using specific safety gear can be genuinely challenging. When asked whether workers could use safety suits without separate boots, Mr. Rohana explained: “Yes, we have imported full safety kits, including boots, but sometimes they are too large, and workers avoid wearing them.” According to Mr. Rohana, while measures such as safety belts and gas checks are in place, enforcing the consistent use of personal protective equipment remains challenging, often due to union-related issues and worker preferences. Training workers to use protective gear effectively takes time, he said. Authorities acknowledge that building a culture of safety requires time and emphasise the importance of educating workers. Mr. Rohana said CMC monitors worker health through programmes that include annual medical examinations done by .dedicated teams. Wearing safety kits is crucial because they not only protect workers from injuries and health risks but also reflect the professionalism and dignity of their work. Consistently using safety equipment promotes a culture of safety, reduces accidents, and builds public confidence in essential services, ensuring that development work is carried out responsibly and efficiently. | |
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