Hanoi Sewerage and Drainage Co has deployed workers along a 1.95km stretch of the river, targeting around 23,000 cubic metres of sediment. Sludge layers are estimated to be 70-80cm thick.
To avoid peak-hour congestion in densely populated areas, operations run from 8 pm to 3 am. Late on February 24 on Phan Trong Tue Street, a four-tonne suction truck, four seven-tonne tankers and a water tanker operated continuously, while an excavator mounted on a floating platform dredged sludge from the riverbed.
“Safety for workers and road users is our top priority, so we direct traffic from a distance,” said Nguyen Van Pha, 55.
Nguyen Van Minh, an excavator driver with nearly 20 years’ experience, said working heavy machinery in the river demands skill and caution. “You never know what obstacles lie beneath the surface,” he said, adding that rain and strong winds make conditions more hazardous.
Shortly before 11 pm, crews halted operations when a suction hose began shaking violently. After dismantling the pipe, they removed a sack and half a brick lodged inside. Workers said while the machine can draw in stones and hardened sludge, larger debris can block the system.
Vu Van Trinh, an 18-year veteran of the company, said the job carries significant risks. Sharp objects, syringes and construction waste are often concealed beneath the sludge. Despite protective gear, he has previously suffered cuts.
The project uses the C2 dredging method, in which excavators load sludge into containers, suction trucks transfer it to tankers and the waste is transported for treatment. Working three shifts a day, crews remove about 500 cubic metres daily, including roughly 170 cubic metres per night in favourable weather.
Dinh Cong Hoa, deputy director of the company’s mechanical construction unit, said the team aims to complete the work before June 30 to ensure smoother water flow and reduce the risk of urban flooding during the monsoon.
Under floodlights in the early hours of February 25, workers continued despite the stench, driven by what they described as a responsibility to keep the capital’s waterways clear ahead of the coming storms.
