The river-training works for the Padma Multipurpose Bridge project are scheduled to be completed by August this year, according to official sources.
Of the $2.9 billion allocated for the entire project, $1.1 billion was designated for the river training component - demonstrating the massive scale of these works.
Experts have described the training work as one of the most challenging river training endeavours in the world, thanks to the Padma's reputation as a highly turbulent and unpredictable waterway.
"The river training area is located on both sides of the river, upstream and downstream of the main bridge," Ren Hao, a key engineer at Sinohydro Corporation, a subsidiary of PowerChina, told The Financial Express.
"The training area on the north bank is about 1.5 kilometres long, while the south bank section is about 11.5 kilometres."
Sinohydro began work on the river training project on December 31, 2014.
"The project represents the largest ongoing river training works in the world," said Han Kun, deputy country head of Sinohydro. "The main construction activities were completed on August 6, 2023. Currently, we are conducting maintenance operations, with the entire project scheduled for finalisation by August this year."
The key components of the river training works include dredging and backfilling, earthwork embankment construction and underwater and onshore bank protection, he added.
"The project involved dredging and backfilling around 100 million cubic metres of trench," Mr Hao said. "Over 21 million geobags were used for underwater bottom and slope protection, along with roughly 13 million CC blocks placed underwater and above water."
About the challenges of the work, Ren Hao said, "The soil is predominantly made up of silts and silty fine sands with a fineness modulus of 0.1mm. It also has a high mica content, uneven quality across different strata and low overall strength. Besides, it is easily scoured, has poor slope stability and carries a more than 50 per cent chance of landslides."
He said the dredging design was complex. "The design specifications outlined in the contract demand a tolerance standard of ±0.25 metres, with some areas even stricter at ±0.15 meters. This requires exceptionally high precision."
"Therefore, it was necessary to invest in large-scale dredging equipment. The combination of high-precision construction requirements for powerful equipment like large reamers and mud pumps, coupled with the unstable soil, posed risks of landslides and collapses," Mr Hao elaborated on the challenges.
To address the challenges, the company employed four J series dredgers, which are among the strongest classes available.
mirmostafiz@yahoo.com