105 billion embankment in Dong Thap collapsed for the 4th time

Dong Thap After more than three years of use, the embankment protecting the Tien River bank, Binh Thanh market area, Thanh Binh district has been eroded four times, threatening people's lives.

The Tien River bank from Cai Dau Canal to Vam Phong My, about 3 km long, has been seriously eroded for many years, threatening hundreds of households, markets and National Highway 30 - the main artery of Dong Thap. In 2015, the province decided to invest 90 billion VND to build the first 850 m embankment (market area and Cai Dau Canal).

The project was invested by the Department of Agriculture and Rural Development of Dong Thap province and constructed by Nhan Binh Joint Stock Company, and completed after 4 years. However, from the time of construction until the project was put into use, the embankment continuously eroded. In 2019, 40m of the embankment eroded, 9m deep into the bank, causing all reinforced concrete piles and the embankment roof to slide into the river. In the following two years, the embankment eroded twice at the same location, 60m long, causing the embankment foot and top to collapse into the river.

The Tien River embankment collapsed in March 2023. Photo: Ngoc Tai

After three times of embankment collapse, the quality inspection unit determined that it was due to objective factors such as: curved and narrow riverbed, complex flow, weak geology, sand mining. Besides, there were also subjective reasons such as: design documents did not fully assess the unfavorable factors, lack of survey, data collection for embankment design, construction of embankment roof with sandbags did not ensure technical standards (falling not according to design).

Because the embankment is still under warranty, the parties involved, depending on their level of responsibility, must spend money to repair it, a total of about 16 billion VND, with the budget spending an additional 3 billion VND. In addition, the province must pour in an additional 19 billion VND to fill the vortex to limit the impact on the project. However, by mid-March this year, the embankment section of the Tien River embankment project continued to erode 30 meters inside Cai Dau canal.

This time, the Department of Agriculture and Rural Development of Dong Thap province determined that the embankment subsided due to the impact of the bridge construction process (shocks caused by the installation of bridge piers) nearby. The investor requested the removal of the sidewalk at the subsidence location, waiting for the consultant to monitor, then inviting the relevant parties to agree on the handling, with the spirit that the repair costs will be paid by the bridge project.

Tien River embankment (right) aims to protect about 200 households. Photo: Ngoc Tai

While the current state of the old embankment has not been completely repaired, Dong Thap continues to invest in adjacent embankment sections of 2.4 km long with a cost of more than 350 billion VND, bringing the total investment for 3 km of embankment to more than 460 billion VND. Monitoring results in October 2022 showed that at this 3 km riverbank section, there are still 7 vortex holes, tending to move closer to the foot of the embankment.

With the current disadvantages, experts predict that if even one disadvantage arises, such as continued erosion of the riverbed, it will have a major impact, causing overall instability of the project. Therefore, the inspection unit recommends implementing a series of other construction solutions, meaning that it is likely that additional budget will be required to protect the embankment.

The embankment collapsed in early April 2022. Photo: Ngoc Tai

Mr. Vo Thanh Ngoan, Deputy Director of the Department of Agriculture and Rural Development of Dong Thap province, admitted that the embankment protecting the Tien River bank has repeatedly collapsed because initially the calculation of the safety factor had just reached the threshold, aiming to reduce investment costs, without calculating the adverse factors that will impact over a long period of time.

According to him, the current solutions are only temporary. In the long term, it is necessary to consider adjusting the flow by using intermittent counter-pressure platforms, buried under the foot of the embankment to reduce the pressure of the water against the shore.

"Some scientific topics have mentioned the solution of dredging the opposite river bank to clear the flow," said Mr. Ngoan, adding that at the embankment section that frequently erodes, the river narrows to 550 m while the widest section on the Tien River is 1,200 m.

Ngoc Tai

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