Landslide of Lam River embankment through Nam Cuong commune: Need urgent reinforcement

(Baonghean) -Due to the strong landslide speed in the Nam Cuong commune (Nam Dan), the Lam River flow encroached on the village and fields, so in 2012, Nam Dan district started construction of the Nam Cuong embankment project. The project is worth 30 billion VND, 1.83 km long. The project has not been put into use for long but has already experienced landslides at the foot of the embankment and subsidence of rock cages. The total subsidence length is about 70m. If not promptly repaired, the above project is at risk of being completely damaged.

Although it is the dry season, the water level of Lam River is still quite high. Going through Yen Xuan bridge to hamlet 3, hamlet 4 of Nam Cuong commune is the embankment. This construction has been built to block the river water so that the fields of the people here do not lose crops. Mr. Tran Van Nuoi, ​​a veteran in hamlet 3, Nam Cuong led us to the embankment, pointed to the damaged and sunken areas and said: "Every morning I go to exercise here, we know everything about how this project is constructed. The subsidence is estimated at about 70m, some rock cages have fallen into the river. When the embankment collapsed, 2 groups came to inspect, the contractor brought rocks to reinforce. They poured rocks directly onto the subsidence area". Observation: in some places the connection between the rock cages and the embankment no longer exists. A crack of about 30cm appeared, causing the concrete connecting the foot of the embankment and the rock cage to be far apart. According to the design, the revetment is constructed with a concrete frame, divided into cells, and covered with a tarpaulin at the bottom to prevent sand and soil from entering. The outside is made of rubble, and the base of the revetment is poured with 2m of concrete.



Sand mining near the foot of the embankment

Mr. Nguyen Hai in hamlet 3, Nam Cuong commented: "The subsidence is probably due to the strong sand mining in the riverbed. There was a day when the sand suction ship was so thick that the engine was running so loudly that people could not sleep. In recent days, the ships have gradually withdrawn due to tax collection." Looking out at the riverbed, we saw two more ships still sucking sand, heading towards the Yen Xuan bridge sand wharf. It is possible that the sand was sucked from the riverbed too strongly, the riverbed was sagging, so the sand on the banks also flowed along, causing the subsidence. But it could also be due to other reasons.

It is known that the Nam Cuong embankment project is divided into 5 packages. The capital is allocated in small amounts, in 2011 and 2012, only less than 10 billion VND was allocated. To fix the problem, the contractor brought rocks to dump directly on the subsidence area, and moved the rock cages back. But the people here said that this solution was not possible. The old rock cages should have been pulled up, new rock cages put down, and concrete poured over the cracked area. As for dumping rocks on the old rock cages while these rock cages were falling into the river, those rocks were "nothing"!



Lam River embankment section through Nam Cuong is collapsing.

Mr. Tran Van Nuoi, ​​hamlet 3, Nam Cuong said: The embankment should be built in steps to resist the impact of the waves, but making a flat roof like that is not very sustainable. Indeed, while the stone blocks do not have cement, with the impact of the Lam River water in flood season, the boulders can easily fall down.

Mr. Dinh Xuan Que - Vice Chairman of Nam Dan District People's Committee said: "The district has known about this, but in order to handle it, we have to wait for the water to recede before we can find out the cause and find a specific solution. Currently, the water is very high. This project has not been handed over and accepted yet. Regarding the capital, the project has only paid 7 billion VND to the contractor."

The absurd thing is that the Yen Xuan bridge nearby is seriously deteriorating, and this is the North-South railway line, but sand dredgers in this area have been operating non-stop for many years, despite repeated reports in the press. Surely the subsidence of the embankment is partly due to indiscriminate sand dredging that the authorities are helpless to do. The investor and contractor of the project need to promptly inspect and seriously fix the problem.

Chau Lan