Restoring river navigability

Govt to procure hopper, water injecting dredgers

In order to restore river navigability in the country, the government has decided to procure hopper and water-injecting dredgers at a cost of Tk 430 crore. This is for the first time in the country that such dredgers are being procured to restore 24,000 km of waterways on major rivers for the smooth movement of vessels. The state-run Bangladesh Inland Water Transport Authority (BIWTA) has been collecting these dredgers as part of the government's procurement of 35 dredgers, BIWTA sources told The Independent.

State Minister for Shipping Khalid Mahmud Chowdhury said that the Prime Minister has given a directive to take necessary steps to prevent river grabbing and pollution. “We are working in this regard as per the Prime Minister’s directive. Everything will be done to restore the country’s rivers by freeing them of encroachment. So, we have decided to introduce hopper and water- injecting dredgers in the BIWTA’s dredger fleet for the first time in Bangladesh,” he added.

“Experts from Bangladesh University of Engineering and Technology (BUET) have surveyed the rivers and submitted their reports to us. In the meantime, our engineers have also visited dredger-manufacturing countries around the world. So, we will be able to restore the country’s rivers after completion of procurement of these dredgers,” Chowdhury said.

According to the BIWTA chief engineer (dredging), MA Matin, billion tons of silts come from the upstream each year and get deposited in Bangladesh’s river beds, leading to poor navigability during the dry season.

“We have a shortage of necessary dredgers

to restore the country’s rivers. So, the government has given approval to procure two hopper dredgers and two water-injecting dredgers. For this, international tenders will be invited soon,” he said.

The BIWTA official also said that large dredgers are needed during full monsoon. “At least Tk 226 crore will be needed to procure a large hopper dredger with a dredging capacity of 2,000 cubic metres per hour and Tk 150 crore for a small hopper dredger with a dredging capacity of 1,100 cubic metres per hour,” he added.

He further said that Tk 54 crore will be needed to procure two water injecting dredgers.

Meanwhile, the dredging department has already invited international tenders to procure 11 dredgers as part of a project to procure 35 dredgers.

According to experts, a trailing suction hopper dredger (TSHD) is mainly used for dredging loose and soft soils such as sand, gravel, silt, and clay. A pump system sucks up a mixture of sand or soil and water and discharges it in the ‘hopper’ or hold of the vessel. Once fully loaded, the vessel sails to the unloading site.

Water-injection dredging uses water pumps connected to a series of nozzles on a horizontal jet bar. The nozzles inject large volumes of water at low pressure directly onto the sediment build up. When dredging, the operator lowers the boom of a dredge to the bottom of the body of water.

A rotating cutter-bar then uses ‘teeth’ to loosen the settled material, as the submersible pump removes the sediment from the bottom of the waterway. The silt and debris are then transported away for final processing.

 

 

Restoring river navigability

Govt to procure hopper, water injecting dredgers

In order to restore river navigability in the country, the government has decided to procure hopper and water-injecting dredgers at a cost of Tk 430 crore. This is for the first time in the country that such dredgers are being procured to restore 24,000 km of waterways on major rivers for the smooth movement of vessels. The state-run Bangladesh Inland Water Transport Authority (BIWTA) has been collecting these dredgers as part of the governments procurement of 35 dredgers, BIWTA sources told The Independent. State Minister for Shipping Khalid Mahmud Chowdhury said that the Prime Minister has given a directive to take necessary steps to prevent river grabbing and pollution. We are working in this regard as per the Prime Ministers directive. Everything will be done to restore the countrys rivers by freeing them of encroachment. So, we have decided to introduce hopper and water- injecting dredgers in the BIWTAs dredger fleet for the first time in Bangladesh, he added. Experts from Bangladesh University of Engineering and Technology (BUET) have surveyed the rivers and submitted their reports to us. In the meantime, our engineers have also visited dredger-manufacturing countries around the world. So, we will be able to restore the countrys rivers after completion of procurement of these dredgers, Chowdhury said. According to the BIWTA chief engineer (dredging), MA Matin, billion tons of silts come from the upstream each year and get deposited in Bangladeshs river beds, leading to poor navigability during the dry season. We have a shortage of necessary dredgers to restore the countrys rivers. So, the government has given approval to procure two hopper dredgers and two water-injecting dredgers. For this, international tenders will be invited soon, he said. The BIWTA official also said that large dredgers are needed during full monsoon. At least Tk 226 crore will be needed to procure a large hopper dredger with a dredging capacity of 2,000 cubic metres per hour and Tk 150 crore for a small hopper dredger with a dredging capacity of 1,100 cubic metres per hour, he added. He further said that Tk 54 crore will be needed to procure two water injecting dredgers. Meanwhile, the dredging department has already invited international tenders to procure 11 dredgers as part of a project to procure 35 dredgers. According to experts, a trailing suction hopper dredger (TSHD) is mainly used for dredging loose and soft soils such as sand, gravel, silt, and clay. A pump system sucks up a mixture of sand or soil and water and discharges it in the hopper or hold of the vessel. Once fully loaded, the vessel sails to the unloading site. Water-injection dredging uses water pumps connected to a series of nozzles on a horizontal jet bar. The nozzles inject large volumes of water at low pressure directly onto the sediment build up. When dredging, the operator lowers the boom of a dredge to the bottom of the body of water. A rotating cutter-bar then uses teeth to loosen the settled material, as the submersible pump removes the sediment from the bottom of the waterway. The silt and debris are then transported away for final processing.