Chittagong port dredging marred by plastic wastes in riverbed

Plastic materials clog the head of a suction pipe of a dredger during dredging of River Karnaphuli. Credit: New Age

Dredging at Karnaphuli River, where the Chittagong seaport is situated, is seriously hampered due to the presence of huge plastic materials, including plastic bottles and polythene bags, in the riverbed.

The ongoing capital dredging work is thus facing massive disruption, which the Chittagong port officials find as a threat to the navigation of large vessels.

Port officials are now maintaining a minimum depth requirement of the port’s main channel through maintenance dredging to keep it navigable.

Chittagong Port Authority’s chief hydrographer, Commander M Arifur Rahman, told DPC the cutter suction dredger failed to cut the wastes and mud in the Karnaphuli River bed because the layer of plastic materials was found in up to 2 to 7 m depth.

He said the contractor has proposed that it will bring a grab hopper dredger to clean the riverbed.

Rahman said before bringing a large grab hopper ship from abroad they are now using mini grab hoppers for dredging a 400-metre area to check whether the technology will work or not.

“Without confirmed proof, we do not want to bring the grab hopper. So, we are examining how it works,” he said.

Loading and unloading of bulk cargoes in a significant part of the Chittagong port jetties have remained suspended due to the low water draft. So, the government dredged a 250-m-wide and 2.5-km-long area and lifted about 4.2 million m3 of sand and wastes about one year ago.

The port authority awarded the $2.85 million dredging work to the Bangladesh Navy, which later appointed China-based E-Engineering to complete the field-level task.

Rahman said due to massive siltation, Chittagong port’s jetty number 1 has gone out of work as vessels cannot reach it due to low draft.

A 400-m jetty was leased out to three local conglomerates for handling their goods but could not be handed over to them as they are non-navigable. The port incurred a huge loss due to this problem, Rahman said.

Replying to a query, he said another 1.5 years may be needed to complete the dredging work. Only 19 percent of the work has been completed within a year period as all work could not be done due to the presence of a thick plastic layer.

The main channel of Chittagong port, the country’s prime seaport, is also facing navigability threats, and officials assume that the presence of plastic wastes also may be found there.

About 92% of seaborne export-import of goods of Bangladesh is being done through Chittagong port. The port handled 3.088 million teu of containers and concluded 2019 registering 6.34 percent growth. At the same time, the port also handled 103 million tonnes of bulk cargoes and saw 7.03 percent growth.