Extremely Simple: How China’s CHEC is Dredging the Yuzhny Port

China Harbor Engineering Company Ltd. (CHEC) has begun dredging work in the waters of the Yuzhny port. What is the specific nature of the dredging process, how many vessels will be involved in it, and why is a suction dredger waiting for work?
Mykola Zasiadko 01 September 2017 23:18

"Filipich, it is clean! We can leave," a sailor shouts to the captain of the Neptune pilot boat during the cleaning of a gangway. Filipich, whose full name is Volodymyr Filippovich, quickly completes the paperwork and starts the engine of the Neptune. "Let's go and see how the Chinese guys work," the captain of the pilot boat said. It is less than a week since China Harbor Engineering Company Ltd. (CHEC) began dredging works, and the Chinese have already become legendary. A man nicknamed Lenia, who speaks Ukrainian rather well, is particularly popular. Unfortunately, we cannot meet Lenia, which only confirms his legendary status.

"The Chinese do not like excessive attention. They are all about work. Therefore, it will not be possible to talk to them," said Olha Humen, a spokesperson for the Yuzhny port authority. Instead of the Chinese Lenia, we were able to talk to Anton Stoian, a leading engineer at the Yuzhny Port Authority’s department of hydraulic structures and capital construction. He was able to discuss the details of the dredging process because he is in charge of technical supervision of construction works, including dredging works, at the Yuzhny Port Authority.

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Localization of dredging

We begin our conversation with the duration of the dredging works. A little confusion about this issue arose recently, when the Ukrainian Seaports Authority said that the dredging works would be completed in March 2018 while CHEC said they would be completed at the end of 2019. "China Harbor Engineering Company is contracted to implement two dredging projects in the Yuzhny port. Under the first contract, the implementation of which has just started, the deadline is March 31, 2018. This contract provides for performance of dredging work in the waters around the port’s ​​berths Nos. 23-25. ​​The second project involves reconstruction of the approach channel and the approaches to the berths Nos. 5 and 6. It should be completed by the end of 2019," Stoian said.

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Next, we visit the sites of the dredging work in the northwestern part of the Adzhalyk estuary, where the berths Nos. 23-25 will be built. An MV Cargo grain terminal will be built next to these berths.

Does the dredging work interfere with the construction of the MV Cargo terminal?

Stoian: No, it does not. Yes, the works are being performed at sites located near each other, but these are different sites and they do not overlap in any way.

CHEC will remove about 4.4 million cubic meters of soil from the bottom of the water during the dredging work at this site. The design depth is 16 meters, but the current depths range from 0.5 to 6 meters.

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The subtleties of dredging

Asked about the "subtleties of the dredging process," Stoian said, "It is extremely simple. A grab with a volume of 27 cubic meters is lowered to the bottom of the water with the help of a pulley system. The grab scoops up some soil, pulls it to the surface, and pours it into a self-propelled or non-self-propelled hopper. The hopper itself – or with the help of a tug – transports the soil to a dumping site located 20 kilometers south of the port basin. A dredger works with three hoppers: while one hopper is being loaded, the second transports soil to the dumping site, and the third waits to be loaded with soil. Independent environmentalists are also constantly working in the port. Once a week, they enter the water basin on a vessel to take soil and water samples from the soil dump and analyze them for compliance with the relevant requirements.

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How is the dredging itself performed? Do they dredge to the desired depth immediately or gradually?

Stoian: The dredger performs dredging moves. Each grab dredger is assigned its own section. In total, three dredgers will be involved in this project. A section with an area of 350,000 square meters is dredged consistently. They first remove 1.5-2 meters of soil and then move to the other sections. When 2 meters of soil has been removed from all the sections, they remove another 2 meters. This process continues until the desired depth is reached,” he said.

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Chinese pioneers

Six vessels are currently involved in the dredging operations in the Yuzhny port’s water basin: one dredger, three hoppers, one tug, and one utility boat. The utility boat transports people, delivers fuel, and performs related work, such as measuring.

These six vessels are the first batch of CHEC’s dredging fleet at the Yuzhny port. Thirteen more vessels will arrive at the port by the end of the summer to join the dredging operations. The number of dredgers will increase to four and the number of hoppers to 11.

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Why is the dredging work being performed with a grab dredger and not a suction dredger?

Stoian: Firstly, the contractor chose this type of equipment. It believes it will perform the work more productively and quickly with a grab dredger. Technically, these works can be performed with a backhoe dredger or a scoop dredger. It will be more difficult to do the work with a suction dredger because the area in which a vessel can maneuver at this site is small. In addition, the soils at the site (loam, tight clay, or silt) belong to the third and fifth categories of dredging complexity. A suction dredger does not handle such types of soil. The Chinese company will use a suction dredger for the project involving the dredging of the approach channel.

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After the dredging

"The Yuzhny Port Authority and China Harbor Engineering will face a difficult period after completion of the dredging works. They have to reach the target depth. Theoretically, they can dig deeper, but they will be paid in accordance with the parameters of the project, i.e. 16 meters. The Chinese contractor is obliged to measure the depth at the end of the work. A third-party contractor will do the same. As the customer, the Yuzhny Port Authority will compare both figures and accept the work if the figures coincide. Separately, the Scientific Research and Design Institute for Maritime Transport (ChernomorNIIproekt) is constantly supervising the work, checking several times a month to ensure that the contractors achieve the target.

“The warranty period for the dredging work is 12 months. Another condition in the dredging contract is that the level of sediment accumulation in the water basin should not exceed 30 centimeters. If it is more than this, then the contractor will have to finance removal of the sediment with its own funds. Accumulation of sediment in the water basin is an irreversible process. It is caused by the constant movement of ships or natural processes in the water basin, as a result of which the bottom of the water basin is contaminated with sand and silt. We will need to perform annual maintenance dredging after the warranty expires," Stoian said.

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Waiting for a new beginning

The Tong Li trailing suction hopper dredger had already arrived at a berth before the Neptune sailed. The Tong Li will soon get involved in the dredging project for "Reconstruction of the Maritime Approach Channel and Inland Water Approaches to the Yuzhny Seaport’s Deep-Water Berths Nos. 5-6," which provides for dredging the approach channel to 21 meters.

"The dredger will start work on the second project in August. It will work on the maritime approach channel. The grab dredger will be deployed when it reaches tight soil," Stoian said. This is a good reason for another visit to the port.

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