Measures for Environmental Dredging of Harbor Channel

In the process of implementing the dredging project of port and waterway, the technical operators and relevant departments need to set up the idea and concept of environmental protection strictly, and effectively promote the dredging construction of port and waterway under the guidance of reasonable cost and effective technical operation, so as to make a contribution to environmental protection. At the same time, it has been proved that only by fully following the principle of ecological maintenance can the dredging construction of ports and waterways be effectively promoted, so as to improve the navigation capacity of ports and waterways.

1. Overview of port-channel dredging project under the environmental concept

 1.1 Concept of the port-channel dredging project

The impact and development of harbor navigation dredging projects on the environment should not be underestimated. Therefore, before the implementation of the port-channel dredging project, it is necessary for relevant departments to analyze and predict the port situation in this region, so as to improve the environmental protection thoughts and concepts of all construction personnel, thus effectively strengthen the quality of ecological protection, which is also one of the important principles to promote the construction and development of ports and waterways. The concept of environmental protection is to protect the original state of the undamaged ecological environment and restore the damaged ecological environment as much as possible, so as to protect the local environment effectively. Therefore, environmental protection measures generally need to combine physical measures and chemical measures. But the port waterway dredging engineers should also be aware that in the construction of environmental protection is not once and for all, the environment will change over time, so you should try to promote the balance of the environmental construction and waterway dredging construction, thus effectively realize the unity of social benefit and economic benefit.

 1.2 Analysis of the characteristics of the environmental dredging project

The first is accurate positioning and excavation. Under normal circumstances, pollutants will be deposited in port waters, but their thickness will be thinner, generally between 10 and 50cm, but the maximum is no more than 1m. The scope of excavation depends on the distribution of sediment, and the excavation face should be consistent with the distribution of sediment. In the actual dredging process, we should not only remove the polluting substances in the sediment, but also minimize the development and destruction of non-polluted sediment, so as to effectively avoid the construction and treatment of channel sediment layer at the bottom of the channel, and thus control the cost of sediment mining within an effective range. It can be seen that the positioning accuracy and excavation accuracy of environmental dredging should be controlled within a reasonable range, and much larger than the dredging range of general waterway.

The second is to control secondary pollution. In the course of sediment dredging, the re-suspension of sediment during dredging is usually not considered. At the same time, a small amount of sediment is neglected in the course of sediment transportation without affecting the construction progress and quality. The main reason for this is that the sediment particles will increase greatly in a short time, but after the completion of the project, the suspended solids will be transported out of the construction area very quickly. Therefore, in order to comprehensively promote the quality of the port-channel dredging project, it is necessary to reduce the secondary pollution of sediments. In terms of construction equipment and technology, necessary measures and devices should be installed, so as to effectively reduce the secondary pollution of sediments to the port water body.

Thirdly, it is a safe disposal device for polluted sediments. The technical operators shall properly treat the removed sediments and carry out pollution prevention and recycling to prevent the re-destruction of groundwater and its environment. It should be noted that the discharge site should strictly control the concentration of drainage.

Finally, there should be professional monitoring and defensive measures. Technical operators need to strictly monitor and manage the diffusion range of mud, mud concentration, and suspended particle quantity and backwater concentration, so as to effectively promote the construction quality of the project.

2. Environmental dredging effects in ports and waterways

 2.1 It intensifies the stirring and diffusion of pollutants

One of the most important technical requirements for dredging ports is to clean up the sediment near the ports. The most common method is to dump the sediment into the ocean, greatly increasing the pollution in the ocean. Especially if the construction workers fail to deal with the pollutants in the waterway before the construction, the agitation and diffusion of pollutants in the water will be caused, thus greatly deepening the pollution level of the water. In addition, if there is no effective treatment and transportation of the abandoned soil in the channel dredging project, it will cause serious pollution to the groundwater of the abandoned soil disposal site, thus contaminating the nearby environment and affecting the local residents’ life and transportation development.

 2.2 Damage the aquatic ecological environment

In the dredging process of the harbor channel, the common pollution type is the pollution of water by suspended matter. The specific principle is that inorganic suspended substances mainly increase the turbidity and pollution degree in the water body, and pollute a large number of organisms in the water body by relying on the burial effect after settlement, thereby affecting the reproduction of organisms in the water body and seriously damaging the ecological balance system in the water body. Meanwhile, in the dredging project of the port channel, the concentration and pollution of suspended solids in the water are closely related to the location of the dredging vessel. The closer a boat gets, the higher the concentration of suspended matter in the water, and the lower the light transmittance, which poses a threat to the water ecosystem.

 2.3 Noise pollution and ship pollution

During the dredging project of the harbor channel, a large number of large dredging equipment will be used, which will cause serious noise. In the actual dredging and dredging project, once the dredging vessels make noise, they will also cause pollution to the local ecological environment. At the same time, the docking of dredging vessels will also pose a threat to the ecosystem in the water. In particular, once the leakage of oil and sewage occurs at the bottom of the cabin, the ecological environment around the waterway will be affected, leading to serious qualitative changes in the surrounding waters, thereby reducing the survival rate of organisms. In addition, in the construction process of ships, once sewage discharge occurs, it will also pose a threat to the biological and water quality in the water body, thus reducing the survival rate and reproduction rate of biological.

3. Environmental protection concept of the port-channel dredging measures

 3.1 Design reasonable dredging operation plan

Dredging engineers need to carry out strict analysis and investigation of the pollutants and deposition characteristics at the bottom of the sediment, especially the strict measurement of the total amount of sediment. Before carrying out actual port dredging, the construction personnel should make a full investigation of the local natural conditions and hydrogeology, so as to provide effective information guarantee for further dredging. To ensure the scale of the excavation work arranged, to divide the specific dredging work scope and to formulate reasonable dredging construction methods, so as to promote the maintenance of equipment and develop relevant construction regulations.

 3.2 Determine reasonable times and seasons

As for the creatures at the bottom of the harbor, they need to reduce their activities during the winter, i.e. hibernate, so dredging of the bottom of the harbor dredging should be done during the winter to minimize the risk. At the same time, to avoid the growth period of underwater organisms, the most important thing is to carry out practical construction in winter or in the dry season, without changing the growth cycle and survival rate of underwater organisms.

 3.3 Strengthen control during construction

First, in the dredging and excavation process, the amount of stirred contaminated sediment should be minimized, and the predicted leakage prevention and diffusion measures should be taken to ensure the concentration of water inhalation and prevent the suspension from causing serious pollution to the water. Second, secondary pollution should be prevented in the dredging process. On the premise of not affecting the quality and progress of the construction, the number of fine particles of sediment should be increased in a short time. After the completion of the project, suspended solids will be transported outside the construction area, so as to effectively reduce the pollution of sediments and suspended solids to water bodies and waterways. Meanwhile, the maintenance and supervision of construction equipment should be strengthened to prevent oil leakage from vessels and improve the safety of construction operations. Third, the contaminated sediments should be treated effectively. Reasonable operation techniques should be used to strictly control the concentration of discharged tailwater after they are removed.

 3.4 Scientific treatment of contaminated sediment

First, residual water should be comprehensively treated. Due to the large number of pollutant particles in the dredging process of the channel, suspended particles in the sediment can be effectively removed by intermittent operation and other forms, so as to improve the quality of the residual water. Secondly, promote the reasonable stacking of the construction site, and conduct the sealing and biological stacking and removal of the bottom sediment. According to the volume of the bottom sediment and the water content of suspended objects, the distribution of the bottom sediment is reasonably analyzed and predicted, so as to effectively improve the quality of channel dredging and promote the balanced development of local ecology.

4. Conclusion

To sum up, based on the concept of environmental protection, to improve port waterway dredging engineering quality, you need to improve the environmental awareness of all construction personnel, adopt a scientific and reasonable method to analyze and predict dredging, and formulate an effective method of dredging, sediment, and sediment, and suspended solids are removed, so as to promote the ecological balance of the near the harbor.