Sujo International is a company with a strong team of industry experts operational on many continents, but with its corporate base in The Netherlands. Most dredging activities require well-prepared plans to be able to optimise the execution and thus creating savings on both operational and capital expenses.
We believe we have these strengths in-house with our vast team of industry leaders and we strive, besides a prefect execution of the job, also to capacity building whereby we aim to transfer our knowledge to our clients enabling them to continue long-term projects with an indigenous workforce.
The first major objective of dredging is the recovery from under water material, which has some value or use.
The second main objective of dredging is the creation of deeper water. If the natural depths in an area are increased for the first time the activity is known as ‘capital dredging’, ‘development dredging’ or ‘new works dredging’. With capital dredging the full range of geotechnical materials may be encountered. ‘Soft’ material, such as sand, silt and clay, may well be mixed with much stiffer clays, boulders and in some cases rock. This activity covers the construction of new harbours, ports, basins, canals and waterways.
Deepening below the pre-existing bed levels can result in sediment being moved into the deepened area by the actions of water currents and waves. The siltation then has to be removed to maintain the required depth. This type of dredging is known as ‘maintenance dredging’. In some situations maintenance dredging may be required only once every few years. In others it may be needed two or three times each year. And in others it may be a continuous operation throughout the year.
Dredging for deeper water or greater cross-sectional area may be undertaken for many different reasons. The dredging may be part of a water supply or flood relief project.
Dredgers can be used to construct reservoirs, deepen flood-prone rivers and form irrigation channels. The storage capacity of reservoirs subject to siltation can be maintained by dredging, and hydroelectric power projects can be assisted with their water supplies.
The more common reason for seeking deeper water is to improve navigation. This applies to ships and structures of all types, in the sea, in estuaries and in inland waterways. Navigational dredging is the most common form of dredging activity and is undertaken in ports, harbours and shipping channels throughout the world. In some locations the dredging may be for vessels with deep draughts, such as large oil tankers, bulk carriers and container ships. In others it may be for coasters or inland waterway barges, fishing vessels, naval vessels, ferries or leisure craft. Some of the work may involve increasing the natural depths as ships become larger or new ports are developed. Much navigational dredging is the periodic removal of sediment deposited in the deepened channels. Maintenance dredging is a necessity for almost every navigable waterway and port in the world.
Planning the dredging project requires that the work is seen to be practically and economically feasible. Different site conditions and material types and quantities require different types of dredging equipment. Thus there must be the ability to determine those site conditions which affect the likely production of the dredger and hence the cost and time to project completion. Even such relatively familiar construction activities as surveying, setting-out and measurement present many difficulties when the site is under water and cannot be seen. The problems of horizontal and vertical control require special equipment, techniques and skills. Geotechnical investigation to determine the nature of the material to be dredged becomes very important. Wrong information or an inaccurate assessment can result in important production and project delays - probably at considerable cost. It is not always recognised that the prime objective of a dredging site investigation is to allow the feasibility of dredging and the expected production to be assessed. The more usual indications of bearing capacity or consolidation rate are not of major importance.
Every cubic metre of material dredged has to be relocated. If the objective is to create deeper water and to recover the material, a suitable relocation site has to be identified. This is becoming increasingly difficult. Licences and approvals are required to relocate dredged material. The traditional relocation by offloading in the sea may still be the best practicable environmental option, but other possibilities have to be investigated. Relocation of the material may be complicated by the presence of contaminants. These may require special, and costly, techniques for all phases of the dredging cycle. Maintenance dredging of inland waters presents particular problems for relocating the dredged sediments - Where can the large volumes of sediment be relocated ? The environmental impact of the dredging project may require assessment. The possible effects of the extraction and relocation operations will need to be reviewed as well as the potential impact of the completed works. Approvals and permits are required for dredging projects and it takes time, energy and resources to obtain these.
With vast experience accumulated over decades, the Dutch shipbuilders are the market leaders for the design and manufacture of efficient and integrated dredgers and dredging equipment. The wide range of products supports every dredging need.
Our close cooperation with one of the leading companies, Damen Shipyards gives us huge advantage in optimising our performance
Sujo International believes they can perform any required project with the strong team they have available
As Sujo International is a total solution provider, we also deliver all the auxiliary equipment, such as booster stations, pipelines and instrumentation to optimise the total dredging process. In addition, we can supply dredging support vessels, such as Multi Cats and Shoal busters, Stan Tugs as well as Survey Vessels.
To ensure the continuous and smooth operation of our and our clients’ dredging systems, Sujo International offers repair, maintenance and training both on the job site as well as from dedicated Service Hubs.