International Dredging Review

International Dredging Review

Prof. Jan de Koning died suddenly in Amsterdam on April 12 at the age of 78. He had retired on September 29 1993 after a 42-year dredging career that included developing important dredging techniques obtaining 29 patents for dredging equipment and guiding many dredging students in his role as professor of Dredging Technology at Delft University.

He remained active in his profession during his retirement despite his aim of “being a spectator” instead of a participant.

Prof. de Koning is survived by his wife Attie three sons and 11 grandchildren all living in Amsterdam.

He was born on October 25 1924 in Medemblik the Netherlands to a dredging family and began working on dredges at age 16. He received his technical degree in engineering from Haarlem Technical College in 1944 during the occupation of Holland by German forces. He would have been required to go to Germany to work and evaded this by hiding in his father’s dredge sleeping in a hammock in the engine room until the Allies liberated the country in October 1944. He had gone back to school to pursue further studies but the university was closed when the Allied forces came and Jan and his brother worked for them repairing bridges and other structures.

He enrolled as a student at Delft University of Technology when it reopened in 1945 and he stayed until 1951 earning his Master of Science in Civil Engineering. At that time he joined Amsterdam Ballast Dredging Company (now Ballast HAM) and began a soil improvement job on the Amsterdam-Utrecht Highway a job that included dredging. He began studying sedimentation and the movement of soil through pipelines and in 1952 was offered a job as manager of the dredging project at Calcutta a fantastic opportunity for a young engineer he recalled. But a medical checkup revealed that his health would not permit him to continue in the field as a practical engineer.

“So I became a theoretical engineer” he told IDR at his retirement.

When the dikes in the south of Holland broke in the disaster of February 1 1953 the young de Koning was sent into the field to supervise the repair in one area. He was put down by helicopter on a water-surrounded dike and began organizing the closing of six holes in the dike using sandbags.

He explained that he calculated the area of each hole and the number of sandbags it would take to fill each one. He had all the sandbags assembled on the dike at once and then instructed the workers to quickly place them into the breach which kept the water from overtopping the repair project in progress. He stayed in the area until 1955 in charge of the St. Philipsburg reclamation project helping to repair roads and other infrastructure before returning to Amsterdam Ballast and his research activities.

One of his first problems was to find a way to dredge a sand supply lake deeper than 30 meters which was the limit to the depth a hydraulic dredge could dig at that time. After six months he thought up the submerged pump which allowed dredging to 50 meters deep. This was put into practice in March 1960 resulting in more production using less power — a three-fold increase in efficiency. Since then the submerged pump has become a standard hydraulic dredging method throughout the world.

Another significant achievement was design of the Constant Tonnage Loading System (CTS) for trailing suction hopper dredges.

Until 1970 hopper dredges were built according to the density of settled sand in the hopper – 2000 kg per cubic meter – to bring them to full draft. This constant volume system decides the net carrying capacity. However if silt is being dredged – 1200 kg per cubic meter – the hopper can be filled to capacity without nearly the volume of material.

Prof. de Koning suggested building dredges with larger hoppers whose draft could then be regulated depending on the density of the material being dredged. He presented this theory in a paper entitled Constant Tonnage Loading System of Trailing Suction Hopper Dredgers published in the proceedings of the International Course on Modern Dredging held in June 1977 in The Hague. The first dredge to use this concept was the Humber River now the Vasco de Gama owned by Jan de Nul of Belgium

When Great Lakes Dredge & Dock Company formed North American Trailing Company and began building their Manhattan Island class of dredges in the late 1970s Prof. de Koning worked with them on the design to include the CTS. He also formed a design partnership with Penta-Ocean Construction in Japan.

During his career at Amsterdam Ballast 29 patents were issued in his name. He was especially involved in offshore dredging and swell-compensated cutter suction dredges.

In 1978 after 26 years with Amsterdam Ballast he accepted an offer from Delft University to become professor of Dredging Technology in their Mechanical Engineering and Marine Technology department where he began “the best 16 years of my life training two generations of engineers.”

“We will never forget Jan de Koning with his white blazing hair who was one of the important personalities in dredging of the 20th century” said Dr. Sape Miedema Associate Professor of Dredging & Delft University and the first person to win a Ph.D. in dredging which he did under Prof. de Koning in 1987.

The Chair of Dredging Technology was founded in 1922. Jan de Koning was the third full professor appointed to this chair after Prof. Van Wijngaarden and Prof. Bos.

His main achievement was to teach designing dredging equipment based on research into the dredging processes. From 1977 until 1993 about 80 students graduated with their master of science degrees and two with their Ph.D. degrees: Dr. Miedema and Vaclav Matousek.

“Most of them still work in the dredging industry” said Dr. Miedema.

In Prof. de Koning’s years at the Delft University research was carried out into the cutting of sand clay and rock into the dynamic behavior of dredges under offshore conditions and into hydraulic transport. In the mid 1980’s he established a new laboratory partly financed by the Dutch dredging industry.

“Due to his many international contacts with the industry institutes and governments students could carry out realistic assignments and join him on the famous foreign field trips to Egypt the United States Singapore Indonesia India and China” said Dr. Miedema. “Jan de Koning believed in managing a dredging company from practical experience. Many students would tell him they wanted to manage a dredging company after graduation. He would point to the corner of his office and say ‘there are a pair of boots use them first before you want to be a manager’” he recalls.

Although Jan de Koning lived a quiet life after he retired he stayed involved with the research at the university. He was a member of the Ph.D. committee scheduled for July 3 that would review Marco den Burger’s dissertation entitled “Mixture forming processes in dredge cutterheads” and talked to Marco the day before he died.

“At his funeral one of his sons told me that he discovered his father had many children his students. He did not only teach dredging but also gave many students wise lessons for their future life and career” said Dr. Miedema.

Prof. de Koning was one of the founding fathers of the World Organization of Dredging Associations (WODA) and was its chairman from 1980 to 1986. He helped found the Central Dredging Association (CEDA) in 1978 and was its first president serving from 1978 to November 1990.

During his period of office he directed the organization on its path to promote the exchange of knowledge in all fields concerned with dredging to bring together members of the dredging profession to exchange views and to strengthen the image of the profession.

“We are all very grateful to Prof. de Koning for his devotion to the aims of CEDA and for his enthusiastic service of the association” said Dr. Anna Csiti general manager and Dipl. Ing. Rewert Wurpts president of CEDA in a joint statement announcing Prof. de Koning’s death.

Prof. de Koning was also involved in the creation of the Eastern Dredging Association (EADA) the dredging association that completed the world-wide embrace of WODA.