May 6, 2021
(online seminar)

What shall we do with the dredged sediment?
International experiences and good practices for the disposal and utilisation of sludge at large shallow lakes

As the continuation of the online seminar on sediment dredging experiences and practices at large shallow lakes (organised in March 16, 2021), the Lake Balaton Development Coordination Agency, Hungary, organized an other online event in May 6, 2021.

In shallow lakes, sediments play an extremely important role in the nutrient cycling. As a result of high external loads of nutrients in the past, sediments became storages of such substances. Removal of the most active, most polluted surface sediment layer (10-30 cm) by thin layer dredging is a common technique in water quality/eutrophication control. In addition to overall water quality improvement of a shallow lake, dredging may contribute to providing better quality and utility value for beaches and small-boat harbours.

In the previous seminar, we reviewed the scientific background of sediment dredging in shallow lakes, and the experiences at Lake Balaton and good dredging practices from abroad. This time, we focused on the disposal and utilisation of removed sediment. In the seminar, firstly we briefly introduced the current situation at Lake Balaton and, as an international outlook, the current situation at Laguna de Bay in the Philippines. Then we reviewed the concerns and questions about the disposal of sediment, and introduced some alternative solutions and technologies available for the utilisation of sediment based on international experiences. In addition, we aimed to analyse whether dredging can provide a permanent solution for keeping good water quality in long-term.

The seminar was organized on ZOOM platform.


9.00 – 9.30Joining to the online seminar
9.30 – 10.00Welcome Remarks and setting the scene: What is our present knowledge? – Summary of the previous seminar and the case of Lake Balaton
Dr. Gábor Molnár, Managing Director, Lake Balaton Development Coordination Agency (LBDCA)
10.00 – 10.20To dredge or not to dredge? International outlook: Introducing the current situation at Laguna de Bay (the Philippines)
Adelina C. Santos-Borja, Vice Chairperson of the Scientific Committee of the International Lake Environment Committee Foundation (ILEC) and Chairperson of the Southeast Asian Limnological Network (SEALNet)
10.20 – 10.40What to do with the sediment? Concerns and solutions of sediment (re-)use at freshwater lakes
Polite Laboyrie, Witteveen+Bos, the Netherlands, representing the Central Dredging Association (CEDA)
10.40 – 11.00
Alternatives of sediment disposal – Technologies and practical solutions based on international experiences
Harri Uusi-Rauva, Vice President of Sales, Watermaster Aquamec Ltd.
11.00 – 11.20Does dredging provide a permanent solution? – Examples of how to increase the probability of keeping good water quality in long term
Dr. Martine Kox, Deltares, the Netherlands, representing the Central Dredging Association (CEDA)
11.20 – 11.50
11.50 – 12.00Closing Remarks

The language of the event was Hungarian and English, with simultaneous interpretation.