Latest News – DredgDikes

Melioration Engineers visit the DredgDikes research dike

Stefan — Fri, 08 Jul 2016 10:30:50 +0000

A visit of the Rostock DredgDikes research dike was orgainised on Saturday, 4 June 2016. A group of 25 melioration engineers (former students of Melioration Engineering at the University of Rostock) used their 40th seminar group anniversary meeting to visit the research dike. There was great interest in the investigations and the alternative dike construction materials with good discussions on the topic. The DredgDikes consortium would be happy to host interested groups to further discuss the issue of dredged material in dike construction.

A group of Melioration Engineers on excursion at the DredgDikes research dikes

Obituary: Prof. Zbigniew Sikora

Stefan — Wed, 03 Jun 2015 09:07:09 +0000

On 12 May 2015 Prof. Dr. hab. inz. Zbigniew Sikora, the Polish DredgDikes partner, a world-famous geotechnical engineer, one of the most important geotechnicians in Poland and a good friend to the project partners passed away after a serious illness. He was laid to rest on 16 May on the comunal cemetary in Kosakowo. We mourn a respectful person and share the sorrow with his family and friends.

DredgDikes final workshop

Stefan — Tue, 16 Dec 2014 09:34:16 +0000

DredgDikes Final Workshop Audience

On December 8, 2014 the final DredgDikes workshop took place in the Steigenberger Hotel Sonne in Rostock. The meeting combined the final official meetings of the steering and monitoring group and a workshop for future project cooperations on EU level.
Prof. Saathoff welcomed all participants in Rostock, followed by four presentations about the project results from Rostock and Gdansk.
Then Dr. Cantré led a discussion about the DredgDikes guideline, to which the participants contributed with many helpful comments.
In the afternoon, Mr. Graage and Dr. Hiller (Steinbeis Team Nordost) spoke about future EU funding possibilities for topics associated with the DredgDikes project, followed by a group workshop in which two main project ideas were developed for application in an EU funding programme.
The meeting was summarised by Prof. Saathoff and Prof. Sikora and the intensive work of the project partners as well as all contributions by associated organisations and contractors were very much appreciated.
The day was concluded with a joint visit of the Rostock Christmas market.

Final sampling and investigation of soil chemical parameters at the German DredgDikes test and pilot dikes and vegetation development

Partner5 — Mon, 13 Oct 2014 09:32:19 +0000

In September 2014 the final investigation for chemical soil analyses at the German test dike and pilot dike were carried out. The samples will be analysed till October and the results should show the risk potential through the applicated dredged material and changes in the contents through application, weather conditions and repeated filling and infiltration (test dike). The samples will be investigated in great extent of heavy metals and organic contaminants as well as basis parameters like pH, TOC, lime content and salt and nutrient ions in solid and eluate. The initial investigations of the materials showed already very low contents of heavy metals and organic contaminants which are below the classification values of the LAGA M20 which is applicable analogue for the application of dredged material in technical constructions. According to the origin the materials contain high contents of salts and nutrients. First results at heavy metals and organic contaminents show no significant change of the conditions in the dike constructions itself. Only the very washable chloride shows decreasing contents in the eluates.

Figure 1. Sampling at the test dike – many single cut-in points for mixed sample

The initial investigations showed no contamination at the heavy metals or organic contaminants according to the critical values of the LAGA M20 (technical rules of the interstate working group for wastes: requirements for the reuse of mineral wastes, part II, classification values Z1 and Z1.1) and cause no potential risk for the different goods. Heavy metals and organic contaminants are chemical bounded, stable and badly leachable under the conditions in the ripened material from the IAA Rostock. The materials show higher salinity and organic matter content than traditionally used materials for dike construction founded by the origin in brackish water bodies.

Figure 2. Installed tipping counter and leachate sampling

A discharge of heavy metals from the leachate could not be detected at the beginning of the investigation. A second investigation after the filling experiments (dredged materials saturated with brackish water) in September 2013 showed increasing contents of zinc and mercury in comparison with the first period January 2013 but still below the critical values. The contents of the nutrients phosphor and nitrogen – which are seen critical for the water environment – are generally at a very low level. On contrary there are a great amount of salt ions (chloride, sulfate and sodium) as well as potassium and magnesium which will be discharged from the material. All these elements are relatively easily soluble and there available contents are above the need of the plants so that the oversupply underlies the leaching.

Figure 3. Development of the conductivity in the leachate depending on filling experiments (blue area – range of brackish filling water)

As expected the result so far show the need for the monitoring of the salt and nutrient ions if dredged material shall be applied. The heavy metals play no great role at the potential leaching. Beneath this topic there exist potential risks of dislocation of solid matter at injury of the vegetation cover which can enable the eroding water the transport of soil particles. For dike constructions with dredged material the knowledge of the construction site, the composition of the dredged material and potential affected goods is important. Consequently dike of dredged material from brackish sediments should build near the coast line so that discharging salty water can go directly with the recipient in the Baltic Sea.

The monitoring of the vegetation development shows that within one year at all different deedged materials a good turf will establish. After some difficulties at the beginning during the germination, necessary re-sowing and increasing growth of weeds (confined with mowing) a thick and green vegetation cover was developed. Also in the second year after seeding the vegetation cover is close and green. Bare areas are closed within this period. All togheter a good cover ratio could reached. After the filling experiments a new turf could established with a certain regenaration period whereat the formation of species is changing and more weeds were discovered.

Figure 4. Test dike in Oktober 2014

In Körkwitz the pilot dike shows now in Oktober a good and green vegetation cover. In the beginning of August a first cut and removing of rests were necessary because of the increasing growth of weeds. So there are still some bare areas where the weed stood very dense.

Figure 5. Pilot dike at the Körkwitzer Bach in Oktober 2014

The investigated soil layers at the compaction testing fileds showed in both materials (M1 and M2) a good and relatively dense rooting in the fisrt 20 cm. Also in deeper layers the networked root systeme reached within two years after seeding. The investigation of the root density at the test dike showed also the networked root systeme in the first determined cm and a high root density over these soil horizons.

Figure 6. Rooted layer of 60 cm at the compaction testing field

Figure 7. Networked root system with geosythetic product

Shrinkage and swelling, frost and animal activities as well as rooting stimulate the aggregation of soil. At first these processes occures in the upper cm of the soil but alter they proceed in the depth and also effect a increasing permeability.

Dissemination of the project issues at the 8. dredging seminar in Rostock

Partner5 — Mon, 13 Oct 2014 09:07:26 +0000

The dredged material seminar which took place in Rostock, 24 to 25 September 2014 was again a great success. This conference is an established event and is organized by the Steinbeis Transfer Centre of Applied Landscape Planning under the auspices of the technical committee on dredged material of the HTG (German Port Technology Association) and the University of Rostock. The conference addresses scientists, authorities and industries and brings together the different scientific fields to develop the German dredged material management efficiently and sustainably.

The lectures cover the most recent research and development in the field of dredging in Germany, however, brainstorming and discussion of the different aspects of the dredged material management are equally important aims of the seminar. This year over 100 participants mostly from Germany were also informed about the application of dredged material in dike construction with lectures from Rostock, with the latest news from the EU project DredgDikes.

Impressions from the dredging seminar in Rostock in September 2014

DredgDikes Tasks in Denmark Completed

Stefan — Thu, 02 Oct 2014 09:21:02 +0000

During the 3rd Mini-Call of the South Baltic Programme the DredgDikes project successfully applied for additional funding to perform investigations in Denmark. The marine investigations company Orbicon from Roskilde was contracted to take samples from six locations in the Danish Zealand region. The samples were then analysed in the geotechnical laboratory at the Chair of Geotechnics and Coastal Engineering, University of Rostock as well as a geochemical laboratory in Rostock.

The contractor also prepared a comprehensive study about the legal framework and actual possibilities for the use of dredged materials in dike constructions in Denmark and evaluated the results of the sediment analysis in accordance to the Danish regulations.

The report of the study is available in the download section of this website.

Overflowing tests on the Polish DredgDikes research dike

Stefan — Tue, 30 Sep 2014 12:01:18 +0000

In the first week of September 2014 joint forces of Gdansk University of Technology and Rostock University performed one-week of overtopping experiments at the Polish DredgDikes research dike. We have studied the erosion process on a substantially different dike construction, compared to the German research dike, made from sand-ash composite soil. The results of the experiment are being processed now in Rostock and will be carefully studied with respect to stability and erosion resistance. In the meantime the team at GUT continue numerical modelling of flooding scenarios and to make contributions to the “Best Practices Gudeline”.

Overflowing tests on the Polish DredgDikes research dike

For the overflowing tests, the 60cm flume system was used again. The maximum specific discharge was 500 l/(s*m). The experiments showed that the grass cover, which was applied using pre-vegetated grass sods placed on top of the clay and Tefra slopes, had not clung into the subsoil sufficiently. Thus, during a discharge of more than 200 l/(s*m) the top soil and vegetation was destroyed.

The bare clay cover showed erosion after a discharge of 50 l/(s*m) for 10 minutes, while the sand ash mixture performed better, showing only little erosion after 40 minutes of overflowing with discharges up to 200 l/(s‘m). Thus, it can be assumed that after a destroyed grass cover, the sand ash composite would still be stable for some time, however, a good vegetation cover is generally more effective.

For a durable vegetation cover, however, a solution other than pre-vegetated grass sods will have to be used.

Flume experiments on the Polish DredgDikes research dike

Crack detection on the German DredgDikes research dike

Stefan — Wed, 03 Sep 2014 06:26:23 +0000

In the week of 1 to 5 September 2014 Dr. Zielinski from Gdansk, who has been working at the Strathclyde University in Glasgow until recently and being a well-known specialist for geophysical methods to detect cracks in embankments, is performing 3D electical resistivity tomography (ERT) measurements on the German DredgDikes research dike. With this method existing cracks in the cover layer as well as the moisture distribution in the whole dike cross-section is made visible in three dimensions. A selection of images shows the actual measurements. The results will be presented on this website as soon as the data will be evaluated. The DredgDikes project would like to thank Dr. Zielinski for his voluntary research work on the research dike.

ERT crack detection at the Rostock DredgDikes research dike

ERT electrodes installed on the dike crest at the DredgDikes research dike

Additional DredgDikes Installation Testing Field

Stefan — Tue, 02 Sep 2014 09:03:18 +0000

Based on the experience from the research and pilot dikes regarding inhomogeneities of the dreged materials, the quality control using the degree of compaction is difficult. Particularly the high variation of local water contents in the installed materials are problematic. Therefore, an additional installation testing field was prepared in Rostock.

In the installation tests two different materials were installed (a fine-grained and a sandy dredged material). The materials were homogenised using a screening bucket fixed to an excavator. For comparison, also non-homogenised material was installed. Compaction was realised with the excavator shovel, the excavator tracks (replacement for the bulldozer), a small compactor and a large sheep‘s foot roller compactor.

The tests are now being evaluated in the frame of a master‘s thesis. The results will be available on the project website by the end of 2014.

DredgDikes Installation Testing Field

DredgDikes Installation Testing Field – Compaction

DredgDikes Installation Test – Homogenisation

South Baltic Conference on New Technologies and Recent Developments in Flood Protection – A Great Success

Remigiusz — Thu, 12 Jun 2014 06:14:33 +0000

The South Baltic Conference on New Technologies and Recent Developments in Flood Protection which took place in Gdansk, 5-6 June 2014 was a great success. 145 participants from 7 European countries took part to discuss the interesting presentations.

Particular emphasis have been put on the application of the new materials (including anthropogenic ones) and improved geo-engineering technologies for increased efficiency of dikes and other flood protection structures. Other important aspects presented during the conference were modelling and monitoring technologies as well as legal and administrative issues related to the flood protection and mitigation. The warm and sunny weather allowed the presentation of experiment on the Gdansk research dike.

The conference was officially opened by
Prof. Józef E. Sienkiewicz, Vice-Rector for Scientific Research of Gdansk Univeristy of Technology,
Czesław Elzanowski, Pomorskie Voivodship,
Prof. Fokke Saathoff, DredgDikes project leader,
Prof. Zbigniew Sikora, coordinator of the polish part of DredgDikes project.

The opening lecture titled “Stability And Defence Of Flood Protection Dykes” was presented by Prof. Heinz Brandl – from Vienna University of Technology.
The conference sessions were opened by Prof. Ivan Vaníček from Czech Technical University in Prague with lecture titled “Earth Structures As Main Anti-flood Protection Systems”.

The conference proceedings are available for download HERE.

The organising team would like to thank all speakers, participants and helpers to make the conference such a successful event!

Prof. Saathoff and Prof. Sikora

Prof. Dembicki, Prof. Brandl, Prof. Vaníček

Conference Venue

Visit on test dike