Development of a mobile, multi component Down-The-Hole coring rig for recovery of high quality, long soft sediment cores
Geotechnics, Hydraulic Engineering
Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Physical Geography
Final Report Abstract
The new soft-sediment coring system HIPERCORIG was developed to recover continuously, undisturbed samples of lacustrine sediments from lake bottom and similar environs. It was needed to close the gap between industrial, expensive drilling vs. manually-operated piston coring. HIPERCORIG consists of an innovative combination of hydraulically hammered downthe-hole coring system capable to reach up to 100 m core length in up to 200 m water depths with an established piston corer. The major progress achieved with the device is not only the continuous sampling of undisturbed sediments but also the capability to penetrate hard-layers such as sand, gravel or tephra. The set up can be divided into sinking and buoyant parts consisting of a piston-hammer system, casing pipe and ground plate in the lake, connected via Kevlar ropes to the swimming barge with a coring rig, anchoring system and auxiliary installations. The deployment in the lake is controlled via two underwater cameras. The platform with the drill rig is kept atop the leg site through four anchors, the cables and winches that allows for adjustment according to drift in lakes, estuaries and shallow marine conditions. The complete system consists of modular elements to be shipped in four 20-foot-containers including two zodiacs equipped with outboard motors. The performance was tested and further developed in two tests. The first test in 2018 at Lake Mondsee reviewed the overall functionality. Several new developments completed the system, e.g. a technique has been developed which allows to drill out of the casing. A total of 64 m of core was recovered and is currently being studied at the University of Innsbruck. For the second test in 2019 on Lake Constance the goal was to approve deep water operability. At a depth of 204 m, the ground plate was positioned with the platform anchored vertically at lake surface. After positioning the casing was connected and drowned through moon pool, water column and ground plate, a process that had to be repeated due to various technical problems. The first sediment coring run reached a depth of 24 mblf with the upper 11 m of sediments consisting of Holocene lacustrine clays with increasing intercalations of silt, while late Quaternary glacial sands dominate below 11 mblf. From this depth on it was necessary to clean the casing pipe from sand grains using a specially built tool. Unfortunately, this application caused core loss of about 15 cm at the end of each core run. However, overlapping (double) coring was applied to compensate this loss. In order to achieve overlap the second coring run was begun with an offset of 0.5 m. The second coring ended at a depth of 20.5 mblf. Additionally, three surface cores each of 2 meters length were taken to gain extra material from the uppermost very soft and non-compacted youngest Holocene lake deposits. The drilled core material is currently being analyzed in collaboration with different institutes in Germany and in Switzerland, including Universität Bern, TU Braunschweig, MARUM Bremen, University of Konstanz, Seenforschungsinstitut Langenargen, GFZ Potsdam, IOW Warnemünde. The modular platform system for sediment coring can be set-up within 5 days by a crew of at least 4. It can be assembled as barge with coring rig in a harbor, simple docking station or solid ground shore even in remote areas. A crane service is needed but – should the need arise - the containers could also be unloaded by manpower using the hoisting system of the containers. In any case, the mobilization and demobilization of the four 20 ft containers must be possible to and from the launching site. Because the core material gained cannot be stored on the platform due to lack of storage and cooling capacity such infrastructure is necessary on shore in addition to the support for the platform and crew. The system is now available for the community in Earth and environmental sciences. A call for projects will be published. GESEP Consortium e.V. has accepted the duty to support projects in utilizing this tool and prioritizing operations. Fraunhofer IEG, Institution for Energy Infrastructures and Geothermal Systems, Bochum, will host HIPERCORIG and will be responsible for maintenance and operation. Deutschlandfunk, 17.06.2019: https://www.deutschlandfunk.de/klimaforschung-100-meter-tiefe-bohrung-im-grund-des.676.de.html?dram:article_id=451542 Wissensmagazin “Gut zu wissen”, 13.12.2019: https://www.br.de/nachrichten/wissen/hat-der-klimawandel-spuren-im-boden-hinterlassen,RkYDYtA or: https://www.youtube.com/watch?v=4SB4Me1CNYY
Publications
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2019. Deep Lake Sediment Sampling on Lake Constance using HIPERCORIG. GeoMünster 2019, Annual Meeting DGGV and DMG. Münster, Germany
Harms, U. Raschke, U., Schwalb, A., Wittig, V.
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HIPERCORIG-The new coring tool for sediments in operation. IPA-IAL Joint Meeting, Stockholm, Sweden
Schwalb, A., Wittig, V., Bracke, R., Harms, U., Niederreiter, R.
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2020. Novel piston coring for environmental research tested on Lake Constance. EGU Annual Meeting, Vienna, Austria
Harms, U., Raschke, U., Schwalb, A., Wittig, V.
