WorldWide Drilling Resource®

32 MARCH 2020 WorldWide Drilling Resource ® The Right Tool for Core Sampling in Soft Sediments Adapted from Information by Royal Eijkelkamp Before deepening the Ghent-Terneuzen Canal, engineers need to know more about the geology beneath the waters. Belgian drilling company Geosonda recently completed sediment sampling on the canal using a patented sampling system, the AquaLock 70 by Eijkelkamp. The project was carried out from a barge using the SRS ML SmallRotoSonic drill equipped with the unique sampling system. Hans Jacobs, team manager for the com- pany’s drilling department, led the project. “Geosonda is active in soil research for en- vironmental, geotechnical, and archaeology- related projects. During this project, we worked from a barge in Ghent-Zelzate to take sediment samples from the Ghent-Terneuzen Canal. The layer of sand just below the silt layer is very important in this case, because the canal will be deepened to a certain depth. However, before the work can start, the purpose of the material to be removed had to be investigated. In addition, this research helps to determine the correct way to excavate or dredge the riverbed.” When an engineering firm tasked the company with taking 16-foot sediment core samples from the river, Geosonda decided the right tool for this job would be Eijkelkamp’s AquaLock 70 system. This system uses a piston sonic proof sampler. Before drilling, the AquaLock is filled with water, which locks the piston below in the cutting shoe. The AquaLock is vibrated down directly to sampling depth where it takes a long and practically undisturbed sample. The AquaLock stays empty until the piston is unlocked. Lowering push rods through the drill pipe opens the valve on top of the AquaLock, which unlocks the piston, allowing it to move freely and take an undisturbed sample. After sampling, the spring push rod is removed, which causes the valve to close, creating a vacuum which holds the sample during retrieval of the AquaLock sampler. Once retrieved, high-pressure water is applied behind the piston for sample extraction. This system is particularly helpful with continuous sampling as no cas- ing is needed and the blocked piston will displace a collapsed hole. The de- sign of the system provides an enormous advantage when drilling in fine, wet, or even slurrified materials and leads to quality sample recovery. In fact, this system was specifically developed for alluvial deposits and soft sediments. Although these for- mations are pretty easy to drill through, it can be difficult to get high-quality samples from them. This is especially true for hy- drogeology, such as heaving sands, tailings, delta, and maritime formations, etc. Geosonda understood the value of using the AquaLock and its sonic drilling system for this particular project. “Geosonda has several drilling techniques in-house, but sonic delivers the best quality and full recovery in these softer formations time after time. These good quality samples ensure we can make a very accurate description, which is very important for an in-depth study of the water. This allows us to formulate fantastic, detailed descriptions and take high-quality sediment samples,” stated Jacobs. “Looking back at this project, I am very satisfied. We finished faster than we thought, and we worked very effectively with the crew on the pontoon. I expect that we will carry out many more of these kinds of projects in the future, especially in combination with this SRS-ML and the AquaLock in the Eijkelkamp SonicSampDrill. It’s a technique that allows you to make a quick screening and get high-quality samples,” he concluded. AquaLock combines the advantages of the very rapid, smooth, and powerful sonic drilling technique with the advantages of a piston type core sampler. It can be used for continuous sampling or discrete sampling and is available in three different diameters to match the requirements of each project. The barrels are made of stainless steel and contain a valve-operated drive head, internal floating piston, as well as a choice of cutting shoes and ring bits for differing lithologic conditions. Be sure to stop by the Eijkelkamp North America/Fraste booth at CONEXPO-CON/AGG on the festival grounds - F1047 Hans Jacobs C&G C O N S T R U C T I O N D I S C U S S I O N

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