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The difference in driving speed between conventional hammering and a Vibratory Hammer - Saving significant installation time for OWF Monopiles
Increasing installation efficiency is a key component of LCOE reduction for the offshore wind industry. By reducing the installation time for key components such as Monopiles, significant savings on vessel hire can be made.
The 2018 average installation rate, where the vessel installed both monopiles and transition pieces, is 2.27 Days per Foundation (DpF). When using Vibratory Technology the DpF can drastically been reduced.
These video's were made during a comparison test in Germany and what you see is the actual speed. For the test we used the exact same Monopiles and exact same soil conditions. Besides the installation speed advantage, vibrating technology is less harmful to the sub-sea environment (Marine mammals, fish and other sealife) because of the much lower noise level during installation.
As noise disturbance is getting more attention because of changing regulations and increasing public concern, Dieseko Group invests in solutions that minimize noise pollution. Recently an external expert carried out an independent test to measure underwater sound levels during the dismantling of offshore wind farm Lely.
Four piles having a diameter between 3200 mm and 3700 mm and a length of 26 m long were removed from the seabed by our largest vibratory hammer, the PVE 500M. The hammer creates a centrifugal force of almost 1100 mt at 500 kgm eccentric moment and 1400 rpm. The PVE 500M was not equipped with soundproofing measures, in order to understand the effect of our basic design. The results of the measurements are very promising. The German authorities, by means of the BMU 2013 “Konzept für den Schutz der Schweinswale vor Schallbelastungen bei der Errichtung von Offshore-Windparks in der deutschen Nordsee (Schallschutzkonzept)”, prescribes threshold values of 160 dB re 1μPa²s as a maximum Sound Exposure Level (SEL) and 190 dB re 1μPa as a maximum peak Sound Pressure Level (SPLpeak-peak) both at 750m from the source.
The equivalent values obtained during several tests with Dieseko Group vibrators are 112 – 135 dB re 1μPa²s and 132 – 161 dB re 1μPa, which are substantially lower than the maximum allowed levels at 750m from the source. Therefore, it can be concluded that the application of Dieseko Group’s vibratory hammering techniques do significantly contribute to underwater noise reductions at offshore piling projects.
PVE 500M dismantles wind farm Lely in only 3 hours
The heaviest single PVE vibratory hammer of Dieseko Group successfully dismantled wind farm Lely in the Netherlands. The Nuon Lely offshore wind farm was built in 1992 and had to be dismantled. After 24 years the wind farm was approaching the end of its life cycle and was becoming less profitable.
The dismantling of the wind turbines started in October 2016. The PVE 500M was used to extract the foundation of the wind turbines. Four piles, each 26m long and with a diameter of 3.20 to 3.70m, were removed one by one from the seabed and carried off via pontoons. Because of the enormous centrifugal force of the vibratory hammer, the piles were extracted in only 45 minutes each. The PVE 500M, which is a combination of two 250 kgm carters patented according to our GIANT system, has proven once again to have the power to extract 70 to 80 tons piles without any problems. The PVE 500M is a reliable vibratory hammer which managed to do the job in record time. The project is successfully executed by Hebo Maritiemservice.
During this project the Dieseko Group R&D department carried out several underwater sound tests. The main goal is to gain more insights in sound effects. Results will be shared in a later stage.
Independent tests, carried out by RWE Innogy, Bilfinger Offshore, DONG Energy, EnBW, E.ON and Vattenfall, show that vibratory piling is faster and less noisy, compared to impact hammering. The tests, which are executed with the PVE 500M, show that the vibratory installation method has a major impact on the lateral load-bearing capacity of piles. That’s why Dieseko Group is convincing utilities, contractors and certifying bodies to incorporate vibratory hammer driving as an alternative solution for impact hammer driving. Test results show that our PVE vibratory hammers are a good solution to drive down costs, installing monopoles faster, more cost efficient and with less handling time.
Read the article published by Offshore Wind here. http://www.offshorewind.biz/2015/11/23/vibratory-piling-faster-and-less-noisy-tests-show/