Heerema has halted piling works for the Changhua offshore wind farm in Taiwan after installation vessel Aegir suffered a dropfall incident while installing a foundation. The company is currently investigating the cause of the incident.

A dropfall is an incident in which the pile goes into sudden freefall during pile hammering due to layering in the soil. The snap loads following a pile drop can be very high and exposes both personnel and equipment to high risk, says specialist equipment provider Crane Master.

In the case of the Aegir, the crew got away unscathed. ‘There were no injuries as a result of the incident, and no environmental impact has occurred. As far as we are aware, the piling frame and pin pile are not damaged and the hammer has been retrieved and is back on Aegir’s deck,’ Heerema states.

The incident occurred on June 15th. The Aegir had just started its work for the Changhua Windfarm Phase 1 Demonstration project. The vessel has been hired to install the 21 four-legged jacket foundations for the 5.2-megawatt turbines.

The installation takes place 8 kilometres off the coast of Changhua county at a water depth of 18 to 28 metres. According to Heerema, conditions at the site are harsh and the foundations must be able to withstand extreme Taiwanese circumstances such as earthquakes, typhoons and high waves.

If the incident will have further implications for the development of the project is unknown. Heerema stated that work has been temporarily halted to carry out a thorough investigation.

The Changhua offshore wind farm is situated in Taiwanese waters and is a project of the Taiwan Power Company. The EPC-contract was awarded to a consortium of Jan de Nul and Hitachi, which subcontracted the foundation installation to Heerema.

Pile drops

Pile drops are becoming an increasing concern for the offshore industry as energy projects move to harsher locations. For the Japanese offshore wind market, for example, several research projects have been launched to find workable solutions for the new types of soil and frequent earthquakes in the area.

The videos below show what happens in the case of a pile drop.

Picture by Kees Torn.

This article first appeared on Project Cargo Journal, which is another publication of SWZ|Maritime’s publishing partner Promedia.