Grouting at Barrows finishedDensit has finished the grouting of transition pieces to monopile foundations at the Barrow Offshore Wind Farm in the East Irish Sea. With the grouting of foundations at Barrow more than 200 or 70% of all offshore wind turbines are installed on a durable and cost-effective Ducorit® grout connection between monopile and transition piece.

Barrow Offshore Wind Farm is located in the East Irish Sea and comprises 30 3MW wind turbines installed on a monopile foundation.

The foundation concept consists of a 4.75 m monopile driven into the seabed. With a 6.7 m overlap a transition piece with boat landing, ladders and a platform to allow future maintenance access to the turbine are slid over the monopile. The annulus in the overlap is grouted with Ducorit® S5. On top of the transition piece a 75 m tall tower is later installed.

The Ducorit® grout is mixed and pumped through flexible hoses from a jack-up positioned close to the monopile into the annulus between monopile and transition piece. The installation, adjustment and grouting of each transition piece to monopile lasts less than two hours.

Requirements for the Ducorit® grouted connections are, as for

the remaining structure strict due to the extreme and fatigue loading governed by the dominant moment loading. The unique high performance Ducorit® grout fulfils all strict requirements.

Besides being a cost-effective way of connecting transition piece to monopile, the unique properties of Ducorit® grout supplies other advantages:• The method allows for pile installation tolerances in the grouted connection, ensuring tower verticality• Installation efficiency is im- proved because attachments as platform, ice cone, boat landing and so on can be part of or pre- installed on the transition piece• Structural strength - 130 MPa and stiffness properties 55 Gpa• Outstanding fatigue strength proven through scale test made at the University of Aalborg• Fast strength development

Offshore Newsletter No. 6 February 2006

Ducorit®

grout solutions

Information about recent projects: www.densit.com

Order for grout services atBurbo BankMT Højgaard has awarded Densit an order to grout the annuli between transition piece and monopile of the 25 wind turbines at Burbo Bank.

Burbo Offshore Wind Farm is thus the ninth offshore wind farm that use the efficient, durable and cost-effective Ducorit® grout solution for connecting transition piece to monopile.

The foundations, delivered by MT Højgaard consist of a monopile driven into the seabed. After pile installation, transition pieces will be grouted in place by using high strength Ducorit® grout.

The installation of the foundations is expected to start in May 2006 and will be carried out from a large jack-up rig. The wind turbines will be delivered by Siemens Wind Power and the wind farm will be taken into operation in September 2007.

Previously Densit has worked with MT Højgaard at the offshore wind farms, Horns Rev and Kentish Flats.

Horns Rev