Wind Farm, Roos

Key Information

Owner: Renewable Energy Systems Ltd.
Engineer: N/A
General contractor: Forkers Ltd.
Period of works: September 2012 – November 2012

Project description

Roos wind farm consists of 9no. wind turbines in the East Yorkshire Region. Of the 9 turbine foundations, 5 are located in an area of poor quality marine alluvium soils requiring deep piled foundations to ensure compliance with the strict specification and validation requirements set by client RES and the turbine supplier Vestas.

The associated 5 crane hardstandings (40m x 28m) in the same area required an extensive ground improvement solution. The mobile crane weighed 750t, therefore the stability was critical and needed to be ensured.

Ground conditions

The area is layered with poor quality marine alluvium soils.The soft marine alluvium thickness can vary from 5 to 18m depending on the area.
From top to base, the typical ground is:

  • Stiff clay
  • Soft organic clay
  • Stiff clay
  • Glacial deposits

Solution

The 5 turbine foundations in the area of soft marine alluvium soil have been treated with deep piles, which consisted of 600mm CFA piles from 25 to 30m deep, completed by Westpile.

The 5 adjacent mobile crane hardstanding have been treated with extensive ground improvement, using a Controlled Modulus Columns technique, 320mm diameter, from 5.5 to 21m deep. 3 different CMC rigs have been used, with at least two simultaneously, 2 type Enteco E500 and 1 type Liebherr LB20.

Main Figures

Controlled Modulus Columns

4911 No – Dia 320mm 55,565 lm

2 Permanent rigs.

Vertical Drains

Vibro Menard installed 18,511 vertical drains to an average depth of 7.3m.

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