Determining sound foundations for offshore wind

The contract will see Soil Mechanics carry out a detailed ground investigation for the proposed wind farm, which will have up to 30 turbines capable of a peak output of up to 90 Mega Watts of electricity. Once operational the turbines will be able to generate green electricity for approximately 60,000 homes. The over water investigation will take ten weeks to complete.

The project will encompass a variety of drilling challenges involving combined cable tool and rotary core boreholes to between 40 to 50m using high quality Geobore S coring.

This will be followed by in-situ high pressure dilatometer monitoring of load-displacements to determine the strength and stiffness properties of the soils and rocks. Down-hole geophysical logging will also be undertaken using acoustic televiewers to scan the borehole walls and detect fractures for evaluation.

In addition to sample acquisition, the project will include 30 Cone Penetration Tests (CPTs) up to 20m deep. These tests will be used to interpret the ground conditions, and measure the resistance and strength of the seabed.

Regional estimator John Stephenson said, ‘We will utilise the jack-up platform ‘Haven Seaway’. With its 34m legs in place, and operating continuously with day and night shift crews, work is well underway on the 15 borehole site, one and a half kilometres out to sea. Constant monitoring of the sea condition and the reliable forecasting of weather fronts five days ahead will help us meet our in the field deadline on programme. Specific health and safety requirements have also been carefully considered with all members of the Soil Mechanics team having completed an offshore survival course prior to work commencement.’

Teesside Offshore Wind’s technical manager Gareth Lewis added, ‘This work forms part of a series of investigations and monitoring to finalise the foundation design and take the project forward towards construction with a view to commissioning the wind farm around 2011. The information Soil Mechanics will provide is crucial to understanding the ground properties and the bearing it can have on this whole process.’