In-Situ Stabilisation- Tullymurdoch Wind Farm

Tullymurdoch Wind Farm consists of seven new turbines 18,150m2 of tracks 7,700m2 of crane pads and turning heads and 9000m3 of cut and fill.

The ground investigation report showed the conditions at Tullymurdoch would be very challenging across the site due to high moisture content.  It was decided the most efficient way to complete the project would be to use a dedicated in house soil stabilisation team.  Cambrian have invested heavily in the most modern soil stabilisation equipment available not only for use on wind farms but across a wide variety of engineering projects.

Stabilisation can be beneficial in many situations such as planning conditions, reducing construction traffic, environmental benefits or for locations that don’t have readily available stone for construction.  Soil stabilisation can reduce construction traffic movements to site and on site by up to 78%, it can also reduce construction time.

Due to the high moisture content across the Tullymurdoch site none of the material in its natural state was suitable for use as fill material for the construction of crane pads or roads the material on average had a natural CBR value of 1.2%.

By adding, in most cases a small percentage, of lime for fill and lime and cement for capping layers most site sourced materials can be used for construction avoiding the need to dig out and replace with expensive imported stone.  The introduction of Lime causes an exothermic reaction with the moisture in the soils evaporating the moisture almost instantly.

On the Tullymurdoch project the design stated a 2 layer system of Stabilisation 350mm layer of lime improved sub grade and 300mm of lime and cement capping.  Once the cement has been added and compaction reached we then over laid the stabilisation with 150mm of stone.  It was thought because of the ground conditions the minimum thickness of stone required to construct would have been 800mm-1.2m plus geo textile.  In total, based on the lower 800mm assumption, that would have been 50,688tn of imported stone 2,816 truck movements to site.

Because of the use of stabilisation we reduced the thickness of stone to 150mm a total of 9,504tn and 528 truck movements to site.  Including the powder required for the stabilisation this amounted to 56 truck movements to site.

In total 584 movements to site saving 2,232 movements through the local village and surrounding areas.