Natural Power begins Scottish wind farm investigations

Natural Power has secured contracts from Vattenfall to carry out ground investigations for the 100MW Ourack and 90MW Quantans Hill wind farm developments in Scotland, providing the geological and geotechnical evidence needed before detailed construction decisions are fixed.

The programme combines rotary core borehole drilling, sampling, geological logging, trial excavation, and on-site geotechnical testing. Natural Power will also undertake peatland surveys, electrical resistivity and seismic refraction work, and aerial topographical surveys using semi-autonomous drone technology.

Taken together, those methods will create a connected model of the sites rather than treating each proposed turbine location as an isolated investigation point. Boreholes can establish strata, rock quality, groundwater conditions, and the depth of suitable founding material, while trial excavations provide direct evidence of shallow soils and the behaviour of material likely to be disturbed during earthworks.

Geophysical surveys extend the available information between intrusive investigation locations. Electrical resistivity can help identify variations in moisture and material type, while seismic refraction provides evidence of subsurface layering and rockhead. Drone-derived topography then connects the ground model to gradients, watercourses, proposed access routes, crane hardstandings, cable corridors, and the wider construction layout.

Peat surveys carry particular weight on upland Scottish wind projects because peat depth, condition, and stability can alter foundation design, drainage, track alignment, excavation quantities, and restoration plans. Better information at this stage can reduce unnecessary disturbance and improve the accuracy of peat-management and construction environmental controls.

Ourack is the more advanced of the two developments. The Highland scheme was consented by the Scottish Government’s Energy Consents Unit in March 2025 after its layout was reduced to 17 turbines of up to 180 metres, with an approximate combined capacity of 100MW.

The design has changed substantially since early consultation. An initial 50-turbine concept was reduced as the site boundary, environmental effects, landscape considerations, and consultation responses were assessed, while another turbine was subsequently removed following concerns over visual impact.

The consented layout therefore carries a lengthy design history that the new ground data must translate into buildable foundations, tracks, drainage systems, crane areas, and associated electrical infrastructure. A planning drawing can identify where a turbine should stand; it cannot determine the depth of rock, the volume of unsuitable material, or the conditions that construction traffic will encounter.

Quantans Hill is proposed north-east of Carsphairn in Dumfries and Galloway. Vattenfall’s current project description sets out a 14-turbine development with battery storage and a stated capacity of 90MW, placing the ground investigation within an active planning and engineering programme rather than a speculative site search.

The two projects occupy different locations and have reached different regulatory stages, but many of their delivery risks overlap. Turbine components require abnormal-load access, large cranes need stable and level working areas, and electrical infrastructure must be installed across ground conditions that can change considerably over short distances.

Drainage and watercourse crossings must also function without creating erosion, pollution, or long-term maintenance problems. Small changes to track alignment or excavation depth can alter water movement, peat disturbance, aggregate demand, and the amount of material that has to be removed, stored, or reused.

Ground investigations therefore support temporary works as well as the permanent assets. A completed turbine foundation may perform as designed, yet the haul road used by concrete wagons, cranes, drill crews, and component transporters can still fail if weak ground or groundwater conditions are underestimated during construction.

The findings will also influence quantities and procurement. Rockhead depth affects excavation and concrete volumes, suitable site-won material can reduce imported aggregate, and accurate topography improves cut-and-fill calculations. Each uncertainty removed before tendering gives contractors a firmer basis for pricing plant, programme, haulage, temporary access, drainage, and environmental protection.

Natural Power’s construction and geotechnical teams will manage the work as an integrated package. The company has supported Vattenfall on UK renewable-energy projects for more than 15 years, and the latest appointments extend that relationship across two developments with different designs and consent positions.

For Vattenfall, the immediate output will be survey data, although its commercial value depends on how effectively it changes the design. A better coordinated evidence base can reduce provisional allowances, limit redesign after mobilisation, and identify where specialist foundation, drainage, or access solutions are needed before those requirements become site problems.

The investigations cannot remove geological or environmental risk; Scottish upland construction rarely offers that convenience. They should narrow the range of assumptions carried into detailed design and procurement, allowing the project teams to distinguish genuine constraints from conservative allowances.

That distinction becomes more important as onshore wind schemes adopt larger turbines, heavier components, and more demanding logistics. The towers and blades dominate the visible development, but the ground beneath the tracks, hardstandings, foundations, cables, and substations will determine how efficiently either project can be built.