There are three general types of foundations used to securely anchor wind turbines to the earth. These are described as: the Tube-Style (P&H), Gravity (mushroom), and Rock-Anchored.

Based on initial geotechnical borings on your project land, our Civil Engineers choose foundation designs that hold fast in strong winds, are low cost to build, and have low construction risk (proprietary).

However, with permit, many borings must be performed in order to determine the composition wind farm's soil, rock, and sub-surface environment. This is necessary for proper construction and to comply with post-permitting regulatory requirements. Final foundation design cannot be determined until these borings and further soil analyses have been completed.

Tube-Style (P&H) Foundation.

The tube-style foundation uses a patented tube design by Patrick and Henderson, Inc., that reduces overall impact and costs. The design requires only an 18-20' diameter, 40' deep hole, which is either excavated or blasted to the required depth. The hole is then lined with two concentric steel tubes; bedrock anchors and steel reinforcing are installed; and electrical and communications lines are brought in. The ring of the "doughnut" is then filled with concrete, and the center back-filled with earth. Pouring a concrete cap on top completes the foundation.

Advance Development Services, Inc. is a licensed contractor and P&H foundations installer. We work closely with the Engineering Office of Patrick and Henderson, Bakersfied, CA, on all phases of the development; starting from soil and geo work, through design, permitting and inspections.

After building access roads and clearing areas for turbine pads, test holes will be drilled around the optimal perimeter for each foundation tube, to confirm foundation type and the depth to bedrock. If soil analysis does not support the P&H foundation, Advanced Development Services, Inc. will choose one of the other two alternatives described on this website. 

Gravity Foundation.

The gravity foundation, shaped like an upside-down mushroom, is designed to be installed in poorly consolidated soils.  The foundation system has the effect of holding the wind turbine upright through sheer weight and leverage.   The design is used widely, but requires the most concrete to build, and thus may not be the most cost effective.

Rock-Anchored Foundation.

If a wind turbine is sited on solid, non-fracturing rock, a series of anchors can be drilled into the base stone and then tied to a foundation cap on the surface. This “rock-anchored” type of foundation is less expensive to build than a gravity foundation, but can only be used where the rock formations are close to the surface and their geological structure will hold anchors securely, over time.