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Energy

Project Details

Name: Wind Farm Project
Location: West Central Texas

Client Benefits

Through Kleinfelder's practical and economical approach in providing these additional services, it was determined that the existing foundations could be kept without reconstruction or retrofits. The third-party reviewer concurred, saving the client approximately $200,000

Trusted Advisor In Energy

West Central Texas and Kleinfelder are seeing banner years for wind energy. As the world's fastest growing renewable energy source, wind energy is clean, cost-competitive to other fuel resources and the least expensive of renewable energy sources. Although wind is a highly variable resource, it can be readily incorporated into electric utilities. Vast areas with high wind power potential exist in Texas and are being utilized by developers and electric utilities active in the nascent industry. The number of commercially available sites will expand as turbine technology improves and development costs continue to drop.

Kleinfelder was contracted by the design-build contractor of a wind farm project located in West Central Texas to provide geotechnical recommendations for the first 67 wind turbine foundations and an electrical substation of a large 330-megawatt renewable wind energy project that is being developed by AES Corporation in three phases. The geotechnical report included electrical resistivity tests and seismic refraction surveys, as well as corrosion potential for concrete and steel structures.

During construction, Kleinfelder provided materials testing and inspection services. This consisted of full-time inspection of concrete, soils and grout associated with almost every phase of turbine construction.

The foundations for these turbines utilized a proprietary design that includes slurry concrete backfill to bed the foundation within the rock formation. Upon completion of the foundations, Kleinfelder determined that several of the turbines were backfilled with slurry concrete that did not meet strength requirements. As a result, the design-build contractor was faced with reconstructing or retrofitting several turbine foundations. Kleinfelder was then contracted to obtain numerous core samples of the backfill in order to ascertain strength.

Goodman Jack and TEXAM pressuremeter testing equipment were utilized to determine the lateral stiffness of the surrounding soil. With the Goodman Jack and pressuremeter tests data in hand, Kleinfelder provided analysis to determine the most appropriate soil/structure interaction for the foundations in question. Kleinfelder found that the soils/fractured rock had slightly higher lateral stiffness characteristics than originally estimated; therefore, a reduction in the grout strength was allowed. Through Kleinfelder's practical and economical approach in providing these additional services, it was determined that the existing foundations could be kept without reconstruction or retrofits. The third-party reviewer concurred, saving the client approximately $200,000.

After successful completion of services on the first phase of the three-phase project, the design-build contractor contacted Kleinfelder again to provide similar geotechnical recommendations for 155 new wind turbines and an associated substation. More than twice the size of the original project, Kleinfelder faced a logistical challenge due to the very short timeframe allotted for the second phase.

The strong economic conditions of the state of Texas made obtaining contractor drilling services very difficult. Kleinfelder was able to utilize the firm's drill crews from Austin as well as Midland. At one point during this project, there were six drill crews in action. Exacerbating the drilling timeframe were the exceptionally challenging onsite drilling conditions. Drilling the bedded limestone formation was complicated due to numerous issues, such as variable hardness, need for air rotary drilling, remote location of the site, the presence of subsurface voids and the need for specialty core bits. Obstacles were successfully managed with the knowledge and expertise of Kleinfelder's drill crews and field personnel.

This project is a fine example of how a group of inspired engineers and field crews working as a team can find solutions to complex situations and come to the aid of a client. Subsequently, Kleinfelder is considered to be a trusted advisor for more than four wind turbine clients in Texas and is now receiving national recognition as the geotechnical consultant of choice for these types of projects. In the last four years, Kleinfelder has provided services for 13 wind farm facilities in the West Central Texas area.