Withrow Wind Project

(Douglas County, WA)  Landau Associates conducted the preliminary geotechnical investigation for the Douglas County PUD Withrow Wind Power project. The preliminary design calls for installing 55 1.5- and 2.0-Megawatt wind turbine generators. Construction of new roadways will be necessary to reach the sites where the new turbines will be erected. Due to the size of the project and the limited subsurface information, a preliminary geotechnical study was conducted, to be followed by a design phase. 

We collected subsurface information at the locations of three wind turbines for the preliminary geotechnical study. The subsurface information will be used by the design team to provide recommendations and engineering parameters for a preliminary foundation design and to determine the most cost-effective method of accessing and investigating the remaining sites. Recommendations for mat foundations, including elastic settlement and rebound, uplift anchors, and substation transformer pads were included in the preliminary geotechnical study. We also provided recommendations for a subsurface exploration program for the design phase. The recommended subsurface exploration program will include at least one boring at each wind turbine location, pressure meter testing, suspension logging testing, and a seismic refraction survey.