Thumb Wind Park

Location: Huron and Sanilac Counties, Michigan
Installed Capacity: 129.6 MW
Construction Cost: $200,000,000+
Year Commissioned:   2012

The Thumb Wind Park project is located within Huron and Sanilac Counties, Michigan. The project is divided into three sites comprised of: McKinley Wind Park, Minden Wind Park, and Siegel Wind Park. The total nameplate capacity of the three sites is 129.6 MW derived from 9 GE 1.6 wind turbine generators (WTGs) constructed and installed at McKinley; 32 GE 1.6 WTGs constructed and installed at Minden; and 40 GE 1.6 WTGs constructed and installed at Siegel.

RRC provided geotechnical engineering, structural engineering, and construction materials testing for all three sites included in the project. The wide geographic spread of the three wind park sites, tight design deadlines, and construction schedule constraints promoted members of RRC’s team to work seamlessly to assure deliverables were submitted on time as well as proactively providing support during construction.

The subsurface soils and bedrock conditions along with variable groundwater conditions were challenging throughout the three sites from a geotechnical engineering perspective. The variability of glacial till deposits, soft unsuitable organic soil deposits encountered within some locations, and variable groundwater conditions were carefully reviewed and analyzed during the design phase. Practical remedial measures were provided to address these issues.

Due to the challenging geotechnical conditions encountered, it was particularly important for RRC to collaborate with the geotechnical design team to optimize and provide cost-effective foundation designs. RRC provided design and sizing for concrete, reinforcing, embedment rings, and anchor bolts for the wind turbine foundations to adequately resist the loadings provided by the turbine supplier.

RRC provided continuous engineering support during construction to effectively provide measures to address issues related to foundation dewatering, unsuitable foundation subgrade, and for an access roadway area where peat deposits were exposed. The remedial measures provided by RRC were cost effective, soundly engineered, and helped with maintaining the aggressive construction schedule.