The Bowman Wind Farm is a proposed 200-megawatt (MW) wind energy facility in southwest North Dakota. The site also includes a 400 MWh battery energy storage system. As part of the permitting process for the Bowman Wind Farm, Apex Clean Energy sought noise control engineering services. These services were in support of Apex’s application for a project permit and to assess compliance with existing North Dakota Public Service Commission standards and applicable local regulations.

RSG’s work included preparing a modeling report for the project and participating in testimony and a hearing. Our team conducted sound propagation modeling using IEC 61400-14 manufacturer sound power levels. In addition, we followed the ISO 9613-2 standard and procedures outlined in “Regulating and Predicting Wind Turbine Sound in the U.S.” We used the Cadna/A sound prediction model. This considers varying terrain, source spectral content, and several other factors that influence sound attenuation and propagation.

The final report we prepared discussed local and state noise limits, provided site maps, and described our modeling procedures. It documented modeled results from the proposed wind turbines and substation. The report also documented modeled results from the proposed energy storage system, which included inverters, transformers, and cooling equipment. Importantly, our findings indicated the project would comply with the applicable noise regulations. Our team also provided live expert testimony before the North Dakota Public Service Commission regarding RSG’s noise analysis of the project.