Project Challenge: The proposed construction included two electrical power generating plants and associated above ground and subsurface infrastructure. Since the planned power plants have several infrastructure elements, including the gas turbines, that are designed to operate at very high rotations per minute (rpm) and are sensitive to vibrations, the existing soil and/or rock geotechnical parameters for design of the plant element foundations was critical to the project. Electrical generating projects also have earth grounding potential and soil corrosivity concerns both from a design standpoint and from a worker safety standpoint.

Innovative Solution: Ninyo & Moore's geophysical services included seismic refraction surveys for depth to bedrock and rippability of materials in general accordance with ASTM D5777, surface-based multi-channel analysis of surface waves (MASW), shear wave seismic surveys for 2-D velocity profiling of the subsurface, and refraction microtremor (ReMi) seismic surveys in combination with our MASW survey results to provide site specific seismic site classification in accordance with IBC Vs33 (also known as IBC Vs100). Our results from these surveys also provide methods to calculate dynamic soil and rock parameters for the project site potentially affecting the project foundation designs. Ninyo & Moore also conducted electrical soil resistivity surveys for the purposes of earth grounding potential and soil corrosivity. Our survey data was also used to construct multi-layered models of the on site soil resistivity depth structure using methods in general accordance with IEEE Std. 81-2012, Annex B. The results of our resistivity surveys gave parameters influencing design estimates of soil corrosivity, and estimates of grounding potential.