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EARTH DYNAMICS LLC ReMi Analysis 1200 Alder St October, 2025 Page 1 1.0 INTRODUCTION Foundation Engineering Inc. engaged Earth Dynamics LLC to conduct a geophysical exploration at the site described as The Mark at Eugene located at 1200 Alder Street in Eugene, Oregon. This study was requested and authorized by Ms. Mallory McAdams of Foundation Engineering Inc. The geophysical field work was completed by Mr. Daniel Lauer of Earth Dynamics LLC on October 31, 2025. This report describes the methodology and results of the geophysical investigation. 2.0 SCOPE OF WORK The purpose of this study is to characterize the subsurface shear wave velocity at the site. These data are needed to help determine the seismic response of the site to earthquake loading. The exploration consisted of one twenty-four channel refraction microtremor (ReMi) array. 3.0 METHOD The ReMi technique provides a simplified characterization of relatively large volumes of the subsurface. The method can be used to estimate one-dimensional shear wave velocity profiles and provide site-specific soil classification data as described in ASCE 7- 22 (2022). In a ReMi survey, geophones are deployed at designated intervals along a linear array. The resolution and depth of investigation depends upon the geophone cut- off frequency, spacing of the geophones, the total array length, and the frequency characteristics of the Rayleigh waves at the site. For “rule of thumb” survey planning, the nominal depth of investigation is assumed to be approximately one-third of the geophone array length. The theoretical basis of the ReMi method is the same as Spectral Analysis of Surface Waves (SASW) and Multi-channel Analysis of Surface Waves (MASW) as first described to the earthquake engineering community by Nazarian and Stokoe (1984). However, ReMi does not require a frequency-controlled source and the field equipment is much more compact and economical. A complete description of the theoretical basis for ReMi is described by Louie (2001). In ReMi analysis all interpretation is done in the frequency domain, and the method assumes that the most energetic arrivals recorded are Rayleigh waves. By applying a time-domain velocity analysis, Rayleigh waves can be separated from body waves, air waves, and other coherent noise. Transforming the time-domain velocity results into the frequency domain allows combination of many arrivals over a long time period and yields recognition of dispersive surface waves.