We determined the seismic model of the soil column within a residential project site in Istanbul, Turkey. Specifically, we conducted refraction seismic survey at 20 locations using a receiver spread with 48 4.5-Hz vertical geophones at 2-m intervals. We applied non-linear tomography to first-arrival times to estimate the P-wave velocity-depth profiles and performed Rayleigh-wave inversion to estimate the S-wave velocity-depth profiles down to a depth of 30 in at each of the locations. We then combined the seismic velocities with the geotechnical borehole information regarding the lithology of the soil column and determined the site-specific geotechnical earthquake engineering parameters for the site. Specifically, we computed the maximum soil amplification ratio, maximum surface-bedrock acceleration ratio, depth interval of significant acceleration, maximum soil-rock response ratio, and design spectrum periods TA-TB.