Water Storage Facilities on Mt. Scott The City of Portland Water Bureau initiated a study to review the seismic stability of 28 water storage facilities. The tanks included relatively short concrete tanks, tall steel standpipe tanks, and elevated steel tanks.
Each tank site was reviewed to determine the subsurface soil and groundwater conditions. Ground response spectra were developed for three foundation soil types using the most current estimate of earthquake magnitude and ground shaking. The response spectra curves were used to evaluate the dynamic response of the tanks using structural analysis and computer modeling.