Crescent City Washington Tank Retrofit
Kelsey Structural provided the structural retrofit design of the existing 4.15 MG Washington Tank for the City of Crescent City, located in Crescent City, CA. The reservoir is located in an area of extreme seismicity which resulted in significant tank deficiencies including overstress of all courses of the shell, seismic instabilities, insufficient foundation sizing, lack of anchorage and insufficient adequate freeboard. Retrofit design of the existing AWWA D100 welded steel tank included a new concrete ringwall foundation with retrofit anchor bolts and chairs welded to the existing shell and shell overstress and freeboard recommendations to limit operating water heights in order to prevent shell damage and sloshing damage to the roof structure during a seismic event. Structural detailing of the concrete ringwall foundation, reinforcing and anchorage was also provided.
Kelsey Structural performed the structural condition assessment of the IWA Plant 2 facilities including two well structures, a booster pump station and welded steel reservoir. Work included structural site investigations at each facility to document structural condition, complete seismic analysis of each facility and a comprehensive series of technical memoranda summarizing the assessment findings with corresponding improvements recommendations and preliminary cost estimates. The results of the assessment identified several critical structural elements as being deficient in terms of seismic performance and current code requirements, with recommendations being made for complete replacement of the existing booster pump station along with seismic retrofits to one of the existing well facilities and lowering of the maximum operating water level in the reservoir to provide sufficient freeboard to allow for sloshing.