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, structural and seismic analysis and rehabilitation design of the existing Coronado Water Tank 1021 at Naval Base Coronado, CA for NAVFAC. The structural condition assessment consisted of a visual observation of the tank exterior and interior as viewed from the roof hatch as the tank could not be taken out of service for interior inspections. Moderate to severe deterioration of the tank coating systems and roof structure were identified. Structural and seismic analysis determined critical deficiencies of both inadequate freeboard and insufficient anchorage to the foundation. A technical memorandum was developed summarizing these findings with repair recommendations provided to remove and replace the existing roof with additional freeboard provided and an optional item of retrofitting the tank foundation and anchorage to meet current code compliance. The project progressed to the design and construction stage where the existing roof was removed and replaced with a modern steel roof system and knuckle shell connection which provided adequate freeboard for the tank with new interior and exterior coatings applied in addition to a new cathodic protection system capable of mitigating future corrosion. Additional safety features such as a new interior ladder, new roof platform, handrailing and roof tie-offs were also provided. 
Kelsey Structural provided the structural design and review for a new 2.0 MG Recycled Water Tank for the City of Oceanside San Luis Rey Water Reclamation Facility (SLRWRF). The new tank is a partially-buried AWWA D110 prestressed concrete tank measuring 107’ in diameter and 34’ tall, with two-way concrete roof slab system supported by 21 columns. Structural design included D110-13 tank core wall, vertical and circumferential prestressing, seismic cables, bearing pads, two-way concrete roof slab and columns, wall footings and thickened slab-on-grade foundation designed to accommodate differential settlements across the radius of the tank. Design considerations were made for soil subgrade preparation due to liquefaction potential at the site, and required soil improvements by means of wet soil mixing to minimize potential settlement of the tank. Kelsey Structural served as the Structural Engineer of Record, stamping both the structural calculation package and structural drawings.