SGH evaluated the hydrology and hydraulic studies for the adjacent river, including a case where water overtops the culverts during the design flood event. We worked with the owner to select the design event based on the library’s contents, develop strategies to improve resiliency, and reduce the risk of significant content loss due to flooding.
We determined the existing structure was not designed to resist the hydrostatic loads during the design flood event and could not support buoyancy loads on the base slab. SGH developed options to wet and dry floodproof both the existing and proposed structures. Our concepts included reviewing options for subslab depressurization (with and without a below-grade cutoff wall) and using blow-off valves in the walls, limiting the use of the space, and installing appropriate finish materials for a wet-floodproofing approach. We helped the design team determine which existing mechanical systems should be relocated and which could be left in place and relocated later to a pre-designated area, if flooding were to occur.