A new single-story, slab-on-grade building was planned adjacent to the existing bank. When completed, banking operations would move to the new building and the old building would be demolished. Customers were to receive uninterrupted service between the two facilities.
A geotechnical investigation identified six to ten feet of fill and weak residual clay soils over very stiff to hard weathered shale bedrock. The geotechnical engineer recommended that the proposed structure be supported on helical piles to avoid deep excavations adjacent to the existing building. Helical piles were then proposed for the entire structure to provide uniform deep foundation support. Helical piles can also be installed with little to no vibration “felt” by surrounding structures. Vibrations caused during the proposed construction could activate the bank vault’s sensitive alarm system.