In this ongoing metro project located on the eastern bank of the river Hooghly, a route realignment proposal was made in 2016. In the revised alignment, a deep shaft of length 38 m, width 10 m and depth 24 m was proposed for the construction of a box tunnel in 2020 and the excavation was completed by early 2023. In the later part of 2023, as per project requirement and based on NBC 2016 guidelines, one Exit Shaft was also proposed, the main purpose of which was to connect both the tunnels as well as serve as an emergency egress route to surface, for the passengers in case of any emergency. Due to the very close proximity of the east-bound tunnel from the exit shaft excavation zone, it posed a significant challenge as the construction of the existing deep shaft already caused some deformation, and tunnel bracings were installed to arrest any damaging effect on east-bound tunnel. Therefore, excavation for the proposed exit shaft had to be done in a very controlled manner so that no adverse situation arises. The design of that deep excavation system using secant pile and the design as well as construction challenges faced have been presented in this paper.