I am designing a water tank as per ACI350-06. I want to add a extra reinforcement with the base reinforcement i.e., d16/200 (base reinforcement) and d12/100 (extra reinforcement). Environmental Durability factors for d16/200 and d12/100 are 1.52 and 1.21 respectively. Reinforcement diameter is neglected in the factor as per code. What will be the governing Environmental Durability Factor out of it, I have to consider in the design? I am comparing this factor with factor of safety calculated from provided to required reinforcement.