If the height of the hydraulic gradient line above the floor of thickness t is h and the specific gravity of the material of the floor is G, the minimum thickness t of the floor downstream of the crest-wall, is given by the equation

• A. t = (h - 1)/(G - t)
• B. t = (h + 1)/G
• C. t = (h + 1)/(G + t)
• D. t = (h - 1)/(G + t)

Answer: (A)