By topology matching of this early version "Wing Delta" Main Spillway Design, this blueprint lends credence to an "early" construction "grading" of the "saddle" area if this option moved forward (from hydraulic flow modeling testing & design). The left side "wing" follows the grading into where the 60FT high section of where the Emergency Spillway Wier now exists.
Replacing prior excavated material, even if fractured rock, would have been an unpopular choice. IT would have been easier to design a Tall Emergency Spillway Weir and then taper it. re: discussion on "origin of "focused wash basin". note: See post 1554 for original discussion of the "Wing Delta" Main Spillway Design.
