How fast can water travel? Another hollywood provoked science question

[spingears]

@Greenback

Forget the dam. I’ll try to paint the scenario a little better.
The aquaduct pipe runs straight to the ocean, finally poking out of the coast at 50 feet below sea level. The aquaduct is uniformly 50 feet below sea level. While building the tunnel, a wall was built at the ocean end to prevent sea water getting in to the pipe. Now the wall is vapourized. How fast does the water come through the pipe?

This Q still belongs in DAQD
The 60 mile long tunnel is still 50’ or more below grade unless I missed a description somewhere above and/or below. You did say a level grade for the ‘aqueducte.’