I just tried again with
Click to reveal..
level 2 construction and an adept builder and an adept scientist
and had no luck.

Then I looked at the guide (duh) and it says
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"you will need Construction Level 2..drop a master scientist on the dilapidated aqueduct to supervise, then a master builder to start the actual repair work." So you need all three of the things we've been talking about.