Background: when I moved in in 2018 I had the sewer line replaced. This necessitated cutting a section of the basement floor, which was then filled with concrete:
The contractor left unfilled a small slit from where they sawed the original concrete:
Last week we had a huge, historically-unusual rainfall onto already-saturated ground. There was widespread flooding in the area. In my basement, water flowed up through this slit (and also trickled through a crack between their patch and the original concrete). It flowed steadily across the floor and down the floor drain. After about 12 hours of this, the water stopped flowing up.
What caused this and how should I remedy it? I believe my house has footing drains connected to the sanitary sewer, which I understood to be good protection. Do those drains not protect the basement from water table rise from below?