RickCorey said:>> 'the water table'

Where the soil is wet enough that there's effectively no air. That might not be the true definition of "water table", but that's what I was trying to say. The depth where slow drainage kills roots during hard rains.

My soil is weird--
it has a hard time getting wet (hydrophobic)--water kinda beads on the surface and runs off, down the hill. So, in a hard rain storm we literally have rivers running down the streets but it doesn't soak in. After a storm, the surface may be wet, muddy even, but just under that can still be what I call "puff-dry" and I can have plants that need water after a hard rain because the soil, where the roots need moisture, is still dry.
On the other hand, once it gets wet--ugh--it holds the water and turns to glue for a loooooong time.
When my soil actually gets wet there is not enough air and it kills roots the deadly 'water table' is wherever the soil gets wet.
As I said, we don't get much precip--average about 18 in/yr. We get most of that in the form of snow. If we get enough snow, my soil gets wet when the snow melts. Rarely, we can have slow, soaking rains and the soil can get wet. When I first moved here, I killed a lot of plants-- either dry and crispy because when I watered I didn't reach the roots, or rotten and soggy because when I did reach the roots I created the "water table".
Hence soil amendments--for the whole bed, not by the hole, raised beds, and beds on slopes.
It has made a lot of difference. Water can actually penetrate the amended soil and soak in and the plants aren't trying to grow in muck/concrete.

This, though, is my first experiment without a level change, and a hole, albeit a big hole.
Water drains right down into the bed. I am hoping that any excess goes under the sidewalk and all the plantings and trees on the other side are picking it up.
But, I don't really know where it's going or what it's doing. The sidewalk and porch haven't collapsed, the crocuses are popping up, the roses look great and their leaf buds are swelling, the sedums are happy, and even the alstroemeria is sprouting (that needs a well drained soil too) so I am thinking that it is working well enough.
I'm not going to flood it just to see what happens though.

It sounds like clay, especially the "
run-off" part, and:
>> "On the other hand, once it gets wet--ugh--it holds the water and turns to glue for a loooooong time"

>> Hence soil amendments--for the whole bed, not by the hole, raised beds, and beds on slopes.

I strongly agree with both parts: amendments for the whole bed, and " beds on slopes".

I wonder where the big hole on level ground is draining TO? Oh well, as long as it DOES drain, and not into your basement, it doesn't matter WHERE. But I wish I knew how and why ... maybe I could borrow your method and use it myself.

I always wish I knew "how and why".

Well, maybe it doesn't drain. Like I said, we don't get much precip.
Trust me--I irrigate more than it rains and I didn't really do this to get rid of *excess* water because we don't have that problem here.

Maybe it is more like a sunken, self-watering planter (in which case I'm gonna have some salt problems because my irrigation water is crapola).
We really are so very dry here, I'm thinking the water probably does move, slowly, out into the dryer depths (downhill, we are on the side of a mountain) and I'm pretty sure it gets picked up by the thirsty trees and never makes it to the great salt lake...