A of digging, by hand. With a jackhammer.

It's not apparent from the drawing, but you can see in the previous photos that the northern edge of the lot (down, in the drawing) slopes down to the house. It's not apparent from the drawings or the photo, but the slope is almost solid rock -- apparently known in the local construction business as the "Castro Valley Shale" (though I would call it a "mudstone"...). You can also see in the photos that there is a retaining wall, to hold back that rock.

But now, things have changed:

Note the stump of the poor maple tree. We tried to save some of the plants, but this one was too big to preserve.