Here's the lid on the sump and the hole through which the overflow will use. Now it was just a matter of burying everything. 

The one significant mistake I made was nearly filling the sump full with gravel. My original plan was to not use any gravel inside to give me years and years of trouble free drainage. I was just going to let the silt and debris pile up and one day twenty or so years from now, pull the lid and clean it out.

At the last minute I panicked and thought the sump would push it's way out of the ground without something in it to help keep it's shape - like the frost heave effect. Or the walls might collapse on themselves from the pressure of the ground.

At least I thought it was a mistake, though now that I think about it more, it's probably not so bad. Hell. You're damned if you and you're damned if you don't. 

Within a day or so we had a pretty good rain to test out the system, but at the garage there was a problem. The catch basin didn't appear to be working at all. The water was flowing right over it, around the corner and through the flower bed. 

Luckily it was an easy fix. I had left a significant portion of pipe above the level of the ground at the overflow waiting for the ground to harden up before I cut it. This raised the overflow exit to a height above the garage catch basin. Without water exiting the system, no more water could enter. I grabbed the hack saw, cut the pipe and everything worked fine.