I've used a Terramite with I believe a 12" bucket. I'm assuming you're going to prebuild the "form". Sounds like you ought to be able to pull the form right after you dump the gravel. If you're looking to keep water out of a building, go below the level of the footer.

how long of a trench and what kind of pipe are you using?

Thanks for the comments/questions. I've decided I just have to bite the bullet and do this myself. John, fortunately I'm not having this drainage issue near a building.

Darth, I'm using Baughman 4" 8 slot drain pipe for the branches, in trenches of round river rock with Mirafi 140N fabric, and 6" ADS N-12 for the trunk line. There's a lot of water to move. It's 500 ft of branch lines...I already did one branch of 100 ft. As I progressed, I got better and better at using the backhoe. It's getting to the point where if I'd taken the time I took looking around for excavation contractors (and then parts for their damn track hoes) into instead put it into digging, I would have gotten another 100 ft done!!!

I figure the only companies around here that might have a 9 or 12 inch bucket are "landscapers", and those are exactly the sort of people I want to avoid, for various reasons I won't go into.

Some contractors like plumbers or foundation repair people might have a small machine like that, to get into tight spaces around existing buildings to dig up pipes and such.

Yeah I've heard of those. Not really needed in this case, these trenches are in the middle of open lawn. Just don't need a lot of width.

That is one impressive French drain going in.

Let us know how it goes.

Ditch Witches can make a trench 6" wide which might be too narrow for you,

Yeah. I'm finding the 12" is just right. The reason I thought it was too big was that the first trench I dug was in really chunky, wet soil. In that case, the trench ends up being wider than the bucket. But in normal soil, the 12" gives the perfect sized trench. 9" would make it too narrow to get down in the trench and align the filter fabric.

So to follow up on this...it all worked out. Decided to finish most of the rest of the drains myself with my BX 12" bucket. Near the end of the the process I decided to hire a excavator just for one long section of non-perf pipe...I could have done it myself but was so tired of the hassle of digging trenches by this point. But this reminds me of a friendly tip for anyone doing this: ALWAYS BACKFILL AS SOON AS POSSIBLE. If it rains, the hole can fill back up with runoff dirt quickly. Also: BACKFILL AS COMPLETELY AS POSSIBLE, ESPECIALLY IF YOU ALREADY PUT THE PIPE IN THE TRENCH. This is actually very insidous - if the trench is partly filled, the pipe will tend to float up if it rains. The happened in a few small areas where it fortunately didn't matter.

Alas, it might be some time until I get a year like 2011 where rains over 20" in a month (caused by Irene back then) would really test the system out. I am confident it will work as planned though. In a 'worst case' scenario, I fully expect to see a 6" drain pipe going at maximal discharge.