you won't find the type you're lookin for on the market - they live deeper in the soil, and not in quantities that would 'till' your subsoil, nor provide drainage - sounds like you've already got a good start by adding the compost and worms, just make sure you can continue w/ at least yearly additions of compost, even just as a topdressing, and the worms will breed and take care of the topsoil layer, which is the important part - few things smaller than trees put roots down deep, and those that do can handle the hardpan if they need to

if you have a real drainage problem [kinda wet in CA this year? :-)] then you need to put in some drain tile in that area, also if you'll not be able to work the soil there later, dig it over as deep as you can and incorporate somea that better soil and compost deeper than 6"

Bill

Bill, I am grateful for your advice, which I followed.
A few of the night crawlers were not so appreciative when I started to dig as deep as I could...
I am sorry that endogeic worms are not commercially available. I really liked the idea of them actually eating the soil and making extensive lateral burrows. Even if their impact was not major, I would have liked to try them. Well, at least now I can stop looking. Thank you!

As long as you keeping adding compost material to that area you will attract in worms. The deeper burrowing ones will pull the compost material into their burrows. Itll take a while, but eventually you will have enough worms working the area.

You may want to try out the soil,compost forum for more info regarding how to attract/keep them.

Bryan

a search on yahoo on reducing soil crust will provide some info that may help.