Planting the trees above grade is good. However, I would take the soil off of the top of the root balls. Generally trees come from the nursery in an organc/sand media which is much coarser in texture than the on site soil you've described. Water will have a hard time moving through the heavy soil on top of the root ball and will instead channel around the root ball, allowing it to dry out. Then the whole thing can become hydrophobic.

It sounds like you have a pretty poorly draining and anaerobic backfill soil surrounded by poorly draining native soil. What I would do is put in drainage tubes. I would auger 6 inch diameter holes and insert 4 inch perforated PVC pipes. Then backfill around the pipes with gravel. Some people put a filter fabric sock around the tubes but I see those plug up with silt and clay particles pretty often, which severely limits the effectiveness of the drain. When digging to install the drainage tubes, it's ideal if you can punch through the heavy soil to a more coarse layer beneath. If that isn't feasible, then you'll just have to keep pumping out the sump if it fills up. The bigger the sump, the less pumping you'll have to do. If these are on a slope or there is low ground somewhere nearby it would be great if you could install that tubes that reach to the bottom of the rootball, and then run sidways on a slight downward slope until they daylight out somewhere. If they need it, there is no rule against installing more than one drainage tube per tree.

As far as the trees planted below grade go, there isn't much you can do at this point short of digging them up and and re-planting above grade. Whatever you do, do not try to bring the grade up around the trunks of the trees. You'll just suffocate the roots and make the problem worse.

You can never force plants to grow under conditions they are not adapted to. Subsoil does not occur on top of topsoil under normal circumstances in nature. Likewise, plants will not usually be situated in small pockets of one soil surrounded by a large area of another.

Even trees adapted to wet sites may not tolerate being plunged suddenly into a mire after being grown in better draining material. And there are different kinds of wet sites, with differing combinations of conditions. Many swamp species will be growing in a highly organic mud or muck in nature rather than a subsoil.

If you had a contract for this job what were you contracted to do? If there was no specification for the condition of the soil and you planted and guaranteed the trees anyway I think you shot yourself in an arm and a leg.. If on the other hand your contract was to make the soil amenable to planting as well as planting then you have shot yourself in an arm and a leg. If the soil was to be prepared by someone else but wasn't and you planted guaranteed the trees anyway I think you shot yourself in an arm and a leg.

Unless you are saying you have enough trees that you can afford to give them away because is the soil likely to be better when you plant the replacements?

Ouch.

Well, so far so good. I went around last week, 6 weeks after completion.

None of the trees have sunk significantly. I guess the packing I did was sufficient (or there is a big air space under the tree...)

A couple needed adjustments to the staking to keep them straight.

All are showing new growth.

Some of the aspen are being nibbled on by grasshoppers.

I may have pulled it off.

Good deal, that's very encouraging. I hope it works out for you. Did you put in any drainage? I don't know anything about Canada, but Google tells me you just got through your rainy season. How did the soil moisture go?

I didn't install any drainage. THAT emphatically was not in the contract. Look at the species involved: Laurel leaf willow, swedish aspen, hill poplar, white spruce. All 4 of them are water pigs, with the first three tolerant of long periods of immersion. We've found emprically that white spruce can tolerate a week or so of having their roots under water. And they were the ones I put on slight mounds.

On the other hand, 'rainy season' is a stretch. Currently in this part of Alberta we are running the driest year in 50 years -- about 40% of normal moisture levels over the course of the last year. We've had 5.5 inches of precip total since the first of April. And spring run off filled the 30" culvert under the lease road to a terrifying 2" depth.

The guy I did it for takes the watering seriously. This is why I went to check up on it. Each was damp, but not soggy, so he's doing his job.

We'll see.

The lesson remains: Always take a shovel when bidding on a planting contract.