building hugels on wet ground

We have a flat area of wet ground. I believe it is wet for a number of reasons in combination: a) it's level, and we get a lot of rain, so without a slope it doesn't drain well b) it's compacted by previous recent use of heavy machinery c) part of it is the drainage field for our septic tank. Last winter it was sodden and standing puddles from about October-April. It dried out in the summer but still sported wet vegetation (common rush). We have cut the rush and tilled about 6", and it was looking ok but now we've had a few days of heavy rain and we do have standing puddles again. There may be a possibility of installing a land drain but as it's so nearly flat it's doubtful. I am wondering about the possibility of building hugel beds on it, to take small trees and fruit bushes. I really want to use this area for this purpose (one reason is that it's the most sheltered spot on our land and gets great light) but as it is, it is too wet for nearly all edible trees and bushes.
Would building relatively tall hugel mounds create enough drainage space for trees to thrive in this case? If it's a possibility, then I need some input on what to cover the mounds with. I would not be digging a trench at all, since the idea is to get up and more height. I don't really have another area on the land to grab topsoil from. What could I do? Perhaps buy a truckload of topsoil. Definitely I can get cheap cow muck (manure and straw). If I built the mounds and covered them with cow muck in the fall, do you think I could plant shrubs in them in the spring or would I definitely need topsoil?

Thank you!

Why not dig trenches across it that become swales alongside your hugels and eventually feed them as well? Unless digging will disturb your septic drainage field I dont think it will harm anything, and will give you the topsoil you'll need. You can then build the height by using more wood, cow muck and straw then cover over with your topsoil. You could even grow water chestnuts in the swales or some other bog plant like saggitaria, swamp iris etc.

From my understanding, swales require a slope to work. Part of the reason this ground is so wet is that it is virtually level. I mean, really, really level. So the water puddles - it has no where to run to. I can't really dig a swale without any slope, I'd be digging a pond.
I'm not entirely sure on the septic drainage, I think I can do basic tilling and light digging no problems but I'm wary of going much deeper than say 8".

I hadnt thought of water chestnuts, I don't know anything about them, will look into that great idea though!

There's always a slope unless you live on a salt pan. Swales would work I reckon

We think this area was a former millpond, it's pretty much as flat as one. I will investigate the swales idea further though

Maybe dig out a duck pond in the middle with a broken ring of Hugels around it? Ducks and trees/berries!

I'd also think that Hugels, with their increased surface area and internal venting (space between logs/branches) that they might help wick up some of the excess moisture and evaporate it off. You could probably include some things with naturally high wicking properties to help with that. For example, get some old cotton towels (use natural/biodegradable soaps to wash off the nastier laundry chemicals), bury 1/2 and hold the other 1/2 in the air with branches. It's a bit outside the box and not really within the bounds of PermaCulture but I think it'd help.

Thanks Brian, some interesting ideas there! I don't think we can dig a pond there sadly, as though in many ways it would be a perfect solution, since the area is also part of the drainage field for our septic tank I cannot dig a pond.

I have a seep on my land, and nothing but grass will survive because sometimes it is wet and sometimes it is dry.

I have about decided to set some half-rotted pieces of wood right where it gets the wettest, and see if I can sprinkle seeds on top of the wood and have it grow. I expect that whatever I plant would die as soon as the summers got hot but perhaps I will get a light harvest of spring greens.

It might work better if I half buried the wood, but I am a little afraid to dig right there. It is a steep slope on rather sandy soil.

Wood sticking out of a hugelkultur bed is supposed to act like a wick. You could build it with wooden posts or poles sticking out of the top. Another benefit of this is that bird
Birds well be encouraged to perch on them and you can support plants with them, like pole beans or vines.