[RichardA]

as a result of building a bungalow in the orchard we have to re-level the ground and raise some sections to remodel the garden. I am looking forward to re-planting for what has been lost and adding perhaps new stuff to me such as fig and grape. However, and this is where I would appreciate advice. I have three trees (apple, pear and plum) trained along a fence that have survived the build and the replacing of the fences but which now will have an additional 300 mm of soil over their roots. Do I risk leaving them in situ and burying lower trunk or do I dig out and replant higher (seems risky) or just accept they have to go and then buy new trees (cost and loss of 7 years of maturity). Any thoughts anyone please. I don't want to leave them in "pits" or build little walls round them as will be near an access route, kids running about, will fill with water, weeds and perhaps trap hedgehogs etc.
Best regards

[New shoot]

Trees don't usually survive having the lower trunk buried, so choices are remove and replace, or remove and replant. 

I would have a go at replanting them if it were me.  You will damage roots, so some pruning of the top growth will be needed.  I would also do it as soon as you can.   It may not feel like it, but spring is on the way and sap will be rising soon.

[bayleaf]

Yes I'd replant now. Burying them below the union between the tree and the dwarf rooting stock will lead to problems.

[RichardA]

Thank you both. I have to say that at the time I posted the question I was very much of the opinion that you both have since also put forward. However since then I have had an opportunity to talk to a very experienced nurseryman who specialises in fruit trees within a very long established family fruit tree supply business. His concerns were about the union exactly as you both stated but he suggested that as the trees had done well up to now I should try burying the trunk and he was fairly confident that the trees would probably do OK but would throw up side shoots that would be easily removed. As the trees are along a fence and trained as espalier/fan (depending on variety) this is easy enough.
I think that is what I will do but I do understand there are never any certainties in this gardening game. Thanks again for responding, it is appreciated.
R