Maine et Loire, France

Our location is mainly on heavy clay and limey soil. The springs are therefore very limey and the water in the river is hard. But along our river bank there is a thick layer (around three feet deep) of black peaty soil, possibly natural as the area used to be a marsh, or maybe imported forest product when the river course was changed 35 years ago.
Would it be possible to grow rhododenrons or other acid loving plants there, or would they immediately keel over once the roots got down into the water table?

• 23 May, 2010