Acidic soil planter

I've decided to plant shrubs in this area where previously I had thought of installing a sump pump. Underfloor wetness from past winters seemed to have penetrated from this area, but I'm hoping it's not underground hydrostatic pressure and just the roof downspout, which I've already diverted to the sideyard. It's the opportunity to add more "softness" to the front facade that I can't pass up. Plants can also help with soil retention.

I'm thinking of Rhododendron, so this new soil is an acidic blend. Deep beneath it is an organic compost mix to help break up the heavy clay native for better drainage. Hopefully I'm doing it right this time.