Planting fruit trees in ground that previously had a few railroad ties on it

There had previously been a loading dock that was basically a cribbed railroad tie wall in the shape of a “U” that retained enough soil behind it to create ramp/dock to pull up too. I removed the walls/ties and then removed the dirt to grade. I want to plant fruit trees, plum, peach, cherry in this area. Theoretically the surface area of the ties was small, only three of the ties were contacting the ground and the rest were stacked vertically on top of the bottom ones. I can avoid planing directly in the ground beneath where the ties previously laid, but the trees would be close to there.

What is the leeching potential of the ties over time in this scenario and do fruit trees takes up whatever toxins are in the soil?