Coal ash

[MaggieMcGill]

Hi, hoping someone can advise with this. We bought an old miners cottage a few years back. We've been busy this year digging out leylandi and have bought some railway sleepers to outline a veg patch. The soil however looks like it might have been where the old ash pit was, it looks like the ash from the coal fire was flung here. We've tried adding compost to mix it all up but is this going to affect any veg that we grow or our health?