Pumping Mine Backfill

I hope your environmental folks (local, state, fed) have approved the plan and the cement mixture adequately contains the heavy metals often found in fly-ash. There has been a big brouhaha here in Maryland where fly-ash was dumped in a land fill and now the wells in the immediate area have unsafe levels of heavy metals due the the inadequate (none) control of the leachate. Big lawsuits flying around and much animosity towards the local power utility for not being more careful. I could assume that the mine is below aquifers and therefore leachate is of little concern, but just in case.

I've often wondered if fly-ash added to concrete for road construction would suitably contain the heavy metals and still retain the required strength. But then what becomes of it when the concrete has to be refinished or replaced?

Thanks for the interest! The mine is below the aquifer levels so no environmental or legal issues of of concern.