I asked one of the bosses a couple of weeks ago about the problem.
The reply was in a language used by boffins .
I deciphered it as follows.
They can get the water upto to the surface from the deepest seam but have problems with sediment blocking the pump. . They also have a problem reinjecting the water into a different seam closer to the surface. It sounds like they are trying to put water into a seam that is blocked off which is a bit like trying to put water into a barrel that's already full.
I made two suggestions as I worked with Pumps underground at Wardley.
At Seaham they are using mine water for heating but they pump the water directly into the sea after first removing the Iron Oxide. Not sure if we could remove the iron oxide here due to costs. If they can then the water could be put into the river.