There's a water management system in place. I remember it was quite a big deal at the time with the River Coquet and Northumbrian Water's Warkworth plant being at risk of contamination. 'Environmental disaster' stuff in the local press when the water finally got near the surface.
Anyway, The coal authority stepped in and water management work was completed on time. There's now a pumping borehole 70m deep intersecting the drift - this water goes to some large lagoons and reed beds above the drift.
Summary on the Coal Authority Website.