15 years of gas?
'Cuadrilla initially estimated the UK has enough gas to make it self-sufficient for 15 years at current consumption rates - but this may be underestimated by a factor of four'
If as part of this coming online is to continue to replace coal power stations with gas ones, then won't the time it lasts be that much shorter? Especially so as the increased supply lowers the wholesale price of gas, those power stations will appear that much more lucrative for investors.
By all means continue the trials in a controlled manner, but would be better to see how they fare over a longer term and how it develops in the US before starting to roll something like this out. If the water table is contaiminated, like other commentators have already pointed out, there isn't an easy way to fix that.