The reasons for fracking protests are manifold, but one area of particular concern is the likely long-term effects of unconventional drilling on groundwater aquifers.

With conventional drilling, it was economically feasible to capture up to 95 percent of the natural gas released from shallow rock deposits. With unconventional drilling in deep shale deposits, that figure is generally placed in the 30 to 70 percent range. Granted, 30 to 70 percent of the massive amounts of natural gas locked up in shale, combined with the number of wells being drilled, translates into an enormous amount of natural gas being captured, which is what all the recent crowing about shale gas production is about.

The gas that is released but not captured is free to migrate where it will, including up the well-bore which facilitated its release (even after said well has been capped) and through whatever cracks and fissures, natural or man-made, it may find.

The gas industry would have us believe the groundwater aquifers in shale country are completely protected. We are told the thick layer of rock between shale and aquifer is totally and permanently impermeable. Not all geologists are in agreement on this. Seismic forces can lead to fissures where none existed previously.

But the main focus of natural gas advertising is on the layers of concrete and steel which are placed between the well-bore and the aquifer. That, we are told, will shield the aquifer from all pollution, be it methane or toxic fluid flowback, forever.

Not so. Failure of well casings to prevent leakage is figured at 6 percent to 20 percent from day one to year five of a well, even by industry sources.

But let’s estimate the integrity of wells out 30 years, 50 years, 100 years. Eventually there will be 100 percent failure of steel and concrete casings across hundreds of thousands of wells throughout Pennsylvania, throughout the Northeast, throughout the U.S., throughout the world. Aquifers will be polluted by methane gas and by any residual toxic wastes from fracking that are not disposed of properly.

The “unconventional” wisdom of the gas industry seems to be: “Let’s make a killing on the drilling now and clean up the mess later.” It may well be a mess unparalleled in the history of human existence.

Indeed, drilling is just the beginning.