Ohioâ??s quakes a cautionary tale

THE DEBATE OVER natural gas drilling in the Marcellus Shale in Pennsylvania – an economic boon that must be weighed against environmental impact – literally has been shaken up by events in neighboring Ohio, reminding everyone that water quality is not the only issue for concern.

In December, a dozen minor earthquakes occurred near a 9,184-foot-deep well drilled to dispose of wastewater from the drilling process. Experts from Columbia University believed the Northstar No. 1 disposal well owned by D&L Energy, five miles from Youngstown, was linked to the quakes. As a result, officials in Ohio shut it along with four other wells nearby pending an investigation.

That caution was vindicated last week with the release of a preliminary report by the Ohio Department of Natural Resources. While D&L said the findings were premature in the absence of new testing, the ODNR relied on seismic monitors to determine that the earthquakes were linked to "coincidental events," including the presence of a previously unknown geologic fault line.

It is important to differentiate between drilling for natural gas and drilling a deep injection well to dispose of wastewater from the fracking process (water which, in this case, came from Pennsylvania). It also is worth remembering that these quakes – rated between 2.7 and 4.0 for severity – caused no serious damage.

This unusual series of events is therefore not an argument to cease the search for gas in the Marcellus Shale; it is instead a reminder that special caution is called for when injection wells are being contemplated at exceptional depths. Common sense suggests that proximity to population centers should be an important factor.

Pennsylvania has six injection wells. There is no need for anyone to quake in their boots, but caution is advised.