Marcellus Shale Drilling and Chesapeake Bay Water Quality

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Following up on Ben’s post Tuesday – onshore oil and natural gas drilling can impact water in different ways:

1) Water withdrawals – drilling and hydraulic fracturing (fracking) require large quantities of water. The high-volume slickwater fracking performed on Marcellus Shale gas wells can use up to 3 million gallons of water per frack.  It’s not unusual for a single well to be fracked several times; and for a single drilling location to host several wells reaching out in all directions.  Water can be brought in by tanker truckor pipeline.  The closer the water source, the cheaper it is for the operator, so often they request permission from state and local authorities to take water directly from nearby streams.  As an example, XTO Energy (a division of Exxon) is seeking permission to withdraw up to 250,000 gallons per day from Oquaga Creek in upstate New York, a small trout stream annually stocked by the state.  My father-in-law and his fly-fishing buddies know this stream personally and think this withdrawal would destroy it as a trout stream.  Pennsylvania has already issued many water withdrawal permits for drilling and other activity (map).

2) Water disposal – the fluids used for drilling and fracking contain a wide variety of potential contaminants.  Produced water — water originally held in the target geologic formation that is produced along with the gas — can contain elevated levels of dissolved salts and, in some cases, low level radioactivity.  Spills of these fluids, and leaks in the plastic liners in fluid-reserve pits on the drillsite, can contaminate surface streams and near-surface groundwater.  Standard municipal wastewater treatment facilities are not equipped to remove some of the contaminants in these fluids, so specialized treatment facilities must be built to process this wastewater before it can be released to streams and rivers.

3) Groundwater contamination – when it comes to drilling safety, the devil is in the most mundane of details. Cement, for example. Cement pumped into the bottom of the well, and sealing off the fracked intervals, is the main line of defense to prevent gas and fluids from moving where you don’t want them to go.  Poor cementing was the proximal cause of the disastrous Montara blowout and spill off Australia in 2009, and the fatal BP / Deepwater Horizon blowout and spill in the Gulf of Mexico last year.  A recent Wall Street Journal investigation revealed that problems with cementing are alarmingly common. Casing failures, corrosion, poor drilling practices and other factors can also allow unwanted fluid migration.  The end result: a growing roster of cases where drilling activity is related to the contamination of drinking water supplies across the nation.

By the way, thanks to careless use of drilling terminology by some environmentalists and politicians, a big semantic argument has broken out, focused on whether the hydraulic fracturing procedure itself is the cause of contamination. More on this topic later, but we think this argument misses the mark: fracking is the repeated pumping of fluid into the well at extremely high pressures designed to break open rock, so any weakness or flaw in the well design or construction (like a poor cement job, for example, or cheap imported steel casing) is much more likely to lead to failure in a fracked well, than it would in one of Dad’s old-fashioned unfracked wells.

By The Way, Part Deux: National energy legislation in 2005 exempted the drilling industry from disclosing the chemicals they use in fracking, making it difficult for homeowners to monitor the quality of their drinking water without spending a fortune on water analysis. ShaleTest is a new outfit that is trying to help homeowners with this.

4) Stormwater runoff contamination of surface waters – this is the unglamorous way that streams, ponds, wetlands and rivers could be impacted by drilling activity.  A drill site, after all, is essentially a concentrated construction zone several acres in size: trees and brush are cleared, the land is graded flat, gravel is trucked in and spread out to create a space for all the trucks, equipment, supplies and people needed to drill, frack and complete a well.  Access roads are built; pipelines and other utilities are installed.  All of these elements of drilling infrastructure are potential sources of muddy runoff when it rains, changing the physical and chemical properties of streams with impacts on the aquatic life and downstream water users. The construction industry in general is subject to Clean Water Act rules to control stormwater runoff, but – yes, you guessed it – the drilling industry is exempt from those rules.

Ben’s work is focused on investigating if this potential for runoff really is a measurable problem.  If so, it could complicate the decades-long, multimillion dollar effort to restore water quality in the Chesapeake Bay.  This excellent map, created by SkyTruth volunteer Dorn Moore of Greenspace GIS, shows that over one-third of the Bay’s watershed overlaps with the Marcellus Shale gas play.Assuming one drilling location per square mile, that could mean as many as 25,000 drilling sites will be built in the Bay watershed (even more as other geologic formations, like the Utica and Ithaca Shales, are targeted for drilling).

If these sites cause measurable degradation of water quality, that could be very bad news for the Bay.

Fracking – Safe or Not?

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There has been a lot of buzz lately about stimulating production from gas and oil wells using the relatively new technique of hydraulic fracturing — fracking, fraccing or fracing for short. Most of the new natural gas wells drilled in this country rely on fracking to yield economically attractive quantities of gas, especially in the booming shale-gas drilling plays unfolding around the country (Barnett, Marcellus, Haynesville, Fayetteville). Shale-oil drilling (not to be confused with oil shale) is the second wave that’s building fast (Niobrara, Bakken, Eagle Ford). These so-called “unconventional” gas and oil targets were bypassed for years until advances in horizontal drilling and fracking provided the key to unlocking these significant gas resources. Now they are becoming the main focus of drilling activity in North America, affecting many residential and even urban areas where drilling was once considered inconceivable.

Natural-gas wells on public land in the Jonah Field of western Wyoming. Fracking is routine for most gas wells drilled now in the U.S. Photo courtesy EcoFlight.

Recent highly publicized drinking water contamination incidents linked to gas drilling, and the popularity of the documentary film Gasland (can you light your tap water on fire?), have raised the public profile of this game-changing drilling process. The U.S. Environmental Protection Agency is studying the safety of fracking. Congress is holding two hearings this week, in the House and in the Senate, to try to get some answers. No doubt many of the problems stem from the mundane details of drilling that can plague any complex construction job: bad well design and construction, ill-advised shortcuts, and – the leader of the pack – poor cementing.

Industry wants us to believe that if we just fix those problems then fracking can be done safely. Disclosing the chemicals used in fracking at each drilling site, so homeowners know what to test their water for, would be a good start.

Tanks for handling fracking fluids at a new Marcellus Shale natural-gas well site in northeast Pennsylvania. Photo courtesy J. Henry Fair.

But we wonder if hydraulic fracturing is intrinsically unsafe, even if the well design and construction is totally by-the-book. Here’s why: fracking works by levering open fractures in the rock, and propping those fractures open with sand (or synthetic microbeads). Tectonically “open” fractures, that are aligned parallel to the regional stress field, are most susceptible to being pried open. If a frack job intersects pre-existing open faults or other natural fractures in the bedrock — especially vertical fractures that can span multiple geologic formations above and below the target zone — how do we ensure that fracking fluids don’t migrate in unpredictable ways via these natural flowpaths?

Smart drillers don’t want to lose all their fracking fluid into a single fracture or fault: it’s expensive, a waste of time, and doesn’t accomplish what they want. But avoiding those features requires doing borehole imaging studies on the well to identify and map them, which also costs time and money. It’s not hard to imagine a driller weighing the expense of borehole imaging surveys vs. the risk of performing an ineffective frack job.

We know just enough about this to raise a few questions, and would appreciate some real experts weighing in by commenting on this post:

  • What do companies do to avoid the undesired result of fluids migrating out of the fracking target zone?
  • What actions to avoid this result are required, and how are they verified by regulators?
  • What actions are voluntary, and how commonly are they used?

Thanks in advance for sharing your expertise on this important issue!

Natural Gas Drilling, Hydrofracturing, and Ground Water – Drink Up?

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A couple of YouTube videos have been making the rounds and causing some alarm among the ever-increasing number of homeowners who have active natural gas drilling in their area, and rely on groundwater for their drinking water supply. This video shows common, normal operations at a modern natural-gas drilling site in western Colorado, operated by the Canadian company EnCana, a major player in the Rockies. One video shows drilling fluids being stored onsite in a plastic-lined open pit (a “fluid reserve pit”) while the well is hydrofractured, or “fracced.” The other video shows this same pit being closed: as a crew removes residual fluids and pulls out the liner, a bulldozer buries the pit.


We’ve created a small gallery showing the drill site depicted in these videos, and adjacent residences. Although the operations depicted are probably allowed by Colorado law, nearby homeowners who have water wells for drinking and bathing are concerned about these practices as drilling permeates the area. Multiply this scene tens of thousands of times, and you get the idea what’s been happening in recent years with drilling in many parts of the country.

UPDATE 9/16/09: In response to a comment, we thought folks might appreciate these links to other resources about fracking:

  • A summary report on chemicals found in fraccing fluids, their toxicity, and health effects
  • Tables that list chemicals used in drilling and fraccing
  • This press release from The Wilderness Society supporting pending legislation that would require companies to publicly disclose the chemicals used in fraccing
  • Announcement that EPA found fraccing chemicals contaminating residential water wells in Pavillion, Wyoming
  • A wealth of additional information on hydrofracturing from Earthworks

Roan Plateau – EWG Report

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Environmental Working Group just released a compelling report that shows the history of gas and oil drilling on and around the Roan Plateau in western Colorado. This work puts the numbers behind the tremendous burst of drilling illustrated by SkyTruth images.