More than 860 trillion cubic feet of shale gas sit under American soil — enough to feed our consumption for generations and enough to solve one of the great problems of our time: our dependence on foreign oil.
So it’s no surprise that many Americans are excited about the promise of shale gas.
And it’s no surprise that the waste industry, dealing with sluggish volumes of household trash, is excited about the promise of a growing waste stream from shale gas drilling.
In the tri-state region of Pennsylvania, Ohio and West Virginia, the waste from shale gas drilling has gone from zero percent of the total stream in 2008 to 6% in 2012. During the same period, the number of landfills accepting drill cuttings and drill mud — the waste created from the drilling process — has jumped from one to more than 35.
“I won’t say we’re at the tip of the iceberg, but we’re pretty close to the tip of the iceberg in terms of developing this resource,” said Eric Chiado, an engineer and principal with Civil & Environmental Consultants Inc. in Pennsylvania. “There are many, many years — decades — still to go in terms of developing this resource and developing the structure to bring it to market.”
Chiado’s thoughts came during a Waste Expo educational session on the changing waste stream. As he laid out the statistics of waste generation from drilling, landfill operators — always hungry for volume — could have been forgiven for leaning forward.
The stats: about 500 tons of drill cuttings from a vertical bore; about 1,000 tons more from each horizontal; tens of thousands of barrels of flow-back fracking water; and the number of wells doubling every year in Pennsylvania, one of the 15 states where shale gas is in play.
In 2011, 1.2 million tons of drill cuttings were landfilled in Pennsylvania alone.
There is a downside of course, and Chiado told a cautionary tale for landfills that might consider accepting this waste. Among the problems and concerns:
* Stability. On the working face and in the waste mass in general, drill cuttings do not behave the same as MSW.
“These drill cuttings, these shale wastes, are generally very heavy,” he said. “They are typically wet, and above all else, they possess variable shear strength properties. So obviously those types of properties have a detrimental effect on waste stability.”
* Leachate quantity and quality. The composition, wetness and low permeability of drill cuttings generally increase the amount and alter the chemistry of leachate. Exactly how much is unique to every site.
The fine particulates in drill waste can also gum up leachate collection systems, he added. “Those fine grain materials have the potential to eventually migrate into your collection system, blinding that off.”
* Landfill gas generation. Drilling cuttings are inorganic and when a significant portion of a landfill’s waste mass is inorganic, gas generation is affected compared to a site packed with MSW.
Asked about the subject later, John Casella, CEO of Casella Waste Systems Inc., said: “There’s no question that by putting drill cuttings into a landfill you’re clearly going to reduce the amount of gas that’s generated, because it’s inorganic. You’re not putting putrescible waste in. You’re now putting drill cuttings in.”
The fine particles of the waste can also migrate into landfill gas wells, Chiado said.
* Low-level naturally occurring radiation. Chiado said that some radiation detectors at Pennsylvania landfills have been triggered because of the introduction of drill cuttings.
His state is three months into a study on the radioactivity of drilling waste.
* Market volatility. Perhaps the biggest yield sign to drilling waste sits far away from the landfill.
“It’s a very different business than MSW,” Casella said. “I think out into the future, it’s clearly going to continue to be fairly volatile, because it’s all driven by [natural] gas prices. If [natural] gas prices go down to $2 again, drilling will stop.”
“It’s a different business model than the steady stream of MSW.”