Pennsylvania company testing a way to recycle drill cuttings and conserve space at landfills.
The oil and gas industry produces millions of tons of drill cuttings every year, most of which end up in landfills. But a Pennsylvania environmental company is testing a recycling process that could result in a beneficial reuse of the cuttings and conserve valuable landfill space for public use — and reduce disposal costs for drilling companies along the way.
Clean Earth is working with the Pennsylvania Department of Environmental Protection (PADEP) to determine if a process developed at the company’s plant in Williamsport could render drill cuttings suitable for various uses, including building drilling pads, constructing haul roads, mine-reclamation efforts and structural fill on industrial/commercial construction sites, says Averil Rance, the company’s vice president of environmental health and safety.
“That’s what we hope to prove out as we finish our research and development,” Rance says. “Some cuttings will still go into landfills. But in our opinion, quite a bit of them can be beneficially reused. We’ll know for sure by spring 2017. We have already generated reams of data that will allow the PADEP to make an informed decision about how drill cuttings will be managed.”
BENEFITING THE INDUSTRY
A process that can recycle drill cuttings would benefit the oil and gas fracking industry. While national statistics regarding drill-cuttings production are difficult to find, the PADEP reports that the state’s gas and oil industry produced 1.52 million tons of drill cuttings in just 2014 alone, of which 1.42 million were placed in landfills. And until the recent industry downturn, the Bakken Shale region produced about 2 million tons of cuttings annually, most of which are disposed of in landfills. And according to the Marcellus Center for Outreach and Research at Pennsylvania State University, an average well in the state produces 937 tons of drill cuttings.
Moreover, as more and more landfills reach peak capacity, existing space is at a premium — and it’s difficult to get approval for new landfills. And even when they get approved, the process is expensive and prolonged. “By recycling cuttings, you reduce the material going into landfills, which extends their life for public use,” Rance points out. “It also mitigates the need for construction materials that come from quarries and other sources, so recycling cuttings reduces the destruction of natural resources.
“Also, it’s cheaper to recycle than to pay tipping fees at landfills,” he says, noting another advantage. “At the end of the day, reusing drill cuttings could be much more economical for drilling companies.”
In and of themselves, drill cuttings aren’t contaminated, except for traces of indigenous metals — such as arsenic and lead — and some naturally occurring radioactive materials that get churned up as the drill bit does its job. Drilling fluids are a much bigger culprit; the fluids, which mix with the cuttings, can contain chlorides, barium and oils, although most of those elements are removed from cuttings via on-site cleaning/separation processes at drilling pads, Rance says.
Officials at Clean Earth first became interested in recycling drill cuttings when they noticed a similarity between cuttings and dredged material, which the company already recycles. (A facility the company operates in New Jersey — one of its 14 East Coast recycling, treatment and processing facilities — is allowed to receive and process more than 6,000 cubic yards of dredged materials per day.)
“In taking a look at the nature of the material and how it was being generated, it became obvious that, from a physical standpoint, the material behaved very much like processed dredged material,” Rance says. “So we sat down with key permitting folks at the Pennsylvania Department of Environmental Protection and said we’d like to try to process drill cuttings.” PADEP officials were intrigued enough with the concept to grant Clean Earth a research and development permit to accept and process up to 1,000 tons of cuttings per day, Rance says.
To test the veracity of Clean Earth’s process, PADEP officials asked the company to demonstrate that recycled cuttings — which are tested to ensure they meet state criteria — could be used to cap specified brownfield sites. Thus far, that effort is considered successful, Rance says.
Drill cuttings get transported from drilling pads, either in trucks or in roll-off cans. Upon arrival at the company’s facility, the cuttings are tested to ensure they meet state-mandated criteria for soil-fill standards; Clean Earth rejects cuttings with levels of contaminants that exceed state-mandated parameters. So far, about 90 percent of the cuttings meet the criteria established by the PADEP, Rance says.
Next, the mixture goes into a receiving pit. From there, an excavator scoops it into a pug mill, also known as a paddle mixer. “Think of it as a giant blender that creates a homogenous mix,” Rance suggests. At the same time, a proprietary cement-like material is mixed in to solidify the cuttings and encapsulate the trace amounts of contaminants. “It takes just a few minutes to mix,” he says. “We mix the cuttings in roughly 1,000-ton batches.”
After that, a conveyor belt transports the cuttings into a material storage area, where each batch is sampled to ensure it meets post-process criteria, also established by the state. “We want to be sure it’s clean enough by state standards,” Rance explains. Then the cuttings get placed in concrete storage cells that can hold about 3,000 cubic yards of material. After each 1,000-ton batch passes a sampling test, they can be commingled, he says. “Typically, we wait three to five days for analytics testing,” he says. “During that time the cuttings cure, or dry out, so to speak. By the time it’s done, the cuttings look just like dirt.”
PLAN FOR THE FUTURE
By spring 2017, Clean Earth officials expect they’ll have amassed enough information for the state to decide if it wants to issue general permits that would authorize companies to process and reuse drill cuttings, as long as they follow a regimented, permitted process. “Right now, drill cuttings don’t meet the state’s clean-fill standards, but we’re using their criteria as a measuring stick,” Rance explains.
If the state approves the Clean Earth process, Rance expects that other states may follow suit and allow companies to process cuttings for reuse, since most states have similar approaches to managing contaminated soils. In the meantime, Clean Earth continues to search for other potential reuse applications, such as strip-mine reclamation projects.
“This material came from the earth,” Rance says. “So there’s no reason why it shouldn’t be beneficially reused.”