eFracking looks to break through perceptions

Announce that your company will be “fracking” in their neighbourhood and residents will be on the lookout for drilling platforms and oil derricks.

That’s turned into a public relations problem for environmental remediation companies offering environmental fracturing—or eFracking—a benign treatment that employs the physics of shale fracking to clean up contaminated sediment and groundwater.

Successful oil and gas fracturing dates back to 1949, more than 40 years before the commercial availability of eFracking. Using this technique, drillers inject water, surfactants, trace chemicals and fine sand into hydrocarbon-rich shale formations. The sand particles prop open the fractures created by the fluid, releasing oil and gas.

“The physics of eFracking are similar to oil and gas in that pumps are used to drive water, sand and amendments into the ground,” says Bruce Tunnicliffe, president of Vertex Environmental Inc. of Cambridge, Ont. “However, where oil and gas fracking sites cover hectares, eFracking is performed on a small scale, usually less than 1,000 square metres, and requires only a fraction of the water used by gas and oil drillers.”

The fluid used in eFracking is 99.5 per cent sand and potable water with the addition of a small amount of bio-degradable sugar-based polymer. Sand content is critical, because it creates the medium required to move soil amendments through the fractures in the soil.

“You need to inject under enough pressure so the ground opens up,” says Tunnicliffe. “That’s why the eFracking treatment works better in clay and tighter soils instead of loose, sandy soil. Once you create these thin bands of sand, water flows easily through those newly fracked sand layers, allowing you to reach the contaminants you need to treat.”

Some remediation chemicals, such as oxidants like permanganate, work immediately to neutralize solvents. Others, such as zero valent iron, may remain in the ground for years to continuously and slowly remediate subsurface contamination. The use of eFracking makes such in situ approaches viable, even in clay and bedrock.

While Vertex develops the overall remediation approach, Tunnicliffe sub-contracts the fracture network design and actual fracking work to such companies as TOTERRA Remediation with Canadian offices in Calgary and Burlington. The company supplies large, specialized pumps, fracture fluid, downhole tooling and trained personnel.

The ability to control the initial depth and size of the fracture is part of the expertise the company provides using custom-designed equipment.

“The secret sauce of what we offer is the carrier fluid and how we initiate a fracture using the downhole tooling,” says Scott Barker, vice-president of TOTERRA. “We have five or six different tools that we can snap onto drill rigs to offer a great deal of flexibility, depending on the local lithology. We can even reach contaminants underneath buildings without major excavation—just drilling.”

As TOTERRA technicians control the initial depth and radius of the fracture, three-dimensional mapping equipment verifies the location of the entire fracture network. This system keeps tabs on the location of the network relative to the contaminant plume, to ensure that injected fluids treat the contamination without spreading it.

“The borehole is used as the extraction well to remove contaminants or as the injection well to deliver treatment amendments,” says Barker. “We can almost immediately apply a vacuum to the borehole using a vacuum truck. We might then treat extracted chemicals on site, or transport them elsewhere for treatment.”

Barker notes that, like the oil and gas industry, TOTERRA favours hydraulic eFracking, while some contractors offer pneumatic eFracking.

“Air doesn’t carry the treatment amendments very well,” he says. “Also, air tends to follow existing fractures instead of creating new ones.”

The price of eFracking currently ranges around $16 per ton of treated soil. Whether that’s considered expensive or not depends on the project, including the remediation budget, type of soil, type of contamination, local groundwater patterns and the speed at which the client wants the remediation to take place.

“It depends on the client’s goals,” says Tunnicliffe. “If eFracking can save years of remediation work on a site waiting to be developed, then it would be very cost-effective.”