EXPLAINER | Deep Injection Wells: How Drilling Waste Is Disposed Underground
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Deep Injection Wells: How Drilling Waste Is Disposed Underground

clearfield county

Courtesy of Marianne Atkinson

The Irvin deep injection well in Clearfield County is operated by Exco Resources.

Deep injection wells are also called brine disposal wells, and are officially known as class II underground injection wells. They can take any fluid related to oil and gas drilling, including frack waste water.

In Pennsylvania, the wells are regulated by the Environmental Protection Agency through the Underground Injection Control Program (UIC). The EPA took over the task of permits, inspections and enforcement from state regulators in 1985.

According to the Environmental Protection Agency, there currently seven active deep injection wells for oil and gas waste in Pennsylvania. Three others have received permits from the EPA that either remain inactive or are being appealed.

The oil and gas industry uses injection wells to dispose of waste water, which has a high salt content, as well as chemicals, heavy metals, and radioactive material. Much of the frack water produced in Pennsylvania gets trucked to Ohio, which has more disposal wells. Water can also be treated at private treatment facilities. The process cleans most of the water, but at least some smaller amount of fluid, or solid “cake,” still needs to be injected back into the ground, or taken to a landfill. Prior to 1985, operators were allowed to dispose of brine in the state’s waterways.

No fracking is permitted with deep well injections. The wells are cased, and the waste water is sent thousands of feet below the surface, usually to a sandstone, or limestone formation.

Three of Pennsylvania’s deep injection wells are commercial, which means they can take water from any energy company. The others are permitted only to dispose of their own frack water. Some take as low as 4200 barrels per month, but most of them can take about 30,000 barrels a month. EXCO Resources operates two in Clearfield County. The EPA temporarily shut down one of those injection wells and fined the company in 2012 after the company noticed the well was leaking brine and continued injecting fluids into it for months without notifying the EPA.

Other operators include Bear Lake Properties, Columbia Gas, Cottonwood and CNX Gas. Those wells are in Beaver, Somerset and Warren counties. When it comes to pressure, the wells are permitted to take between 1300 to about 3200 pounds per square inch. The two newest permitted wells will be operated by Windfall oil in Clearfield County and by Seneca Resources in Elk County. But local officials and residents have challenged those permits and they’re currently under review. All ten permitted deep injection wells are in the western part of the state.

Lately, these types of deep injection wells have been linked to earthquakes in Texas, Arkansas and Ohio.

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