The Overlooked Threat to Our Nation's Drinking Water
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Wastewater from oil and gas drilling operations – disposed of deep underground – recently burbled to the surface in Oklahoma. It wasn’t a one-off. Similar contamination from so-called “injection wells” happened at seven locations across Oklahoma and at twelve California locations between 2008 and 2010. Elsewhere, 673 wastewater injection wells in Kansas and 429 in New Mexico failed safety tests, meaning they’re at risk from leaking into aquifers and drinking water, says a recent ProPublica investigative report.
Deep disposal of industrial waste via injection wells has been common practice in the U.S. since the 1930s and was widely considered to be safe. More than 150,000 active injection wells dot the nation, absorbing 2 billion gallons of waste daily from the oil and gas, chemical, agricultural, and pharmaceutical industries, according to the EPA, which supports the practice as a way to protect soils and surface water from contamination.
Injection wells currently underlie at least 32 states, including those around the Great Lakes, on the Gulf Coast, in Appalachia, Oklahoma, Kansas, Texas, and California.
But as contamination incidents in Oklahoma, California, Louisiana, and Florida, show, this pollution may not stay down. The injection wells used are mostly old oil and gas drill holes; they have no container at the bottom to trap waste. Thousands of injection wells are now leaking, bringing chemicals and waste to the surface or into shallow aquifers according to ProPublica.
Of particular concern are injection wells that are now disposing of huge amounts of wastewater from natural gas hydraulic fracturing, or fracking, wells across the country.
Drilling companies use an average of 5 million gallons of water per “frack” to crack apart underground bedrock and release natural gas. Into that water they mix chemicals – biocides to kill bacteria, scale inhibitors to clear pipes, and lubricants to ensure smooth machinery operation. They also add proppants – tiny particles of sand, quartz or ceramics to hold underground fractures open, allowing gas to flow up to the surface.
The problem is that some of this contaminated water flows back to the surface too, along with added contaminants picked up deep underground, such as naturally occurring salts and radioactive elements.
Companies dispose of this frack wastewater differently depending on the region, though each method is problematic. In the Midwest, West and South, injection wells are standard practice. In the Northeast, wastewater is disposed of in three ways: It is trucked to Ohio for dumping down injection wells; or processed at municipal sewage treatment facilities and then piped into local rivers; or treated onsite and reused in fracking.
Wastewater disposal underground is popular because it’s typically cheaper than treating or recycling. But now that injection wells have been shown to cause surface water pollution, the practice should be carefully reconsidered. Injection wells also forever deprive drought-prone areas of the nation of trillions of gallons of invaluable fresh water.
When selecting disposal alternatives, U.S. and state regulators should recognize that frack water treatment at municipal sewage plants, as done in the Northeast, may not be a good solution, either. Such plants were designed to treat sewage, not the radioactive compounds that can be found in frack water, which can pass straight through the plants into local waterways.
Another problem: when the salt in frack water is combined with the chlorine used at some water treatment plants, it forms chemicals called trihalomethanes that increase the risk of bladder and other cancers with long-term exposure. Not only that, the chemicals in frack water can kill the beneficial bacteria used in sewage treatment plants, making the treatment process less effective.