The Environmental Case Against Fracking (Part 4)

Risks to Surface and Groundwater

Potentially, fracking can open cracks thousands of meters underground and connect shallow drinking water aquifers to deeper layers. Investigations have shown that this is relatively unlikely because the depths of sand formations are about 1000-3000 m and data show that man-made fractures rarely propagate more than 600 m. It is more plausible to consider that fractures may connect to a natural fault, an abandoned well, some other underground pathway and allow fluids to migrate upward. Another path is through poor well integrity. That permits direct contamination of groundwater with fracking fluids or materials that seep through these fissures into groundwater. (Jackson et al. Annu. Rev. Environ Resour. 2014.39:327-362, the source of much of the information in this article.)

The best-known contaminant is methane and there are graphic pictures and videos of tap water flowing into a sink being set afire due to the high concentrations of methane or ethane.  This occurred in homes near the Marcellus Shale in Pennsylvania where investigations showed 17-times higher methane concentrations and higher ethane concentrations consistent with a fossil fuel source. Poor casing and cementing were the most likely causes. Industry drilling experts believe that methane migration through casing and cementing problems is a major environmental concern for horizontal drilling and hydraulic fracturing. 

In Pavillion, WY, EPA investigators found benzene at 50 times safe levels in ground water, along with pollutants such as toluene and 2-butoxyethanol, a solvent common in hydraulic fracturing fluids. Fracking in this sandstone formation was as shallow as 322 m and local drinking-water wells were as deep as 244 m. Thus, there was a little vertical separation between fracturing and drinking water and a high probability of contamination. A sampling of 100 drinking water wells overlying the Barnett shale documented significantly higher levels of arsenic, selenium, strontium, and total dissolved solids in water wells less than 3 km from shale-gas wells. 

Contamination of drinking water from fracking or fracking-related activities is real and well documented. Much of it appears to be due to defects in the fracking pipe that allows direct contamination of groundwater. Some, as in Wyoming, is due to fracturing of the ground where drilling has little vertical separation between the fracturing depth and depth of drinking-water wells.

The wastewater generated during the production of oil and gas is a major issue. The United States generates more than 2 billion gallons of wastewater every day from oil and gas operations. These are categorized by the EPA as “special waste “and exempt from federal hazardous waste regulations and constitute a serious challenge to our freshwater resources.

This “special waste” water is classified as flow back or produced water. The former is the fluid that returns to the surface after hydraulic fracturing and before oil and gas production begins. It is about 10–40% of the injected fracturing fluids and chemicals pumped underground that return to the surface. This is mixed with an increasing amount of natural brines from the shale itself. Produced water flows to the surface during extended oil and gas production in primarily reflects the chemistry and composition of deep formation water. These are naturally occurring brines that are quite saline and may contain potentially toxic levels of elements such as barium, arsenic, and radioactive radium. Jackson et al. indicate that the balance of flow back and produced waters from the Marcellus formation in 2011 was 43% flow back and 45% produced. The remainder was drilling fluids. As wells age, there is an increasing amount of produced water. 

Wastewater from fracturing is usually pumped deep underground. Approximately 30,000 injection wells are used to dispose of more than 2 billion gallons of brine from oil and gas operations daily. Wastewater in this country also is sent to private treatment facilities and sometimes recycled or reused. In 2011, companies reported that 56% of wastewater from the Marcellus formation was recycled with most of the remainder sent to water entry by facilities. Currently, wastewater is increasingly sent to facilities with advanced treatment technologies at rates approaching 90% reuse. This is a significant step forward in protecting the earth’s crust, and probably was occasioned by the earthquakes that were caused by pumping wastewater underground. In Europe, deep injection of wastewater is not permitted unless the water is used to enhance oil and gas recovery.

There are other disposal methods, but these are certainly not preferred. Some wastewater is sent to municipal facilities for treatment even though some of these facilities are unprepared to handle the volume and chemicals involved. Some states allow wastewater to be sprayed onto roads for dust control. An experimental application of flow water onto an area of forest in West Virginia killed more than half of the trees within two years. A curious clause in the EPA’s regulations allows operators to release wastewater directly into the environment if the operation is west of the 98th meridian; that is, into relatively arid areas. It may also be released if the water has a use in agriculture or wildlife propagation, such as water for cattle. The practice is not common, but still occurs.

There are two pathways of importance for water contamination from wastewater: surface leaks and spills and inadequate treatment before wastewater discharge. For the former, violations are well documented – in Pennsylvania and in Weld County, Colorado, for example. They require containment as soon as possible since they carry benzene, toluene, ethylbenzene, and xylene into groundwater. The inadequate treatment before wastewater discharge also is well documented in Pennsylvania, by way of example, where water carrying four times the concentration of salt as seawater and with elevated levels of barium, radium, and organic compounds was discharged into rivers. Some salt concentrations and effluents were 5000 to 10,000 times more concentrated than salt than in the river water upstream from the facility.  Other issues involved with discharge of wastewater include the formation of carcinogens, trihalomethanes, particularly associated with bromine release; the disposal of radioactive drill cuttings; and the large amount of water required to dilute the saltwater released into surface waters. The volume of wastewater generated from oil and gas operations is about 1 trillion gallons annually in the United States. This enormous volume leads directly to the potential for induced seismic activity which I discussed in an earlier blog.

The angry public response to these abuses has led to efforts by the oil and gas industry to curtail air pollution and mitigate wastewater contamination. However, they continue and with the increase in residential fracking that we are experiencing, particularly in the Western part of our country, constitute a continuing hazard to the environment and to the health of animals and people who live there. Please see my earlier blogs on the health effects of fracking. We must use every political means at our disposal to bring this contamination to a halt.