Fracking, thousands of spills and accidents in US oil and gas wells

Spills of polluted fluids and chemicals from 16% of unconventional hydrocarbon wells

According to the study of "Unconventional Oil and Gas Spills: Risks, Mitigation Priorities, and State Reporting Requirements" published by Environmental Science & Technology by a team of US researchers led by Laureen Patterson of the Harvard Law School's Environmental Policy Initiative, the situation of the pollution generated by the USA fracking wells is serious: every year, from 2 to 16% of oil and gas wells exploited by the fracking technique in Colorado, New Mexico, North Dakota and Pennsylvania there have been spills of hydrocarbons, water filled with chemicals, fluids of hydraulic fracturing and other substances. The largest spillage tested by the study resulted in the leak of 100,000 liters of polluting liquids.

The study dealt with unconventional oil and gas spills in 31,481 wells operated by fracking technique in the 4 US states between 2005 and 2014, identifying 6,648 spills over the past 10 years. In all states, the first three years of a well's life, during drilling and hydraulic fracturing, have had the highest production volumes but also the highest risk of spillage. A significant part of the spills (from 26% in Colorado to 53% in North Dakota) occur in wells that have suffered more than one spill, "Which suggests that wells in which spillages have already occurred deserve more attention," they say researchers.

Figures that worsen many of the previous study, "Environmental Impact Assessment of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources" of the Environmental Protection Agency (EPA) on fracking in 8 US states between 2006 and 2012, which had concluded that there were 457 spills.

Patterson, interviewed by BBC News, explains why this strong difference: "The EPA has only looked at spills during the same process of hydraulic fracturing, which take place only in a period ranging from a few days to a few weeks. We have investigated spills in unconventional wells from the time of perforation throughout the production, which could last decades. "

In North Dakota, there were 4.453 accidents 

recorded

 , much more than in Pennsylvania, Colorado and New Mexico, and this can be explained with the different types of reporting. In North Dakota there must be reported any spill over 42 gallons, while in Colorado and New Mexico starts from 210 gallons.

Most of the spills occur during the first three years of wells activity and about 50% of spills occur from the pipelines for the transport of polluted fluids.

"The causes are quite different," says Patterson. "Equipment failures are the major factor, loading and unloading of trucks with material is a far more common human error than in other places."

. Researchers are convinced that "making state data on spills more consistent and accessible could provide stakeholders with important information on where to target efforts to identify and prevent 

future

 losses. However, reporting obligations differ between states, which requires considerable effort to make the data usable in order to be able to analyze them. "

Another author of the study, Kate Konschnik, also of the Harvard Law School, concludes: "Analysis like this is really important to defining and reducing the risks for water supply and human health. Writing state regulations for reporting these factors in mind is crucial to ensuring that correct data is available in the industry, the states and the research community, and in an accessible form. "