Marcellus Shale is a large deposit of black shale deposited broadly across the Appalachian Basin and into Ontario, Canada and is characterized by rich, unoxidized carbon. Natural gas deposits trapped deep within the shale is extracted through a process known as high volume hydro-fracking.
…fractured rock is kept open using a “proppant” typically composed of sand or other chemicals. High-volume hydraulic fracturing is named because it uses millions of gallons of water per well. In order to capture a commercially viable amount of gas from the Marcellus shale formation the well is drilled vertically to approximately 500 feet above the formation and then the wellbore is turned horizontal to tap all the tiny pockets and veins of gas in the shale. In Pennsylvania a typical horizontal wellbore is 4,500 feet.
Investigative journalists reported in 2009 that flowback fluid, the contaminated fluid that returns to the surface during the drilling process and production brine, five times saltier than seawater are threatening Pennsylvania’s rivers.
As gas-drilling operations proliferated in Pennsylvania’s Marcellus Shale over the past couple of years, most of the hundreds of millions of gallons of briny wastewater they produced was eventually dumped into the state’s rivers. Much of the rest is unaccounted for. That news, from a detailed look [1] at the state’s management of drilling wastewater by the Associated Press, should come as no surprise to readers of this site.
As we reported [2] in October 2009, Pennsylvania was largely unprepared for the vast quantities of salty, chemically tainted wastewater produced by drilling operations in the Marcellus, the gas-bearing shale formation that stretches under that state and into West Virginia, New York and Ohio. While the state Department of Environmental Protection called for the fluids to be sent through municipal treatment plants, those facilities are largely unable to remove the salts and minerals, also known as Total Dissolved Solids (TDS), from the waste.
As our story noted, abnormally high salt levels in the Monongahela River in 2008 corroded machinery at a steel mill and a power plant that were drawing water from the river. The DEP suspected that drilling wastewater was the cause and ordered upstream treatment plants to reduce their output. But months later levels spiked again.
_ Of the roughly 6 million barrels of well liquids produced in a 12-month period examined by the AP, the state couldn’t account for the disposal method for 1.28 million barrels, about a fifth of the total, because of a weakness in its reporting system and incomplete filings by some energy companies.
_ Some public water utilities that sit downstream from big gas wastewater treatment plants have struggled to stay under the federal maximum for contaminants known as trihalomethanes, which can cause cancer if swallowed over a long period.
_ Regulations that should have kept drilling wastewater out of the important Delaware River Basin, the water supply for 15 million people in four states, were circumvented for many months.
Some public water works found excessive levels of trihalomethanes, a carcinogen, which form when chlorine used to purify drinking water is mixed with bromide from drilling flowback.
