113
per day. The strategy for the “fire sale” prices was that the liability for proper P&A
of the well was no longer the responsibility of the original operator.
Sometimes a beneficial use such as crop irrigation can be found for O&G produced water if it is relatively fresh. Unfortunately, most of the formation water from
deep production wells is very salty brine that is not useful, at least not on crops. The
TDS in produced water from the Marcellus Shale is about six times higher than
seawater (Hayes 2009). Water produced from the Bakken Shale is up to ten times
saltier than the ocean (Cozzarelli et al. 2017). As mentioned earlier, the brines are
high in chlorides, bromides, various toxic metals, and often contain radium. These
high TDS fluids must be disposed of in a safe and cost-effective manner.
Municipal wastewater treatment plants were commonly used for the disposal of
produced water during the early stages of shale gas development in the U.S. (Soeder
2017). These facilities, designated “Publicly-Owned Treatment Works” or POTWs
by the EPA, are designed to remove suspended solids and plant nutrients from
municipal sewage to prevent downstream algal blooms and fish-killing anoxia.
They do essentially nothing for dissolved inorganic solids, however, and the high
TDS brines went right through them and exited the effluent pipes into freshwater
streams. As one can imagine, this saltwater had a rather negative effect on the downstream biota. A 2011 risk analysis of the disposal of produced water through POTWs
in Pennsylvania concluded that at least 200 m
3
of high TDS fluids from each
Marcellus Shale well were being released as effluent into streams (Rozell and
Reaven 2012). At the time, this was identified as one of the greatest environmental
risks of shale gas development. Despite changes in practices for most shale gas
operators, POTWs are still used for some produced water disposal if an industrial
sewer discharge permit can be obtained.
Another option for surface disposal of produced water is known as a centralized
wastewater treatment plant or CWT. These are commonly privately-owned (versus
municipal) facilities set up for the treatment and disposal of industrial wastewater
from factories and other manufacturing operations. The EPA is currently investigating the amount of shale gas wastewater being accepted by CWT facilities, the available treatment technologies and costs, discharge characteristics, and environmental
impacts (https://www.epa.gov/uog#swdischarges).
In addition to detrimental impacts on aquatic ecosystems, the bromides and chlorides in produced water can also cause human health effects. Although no one is
directly drinking the produced water from an oil well, these chemicals may combine
with natural organic material in surface streams to form halogenated compounds. If
the stream provides a drinking water supply that is subsequently disinfected by
chlorination, these precursor compounds will react with the chlorine to create new
substances known as disinfection byproducts (DBPs) in the treated water (Hladik
et al. 2014). DBPs include brominated tri-halo methane and halo-acetic acids, both
of which have been linked in laboratory experiments to cancer and other health
problems in humans (Coffin et al. 2000). DBPs do not form in drinking water that
has been disinfected using ozone, but ozone treatments are more expensive and
therefore less common than chlorine.
6.3 Water Supply and Disposal
per day. The strategy for the “fire sale” prices was that the liability for proper P&A
of the well was no longer the responsibility of the original operator.
Sometimes a beneficial use such as crop irrigation can be found for O&G produced water if it is relatively fresh. Unfortunately, most of the formation water from
deep production wells is very salty brine that is not useful, at least not on crops. The
TDS in produced water from the Marcellus Shale is about six times higher than
seawater (Hayes 2009). Water produced from the Bakken Shale is up to ten times
saltier than the ocean (Cozzarelli et al. 2017). As mentioned earlier, the brines are
high in chlorides, bromides, various toxic metals, and often contain radium. These
high TDS fluids must be disposed of in a safe and cost-effective manner.
Municipal wastewater treatment plants were commonly used for the disposal of
produced water during the early stages of shale gas development in the U.S. (Soeder
2017). These facilities, designated “Publicly-Owned Treatment Works” or POTWs
by the EPA, are designed to remove suspended solids and plant nutrients from
municipal sewage to prevent downstream algal blooms and fish-killing anoxia.
They do essentially nothing for dissolved inorganic solids, however, and the high
TDS brines went right through them and exited the effluent pipes into freshwater
streams. As one can imagine, this saltwater had a rather negative effect on the downstream biota. A 2011 risk analysis of the disposal of produced water through POTWs
in Pennsylvania concluded that at least 200 m
3
of high TDS fluids from each
Marcellus Shale well were being released as effluent into streams (Rozell and
Reaven 2012). At the time, this was identified as one of the greatest environmental
risks of shale gas development. Despite changes in practices for most shale gas
operators, POTWs are still used for some produced water disposal if an industrial
sewer discharge permit can be obtained.
Another option for surface disposal of produced water is known as a centralized
wastewater treatment plant or CWT. These are commonly privately-owned (versus
municipal) facilities set up for the treatment and disposal of industrial wastewater
from factories and other manufacturing operations. The EPA is currently investigating the amount of shale gas wastewater being accepted by CWT facilities, the available treatment technologies and costs, discharge characteristics, and environmental
impacts (https://www.epa.gov/uog#swdischarges).
In addition to detrimental impacts on aquatic ecosystems, the bromides and chlorides in produced water can also cause human health effects. Although no one is
directly drinking the produced water from an oil well, these chemicals may combine
with natural organic material in surface streams to form halogenated compounds. If
the stream provides a drinking water supply that is subsequently disinfected by
chlorination, these precursor compounds will react with the chlorine to create new
substances known as disinfection byproducts (DBPs) in the treated water (Hladik
et al. 2014). DBPs include brominated tri-halo methane and halo-acetic acids, both
of which have been linked in laboratory experiments to cancer and other health
problems in humans (Coffin et al. 2000). DBPs do not form in drinking water that
has been disinfected using ozone, but ozone treatments are more expensive and
therefore less common than chlorine.
6.3 Water Supply and Disposal