PBIOS - October 2021 - 113

Modern Waste Disposal Is Safe, Green
By Gabriel Rio
A healthy oil and gas industry has
been vital to the United States' economic
progress for more than a century, and
sensible regulation has been key to fostering
industry advancement and ensuring
its continued success for the benefit of
our country, consumers and industry.
For decades, oil and gas operators
have been allowed to dispose of much of
their drilling, completion and production
waste by putting it in sometimes unlined
pits or spreading it on ranchland. These
processes were necessary in the 20th century
to enable the oil and gas industry to
satisfy the incredible thirst for energy
that fueled the rapid expansion of the
U.S. and global economies.
However, in the 21st century, the industry
is undergoing an unprecedented transformation
in response to global concerns
about its operations' impact on climate
change. Emissions from flaring and other
production operations have received growing
attention as investors, the media and the
public increasingly apply pressure to reduce
greenhouse gas emissions. The industry is
responding positively, but we can do an
even better job of improving overall environmental
performance even as we continue
to demonstrate our commitment to advancing
our communities' quality of life.
Already, major producers are pledging
to achieve net-zero carbon dioxide emissions
by 2050, with a concerted effort to
make operational changes that lessen any
adverse impacts from oil and gas operations.
Operators compiling their first sustainability
reports are thinking rightfully
about water recycling, reuse and disposal,
as well as improving their ability to monitor
and capture carbon emissions.
While most technologies and processes
at drilling sites have advanced in response,
waste management practices largely have
lagged. More attention can and should be
focused on cost-effective alternatives to
disposing of drilling and production waste
that is exempt from the Resource Conservation
and Recovery Act. Identifying and
leveraging these alternatives can improve
groundwater and soil protections, and further
shrink drilling's carbon footprint.
Traditional Approach
Drilling and production waste contained
in reserve pits during drilling, including
drilling mud components and
cuttings, are not regulated as hazardous
waste because of the RCRA exemption.
Land application, or land farming, of
mud and cuttings, like the use of earthen
reserve pits during drilling, continues
to be allowed in some states, including
Texas and Oklahoma, while others, such
as Pennsylvania and New Mexico, effectively
prohibit the practice.
Typically, reserve pits are dug near
the drilling rig to circulate returns out of
the hole, or to contain waste mud or cuttings.
But in addition to water, clays, and
drill solids or cuttings, the spent material
often includes hydrocarbons, salts and
other constituents that, if not for the
RCRA exemption, likely would be considered
hazardous waste.
When drilling is finished and the rig
moves off location, construction crews
may bury the reserve pit by pushing the
dirt excavated to build it back into the
pit. Some practices install artificial liners
in the pit, but those liners usually are
thin and unreliable. Alternately, the returns
might be removed from the pit
and applied to nearby farm and ranch
land by spreading the material thinly
and tilling it into the soil. Both practices
leave oil and gas operators legally and
financially vulnerable.
Reserve pits and land farming risk the
possibility of groundwater and soil contamination
that can cost operators sizable
remediation sums in the future. Usable
groundwater often is 50-150 feet below
the surface. Depending on soil permeability,
drilling materials stored in pits or spread
on the land easily can migrate downward.
Material spread on the land and tilled
into the soil also can contribute to soil
contamination from salts and hydrocarbons,
which can contact groundwater when
mixed with runoff from rainwater that
recharges groundwater reserves.
GHG Emissions
Hydrocarbons from land-spread materials
evaporate as they degrade and constitute
GHG emissions. Indeed, third-party
engineers estimate this common, traditional
practice can emit 300 metric tons of carbon
dioxide equivalent (CO2e) for each new
well, assuming a horizontal well design
with three strings of casing, 10,000 feet
of productive lateral length, and 60% recycling
of oil-based drilling mud.
Depending on hydrocarbon chain
length, some hydrocarbons will evaporate
quickly while others move into the air
more gradually as the material is exposed
to sunlight, air and microorganisms that
shorten the hydrocarbon chain. Such gradual
evaporation means land-farmed waste
can become a meaningful source of GHG
emissions for an extended time and contribute
to the country's total emissions.
Since 1970, CO2 emissions alone have
increased by about 90%, with fossil fuel
combustion and industrial processes conProfessional
oil field waste
disposal facilities, including
slurry injection wells
and landfills with multiple
liners, sequester carbonrich
waste streams while
protecting groundwater
supplies and the environment
more effectively than
on-site disposal.
OCTOBER PBIOS 2021 113
PBIOS - October 2021

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