Environmental Impact of the Marcellus Shale
Drilling has long been a part of Pennsylvania's energy history. Since 1859, over 350,000 oil and gas
wells have been drilled. Over one million wells using hydraulic fracturing have been drilled nationally
since the technology was developed in the 1960s, and not a single instance of direct groundwater contamination has been tied to the process.
Yet certain special interest groups warn about water contamination, since hydraulic fracturing requires
large quantities of slickwater-a mixture of water, sand, and naturally occurring chemicals or additives.
The majority of the fluid, over 98%, is water and sand. The sand, typically silica sand, is used as
the proppant and keeps the cracks in the shale open while additives keep the pipes clean by preventing
rust and allowing the gas to travel freely.
Environmental concerns include:
Disposal of fracking fluid. In the Barnett Shale, deep-injection wells are widely used, but this solution is not economical for the Marcellus Shale due to Pennsylvania's tightly formed underground geology. Recycling and reuse are the prevalent methods of disposal for wastewater-the industry as a whole reuses 60% of flow-back, leading to fewer water withdrawals. Eventually, wastewater is transported to large treatment plants. By the time water is injected into streams, it meets Environmental Protection Agency (EPA) and DEP standards for cleanliness.
As drilling continues, new treatment plants will be needed, but building new facilities will not be
easy with new regulations more than doubling the cost of construction. New plants will need to charge
upward of 18 to 30 cents per gallon compared to the current rate of 10 to 15 cents per gallon. These new regulations have been enacted despite evidence that agriculture and mine runoff have a much greater impact on water quality than natural gas drilling wastewater.
Leakage of pits and tanks storing fracking fluid. Used fracking fluid is stored in large dug pits lined with
industrial strength liners. Very specific regulations for erosion and sedimentation barriers, as well as
buffer zones from water bodies, must be followed.
Contamination of drinking water due to hydraulic fracturing. While a legitimate concern, there is no conclusive evidence that hydraulic fracturing has caused the contamination of drinking water in Pennsylvania.
In the last 15 years, 32,000 wells were drilled and there have been fewer than 80 cases (0.25%) of
groundwater impacts from drilling (and no health impacts). In other words, 99.75% of all wells had zero
groundwater impact. Furthermore, a study by the Center for Rural Pennsylvania found up to 41% of the
private wells in the state fail to meet health-based standards for drinking water, suggesting other factors
(e.g. agricultural runoff) are more influential on water quality.
Migration of methane gas. Naturally occurring methane travels from high- to low-pressure areas. Changes
in pressure can be caused by a change in water levels, abandoned mines and wells, current mining and
natural gas drilling. Methane contamination in drinking wells is easily remedied by ensuring proper ventilation. DEP regulations require pre-drilling inspections of water wells within 1,000 feet of a gas well.
Pre-drilling tests gather information on methane activity, well construction, and water quality. Residents are strongly encouraged to have their water tested to ensure irresponsible enterprises are held
fully accountable. If landowners suspect pollution they notify the DEP's Bureau of Oil and Gas Management
within six months of drilling completion for remediation.
Habitat disturbances and water consumption. Construction of new gas wells is bound to disturb habitats
in a limited area, but many measures are taken to lessen the impact. Water withdrawals in Pennsylvania
are heavily regulated. A company must comply with DEP regulations and rules from interstate federal
commissions. For perspective, the consumption of fresh water for electrical generation in the Susquehanna
River Basin alone is nearly 150 million gallons per day, while the projected total demand for
peak Marcellus Shale activity in the same area is 8.4 million gallons per day. Estimated water use for
shale gas development will range from less than 0.1% to 0.8% of all water use in the Basin.
After construction, each company is required to return the drilling site to its original form, including
ground cover within nine months of completed drilling. Horizontal drilling allows six to eight wells on
one well pad-accessing the same reservoir volume as sixteen vertical wells. In other words, gas companies
are able to generate more natural gas with fewer wells, fewer pipelines, and fewer disturbances to
the surrounding environment.
Countless studies have shown that properly drilled and operated wells significantly mitigate environmental
threats. In 2004, an EPA study determined hydraulic fracturing posed no danger to water quality (the EPA is currently in the process of updating this study).20 In 2009, the U.S. Department of Energy's Office of Fossil Energy conducted a study concluding, "State oil and gas regulations are adequately designed to directly protect water resources through the application of specific programmatic elements such as permitting, well construction, well plugging, and temporary abandonment requirements." Additionally, the Interstate Oil and Gas Compact Commission (IOGCC) found hydraulic fracturing
non-threatening to the environment or public health.