Water worries: An introduction to some of the water issues associated with shale gas drilling
by Marla Coppolino, June 22, 2010
Over recent months, it has been nearly impossible to avoid news on the issues surrounding the proposed Marcellus Shale gas well drilling. Yet despite all the information coming through the media each day, we are challenged to make informed decisions with often conflicting reports of the possible consequences to our environment and to our health. How can we best educate ourselves about the issues, and parse the evidence from the opinions? This article aims to provides an introduction to some of the water-related issues that readers, particularly landowners, should consider as they develop their own informed opinions and decisions.
Chemicals used in hydrofracking
The Marcellus Shale is rich in gas reserves, but this gas is not easily accessible due to the nature of its distribution in the rock - the gas is trapped in the shale in tiny pores that are not connected to each other. In order to extract the gas, the shale must be hydraulically fractured ("hydrofractured" or "hydrofracked" or "fracked") by injecting into horizontally-drilled wells large amounts of water mixed with a chemical solution under extremely high pressure. This chemical mixture, referred to be some as a "chemical cocktail," has been a topic of much community concern, as the exact chemicals have not been disclosed to the public due to the proprietary nature of the formulations.
Gas companies typically use a number of safety measures to ensure that the ground layers do not become contaminated, such as adding casings to the drilling wells. Even if the protections were always effective, additional public concerns about the potential negative chemical impacts on the environment arise from the possibility of accidental spills or leaks arising from the fracking procedure, or from the handling and treatment of the solution, before or after the frack.
The Chesapeake Energy Corporation, largest independent natural gas producer in the United States, with gas drilling experience in several states and tentative plans to expand into New York, reports a typical hydrofracking mixture consists of 99.51% water and sand, with the other 0.49% comprised of acid, friction reducer, surfactant, potassium chloride, gelling agent, scale inhibitor, pH adjusting agent, breaker, crosslinker, iron control, corrosion inhibitor, and antibacterial agent. This mixture includes more than 200 chemicals such as petroleum distillates, glycol ethers, hydrocarbons, volatile organic compounds (VOCs), formaldehyde, and benzene. The concentration of this group of chemicals comprising 0.49% of the fracking solution may seem minuscule, but in considering that an average of 3 million gallons of water are used per frack, the amount of chemicals injected into the ground for one fracking process is considerable. Many of these chemicals never biodegrade; they remain in the ecosystem and can potentially migrate up the food chain.
Some of the ingredients in the fracking solution, such as sucrose and silica, are benign in terms of their effect on the environment. Chemicals like benzene, however, are known carcinogens. All chemicals can be looked up in Material Safety Data Sheets (MSDS), and while the exact proportions of these in the fracking mixture remain proprietary information, we can at least educate ourselves about these chemicals in detail through the MSDS, which are accessible public information. There are numerous websites with MSDS information, and the link provided here is for a site that contains over 3,500,000 sheets, with over 10,000 updated or added each week: http://www.msdsonline.com/
According to Katherine Nadeau, water and natural resources program associate of the Environmental Advocates of New York, the fracking fluid's chemical cocktail is just one concern of potential harm to the environment. Even if only pure water was used to frack the wells, the flowback water could still be contaminated by harmful substances, such as heavy metals and radiation. The kinds and amounts of these substances could vary from site to site. Another major concern is that there are salts in the rock layers below southern New York, and flowback water could be high in salinity, containing not only sodium chloride, but also magnesium and calcium salts. Nadeau stresses that treatment for saline water is energy intensive and expensive, and currently the state does not have clear plans for removing the salt from flowback water.
At what levels might fracking chemicals be harmful, if they are either accidentally released or purposely vented into the environment, such as during natural gas processing? Take again, for example, the chemical benzene. Benzene concentration is measured in parts per million (ppm), and only a very tiny amount has the potential to impact the environment negatively. Benzene can be smelled as odor in the air around 5 ppm and tasted in water at as little as 0.5 ppm. At levels between 700 and 3,000 ppm, benzene can cause headaches, dizziness, and loss of consciousness, and brief exposure to 10,000 to 20,000 ppm benzene in the air can cause death. (Source: http://www.eco-usa.net/toxics/chemicals/benzene.shtml.) We also need to consider that benzene is already present in natural and in everyday sources, such as gas emissions from fires, and even from cigarettes and cleaning products that use benzene as an ingredient. Many of us experience some degree of exposure to benzene on a regular basis. Will benzene concentrations increase due to some or all hydrofracking operations, if so, how problematic will the concentrations be? This example is emblematic of questions that need to be asked about many chemicals that might be used in hydrofracking activities.
The Susquehanna River Basin Commission (SRBC) regulates surface and groundwater withdrawals and consumptive uses of water in the area, which spans from south-central New York through the eastern part of Pennsylvania. The natural gas industry falls under their purview as they withdraw water from the Basin's streams and rivers (or purchase from water suppliers) to frack the wells.
Jennifer Hoffman, section chief of monitoring and assessment at SRBC, states that many of the companies drilling in the Marcellus formation are reusing most of the flowback water at other drilling pads. She provides some current figures on water usage in Pennsylvania gas drilling operations, compiled from post-hydrofracture reports that gas companies are required to submit to the SRBC:
Based on these reports, an average, 84% of water brought on site is used. The maximum percentage is 100% and the minimum percentage is 30%.
- On average 10% of injected water is recovered. The maximum percentage is 57% and the minimum percentage is 1%.
- 59% of wells use flowback water in fracking. 56% companies use flowback in fracking.
- On average 88% flowback water brought on site is used.
- The maximum, average, and minimum of water injected are 8.3 mgal, 3.0 mgal, and 0.1 mgal.
- The maximum, average, and minimum of flowback transferred are 1.2 mgal, 0.3 mgal, 0.0 mgal.
- The maximum, average, and minimum of flowback disposed are 1.6 mgal, 0.3 mgal, and 0 mgal.
The average total volume of fluid used per well: 3.2 million gallons.
The importance of baseline data
Nadeau considers one of the most important needs at this time to be acquisition of baseline data, and ideally, to have a policy enforced that has gas companies perform baseline water testing. Baseline data are essential if any quantitative assessments are to be made, particularly before major change is made to an environment. Such data are often used, for example, before dam construction to assess biodiversity and abundance of organisms inhabiting a river. One type of statistical test is the Before-After Control-Impact (BACI), usually employed in cases where human-imposed changes to an area are planned, to document quantitatively consequent changes to the surrounding natural environment. Likewise, scientifically it is essential to measure environmental variables in an area both the before and after hydrofracking. Local water, air, and soil chemistry profiles could be included as baseline data, plus quantitative measurements of wildlife that exist in the area to be fracked.
It is well known that central New York supports a great abundance and diversity of aquatic and terrestrial organisms, and special care should be taken to understand the balance of wildlife that inhabits our surroundings. Implicating hydrofracking processes in toxicity found in soil, air, or water will be much more scientifically credible if there is baseline data to support that contaminant levels rose in association with hydrofracking.
Individual homeowners who use well water as their main water source might also consider some baseline tests for their water. A wealth of information on water testing is available from a page on Cornell Cooperative Extension's website: http://waterquality.cce.cornell.edu/testing.htm
What else should we know?
In thinking about the possibility of future drilling, just a few of the unanswered questions include:
- Where will the water used in the hydrofracking fluid mixture come from?
- How will the flowback water in Tompkins and surrounding counties be treated?
- What will happen to any sludges left over from treatment processes?
- Will levels of VOCs in the air be measured and reported?
When these questions were posed to Lindsey Von Tungeln, landman of the eastern division, north district of the Chesapeake Energy Corporation, he was not able to provide information: "Due to the current moratorium on Marcellus Shale drilling and hydraulic fracturing in the State of New York, Chesapeake Energy cannot speak to what the operations would entail in a specific area."
From a scientific perspective, additional research and preparation, plus strategies to deal with leaks and accidents, remain to be accomplished before shale gas drilling begins in New York. Making informed decisions about the potential drilling of the Marcellus Shale requires that we have a firm understanding of the science associated with the issue.
Marla Coppolino is a free lance science journalist living in Groton, NY. This article is the first in a series by science journalists on some of the science issues involved in Marcellus shale gas drilling.