Hydraulic fracturing is a drilling technique used to access oil and natural gas in low-permeability rock. Its key environmental concerns for AP Environmental Science are groundwater contamination risks and air pollution from VOC emissions.

What Fracking Is (and Why It Raises Environmental Concerns)

Core idea of the process

Fracking increases flow from tight rock by injecting a high-pressure mixture of water, sand, and chemicals to create and hold open fractures so hydrocarbons can move toward a well.

Where impacts originate

Environmental impacts are concentrated at:

• The well pad (drilling, pumping, storage tanks, compressors)

• The subsurface wellbore (integrity of casing/cement)

• The water and waste stream (flowback/produced water handling)

Groundwater Contamination Pathways

How fracking can contaminate groundwater

Groundwater contamination concerns focus on whether pollutants can reach aquifers used for drinking water. Major pathways include:

• Well casing/cement failure: If steel casing or cement is poorly installed or degrades, fluids (or methane) can migrate into surrounding rock and potentially into groundwater.

This diagram shows a typical sequence of nested steel casing strings and cement in the upper portion of a gas well (not to scale). It highlights how multiple cemented barriers are designed to isolate groundwater-bearing zones from fluids moving inside the wellbore. Source

• Surface spills and leaks: Chemicals, fuels, and wastewater can spill during transport, mixing, storage, or transfer; contaminants can infiltrate soil and percolate downward.

• Wastewater mismanagement: Improper containment, illegal dumping, or failures in storage infrastructure can release contaminants that eventually reach groundwater.

What might contaminate groundwater

Potential contaminants associated with fracking operations include:

• Salts (high TDS) from deep formation water

• Hydrocarbons (e.g., petroleum compounds)

• Fracturing additives (varies by site; can include surfactants, friction reducers, and biocides)

• Metals and naturally occurring radioactive materials (NORM) that may be brought up in wastewater

Factors that influence risk

Risk is site-specific and depends on:

• Depth and geology separating the target formation from aquifers

• Well integrity (construction quality, maintenance, and monitoring)

• Proximity of operations to recharge zones, faults, and private wells

• Frequency and volume of chemical and wastewater handling at the surface

VOC Emissions and Air-Quality Impacts

What VOCs are and why they matter

Fracking operations can release volatile organic compounds (VOCs) from:

• Flowback and produced water (evaporation from tanks and impoundments)

• Pneumatic devices, valves, and fittings (leaks during operation)

• Venting and flaring during well completion and maintenance

• Truck traffic and diesel engines supporting the site

VOCs matter because they:

• Contribute to ground-level ozone (smog) formation when reacting with nitrogen oxides in sunlight

• Include compounds with direct health concerns (some VOCs are toxic at elevated exposure)

When emissions can be highest

Emissions can spike during:

• Well completion (early production period when flowback is highest)

• Equipment start-up/shutdown events

• Periods of heavy truck traffic and on-site processing

Pollution Prevention and Risk Reduction (Conceptual)

Practices that reduce groundwater risk

Common protective approaches include:

• Multiple casing strings and cementing to isolate aquifers

• Pressure testing and integrity monitoring to detect leaks early

• Secondary containment for tanks and chemical storage

• Careful wastewater handling and documented chain-of-custody procedures

Practices that reduce VOC releases

Emission-reduction approaches include:

• Leak detection and repair (LDAR) programs for components that commonly leak

• Vapour recovery on tanks

• Reduced venting during completion (capturing gas rather than releasing it)

Key Trade-offs to Keep in View

Fracking can increase domestic energy supplies, but AP Environmental Science emphasises that it can:

• Contaminate groundwater through well integrity failures and surface/wastewater releases

• Release VOCs that degrade air quality and contribute to smog formation