Mining of Coal (College Board AP® Environmental Science): Study Guide

Impacts of mining coal

Habitat destruction

• Surface mining, especially mountaintop removal, destroys forests and ecosystems

• Strip mining removes large sections of soil and rock, permanently altering landscapes

• Loss of vegetation disrupts wildlife populations, leading to species displacement

Groundwater contamination

• Coal mining exposes toxic heavy metals, such as arsenic and mercury, which leach into groundwater

• Acid mine drainage (AMD) occurs when sulfide minerals react with water and air, producing sulfuric acid that contaminates rivers and groundwater

  • Example: The Appalachian region in the U.S. has suffered from AMD due to extensive coal mining

Air pollution

• Coal dust from mining operations can cause respiratory diseases such as black lung disease in miners

• Methane (CH₄), a potent greenhouse gas, is released from coal seams, contributing to climate change

• Particulate matter from coal processing and transport can reduce air quality in surrounding communities

Soil degradation and erosion

• Removing vegetation and topsoil leads to loss of fertile land

• Soil compaction from mining equipment reduces the ability for vegetation to regrow

• Increased erosion leads to sediment buildup in nearby water bodies, harming aquatic ecosystems

Subsurface mining of coal

What is subsurface coal mining?

• Subsurface mining is the process of extracting coal from underground deposits through tunnels and shafts

• Used when coal reserves are too deep for surface mining methods

• Historically very labour-intensive, but modern subsurface mining is now highly mechanised and employs far fewer workers than people often imagine

  • The dominant method today is longwall mining — see below

Longwall mining—the dominant modern method

• Longwall mining is the dominant method of subsurface coal extraction in industrialised countries today

• How it works:

  • A long mechanised cutting machine called a shearer moves back and forth along a coal seam, slicing off large blocks at high speed

  • Hydraulic roof supports advance along with the shearer, holding the roof up over the working face

  • The rock above the worked-out area is allowed to collapse safely behind the supports as they move forward

• Despite its scale, longwall operations use very few workers:

  • A typical longwall face is run by a small team of around 6–10 people per shift

  • Coal is extracted by machinery, not by miners working with hand tools

  • This dispels a common misconception that coal mining still relies on large numbers of miners with picks and shovels working underground

• Longwall mining still carries substantial environmental and safety risks, including land subsidence, methane release, and coal dust exposure

Challenges and costs

• High operational costs:

  • Requires specialized machinery, ventilation systems, and structural reinforcements to prevent collapses

• Worker safety risks:

  • Exposure to toxic gases, explosions, and cave-ins makes subsurface mining one of the most dangerous jobs

• Slower extraction rates:

  • Unlike surface mining, where coal is removed in large quantities, subsurface mining is more time-consuming

• Land subsidence:

  • Mined-out areas collapse, causing ground instability and damage to buildings and infrastructure

  • Can lead to sinkholes in regions with extensive underground mining