Reducing Landfill Safety Risks

Landfills can emit unpleasant odors as well as landfill gas, which can migrate through soil and accumulate in nearby buildings. Some of the more hazardous gases produced within landfills include, methane, carbon dioxide, ammonia and sulfides. While hydrogen sulfide and ammonia are the main culprits in terms of bad odors being emitted from landfills, the odorless gases — methane and carbon dioxide — are of higher concern as they are not as readily detected as their foul-smelling counterparts. Methane is an explosive gas that is highly flammable, and both methane and carbon dioxide can accumulate in nearby buildings where they can displace oxygen and pose a health and safety risk.

Landfill Gas Composition

Landfill gas is produced as organic waste is broken down by bacteria. The amount of gas produced varies according to the age of the landfill, the type of waste within the landfill, the amount of oxygen and moisture present, and the temperature within the landfill. The amount of gas produced will increase if there is an increase in moisture of temperature. Landfill gas production typically peaks between 5-7 years, however, it is not unusual for landfills to continue producing gas for 50 years or more.

Migration of Landfill Gas into Buildings

Landfill gases can migrate off a landfill site, moving through soil to be released into the atmosphere, or into indoor air of buildings sited nearby. Landfill gases that have been emitted to the atmosphere can enter buildings via doors, windows or ventilation systems; or they can move through soil and enter buildings through drains, cracks in the walls or floors of basements, or via points such where electric or water pipes enter the building. Once landfill gases enter a building, they can accumulate in basements, utility tunnels, and other poorly ventilated areas.

Landfill Safety Risks

Landfill Safety Risk 1: Ammonia & Hydrogen Sulfide Health Risks

Exposure to high concentrations of hydrogen sulfide and ammonia in air can cause a wide range of symptoms, including: headaches, nausea, eye, nose and throat irritations, coughing and breathing difficulties.

Landfill Safety Risk 2: Methane Safety Hazards

While landfill gas explosions are uncommon, considering that a large percentage of landfill gas is made up of methane, a highly flammable and explosive gas, especially in confined spaces that are poorly ventilated, it is essential that landfill managers monitor methane levels and take the necessary safety precautions. Methane is considered an explosion hazard when levels reach between 5-15% of the total air volume.

Landfill Safety Risk 3: Methane and Carbon Dioxide Health Risks

Carbon dioxide and methane are colorless and odorless and have a tendency to displace oxygen in confined spaces with poor ventilation. The health risks associated with carbon dioxide and methane stem from oxygen deprivation rather than health effects resulting directly from these gases. Lack of oxygen can lead to an increased heart beat and deep breathing, and in severe cases when oxygen levels drop below 21% of the total air volume, symptoms include: fatigue, poor coordination, nausea and vomiting, and loss of consciousness.

Controlling Landfill Gas Migration

Once a landfill has reached its maximum capacity the landfill mass is covered with cover material several feet deep. Gas collection wells consisting of perforated pipes that allow the gas to easily travel upwards to the surface rather than horizontally outwards and migrate offsite are installed throughout the covered landfill. Landfill gas collected in this manner is either vented into the atmosphere, burned in a flame, filtered, or collected in a gas recovery program. Gas vents need to be maintained to ensure that they are not obstructed by debris or snow, so that gas can escape into the atmosphere rather than accumulate and migrate off site.

Landfill Gas Monitoring

In order to ensure the health and safety of both employees and neighboring communities, landfill managers need to monitor emissions from their sites. This can be done using a handheld gas detection instrument that can take readings of methane and other hazardous gases and alert managers when levels are higher than they should be so that they can take steps to reduce the safety risk.

Featured Image: "HAZMAT Class 2-1 Flammable Gas", Licensed under Public Domain via Commons