Health and Safety Considerations for Landfill Gas Operations

SEATTLE (Waste Advantage): Landfill gas (LFG) monitoring is a critical component of landfill care and operations, but it comes with potential health and safety hazards that can lead to negative health effects and environmental impacts. These effects can be mitigated through a hierarchy of controls, proper health and safety planning, use of protective personal equipment (PPE), and implementation of the proper short and long-term operations and maintenance procedures. Read on for key challenges and tips about how to overcome the health and safety hazards that come with LFG operations.

Potential Landfill Gas Health Effects
LFG is a byproduct of the decomposition of organic wastes within a landfill and consists of approximately 40 to 60 percent methane, 40 to 60 percent carbon dioxide, oxygen, and such other constituents as nitrogen, hydrogen sulfide (H2S), hydrogen, and nonmethane organic compounds. LFG can have several negative health impacts, ranging from headaches, fatigue, itchy eyes, sleeplessness, and stress to serious injury or death. To minimize these impacts, LFG is collected in a gas collection and control system (GCCS), a network of installed wells and piping that are placed under vacuum via single or multiple blowers. A GCCS system is the landfill’s primary tool to comply with both state and federal air regulations, reduce greenhouse gas emissions, help reduce the potential for odors, and feed onsite flare systems or renewable energy sources.

Potential Site Hazards from LFG Facility Operations
For workers at a solid waste facility, it is important to focus both on the daily tasks, while understanding and being aware of the various potential hazards associated with working around the GCCS, as well as other operations and at the landfill’s unique terrain. Hazards may include LFG facility operations, including small GCCS construction work (i.e., excavations), well tuning, and surface emissions monitoring. Common hazards include blind spots, heavy machinery accidents, slips, trips, and falls. Unseen hazards also exist from exposure to methane, hydrogen sulfide, and other constituents present in LFG.

Perhaps less common, but still important, is work around electrical infrastructure related to GCCS and associated beneficial-use operations. Electrical (arc flash) could be encountered by workers at blower/flare stations, condensate pump stations, and gas-to-energy plants. The associated risks with electrical components of GCCS include high voltage shocks, burns, and other serious injuries.

Other LFG-specific hazards to watch out for while performing GCCS construction work include hazards associated with LFG well drilling and trenching. These operations may introduce oxygen into the waste mass, increasing the risk for thermal oxidation events (sub-surface fires). Further issues with each of these hazard areas may include:

• Well drilling: Well drilling leads to LFG well boreholes that can get deeper than 100 feet. Protections are needed to prevent workers from falling into the borehole. What is more, site staff should be careful when encountering waste that is removed through a drill rig from the drilled boreholes. The waste coming from the boreholes is typically high in temperature and will have a strong odor.
  • Deep trenches: While an essential part of the GCCS, deep trenches can result in the presence of hydrogen sulfide (H2S), which poses significant health risks, including headaches, dizziness, nausea, loss of breath, loss of consciousness, long-term respiratory problems, cardiovascular disease, neurological disorders, and potentially death. H2S gas is also highly corrosive and flammable.1
  • Thermal oxidation events: Sub-surface fires pose significant risks when constructing GCCS. According to the U.S. Fire Administration, approximately 8,300 landfill fires occur annually. Signs of these events include higher than normal temperatures measured at the LFG wellheads, subsidence of the ground in the vicinity of the well and/or failure of the landfill surface.

Useful Measures for Mitigating Risk on LFG Sites
Many actions can be taken to mitigate health and safety risks at a landfill. Proper equipment setup for installation of a standard LFG extraction well includes guard rails/fencing, a blower to push fumes away from the excavator operator, and drill rig bucket covering the existing drilled borehole (see Figure 3). Following is a brief overview of some LFG-specific mitigation tactics for the risks detailed previously:

Well drilling: Site technicians and engineers should maintain a safe distance away from the bore holes to prevent falls and contact with hot waste. After drilling, a well safety grate should be installed to prevent cave-ins around the area of the backfilled borehole area. Holes should not remain open when unattended. Warning line systems can be established around the borehole during and after construction for additional safety through the use of caution cones (with barrier between the cones), caution ropes, chains, or a combination of these systems.
• Deep trenches: Ensure that workers have access to appropriate personal protective equipment (PPE), including hard hats, ANSI class 2 or class 3 safety vests, eye protection, gloves, respiratory protection gear, and adequate safety training programs. The PPE listed can also protect workers from hazardous gases, such as H2S gas. Personal gas detectors should be worn at all times when working in or near a trench. Personal gas detectors, when worn properly, warn site personnel via an audible alarm of high measured levels of LEL, O2 deficiency or enrichment, carbon monoxide, and other gases that could potentially pose harm to workers. Pre-entry planning and assessment of deep trenches before work is conducted is crucial, as deep trenches have similar hazards and characteristics to that of confined space hazards.
• Thermal oxidation events: Regularly taking the temperature of waste on landfill sites is crucial when completing well reads post-construction. Reporting hot spots to the facility owner can help the landfill investigate existing issues with their GCCS, as well as mitigate a potential future thermal oxidation event.

Developing a detailed health and safety plan (HASP) outlining protocols for ensuring safety while operating is key to maintaining safe site operations and personnel. Establishing standing operating procedures (SOPs) for each step of operations will also help optimize processes and minimize risks.

Holding pre-construction meetings will help the team assess potential site hazards and discuss mitigation strategies. Daily safety meetings can also help address safety concerns as they arise, which may help reduce risk and protect workers. Employing spotters and having limited access to active construction areas will also help prevent accidents.

Another great tool for maintaining trench safety is witness risers, which are placed in the ground after infrastructure is installed. Installed over and in contact with the installed infrastructure, these risers provide visual markers to prevent trenching into a recently installed pipe. The risers can also be used for access to obtain or mark survey locations before being added to the final record drawing plan set once the survey data is received. While maintaining a safe trench, it is crucial to limit the trench length to what can be backfilled before the end of the day to eliminate the concern for odor, and leachate generation.

Courtesy: www.wasteadvantagemag.com