TAKE THIS SHORT landfill quiz. First question. What is a landfill? A) A construction site; B) A manufacturing facility with an input (vehicles carrying waste materials), a product (safe disposal at the active areas) and manufacturing by-products (landfill gas, leachate and gas condensates); C) Both.
C, of course, is the correct answer, which means that even within the industry, landfills mean different things to different people. As a result, landfill safety varies depending on the different stages of a facility's life. Each stage of landfill operations has its own hazards and solutions.
During a landfill's operating life, disposal and construction operations take place simultaneously and become more complex. Vehicle traffic, unloading operations, gas recovery, leachate management, slope maintenance, road development, special waste streams, alternative daily covers, demolition wastes, landscaping and other green wastes all present different hazards that require constant attention.
Over the years, waste management professionals have identified the related safety issues, and in many cases have implemented practical safety solutions. As a result, landfills now are among the safest places to work in the solid waste industry.
Constructing a landfill presents its own set of safety problems. Often the process is overlooked by owners who assume that hired contractors will handle the safety issues. While most contractors are conscientious business people, landfill owners should not assume that the people they hire have their own safety programs.
The stakes are too high to ignore the potential problems that can occur during landfill construction. For example, various types of construction equipment (e.g., scrapers, compactors) are used to build a landfill. Developing waste disposal cells generally involves excavation. Installing liners and gas recovery and leachate collection systems requires filling areas with clay and crushed stone. A variety of construction equipment and personnel also are used to build maintenance buildings, material recovery facilities and offices.
Construction safety begins by selecting qualified contractors with a proven history of safe work. One way to evaluate contractors is by reviewing their Evaluation of the Experience Modification Rate (EMR), which is issued by their insurance company. Generally, an EMR of 1.0 means the number of a company's claims is average for their industry, while an EMR above 1.0 is given to those with an above-average amount of claims. An EMR of less than 1.0 means the company's claims are below the industry average and usually indicates a history of safe work. Implementation of comprehensive safety training and inspection programs also reflect a contractor's commitment to safety.
Landfill owners expect contractors to use workers who have been trained to work at this specific type of facility. For example, depending on their work assignments, a contractor's employees and sub-contractors must understand the potential hazards of landfill gas and leachate; the dangers of working near active disposal areas; driving restrictions, such as landfill road speed limits; and site emergency procedures. Many landfill operators require contractors to prove that their workers have received or will receive that training.
Generally, the agreement between the landfill owner and the contractor stipulates that the contractor must comply with site-specific and regulatory safety requirements. Many landfill operators perform a review of the contractor's safety programs, which can be used as a benchmark to measure the contractor's ability to perform the work safely. During the contracting or program review process, landfill operators will provide contractors with copies of the landfill's work and safety rules.
State and federal safety regulations require contractors to assess their work areas and workers every day. Landfill operators expect contractors to fully comply with the site's work rules. Periodic inspections often are performed by landfill safety and operations personnel to determine if the contractor is meeting those expectations. (See “12 Steps to Landfill Construction Safety” on p. 78)
Controlling Landfill Traffic
Because over-the-road vehicles, compactors, scrapers and front-end loaders travel over landfill roads together, and employees and refuse collection and transfer truck drivers often move between them, traffic control is a key element of an accident prevention program. Other common problems at landfills include drivers who speed, fail to obey traffic signs and signals, drive too fast for road or weather conditions, and drive with poorly secured loads.
Traffic control safety begins at the landfill's front gate. Incoming loads generally should be inspected at the scale house, and drivers directed to an appropriate disposal area. Commercial trucks should either be sent to a municipal solid waste area or to areas designated for construction debris, landscaping materials and other segregated waste streams. An important part of the facility's safety program is directing the general public — if they are allowed onsite — to a convenience area and away from the landfill's main traffic flow.
Speed limit signs, stop signs and other devices — such as speed bumps — can be used to control traffic flow. Many companies also regularly inspect traffic conditions and stop drivers who are operating too fast or fail to obey the site's traffic rules. Some companies only will ask the driver to comply with the site's rules, but others will issue written warnings to the driver's employer. Those who repeatedly violate site traffic rules can be prohibited from entering the landfill.
Safety in the Disposal Areas
With large vehicles constantly moving in and out, landfill unloading areas can be very busy places. Drivers must be careful to avoid contact with other vehicles, heavy equipment, pedestrians and temporary excavations.
Employees and drivers working in the disposal area must avoid potential hazards, such as items they could trip over, sharp materials and hazardous chemicals in the refuse. When the driver or a crew member leaves the vehicle at the disposal area during unloading, he or she can face hazards from other vehicles that are unloading there or from heavy equipment that may also be working nearby.
To limit the potential for harm, many landfills only allow the driver or one crew member to leave the vehicle while it is in the disposal area. They also will require those who leave their vehicles to wear hardhats, traffic safety vests and hard-soled shoes.
When drivers are in the disposal areas, usually they are told where to unload. Each landfill may have a different procedure. At some sites, a person, called a spotter, is positioned at or near the disposal area to direct drivers to a specific place to unload.
To avoid having the spotter harmed, though, many landfills have turned spotters into loader and compactor operators at the disposal area. Those operators are safely above the surface of the disposal area in a large piece of highly visible equipment where they can guide incoming drivers, in some cases by hand signals, gestures or over citizen band or other types of radios.
Safely managing gas and leachate
The contractor and subcontractor's employees must be aware of the dangers presented by landfill gas and leachate. Landfill gas is naturally produced by the anaerobic decomposition of organic matter at solid waste landfills. Generally, landfill gas is a mixture of carbon dioxide (CO2) and methane (CH4), with traces of other gases and vapors, such as hydrogen sulfide (H2S). In areas where landfill gas may be, or is known to be, present combination gas monitors for methane, oxygen and hydrogen sulfide should be used. Gas monitors for landfill gas are usually set to alarm at 10 percent of the Lower Explosive Limit (LEL) for methane, 10 parts per million (ppm) for hydrogen sulfide and less than 19.5 percent oxygen.
Leachate is the material that is collected from the drainage system under a landfill. The liquid collected from these systems can vary from clear to very dark. Often, these systems will also contain landfill gas in the airspace above the liquid. The composition of leachate is highly variable, depending on the design of the collection system and the material disposed of in the landfill.
Workers who are assigned to service, maintain or expand the facility's gas and leachate collection and treatment systems generally face the greatest risk for exposure to elevated airborne concentrations of landfill gas and significant exposure to leachate. Those workers must be trained on the hazards of landfill gas and leachate and the methods — such as using combination gas monitors for methane, oxygen and hydrogen sulfide — to detect potentially hazardous exposures. They also must be trained to properly use personal protective and, when needed, respiratory protection equipment. (See “The Dangers of Landfill Gas” on page 77.)
Landfills are dynamic places with many potential safety hazards that must be managed. Many operators have been successful at recognizing those potential hazards and implementing practical solutions for eliminating or mitigating them, which has helped make landfills among the safest places to work in the waste management industry.
Dave Malter is president of Bull Valley, Ill.-based Malter Associates.
THE DANGERS OF LANDFILL GAS
Landfill operators have used the following information on landfill gas as a part of their company's hazard communication training.
Landfill gas is produced by the decomposition of organic matter.
Landfill gas has the ability to travel or migrate from areas where refuse has been deposited to excavations and other confined spaces (e.g., trenches, gas vaults and leachate wells) that are located in or near the disposal area.
Landfill gas has a distinct odor, which may vary with the composition of the disposed material.
Generally, landfill gas is a 50/50 mixture of carbon dioxide (CO2) and methane (CH4), with traces of other gases and vapors, such as hydrogen sulfide (H2S).
Methane and carbon dioxide from landfill gas can displace oxygen in confined spaces and in other locations where landfill gas is allowed to accumulate. Methane is flammable.
Hydrogen sulfide gas is regularly found in landfill gas. Hydrogen sulfide is a poisonous gas that can be harmful in very low concentrations.
Locations where the breathing air contains less than 19.5 percent oxygen, more than 10 percent of the lower explosive limit for methane or more than 10 parts per million of hydrogen sulfide are potentially hazardous. No one should enter those locations without appropriate training and safety equipment.
12 STEPS TO LANDFILL CONSTRUCTION SAFETY
To insure a landfill is being managed safely, require all contractors and subcontractors to:
Train workers on the site's safety requirements and have documents on site to show that the training has occurred.
Keep copies on site of their safety program and documents proving that the training has occurred.
Perform daily inspections of their work areas and the employees' and sub-contractors' work.
Check to see that problems identified in the daily inspections are corrected quickly.
Advise landfill management of any significant safety-related conditions identified through the inspections and work activities.
Require their employees to use necessary personal protective equipment.
Keep the mobile equipment (loaders, excavators, etc.) maintained in safe operating condition.
Require the operators of mobile equipment to follow the contractor's or facility's rules for operating, including the facility's requirements for vehicle safety.
Employ safeguards to maintain slope stability during excavation and for workers who enter the excavation areas.
Provide appropriate hazard communication training for landfill gas and leachate to those who may be exposed.
Use the appropriate landfill gas monitors.
Require workers exposed to landfill gas and leachate to wear the appropriate personal protective equipment.