Every landfill is subject to federal, state, and local regulations. The Resource Conservation and Recovery Act covers a set of laws, regulations, and Environmental Protection Agency policy to protect communities and conserve resources. Congress granted the EPA authority to develop regulations and policies to ensure safe management of solid waste, as well as programs to encourage source reduction and reuse of materials.
State officials typically implement the regulations and ensure compliance. They can add more stringent requirements if they choose. “A landfill is like a continuous construction project,” says Phil Roycraft, district supervisor for the northern region of Michigan, Department of Environmental Quality, Waste Management Division. “It needs continuous oversight.” His office performs quarterly inspections on the landfills in their region, in accordance with the law. “You have to be there because a landfill constantly changes.”
Solid waste landfills must be designed and managed to protect the environment from contaminants that can be present in the solid waste stream. To ensure that occurs, all municipal solid waste landfills must comply with the federal regulations in 40 CFR Part 258, also known as Subtitle D of the RCRA. According to the EPA, Subtitle D bans open dumping of waste and establishes minimum federal criteria for the operation of landfills.
The EPA standards include:
- Location restrictions—Landfills must be built in suitable geological areas away from faults, wetlands, floodplains, or other restricted areas.
- Composite liners requirements—A flexible membrane (geomembrane) overlaying two feet of compacted clay soil lining the bottom and sides of the landfill must be used to protect groundwater and the underlying soil from leachate releases.
- Leachate collection and removal systems—A system must be placed on top of the composite liner to remove leachate from the landfill for treatment and disposal.
- Operating practices—Compacting and covering waste frequently with several inches of soil helps reduce odor, control litter, insects, and rodents, and protect public health.
- Groundwater monitoring requirements—Testing of groundwater wells to determine whether waste materials have escaped from the landfill is mandatory.
- Closure and post-closure care requirements—Landfills must be covered and long-term care of closed landfills shall be provided.
- Corrective action provisions—Control and cleanup of landfills must be performed in order to meet groundwater protection standards.
- Financial assurance—Funding for environmental protection during and after landfill closure must be provided.
Engineered Waste Systems offers a system that improves how landfills operate, leading to changes in compliance with some of the EPA regulations while at the same time reducing operating costs, saving landfill space, and protecting the environment.
Formed in 2005 with the intention to discover applications for and to distribute advanced environmental technology, EWS focuses specifically on aerobic digestion and biological processing for the waste industry. The Michigan-based company introduced a patented and innovative biological process called hydrodigestion that provides a cost-effective and environmentally safe solution for landfills. “The EWS system has some benefits,” says Roycraft. “It helps maximize the footprint and achieve functional stability after closure [of the landfill].”
Subtitle D
The EPA supports its commitment to recycling and pollution prevention by monitoring waste management practices. Landfills are regulated under RCRA Subtitle D or the Toxic Substances Control Act. Under Subtitle D, state and local governments are responsible for regulating the management of nonhazardous solid waste and for overseeing municipal solid waste landfills, bioreactor landfills, industrial waste landfills, construction and demolition debris landfills, and coal combustion residual landfills.
Under Subtitle D, states are required to adopt and implement permit programs to ensure that landfills comply with federal standards. But not every landfill complies with every regulation. For example, the Department of Environmental Quality, Waste Management Division, in Michigan, lists the common violations for Type II municipal landfills and Type III construction and demolition landfills, including several that can be addressed by EWS, such as dust, blowing of litter, and odor; failure to ensure a minimum of 6 inches of earth or approved alternate daily cover is used; and excessive ponding and erosion.
Since the 1990s, Subtitle D landfills have been required to have a composite liner at the base to prevent liquids in the waste mass and no more than 12 inches of leachate on the composite liner. This results in a “dry tomb” and relatively dry waste mass. “Subtitle D is the federal standard for landfills,” emphasizes Rick Aho, principal at EWS. “The dry tomb idea is to pull out the water. You catch water in a collection system to remove it. It’s supposed to be dry, but anaerobic [processes] clog the drainage material and retain water.”
To avoid this result, he says landfills can manipulate within Subtitle D by making changes to the initial construction or through retrofits, such as putting in upgrades to the drainage system. “Every anaerobic landfill is being hydraulically manipulated,” explains Aho. “The original specifications of the drainage materials in the landfill are invalid. The drainage materials are being clogged by anaerobic organisms.” Incorporating an aerobic system that digests an anaerobic clog improves drainage, reducing pressure on the liner and thus protecting it. Aerobic digestion lets the landfill system component function as it was designed.
Landfill leachate is created by liquids in the waste or from rainwater. It contains organic and inorganic compounds. Maintaining a landfill requires managing the leachate with proper treatment in order to prevent pollution into surrounding ground and surface waters. The leachate collection system accumulates the leachate so it can be removed from the landfill and treated or properly disposed of. To discharge leachate, Aho says that only landfills with aerobic digestion can clean the leachate enough to be able to discharge without being required to use an expensive conventional wastewater treatment system. “The cost of not trucking leachate can easily pay for the entire system and operation,” he says. Landfill life is extended, GHG is reduced, liability is eliminated, and safety is enhanced.
Pump and haul is an expensive way to manage leachate, Roycraft says, but it’s only one of many, such as a wastewater plant, reverse osmosis, underground injection, aerators to vaporize, and an onsite water treatment plant. An EPA study indicates that a properly constructed liner and leachate collection system has a liquid removal efficiency rate of 99–100%, based on the specifications of the drainage materials. Anaerobic organisms affect every drainage specification of an anaerobic landfill.
“There are no regulations that say you can’t process aerobically,” points out Aho. Aerobic digestion results in the reduction of leachate strength, the elimination of high-strength GHG, and operational improvements. As MSW decomposes in an anaerobic landfill, it releases methane, a greenhouse gas 25 times more potent than carbon dioxide, and other greenhouse gases, which entails the majority of the solid waste industry’s contribution to climate change.
Hydrodigestion accelerates aerobic digestion to quickly reduce the volume of waste, increasing landfill life and facility revenue, and eliminating long-term liability when the facility closes. The process involves creating a supercharged biofilm in selected areas of the waste mass to process organic material with a minimum of fossil fuels and equipment. The end product is a mixture of rich humus, biologically inert plastics, glass, and metals that are biologically stable and incapable of producing methane.
By using hydrodigestion, facilities with leachate treatment capacity or cost problems can concentrate on lowering leachate strength so a water treatment plant can treat it, or groundwater/surface water discharge, Aho explains. “Communities with landfills that are filling up rapidly can emphasize the rapid volume reduction of previously landfilled solid waste.”
Most importantly, aerobic technology changes the options by optimizing and controlling natural processes. Manipulating Subtitle D increases efficiency because landfill owners do more than the minimum requirements. Aho says these improvements often don’t cost a lot of money.
Furthermore, he adds, “Aerobic digestion was designed to work within the regulatory structure of the EPA and almost any state in the United States. Aerobic hydrodigestion takes control of the landfill by manipulating the microorganisms inside.” Both methane and odor are eliminated by aerobic processing, removing the threat of poison gas and deadly bacteria—without the need for a conventional gas collection system because this process produces none of the high-strength greenhouse gases normally associated with landfills.
The RD&D Rule
Landfills in very arid regions of the country lack sufficient moisture or leachate for digestion. “If you don’t have enough leachate to process the MSW, you need to bring in extra liquid,” explains Aho. However, he adds, some states won’t allow recirculation of leachate. “Unless the state petitions for use of the RD&D rule, you can’t bring wastewater or sewage into a landfill.”
An aerobic digester can be designed to minimize or maximize evaporation, depending on the needs of the facility. Processing liquid waste with an aerobic digestion landfill can provide a very significant, high-profit revenue stream. For the community with liquid waste or sewage processing capacity issues, the treatment capacity of an aerobic landfill can be a huge benefit.
Air and Water
Regulations can vary from state to state and from municipality to municipality, but federal regs reach all landfills. For example, the electronic Greenhouse Gas Reporting Tool (e-GGRT) system is part of the EPA Greenhouse Gas Reporting Program, requiring electronic reporting of greenhouse gas emissions, including methane. Most modern landfills are required to have a gas collection system, Aho observes.
New techniques for gas management convert gas to electricity, but Roycraft says it’s still the biggest challenge, especially as sites get bigger (which is the trend) and generate a lot of gas. “Even with a management system, you can still have odor issues.”
EWS’s aerobic system can process material with the intent of producing no high-strength emissions. This is particularly beneficial in California, where non-attainment zones are common. “The microorganisms consume emissions. Emissions (non-CO2) are a fuel—an energy source for microorganisms—and do not escape,” explains Aho. Both methane and odor-causing emissions are consumed by aerobic processing, removing the threat of poison gas and deadly bacteria.
While e-GGRT relates to air quality, the National Pollution Discharge Elimination System permit program addresses the water quality of discharges. Created in 1972 under the Clean Water Act, the EPA authorizes state authorities to regulate point sources that discharge pollutants to the waters of the US. Under NPDES, landfills are required to monitor groundwater for contamination during the life and post-closure periods to guard against the release of hazardous materials. In the US, a 30-year post-closure monitoring period is required. This is typically done by installing a groundwater monitoring system consisting of a series of wells. “To discharge leachate, landfills have to clean the water to drinking water standards,” elaborates Aho. “It has to be nontoxic to fish and invertebrates.”
Landfill operators must routinely monitor the parameters for discharging and must test during discharge. Wet testing for toxicity is expensive but far less expensive than trucking leachate, Aho states. The final goal of hydrodigestion is to produce leachate suitable for discharge into the groundwater when the liner inevitably fails because the contaminants have been digested or rendered inert. Leachate is treated onsite to surface water discharge standard or better. The reduction in the leachate strength of the landfill also reduces liability and treatment cost.
Consequences
Regulations provide parameters for daily cover, dealing with vermin, odors, fire, treated leachate discharge, GHG, and more. Operators must obtain permits and file reports. These permits are designed to protect the public, Aho points out.
One of the benefits EWS offers customers is regulatory guidance: “We will provide your general permit template at no additional cost.” For example, EWS supplies the procedures the operators will follow to discharge leachate, use digested MSW as daily cover, and document the elimination of methane at the facility.
Typically, the EPA relies on the states to enforce the laws, conduct inspections, and oversee permits. DEQ’s inspection checklist includes examining the following: daily cover, interim cover, leachate depth on the liner, leachate management, leachate breakout on side slopes, erosion control on the covered slope, groundwater monitoring system, and general upkeep—blowing litter. They also perform an annual record review.
Over the years, Roycraft says they’ve seen fewer issues as technology in design and construction and operating techniques improve. However, they still respond to customer complaints about odors—per federal regulations. “We have to follow up on nuisance odor complaints.”
Despite improvements, DEQ still sees a broad spectrum of violations. Minor violations often involve daily cover, blowing papers, and odor. More serious violations consist of leachate release outside of the cell or filling outside of parameters. The first step when a violation is recorded is to issue a citation. “We try to resolve the vast majority of issues without fines,” explains Roycraft. “We start with a compliance communication to identify the problem and request a plan to fix it.” It can escalate to a consent order with an administrative penalty for significant or repeat violations.
Lack of compliance can lead to extra testing to meet requirements. That gets expensive, but even worse, non-compliance can result in millions of dollars in fines and repairs to address the issues. Perhaps even more concerning is the possibility of shutdown for being in violation. “Failure to comply puts your license at risk,” says Aho.
A closure is rare, Roycraft notes, adding that inspections continue during the post-closure period. “Less maintenance is required, but they still must pump leachate and maintain cover.”
Education
There are no regulations about aerobic digestion, so when a regulator inspects a landfill using hydrodigestion, there may be questions and concerns. “Show off your system,” advises Aho. “Educate the regulator that it’s not a liability. Document the density of the landfill and the reduction in landfill space used. Show that there are no odors. Give the regulator a sample of leachate that has been reduced in strength by 90%.”
Give the regulator the test results used to reduce your financial assurance, eliminate long-term liability, and slash your operating costs, Aho suggests. “Real-time results can be provided at any time.”
REFERENCES
https://www.epa.gov/landfills/bioreactor-landfills
https://www.epa.gov/sites/production/files/2016-05/documents/17_sunderraj.pdf
https://www.epa.gov/rcra/resource-conservation-and-recovery-act-rcra-overview
https://www.epa.gov/landfills/basic-information-about-landfills
https://archive.epa.gov/epawaste/nonhaz/municipal/web/html/landfill.html
http://www.michigan.gov/deq/0,4561,7-135-3312_4123-38928–,00.html