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Landfill Stewardship

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WM provides solid waste collection services to millions of customers in North America — from households to public venues to large companies. After recycling or diverting various materials for reuse, we safely managed the disposal of over 100 million tons of waste each year, including common municipal trash and highly specialized materials such as medical and industrial waste. We are able to handle this volume by operating the largest network of landfills in our industry while working hard to minimize the impact those facilities have on neighbors and the environment.

Modern landfills are the products of sophisticated engineering, contributing to environmental safety and sustainability. Beyond being safe places to store waste, they are often sources of renewable energy and frequently serve new purposes after closure. WM’s modern landfills in the United States were developed under the federal Resource Conservation and Recovery Act (RCRA), which requires rigorous siting evaluation, site characterization and scientific engineering design, as well as a comprehensive permitting and regulatory approval process that includes public notification and comment. RCRA standards also require a range of measures to prevent environmental contamination, including the use of engineered liners and covers, collection and control systems for landfill gas, and collection and treatment systems for leachate (water that accumulates in and filters through waste).

Thousands of pumps, valves, blowers and flares are required for the safe management of modern landfills. Ongoing collection of data from these assets, often collected by checking meters positioned throughout landfill sites, is essential for landfills’ safe operation.

A new system known as Connected Landfills simplifies this work, equipping landfill assets with internet-connected devices and sensors. Technicians are able to review data remotely via dashboards on mobile devices, allowing them to monitor changes, make decisions and even directly interact with equipment with the push of a button. With less time spent in transit, landfill employees will be able to spend more time managing landfills’ productivity and health. Based on its success, we plan to expand our use of this technology to other sites.

Our modern sites are designed and operated to go beyond regulatory requirements. We continually monitor and work to improve the safety and environmental security of our disposal facilities and are committed to reporting the results of these efforts. We strive to avoid conditions that cause concern for neighbors and communities, including odors and noise, regardless of whether those conditions are covered in our regulatory obligations. We also work with waste sector experts to understand what happens within landfills after they are closed. Studies have shown that modern municipal solid waste landfills tend to improve predictably over time, steadily producing less gas and less (and cleaner) leachate. Many of our landfills are designed and managed to ensure they can be used after closure for commerce, industry or even conversion into wildlife habitat or public parks.

The following efforts are supported by innovative, peer-reviewed science from WM employees working with leading experts in their fields.

Surface and Groundwater

WM’s landfills are living laboratories used to test new technologies to help us improve how we manage stormwater and leachate, and how we design and maintain landfill cover and gas collection systems. To enhance environmental performance, and reduce operational costs, we test the effectiveness of new technologies at select sites before broadly employing them at all sites. In addition, WM utilizes extensive engineering controls and practices to protect surface water and groundwater. We maintain a comprehensive network of more than 6,000 groundwater-monitoring wells around our facilities, and every landfill uses monitoring strategies — many involving sophisticated statistical evaluations — to ensure that adjacent surface water and groundwater is protected.

Our modern municipal solid waste landfill liners capture all liquids, which are then managed according to applicable regulations and design standards. Modern RCRA Subtitle C and D-regulated landfill liners continue to perform as designed, not allowing leakage through the liner and requiring cleanup of groundwater under neighboring properties. We employ hundreds of professional engineers, environmental scientists, regulatory experts and technicians to ensure that every facility works to protect surface water, stormwater and groundwater from potential operational impacts.

We use managed basins, tanks, containment structures and separators to redirect liquids for proper disposal and treatment. We also monitor on-site wastewater treatment plants to optimize efficiency and utilize a toolkit of best management practices for our field operations.

Stormwater Filtration

WM landfills collect and discharge millions of gallons of stormwater each year. The water is then managed to ensure it is clean enough to meet strict state requirements before it is released to water bodies or public treatment plants. A technology called Terra-Tubes slows water flow to allow for settling and enhanced filtration of the water prior to discharging it off-site. The tubes are made of engineered wood and man-made fibers encased in a heavy-duty, knitted cylindrical tube, and are installed at stormwater outfalls.

Natural & Enhanced Leachate Evaporation

Landfills naturally produce leachate from a combination of the breakdown of waste materials and precipitation falling on the landfill. Leachate is typically stored on-site in lined impoundments or tanks before it is treated and eventually discharged. WM has been developing and testing technologies to reduce the volume of water and disposal costs. One of these technologies harnesses nature by constructing wetlands and planting grasslands and poplar groves to naturally filter and clean leachate. WM has used this natural ecological system to treat water while increasing natural habitat for native plants.

We also use a simple technology that recirculates and evaporates leachate using the side slopes of leachate ponds. An electric pump pulls water from the pond and circulates it through lateral pipes that are equipped with sprinkler heads. Water that is not evaporated filters through gravel placed on side slopes to return to the pond. The system can evaporate as much as 20,000 gallons of liquid per day, reducing the volume of water that must be handled at publicly owned wastewater treatment plants by as much as 30 percent.

Another technology deployed at several western WM landfills uses a solar-powered floating recirculation device to draw leachate from deep within the pond and disperse it at the surface. The SolarBee helps maintain warmer surface temperatures that enhance evaporation and eliminates pond scum on the surface that could interfere with evaporation.

WM engineers have also developed a pilot evaporation system that uses waste heat from the landfill’s renewable energy engine plant. The waste heat warms leachate to facilitate evaporation and enhance treatment. The pilot has operated continuously for 18 months and demonstrates the efficacy of this type of evaporation system. Data from the pilot is being used to evaluate other locations where the technology can be deployed.

Innovation in Landfill Cover

A closed landfill’s final cap or cover is one of its most important environmental protection features. It must be constructed in accordance with federal and state requirements and properly maintained for years into the future. A typical final cap comprises several layers of plastic membrane, a drainage system and a covering of soil. These covers are engineered to prevent precipitation from percolating through the landfilled waste.

With approval from the U.S. EPA, WM has permitted over 40 sites for the design and construction of innovative final covers, known as evapotranspiration covers. These covers are constructed of soil and selected vegetation and are specifically designed to store water and release it to plants through evaporation. By working with nature, evapotranspiration covers provide long-term, sustainable protection, are easy to maintain and provide a natural habitat of native plants and grasses.

Renewable Energy Generation: Capturing the Value of Waste

At 146 of our landfills, WM creates economic and environmental value from waste by turning landfill gas into energy. As organic material decomposes in an anaerobic environment, it naturally produces landfill gas, which is roughly half carbon dioxide and half methane. We capture this methane and use it beneficially as an alternative to fossil fuel. This landfill gas, or biogas, is recognized by the U.S. EPA as a renewable energy resource.

We are continually looking for opportunities to develop new beneficial use projects. Proximity and accessibility to energy infrastructure makes projects more cost effective. While larger landfills tend to have greater potential, smaller landfills can also support beneficial use projects. See the latest data on WM’s facilities, fleet and fuel use.

Renewable Electricity

Today, our most frequent application for biogas is to generate electricity that is sold to public utilities, municipal utilities and power cooperatives. In this arrangement, the amount of renewable electricity delivered into the grid by one user must equal the amount of renewable electricity taken off the same grid by another user. This process has been used to offset traditional electricity with renewable energy for decades.

Renewable Fuel

Beyond electricity generation, we are also a leader in converting landfill gas into natural gas fuels that are distributed for use in residences, businesses and commercial vehicles, including our own. Renewable natural gas (RNG) produced from processed landfill gas now fuels 55% of our natural gas trucks.

WM is both a producer and end-user of renewable natural gas. With cleanup to remove water, carbon dioxide (CO2) and other trace elements, the landfill gas can be converted into RNG, a pipeline- quality gas that is fully interchangeable with conventional natural gas. As with electricity, the gas input and outflow must be on the same gas pipeline system, so it is carefully recorded for accuracy.

Our newest and most advanced RNG facility is located at our Skyline Landfill in Ferris, Texas. It began injecting pipeline-quality gas into the Atmos Energy system in early 2020.

Long-Term Stewardship

Just as we strive for safety and environmental quality at all our operating landfills, we want to be stewards of the environment when facilities reach their permitted capacity. WM has an independent, formally designated department, the Environmental Legacy Management Group, that manages the company’s closed landfills. The department is separate from ongoing operations, with specialists experienced in the science and engineering of site closure and long-term property management. These experts bring a fresh eye to inactive landfill sites and are attentive to opportunities for secure, long-term site maintenance, including opportunities for sites to provide new benefits to communities. Currently, WM has seven closed landfills that provide areas for community parks and recreation opportunities.

  • H.O.D. Landfill, Antioch, IL
    • Softball fields
    • Field hockey fields
    • Soccer fields
    • Recreational facilities
  • County Line, Denver, CO
    • Soccer fields
    • BMX track
  • Oyster Bay, Oakland, CA
    • Hiking trails
    • Picnic areas
    • Dog walking
    • Frisbee golf
  • Blackwell, Ontario, Canada
    • Walking trails
    • Dog park
    • Playground
  • Midway and Settler’s Hill Contiguous sites, west metro Chicago, IL
    • Golf course
    • Cross-country course that is currently in development by the county
  • Greene Valley West, metro Chicago, IL
    • Viewing area open to the public at certain times, controlled by the Forest Preserve
  • PJP Landfill, Jersey City, NJ
    • Transferred to the City and NJDEP which allowed for use as a public park

Closed landfills are also often converted into nature preserves and habitat for wildlife. WM landfills host 79 Wildlife Habitat Council (WHC)-certified habitat sites, which together encompass nearly 18,000 acres of land. Read more about WM’s work with WHC and the social and environmental benefits of WM’s nature preserves and wildlife habitat at closed landfills.

Solar Energy

The large geographic footprint of our landfills, and their proximity to existing infrastructure, can make them ideal locations for large-scale solar installations. We continue to increase our commitment to hosting solar generation, a strategy aligned with U.S. EPA’s RE-Powering America’s Land initiative. First launched in 2008, this innovative federal program has resulted in nearly 352 installations on contaminated lands, landfills and mine sites, with a cumulative installed capacity of just over 1,710 megawatts nationwide.

Currently, we lease eight closed landfills for solar development, working collaboratively with the WM Renewable Energy Group. A summary of the portfolio follows:

Site Size Lease Holder
Parklands (NJ) 10.1 MW (dc) PSE&G
L&D (NJ) 12.9 MW (dc) PSE&G
Hunt Road (MA) 6.0 MW (dc) Citizens Energy
Berkley (MA) 3.612 MW (dc) Captona Energy Partners
MT Sullivan (MA) 2.54 MW (dc) Captona Energy Partners
Hudson Stow (MA) 5.83 MW (dc) Captona Energy Partners
Cinnaminson (NJ) 13 MW (dc) PSE&G
Mohawk Valley (NY) 6.0 MW (dc) EDF Renewables

Based upon the continued success of the above noted projects, WM continues to pursue additional opportunities including those in New York and Pennsylvania.

Expertise & Research

As the largest operator of landfill networks in the industry, we provide extensive staff training to assure continuing education and dissemination of current best practices. This training includes classes in landfill design, construction and management; landfill gas systems management; and advanced instruction in air permitting and compliance. These courses are complemented by a range of eLearning modules in the management of greenhouse and other gases. Other learning opportunities enhance expertise in almost every phase of safe landfill operations.

We operate a landfill gas technician training center at the former ELDA Landfill in Cincinnati, Ohio. As recognized leaders in landfill gas management, the intent and purpose of the training center is to use internal expertise to train entry-level technicians to provide continuity and consistency across the enterprise. The training center allows for both classroom instruction on the technical aspects of landfill gas and field proficiency assessment.

We also contribute to new bodies of knowledge through research collaborations with expert stakeholders. WM initiated a study in 2019 to evaluate emerging measurement technologies for determining fugitive landfill methane emissions, with the goal of having a measurement system in place by 2030. Landfills currently must rely on models and other factors to estimate methane emissions. Studies comparing these emission estimates from models to measurements have shown that the existing models can overstate emissions by up to 30 times. Identifying improved methane measurement systems and technologies is key to meeting emission reduction goals.

The study will evaluate satellite and aerial platform data, flux calculations and modeling assumptions to better understand advantages and limitations of these technologies. Building on previous research by WM, academic and governmental partners, this study will compare these technologies to ground-based methods of assessing landfill methane emissions. Our desired outcome is that these technologies will provide data sufficient to track and quantify landfill methane emissions, monitor emission reduction goals and replace or refine the current models used to estimate landfill emissions for regulatory and sustainability reporting.

Highlights of past research include a study evaluating and estimating the capacity of an evapotranspiration cover at a landfill to oxidize landfill gas emissions, which should help landfill operators and regulators agree upon the process for determining when to cease active landfill gas system controls. We also completed a case study on optimal approaches to long-term landfill management. This foundational research is key to identifying long-term stewardship options that are reliable, science-based and designed to assure safety throughout the transition of closed landfill properties to beneficial reuse after closure.

See Environmental Science Research to review a list link of peer-reviewed technical articles and conference papers published by WM experts over the past several years.

Landfill Emissions

Landfill Gas Emissions Recovered CY2019
Thousand standard cubic feet (MSCF)
Total Flow LFG 217,972,987
Total CH4 Flow
– Average 49%
106,411,054
Total Flared LFG – 47% 102,509,748
Total Engine/Turbine LFG
– 37%
81,934,507
Total Other Beneficial use LFG – 15% 33,528,733
Landfill Gas Flared 47%
Landfill Gas Recovered 53%

Energy reduction and GHG sustainability initiatives are deeply ingrained in our business, addressing our customers’ needs, as well as serving as an integral part of our own operations. The need to address climate change and GHG regulations is a primary driver of our customers’ goals to increase recycling and use lower-carbon fuels. Most of our current and planned capital projects will lower GHG emissions in both our own and our customers’ supply chains. As global competition for raw materials and fuel increases, sustainable solutions for managing materials will become a necessity, and, by offering sustainable, lower-carbon management options, WM is becoming competitive in new areas and insulating ourselves from long-term losses.