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Carbon Footprint Calculation Methodology

Carbon Footprint Calculation Methodology

WM’s carbon footprint comprises the anthropogenic Scope 1 (direct) and Scope 2 (indirect) GHG emissions from facilities and activities under our operational control in North America as well as Scope 3 (indirect) GHG emissions.

Scope 1 emissions include direct emissions from landfills, fleet vehicles, support vehicles, heating and refrigerants. Scope 2 emissions include indirect emissions from purchased electricity. Scope 3 emissions include purchased goods and services, capital goods, business travel, employee commuting, upstream and downstream leased assets, use of sold products, third party transport and investments. Our carbon footprint calculation relies on company operating data collected from auditable corporate business, legal and accounting records, which have undergone internal quality assurance. Emissions factors and methodologies come from the following sources:

WM's inventory is calculated in line with GHG Protocols and utilizes best practice methodologies and emissions factors including EPA, The Climate Registry, Department of Energy, and others.

Because a broadly accepted protocol for estimating the carbon mass balance of landfills did not yet exist, WM, along with other public and private owners and operators of landfills, funded the development of the Solid Waste Industry for Climate Solutions (SWICS) protocol by SCS Engineers. The protocol represents a first step in refining existing U.S. EPA models and protocols using peer-reviewed, published research to improve landfill GHG emission estimation. We employed the SWICS protocol in estimating the emissions associated with the landfill operations reported in our company-wide carbon footprint and the voluntary GHG reporting protocols in which we participate. The U.S. EPA’s Science Advisory Board views some sources of biogenic carbon dioxide emissions—including landfill gas and biogenic materials in waste—as carbon neutral.

Carbon storage in landfills can significantly offset GHG emissions from landfills, as recognized by the United Nations Intergovernmental Panel on Climate Change, the EPA’s U.S. Inventory of GHG Emissions and Sinks, the Oregon Climate Trust and the California Air Resources Board—all of which recognize carbon storage in landfilled material as a “sink” in calculating carbon emissions inventories. We have used the SWICS protocol to calculate the amount of carbon permanently stored in landfills from the annual disposal of organic waste —i.e., carbon that will not decompose in the landfill to produce methane.

Additionally, WM has developed and maintained an annual GHG Inventory Management Plan (IMP) as an internal governance and controls document. The IMP is a dynamic document to provide WM with a summary of emission sources associated with the company’s activities, and the associated emissions quantified using standardized methods. Included in the inventory are processes for:

  • Choosing a base year for the GHG emissions inventory against which future emissions will be tracked.
  • Identifying the sites to include in the inventory (organizational boundaries).
  • Identifying the sources within the sites to include in the inventory (operational boundaries).
  • Following a standardized and accepted methodology to calculate the GHG emissions from each identified source.

Our GHG inventory reflects the most accurate means available to calculate GHG emissions within our industry sector. We work with leaders in government, industry and academia, including staff of the multistate Climate Registry and the U.S. EPA, to develop our inventory processes and protocols.

Data Verification and Validation

We participate in multiple forms of data verification. First, in conformance with applicable state or provincial GHG emissions reporting programs, an independent third party is hired to review original data and provide a verification certificate. Accordingly, the emissions from the landfill subject to the Alberta Provincial Specified Gas Emitters Regulatory Reporting Program are third-party verified. Emissions from the landfill subject to State of California mandatory reporting program are also third-party verified. Our facilities are subject to the federal Mandatory GHG Reporting Rule, and they are subject to rigorous validation checks by U.S. EPA as part of its compliance assurance and enforcement program for the reporting rule.

These verifications are conducted in accordance with ISO 14064–3:2006 specification with guidance for validation and verification of GHG assertions to provide limited assurance that the Scope 1, Scope 2 and Scope 3 GHG data was prepared in conformance with World Resource Institute/World Business Council for Sustainable Development GHG Protocol: A Corporate Accounting and Reporting Standard and the internal WM Inventory Management Plan. As a result, 100% of our carbon footprint is verified by a third party.

In a second form of data validation, we report to a third party, such as a government-affiliated data tracking program, which provides quality assurance and quality control to the data but does not provide a verification certificate. Our transportation data is validated through the U.S. EPA SmartWay program; our GHG inventory from energy generation is validated by the U.S. EPA.

Further, WM has contracted with Enel X to collect and pay utility invoices, as well as to track usage data as part of an enterprise-wide utility bill management (UBM) program. Information from the UBM program is audited prior to bill redirection by WM to ensure correct processing of all future invoices. We review data through Enel X’s online dashboard and have the capability to run reports on consumption, cost and GHG emissions on a facility, region, division, country and enterprise-wide basis. With this approach, our data collection and reporting program is robust and transparent.

Life Cycle Emissions Methodology

Our calculation of the potential GHG reductions or avoided emissions that our operations enable includes the following:

Electricity. Production of renewable waste-based energy that is used to replace electricity generated from fossil fuels.

Fuel. The use of renewable natural gas (RNG) to avoid the GHG emissions associated with annual use of fossil fuel.

Recycling. Recycling of postconsumer materials (e.g., paper, aluminum and plastics) using U.S. EPA’s Waste Reduction Model (WARM).

Carbon sequestration. Permanent carbon storage in landfills of biogenic materials that do not decompose in an anaerobic landfill environment.