Landfills play an essential role in managing waste generated by homes, businesses, and industries. Beyond serving as waste disposal locations, landfills are also valuable resources with the potential to generate revenue through the efficient use of space. This is where landfill capacity audits come in.

An annual capacity audit assesses how much airspace was used in the previous year for waste placement; the amount of soil that was used within the operation; and, the remaining airspace still available. Based on this information, an annual capacity audit predicts the remaining life of a landfill. It also predicts how much longer the landfill will be able to operate based on the remaining available airspace.

Despite the potential benefits of capacity audits, not all landfill owners and operators conduct them regularly. In this article, we explore why landfill capacity audits are an important tool in optimizing efficiency and maximizing revenue.

The benefits of a capacity audit:

Capacity audits provide insights into a landfill’s operations and serve as a compass for future improvements. Conducting a capacity audit allows landfill operators to better understand several aspects and provides benefits such as:

• Efficient use of space: By understanding their program’s airspace utilization (waste density), operators can assess how efficiently they are using the available space and optimize waste placement to extend the site's life, thus maximizing return on investment.
• Maximized revenue: Conducting regular capacity audits can help identify unused or underutilized areas of the landfill that can be developed to generate additional revenue.
• Future planning: Capacity audits can give an idea of remaining site life and help operators understand when to trigger planning for the next cell excavation or permitting changes. Capacity audits can also serve as a key input for longer-term master planning efforts.
• Regulatory compliance: Capacity audits can create efficiencies in annual reporting as information garnered from the capacity audit is already vetted for accuracy and completeness and can be plugged into report templates.
• Optimized operations: Understanding factors like soil balance and waste density can help optimize operations around tasks related to daily cover, outlets to get rid of onsite soils, cover soil deficiencies, and more.

How often should capacity audits be conducted?

Capacity audits should be conducted annually, ideally. Anything less than this may result in the loss of multiple years of airspace and could reduce the value of the landfill’s resources. Conversely, through annual capacity audits, operators can accurately track available airspace to ensure they are accepting as much waste as possible as efficiently as possible, thereby increasing revenue from waste disposal fees and maximizing site life.

What’s involved in an annual landfill operational review?

Conducting an annual landfill operational review will generally include the following components:

1. Aerial Survey: Complete an aerial survey within the same two-week period every year. Obtaining survey data from the same timeframe each year will help ensure consistent data and increased accuracy in year-over-year analyses.  
2. Airspace Consumption: Compare current site elevations against prior year elevations, accounting for consumption of landfill volume and site soil usage. Evaluating airspace consumption can help identify potential operational changes related to waste processing efforts and soil usage. For example, soil overuse may consume excessive airspace that could otherwise be used for waste placement and increased return on investment. 
3. Waste Receipt Analysis: Using site-specific scale data, compile waste receipts to identify location-specific waste placement based on waste type and annual waste acceptance. 
4. Airspace Utilization: Calculate the in-place waste density based on the waste receipt analyses and airspace consumption evaluation. Airspace utilization evaluation helps identify a landfill’s waste processing efficiencies and identify possible areas of improvement. Permitted airspace is a landfill’s greatest asset and poor management can negatively impact revenue. 
5. Site Life: Taking into account the airspace utilization factor, the calculated remaining landfill airspace, and pre-determined population and waste generation growth rates, calculate the remaining site life for each landfill cell and the site as a whole. Understanding how much space is left and how quickly it is being consumed provides lead time for future landfill cell development, design, permitting, and financial planning. 
6. Future Operational Soil Needs: Calculate soil volume for the remainder of the site life using the soil-to-waste ratio and intermediate cover soil requirements. Understanding soil volume calculations helps ensure the landfill has adequate soil availability for daily use and final closure needs in accordance with permit requirements.
7. Site Soil Balance: Compare the existing soil stockpiles and future excavation soil volumes against the future operational soil and closure soil requirements to identify the site’s surpluses and/or deficiencies. 
8. Closure and Post-Closure Costs: Update the closure and post-closure cost estimate to help ensure sufficient funding is set aside for the future cost of earthwork, geosynthetics, environmental monitoring, and any necessary design changes related to phased or final closure. Keeping cost estimates current helps ensure adequate notice for financial planning and provides accurate pricing for any financial assurance obligations. 

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