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MUNICIPAL LANDFILL ASSESSMENT

Assessing air emissions from municipal landfills using the USEPA flux chamber technology starts with a detailed map highlighting the footprint of the landfill, and a representative history of the waste material received along with the operational data of waste filling and covering.  A typical assessment may include as many as five or six sub-footprints and an active or working face of the landfill (photo 1). 

In order to reduce the cost for the assessment, each sub-footprint of concern can be screened on the surface using real-time instruments with data collection on a grid or coordinate system.  Ground probe assessment is also used in this fashion (photo 2).  Either a random grid-based testing or scientific site selection approach can be used to select flux chamber testing locations (photo 3) representative of sub-footprint areas.  The emissions of these sub-footprint areas are then collectively used to represent the air emissions from the site.  A common request for air emission assessments happens when a municipal landfill seeks a permit for expansion- either enlarging the facility footprint by constructing additional waste cells, or by increasing the waste receivables. 

Specific data collection objectives include generating representative sub-footprint air emissions, demonstrating compliance with cover requirements in terms of control efficiency, and demonstrating compliance to permit requirements in reference to 'no offsite migration' conditions. 

Testing is typically conducted for methane and carbon dioxide, which compose most of the landfill gas emissions, total non-methane hydrocarbon compounds, reduced sulfur compounds, odor, and hazardous volatile and semi-volatile organic compounds (Photo 4).   Olfactory odor assessment is very common, and 'odor' can be assessed in odor concentration units (dilution-to-threshold units or D/T) and expressed as 'odor flux' for offsite odor impact assessment.  Odor flux is input into dispersion modeling and an isocontour of odor in the neighborhood the surrounding the landfill can be developed and used for a variety of project purposes.  Indirect assessment technologies from inactive and active portions of the landfill can also be performed using technologies such as transect sampling (photo 5) and modeling, or fenceline (photo 6) or neighborhood monitoring and modeling. 

When real-time monitoring using laboratory grade instrumentation is needed for indirect or fenceline assessments, the task generally falls to Dr. Eric Winegar with Applied Measurement Science (photo 7).   This type of monitoring can be used to augment any air pathway analysis by providing verification data to direct measurement assessments.

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