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Surface Emissions Monitoring (SEM)

Surface emissions monitoring (SEM) describes a method for measuring gas emissions at or near ground surfaces.  The term is most commonly referred to the method of detecting methane emissions over the surface of a landfill, but can also apply to monitoring methane emitted from buried natural gas pipelines, measuring methane emissions over covered lagoons and open bodies of water such as tailing ponds, measuring nitrous oxide emissions in agriculture applications, and others.


Generally, work is performed manually by technicians while traversing the study area utilizing a hand-held closed-path detector with an air collection nozzle. Ambient air samples are collected though the nozzle at the ground surface and pumped to the detector where concentrations of the subject gas is measured. 


The purpose of the work is to collect raw data of gas concentrations and/or to detect and isolate leak sources of the subject gas.  


Sniffer has developed the SnifferDRONE™ -  a unmanned aerial system (UAS) designed as an automation tool automating much of the work performed manually by field technicians. This technology now offers industry an alternative to an otherwise hazardous, laborious, and subjective method, by providing a safer, faster, and more effective solution.  Learn more.

Explore the use cases below to learn more about the applications for surface emissions monitoring.


Landfills and Landfill Gas Recovery

Landfills comprising organic materials will generate methane as a natural byproduct of the decomposition process.  Generally 50% of landfill gas is methane.  Municipal Solid Waste (MSW), Industrial, and Construction & Demolition (C&D) landfills emit methane to varying degrees based on the organic waste composition, moisture content, and type and condition of the cover system used to contain the waste.  While the emitted landfill gas is harmful to our environment this emitted gas also represents lost revenue to the landfills since it can be recovered and beneficially converted to energy.

Alternatively, the US EPA has approved an automated method for surface emissions monitoring referred to as OTM-51. Commonly referred to as the SnifferDRONE™ method, this method is an alternative to the traditional manual method of surface emissions monitoring.

Sniffer provides manual and automated services and solutions for US EPA quarterly compliance and comprehensive data collection and information reporting to aid operations in improving gas collection, reducing odors, and benchmarking operations.

The US EPA regulates landfills under the Resource Conservation and Recover Act (Title 40 of the CFR parts 239 through 259

Sniffer services and solutions provided for this market

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Method 21

US EPA Compliance

"Boots on the Ground", manual surface emissions monitoring method for US EPA quarterly compliance.

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US EPA Compliance

SnifferDRONE automation for compliant surface emissions monitoring with US EPA regulations.


Comprehensive Emission Studies

Providing engineers the information to capture more gas, reduce odors, and improve operations.


Sniffer Field Ops™


Mobile app solution used for field reporting, monitoring, and automated reporting to benefit  operations.


Custom GIS Solutions

Improve operational workflow and deliver actionable insights through customized Esri and ArcGIS solutions.


Natural Gas Pipelines

Natural gas is comprised mainly of methane gas.  Emissions of methane from infrastructure during the production, transmission, distribution, and containment of natural gas occurs.  For pipelines, the industry inspects for methane leaks with regular frequency, using aerial-based and foot pipeline patrols.  Together these patrols monitor pipelines and the surrounding areas for issues related to gas leaks and other disturbances.

The US DOT Pipeline and Hazardous Materials Safety Administration (PHMSA) regulations require pipeline operators minimize methane emissions as provided in the PIPES act of 2020 (49 CFR §192.706 for transmission, and §192.723 for distribution leakage surveys).

Sniffer services and solutions provided for this market

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SnifferDRONE Patrol Leak Detection

The SnifferDRONE automation tool works in conjunction with foot patrols to providing a safer and more effective solution for pipeline emissions monitoring.


Sniffer Field Ops™


Mobile app solution used for field reporting, monitoring, and automated reporting to benefit  operations.


Custom GIS Solutions

Improve operational workflow and deliver actionable insights through customized Esri and ArcGIS solutions.

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