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US EPA-Approved OTM-51 / ALT-150

Is your landfill using the most effective method to monitor emissions?


On December 15, 2022, the US EPA issued Alternative Test Letter (ALT-150) announcing broad-based and immediate approval of  OTM-51 (Other Test Method 51 - UAS Application of Method 21 for Surface Emission Monitoring for landfill applications). This new method utilizes the SnifferDRONE to autonomously identify methane leak sources and their emissions, and requires manual verification. 


The Sniffer team provides OTM-51 service to landfill operations throughout the United States.

Why are Companies Converting to OTM-51?

It's the Right Thing to Do!

We know methane emissions are a contributor to climate change and it is generally accepted that we must reduce methane emissions to maintain our quality of life.

Advancements in technology, from drones to satellites, are empowering interveners, regulators, and neighbors with transparent emissions data. This new, publicly available information is forcing the industry to adopt new technologies and methods to better detect and mitigate methane emissions.  

Despite the importance of detecting methane emissions, the industry relies on a subjective, inefficient, ineffective, and hazardous method (Method 21) to inspect for methane emissions.

OTM-51 is the waste industry's first and only method approved by the US EPA for quarterly surface emissions monitoring, automating the inspection via an unmanned aerial system (UAS - drone). It is proven to be the best available method for surface emissions monitoring available today.

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Find More Leaks!

OTM-51 finds more methane leaks! In a blind study conducted by a major waste company, the method resulted in detecting 50% more leaks, and was performed 25% faster than traditional Method 21.

Contact us for a copy of the blind test.

Detecting and remediating more leak sources benefits the environment and improves operations by capturing more gas that can be converted to energy. 

Safer & Less Hazardous!

On average, a technician walks 20 miles to inspect a landfill per the traditional method (Method 21). In addition, technicians walking the landfill for inspection are continually exposed to slip, trip, and fall hazards, rodents, insects (ticks), animals, weather, and other risks. OTM-51 reduces technicians' exposure to hazards by 50% by reducing overall foot traffic to perform the inspection.  

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Cover Integrity Inspection 

During SnifferDRONE flights, the pilot is able to simultaneously inspect the landfill cover system from the drone's 4K camera. The pilot can photograph suspect areas and deviate from the pre-programmed flight path to collect methane data over the area. Manual verification for these areas can also be performed as required. 

Greater Process

& Quality Control

The SnifferDRONE is flown precisely over the area, per pre-programmed flight paths, to collect comprehensive methane emissions data with associated GPS coordinates. Flights can be re-flown to capture data from the same location to compare emissions data over time. Quality checks are also performed to assure proper data collection coverage as required by regulations.  

A Complete Solution!

Software, Automation, and Actionable Information.

Leak locations and cover integrity data are pushed to Sniffer Field Ops™ (SFO) mobile app for technicians to manually inspect the locations quickly, coinciding with the SnifferDRONE flights.  Purchasing a subscription to SFO allows site operations to be alerted to leak locations in near-real time and view all details from their mobile app. Data is filtered to provide binary and actionable information for compliance reporting.  

Gain Additional Insights!

Analytics and calculations can be performed to better understand the cause and frequency of the site's methane emissions, as well as the results of remediation.  

Also consider these additional purposes of using data captured during compliance work:

  • Detect and isolate landfill odorsmore →

  • Capture more gas.  more →

And, it's Cost Competitive!

Sniffer performs OTM-51 at competitive costs to Method 21 inspection.

The time is right to upgrade your quarterly surface emissions monitoring plan.  Here's what you need to do to convert:

  1. Contact Sniffer to obtain a quote for services.

  2. Read and review both OTM-51 and ALT-150 in detail. 

  3. Notify your responsible agency in advance, of your intent to adopt OTM-51 / ALT-150.

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