What is EPA Method 325 Fenceline Monitoring?
Refinery Sector Rule
EPA Methods 325 A & B Fenceline Monitoring are part of the Refinery Sector Rule (40 CFR Parts 60 and 63, Refinery MACT 1 & MACT 2) that was published in the Federal Register December 1, 2015. The rule went into effect February 1, 2016 and Fenceline Monitoring must begin by February 1, 2018 to ensure 12 months of data are available by the 2019 refinery reporting deadlines. You can view the Final Rule as well as Rule History on the EPA's website here.
EPA Methods 325A & 325B
Companion EPA Methods 325A (Sampler Deployment and VOC Sample Collection) and 325B (Sampler Preparation and Laboratory Analysis) select benzene as the representative compound to evaluate the overall emissions from refineries. Passive sampling onto sorbent tubes followed by Thermal Desorption-Gas-Chromatography/Mass Spectrometry (TD-GC/MS) analysis has been established as the standard air monitoring technology for the EPA’s new rule. Passive sampling tube shelter assemblies (as seen in the picture on the right) will be hung at various locations along the fenceline/property boundary surrounding refineries. After two weeks (14 days) passive sampling tubes can be detached from their shelters, re-sealed and sent to a laboratory equipped with TD-GC/MS for analysis. Per EPA Method 325, all tubes must be replaced with freshly conditioned and qualified sampling tubes every 14 days to ensure continuous monitoring.
The EPA defines the scope of EPA Methods 325A and 325B as the collection of volatile organic compounds (VOC's) at facility property boundaries as well as from fugitive and area emission sources using passive (diffusive) tube samplers to determine the concentration of airborne VOC's at or near these potential emission sources. These methods may be used to obtain the average concentration of the select VOC's as well as their corresponding uptake rates. To obtain accuracy, these methods require the collection of local meteorological data, such as wind speed and direction, temperature, or barometric pressure.
The methods provide a low cost alternative to screen fugitive or area emissions as compared to active sampling methods that involve pumped sorbent tubes or time weighted average canister sampling.