Fenceline Monitoring

What is EPA Method 325 Fenceline Monitoring?

Refinery Sector Rule

EPA Method 325 has been written into the December 1, 2015, update to 40 CFR Parts 60 and 63, Petroleum Refinery Sector Risk and Technology Review and New Source Performance Standards. The rule requires continuous monitoring of benzene at refinery fenceline locations using passive sorbent tubes over 14-day intervals. A rolling annual average of the background adjusted benzene concentration is evaluated against the compliance standard of 9 µg/m3. EPA Method 325A details field protocols for the deployment of passive tube samplers, and EPA Method 325B describes the laboratory analysis of the sample tubes using thermal desorption GC/MS. Eurofins is leading the industry in passive and active sorbent technology, supporting a wide range of air monitoring programs and research projects.

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.

While the rule is currently limited to the monitoring of benzene, Method 325 can also be extended to include other compounds of concern at ambient monitoring sites. Additional target VOCs include 1,3-Butadiene, Toluene, Ethyl Benzene, and Xylenes as well as other chemicals for which diffusive sampling rates have been determined. Reporting limits less than 1 µg/m3 can be easily achieved over a 7-day period. Extending the sampling period to 14 days translates to reporting limits less than 0.5 µg/m3.

Partnering with Eurofins brings you:

• Industry-leading expertise on passive sorbent methods including EPA Method 325
• Unmatched thermal desorption GC/MS capacity
• Competitive pricing and value-added services
• Convenient field sample kits for tube deployment and retrieval
• Reliable quality systems to generate data of the highest integrity
• Complementary analytical tools to assist with source identification
• Knowledgeable and responsive project managers
• Technical staff to provide on-site training

Contact our experienced team to find out how Eurofins can support your EPA Method 325 monitoring needs.