Regulatory agencies have pushed for more monitoring in general and fenceline monitoring in particular. A bill introduced in the House requires EPA to add fenceline monitoring at 100 industrial sites. EJ considerations also impact the drive for more monitoring. Reporting is mostly hard copy. However, public perception is looking at a dynamic website condition, with the idea that any delay in posting the data is indicative of industry attempting to hide something. Facilities do not operate in a vacuum. There are background levels of contaminant concentrations. Facilities also tend to congregate for supply line considerations. Wind and weather can impact results. There are high lab and capital costs. There may also be particle size or speciation requirements. Accurate wind field data should allow for proper evaluation of background or transport concentrations that come into the site. This could involve upwind monitoring to show concentrations that may net out the facility contributions. Sensor technology needs to be evaluated to control costs.
There are a number of passive and continuous monitoring approaches. For particulates there are beta attenuation techniques and light scattering monitors. The system also takes an air sample for other measurements. Continuous gas analysis systems are available. They can also be solar powered. Passive techniques do not provide continuous analysis. Refineries are required to do fenceline monitoring for benzene. Absorption tubes were used with a 14-day exposure period. Some exceedances were noted at one refinery. The refinery switched to a continuous system combined with wind data to provide much better temporal resolution. This system pinpointed whether the refinery or external sources were the primary contributor. A construction site used a continuous monitoring system combined with data analysis for particulates and heavy metals. Data analysis allowed the inclusion of telemetry data to again show the primary source and then alerts for actions needed to reduce concentrations. Data visualization also helps alert the facilities.
Looking ahead, drones will likely be utilized to collect and send data to data analysis systems. Both sensors and sampling systems can be included on the drones. The evidence of a plume can be isolated and centered. Trees and towers can be a problem for drones.
Rick Osa & Bryan Engelsen, Environmental Resources Management (ERM)