Upwind/Downwind Sampling for Fugitive Dust Area Sources

Upwind/downwind sampling of total suspended particles (TSP) and particles with aerodynamic diameters <10 µm (PM10) has long been used to detect and quantify fugitive dust emissions from area sources such as construction sites, unpaved roads, mining and quarrying operations, and aggregate processing . In this approach, samplers are located on the upwind side of a facility to quantify the PM flux entering the property. Upwind concentrations are subtracted from those measured at downwind samplers to estimate the incremental PM contributed by the facility. The goal of this study is to identify and characterize ambient air PM10 monitoring instruments and meteorological monitoring systems that can be effectively and economically used to accurately estimate incremental PM10 concentrations contributed by facilities that generate fugitive dust. Upwind/downwind sampling was conducted at two southern California aggregate processing operations (Facilities A and B) to evaluate the utility of these instruments for this purpose: 1) high-volume (1130 L min-1) PM10 filter sampler (Hivol); 2) BGI low-volume (16.7 L min-1) PM10 filter sampler (PQ-200); 3) BGI mini-volume (5 L min-1) PM10 filter sampler (OMNI); 4) METONE E-Sampler based on nephelometer light scattering detection; 5) METONE PM10 E-BAM based on beta attenuation detection through a filter tape; 6) Lovol PM10 (Hivol); 6) TSI Model 8250 DustTrak based on nephelometer light scattering; 7) TSI Model 8533 DustTrak DRX based on nephelometer light scattering and optical particle counting; and 8) Grimm Model 1.108 optical particle counter. The experiment was conducted during the August through October, 2008, period to avoid the autumn rain storms. Since the samplers were operated unattended, except for daily maintenance and sample changing, it was necessary to locate them within the property boundaries at both facilities to obtain adequate security. As a result, monitors were closer to dust-generating activities than would be the case for a test conducted outside the fence line. Time series of five-hour PM10 equivalents for Facility A are shown in Figure 1. Except for the 9/25–26/08 fugitive dust generation events at Site A-1, upwind Site A-2 shows higher PM10 levels than any of the other sites. The lowest PM10 concentrations were found on Sundays (i.e., 9/14/08 and 9/21/08), when Facility A was inoperative and there was negligible traffic on the boundary roadways. DustTrak DRX was removed on 9/26/08, for location within the observable plumes from the different fugitive dust generating activities. The distance from the sample array was <20 m, yet the PM10 levels from these units were more than double those of most of the other samplers, consistent with the generated plumes having localized impacts. Minor wind shifts placed some samplers completely outside of the visible The hivol and lovol PQ200 tracked each other most closely, which is reasonable since both are U.S. EPA-designated PM10 FRMs. However, their PM10 concentrations differ from each other; on average, the PQ200 yielded ~82% of the hivol PM10 concentrations. be refined. The upwind site should represent the neighborhood-scale PM10 level, even if it is not strictly upwind of the dust-emitting facility. The downwind site should represent a mixed plume from the multiple emitters within the facility and not be dominated by nearby fugitive dust sources. The influence of local sources can be assessed by locating an array of OPCs, such as the DRX or Grimm monitors, in a lateral direction with respect to the PM10 filter sampler.