Data-Management and Reporting Software
PICMET-2 (Path-Integrated Concentration - Meteorology software) is Minnich and Scotto’s state-of-the-art computer program for managing its perimeter air monitoring during former MGP site cleanups. PICMET-2 employs the cross-sector averaging technique, conceived of by USEPA Region 7, to automatically generate maximum offsite concentrations for contaminants of concern based on the spectroscopic measurements and onsite meteorology. This technique involves the collection of path-integrated, crosswind contaminant measurement data downwind of the source (concentration units of parts per million times meters, ppm-m, or milligrams per square meter, mg/m2), and then dividing each concentration by the plume width (m) to yield a representative maximum impact along the spectrometer beam (ppm or mg/m3). It provides a conservative methodology for assessing the maximum 10-minute-averaged concentration at any downwind location.
A dilution factor is applied to the maximum beam impact to account for the increasing contaminant “loss” due to atmospheric dispersion as the plume moves away from the site toward the downwind receptor(s). The dilution factor is based on a full array of dispersion modeling performed for all source-beam-receptor relationships and meteorological conditions expected to occur.
The identification of an appropriate plume width depends on three factors: (a) dispersive properties of the plume as it is transported along the mean wind direction; (b) the distance between the source and the spectrometer beam; and (c) the width of the source itself (e.g., excavation area or stockpiled material). Physical dimensions and source-receptor distances are entered manually, while PICMET-2 automatically retrieves and processes all spectroscopic and requisite meteorological data for each 10-minute monitoring event.