摘要: |
ihe report gives results from field tests that characterize the amount and size distribution of particulate matter (PM) emissions from operations at construction sites. Of particular interest is the movement of earth by scraper loading and unloading, grading, transit vehicular movement on unpaved roads, and truck loading and unloading. Major results from the field tests are: (1) emissions of PM with aerodynamic diameter less than 10 micrometers (PM-10) from the loading/unloading of scrapers vary from about 1 to 1000 lb/1000 cu yd, depending on the soil properties and the type of scraper used; (2) PM-10 emissions due to scraper travel between the cut and fill areas can be expected to exceed those due to removal and replacement of earth, if the transit distance is greater than 150 ft; (3) scraper loading/unloading emissions exhibit PM-2.5/PM-10 ratios of about 0.6, approximately twice the average ratio of 0.25 for scrapers in transit, contrasting to most fugitive dust emission sources, whose PM-2.5/PM-10 ratios are typically between 0.15 and 0.25; and (4) emissions from truck loading were 100 times greater than emissions from truck dumping, reflecting the smaller capacity of the loader in comparison to the truck bed and the fact that loading occurs at a higher elevation above ground with greater exposure to ambient winds. |