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PREFERENTIAL RADON TRANSPORT THROUGH HIGHLY PERMEABLE CHANNELS IN SOILS
Citation:
Mosley*, R B. PREFERENTIAL RADON TRANSPORT THROUGH HIGHLY PERMEABLE CHANNELS IN SOILS. Presented at 7th Int. Symposium on the Natural Radiation Environment, Rhodes, Greece, 5/20-24/02.
Description:
The paper discusses preferential radon transport through highly permeable channels in soils. Indoor radon levels (that can pose a serious health risk) can be dramatically increased by air that is drawn into buildings through pipe penetrations that connect to permeable channels in soils. The channels, commonly containing gravel bedding around utility pipes, act as a collecting plenum for soil radon and can draw air from distances approaching 100 m. Equations characterizing air and radon flow in such channels are developed and compared with field data in this paper. This pollutant entry mechanism has recently attracted new attention because of its relevance to entry of volatile organic compounds from contaminated, groundwater, leaking storage tanks, landfills, and other sources of soil vapor contamination. Three test channels were constructed to simulate conditions associated with utility line installations. Site sampling characterized soil radium, emanation, moisture, particle size, density, specific gravity, permeability, and diffusion coefficient properties. Experiments, in which air was extracted through the suction tube, showed that pressures and air flow rates decreased exponentially with distance along each channel, as predicted. Radon concentrations in the channels were lower than in surrounding soil because of their greater porosity and reduced radon source strengths.