RADON TRANSPORT INTO DWELLINGS - CONSIDERING GROUNDWATER AS A SOURCE

A mathematical model is used to investigate whether radon degassing fr om groundwater may contribute to indoor radon levels. Specifically, th e transport of radon in the soil-gas phase from the groundwater-soil g as interface to under-pressurized dwellings is modelled. The question whether radon in groundwater may contribute to indoor radon levels ari ses from observed high radon concentrations in groundwater, and recent findings that advection in the gas phase may be an important transpor t mechanism for radon into slightly under-pressurized dwellings. Most previous radon transport investigations did not consider groundwater a s a potential source for contributing to indoor radon. The mathematica l model includes a method to directly calculate indoor radon concentra tions and an equivalent continuum approach to represent cracks in conc rete foundations. The results of the simulations indicate that partiti ons from groundwater to the soil advectively transported by the gas ph ase to slightly under-pressurized dwellings in relatively permeable so ils such that indoor radon concentrations may exceed 148 Bq/m(3), whic h is the action limit imposed by EPA.