Dobromir Pressyanov, Prof.
Sofia University “St. Kliment Ohridski”
The position of suction pits is of critical importance for the efficiency of the active soil depressurization systems. In many cases the distribution of the radon source in the soil beneath the building foundation is not homogeneous, with variations that can exceed an order of magnitude, especially for large buildings. We present an approach to estimate the most likely radon distribution using radon-in-soil gas measurements at a depth of 60 cm made in points of a contour close to the external perimeter of the building. A model is then employed to obtain the radon distribution in the terrain beneath the building that fits best the values measured on the contour. Obtained this way “radon source strength map” is used to optimize the positions of the suction pits. The quality assurance of the soil gas measurements and the requirements for detectors suitable for soil-gas diagnostics are discussed.