Submitted by Maria.Kapsalaki on Wed, 05/07/2014 - 08:38
Soil gas pollutants (Radon, VOCs, etc...) entering buildings are known to pose serious health risks to building’s occupants, and various systems have been developed to lower this risk. Soil Depressurization Systems (SDS) are among the most efficient mitigation systems protecting buildings against soil pollutants. Two kinds of SDS are currently used: active and passive systems. Active systems are mainly use fans, which enables the mechanical sub-slab’s air extraction. Passive systems use natural thermal forces and wind effect to extract air from the sub-slab.
Cluj Napoca City is the most important city from northwestern part of Romania, having about 350,000inhabitants. The Somes river, also the most important river of this country region crosses the city fromwest to east, but before it crosses a granite massive, named Maguri-Racatau, a region located at 35Km on the upper part of this water course. The first indicators of a possible radon prone area for Cluj-Napoca city and its neighboring was the water radon concentration from the old power supply of thecity with about 37 Bq/L (1nCi/L).
A soil gas measurement method developed earlier  was applied to boreholes drilled to belowfoundation depth. Radon concentration and permeability were measured at 50 cm intervals. Inradon prone areas permeability showed to increase with depth over several orders of magnitude,indicating a low permeability top layer with a thickness of 0.5 m and more. A radon availabilityindex (RAI) was empirically defined and the maximum RAI of each boring proved to be a reliableindicator for radon problems in nearby houses.
One exposure pathway which has a significant influence on the outcome of a site specific risk assessment when volatile contaminants compounds are involved, is the leakage of contaminated subsurface gases into the indoor air environment. Evaluation of this pathway largely is completed with the use of mathematical models. The current level of understanding is that both convective and diffusive contaminant transport processes in the soil and across the subsurface building envelope will contribute to degraded indoor air quality.
The principal soil gases of current concern to building are radon and landfill gas. The flow of these is generally thought to be dominated by viscous flow driven by pressure differences. This paper compares analytical results presented in two previous papers, an experiment to measure the flow of gas in soil and an analytical result found by another technique. The results support the findings of the previous work.
The principal soil gases of current concern to building are radon and landfill gas. The flow of these is generally thought to be dominated by viscous flow under a pressure gradient. This paper presents results for such pressure-driven flow of gas for problems relating to a building with a bare soil floor, for example below a suspended timber floor. The solutions address this problem in two dimensions as a mixed boundary problem.
The principal soil gases of current concern to building are radon and landfill gas. The flow of these is generally considered to be dominated by viscous flow driven by pressure differences. This paper presents results for the pressure-driven flow of gas for problems relating to a building with a bare soil floor, for example below a suspended timber floor. This paper builds on a previous paper by mapping the solution to a mixed boundary problem onto another geometry. In a third paper these results will be compared with an analytical result from elsewhere and an experiment.
During the past 10 years the U.S. Environmental Protection Agency (EPA) has pursued a national strategy to address radon remediation in buildings to meet its goals of radon risk reduction. Initially the approach developed and demonstrated remediation methods and techniques in existing residences with specific attention to the effect of regional climate variations and the differences in housing construction. A number of studies and demonstrations were undertaken to accurately characterize and evaluate the effectiveness of several remediation methods and techniques.
Remedial measures to prevent soil gas infiltration have been implemented on many buildings affected by intrusion of radon, water vapour, methane and other volatile organic compounds (VOCs ). The success of these measures has been well documented for gases such as radon; however similar detailed documentation was not readily available for methane or other vocs. The objective of this study was to evaluate the effectiveness of four different remedial solutions installed on houses. All houses tested in this study had the potential of methane intrusion.