Radon entry into basements: Approach, experimental structures, and instrumentation of the small structures research project

Fisk, W.J.; Modera, M.P.; Sextro, R.G.; Garbesi, Karina; Wollenberg, H.A.; Narasimhan, T.N.; Nuzum, T.; Tsang, Y.W.

doi:10.2172/10178989

Cited by 7 publications

(13 citation statements)

References 7 publications

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“…the soil permeability (k. in m 2 ) is determined from the relationship: (2) where Q is the rate at which soil gas is drawn from the probe in m 3 s-l, J1 is the dynamic viscosity of air (1.75 x 10-5 Pa s at ambient conditions), AP is the disturbance pressure difference between the probe tip and the soil surface in Pa, and S is the shape factor. The shape factor was determined by numerical modeling to be independent of depth and proximity to the structure to within 10% for the given locations of the probes (15). and has a value of 0.3 m. Table I indicates the spatial variability in soil permeability and the effect of seasonal changes in soil conditions.…”

Section: Site and Structure Characterizationmentioning

confidence: 99%

See 1 more Smart Citation

Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Garbesi¹,

Sextro²,

Fisk³

et al. 1993

Environ. Sci. Technol.

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The article has not been subjected to CARB review and does not necessarily reflect their views. Additional funding from NIEHS Superfund Program under Grant 5 P42 ES04699-05 is gratefully acknowledged.Previous studies have reported a large and persistent discrepancy between field measurements and model predictions of pressure-driven entry of soil gas into housesthe phenomenon that causes high concentrations of radon indoors. The discrepancy is often attributed to poor understanding of inherently complex field sites. This paper compares measurements of soil-gas entry made at a fullscale test basement located in natural solid with predictions of a three-dimensional finite difference model. The results corroborate the earlier findings, with the model underpredicting the soil-gas entry rate by a factor of 7. The effect of seasonal changes in soil conditions on soil-gas entry is also examined. Despite large seasonal changes in near-surface soil moisture content and air permeability, there is no observable effect on soil-gas entry, apparently because critical soil conditions near the soil-gas entry location in the structure floor remain relatively constant.

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Section: Site and Structure Characterizationmentioning

confidence: 99%

“…Average soil permeabilities were determined for each region using the data for October 1, 1991, in Table I. Gravel permeability, was determined using laboratory soil-column measurements and was found to be 2.0xl0-8 m 2 (15). there is a significant discrepancy between the modeled and measured values.…”

Section: Numerical Modeling and Comparison With Experimentsmentioning

confidence: 99%

Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Garbesi¹,

Sextro²,

Fisk³

et al. 1993

Environ. Sci. Technol.

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“…Several other indoor radon models and predictions may be found in the literature, e.g. Al-Ahmady (1996), Andersen (1992Andersen ( , 1999, Fisk et al (1992), Font (1997), Font et al (1999ab), Font and Baixeras (2003), Gadgil (1992), Gunby et al (1993), Li et al (1995), Sherman (1992), Wang and Ward (2000) and With and Jong (2011). Several of the models treat selected parts of the many potential radon sources to the radon level in the indoor air environment, where some of the models may be very detailed and involve relatively complex equations covering specific parts of the total radon picture.…”

Section: Introductionmentioning

confidence: 99%

Development of a model for radon concentration in indoor air

Jelle

2012

Science of The Total Environment

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A model is developed for calculation of the radon concentration in indoor air. The model takes into account various important parameters, e.g. radon concentration in ground, radon diffusion resistance of radon barrier, air permeance of ground, air pressure difference between outdoor ground and indoor at ground level, ventilation of the building ground and number of air changes per hour due to ventilation. Characteristic case studies are depicted in selected 2D and 3D graphical plots for easy visualization and interpretation. The radon transport into buildings might be dominated by diffusion, pressure driven flow or a mixture of both depending on the actual values of the various parameters. The results of our work indicate that with realistic or typical values of the parameters, most of the transport of radon from the building ground to the indoor air is due to air leakage driven by pressure differences through the construction. By incorporation of various and realistic values in the radon model, valuable information about the miscellaneous parameters influencing the indoor radon level is gained. Hence, the presented radon model may be utilized as a simple yet versatile and powerful tool for examining which preventive or remedial measures should be carried out to achieve an indoor radon level below the reference level as set by the authorities.

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“…The DDP source probe consists of 15-cm length of cylindrical well screen welded into a pipe (15.4 mm ID, 3.1 mm wall) fitted with a sealed and pointed end [Fisk et al, 1989;Fisk et al, 1992]. The size of the well-screen surface allows the pressure signal to propagate through many meters of soil without excessive attenuation while maintaining soil-gas velocities within the Darcy limit even at a distance of 1 cm from the source.…”

Section: Dual-probe Dynamic Pressure Apparatusmentioning

confidence: 99%

“…The sampling scale (or effective sampling radius) of these steady-pressure permeability measurements has been defined as the distance at which the disturbance pressure field is 5% of its value at the probe's sampling tip [Fisk et al, 1992]. In practice, this is taken to be the theoretically-determined distance at which the pressure field would be 5% of the probe-tip value in a homogeneous medium.…”

Section: Introductionmentioning

confidence: 99%

Scale Dependence of Soil Permeability to Air: Measurement Method and Field Investigation

Garbesi¹,

Sextro²,

Robinson³

et al. 1996

Water Resources Research

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This work investigates the dependence of soil permeability to air on sampling scale in near‐surface unsaturated soils. A new dual‐probe dynamic pressure technique was developed to measure permeability in situ over different length scales and different spatial orientations in the soil. Soils at three sites were studied using the new technique. Each soil was found to have higher horizontal than vertical permeability. Significant scale dependence of permeability was also observed at each site. Permeability increased by a factor of 20 as sampling scale increased from 0.1 to 2 m in a sand soil vegetated with dry grass, and by a factor of 15 as sampling scale increased from 0.1 to 3.5 m in a sandy loam with mature Coast Live Oak trees (Quercus agrifolia). The results indicate that standard methods of permeability assessment can grossly underestimate advective transport of gas phase contaminants through soils.

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Radon entry into basements: Approach, experimental structures, and instrumentation of the small structures research project

Cited by 7 publications

References 7 publications

Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Soil-gas entry into an experimental basement: model measurement comparisons and seasonal effects

Development of a model for radon concentration in indoor air

Scale Dependence of Soil Permeability to Air: Measurement Method and Field Investigation

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