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F-12 REFERENCES APPENDIX G
<br /> DiGiulio,C.Paul,R.Cody,R.Willey,S.Clifford,R.Mosley,A.Lee,K.Christensen and BAROMETRIC PRESSURE,RAINFALL,and SOIL DRAINAGE
<br /> R.Costa,2006a. Comparison of Geoprobe PRT and AMS GVP Soil-Gas Sampling
<br /> Systems with Dedicated Vapor Probes in Sandy Soils at the Raymark Superfund Site. Barometric Pressure Fluctuations
<br /> EPA/600/R-06/111. National Risk Management Research Laboratory,Office of
<br /> Research and Development,U.S.Environmental Protection Agency,Cincinnati,OH, Soil Gas
<br /> November. http://www.epa.gov/ada/pubs/repon.htmi.
<br /> Massmann and Farrier(1992)evaluated the significance of barometric pressure
<br /> Hartman,B.2006.How to Collect Reliable Soil-Gas Data for Risk-Based Applications- Fluctuations on the transport of atmospheric gas into the vadose zone. They examined
<br /> Specifically Vapor Intrusion;Part 4-Updates on Soil-Gas Collection and Analytical situations in which barometric fluctuations will yield a significant affect on the vadose
<br /> Procedures,LUSTLine Bulletin 53,September 2006. zone. Model calculations showed that fresh air may migrate several meters into a
<br /> highly permeable subsurface during large barometric pressure cycles and the depth of
<br /> Smith,Roy-Keith,2003.Guide to Environmental Analytical Methods, 5"Edition.Genium penetration increases as the thickness and permeability of the vadose zone increases.
<br /> Publishing Corporation,2003. Massmann and Farrier(1992)thus suggested that the concentration of volatile
<br /> contaminants may be lower when barometric pressures are high and that soil gas
<br /> SW-846,1996: Test Methods for Evaluating Solid Waste,Physical/Chemical Methods, measurements will show the largest fluctuations during times of rapidly rising or falling
<br /> SW-846:Methods 8000B,8015,8021,82606,Various Revisions,U.S.Environmental barometric pressures. During these large barometric pressure changes,as indicated by
<br /> Protection Agency,Washington,D.C.,1996.SW846 On-line: http://www.el)a.Clov/sw- Figure 8 of their paper,soil gas at 1.5 meters(5 feet)may be diluted with atmospheric
<br /> 846/sw846.htm air by 30 to 50 percent.
<br /> USEPA,1999:Compendium of Methods for the Determination of Toxic Organic Surface Flux
<br /> Compounds in Ambient Air. Methods TO-13,TO-15,TO-17,Second Edition,U.S.
<br /> Environmental Protection Agency,Research Triangle Park,NC,January 1999;EPA Clements and Wilkening(1974)demonstrated empirically that atmospheric pressure
<br /> 600/625/R-96/010b. changes of one to two percent associated with the passage of frontal systems will
<br /> produce changes in the flux of radon from the subsurface by 20 to 60 percent. The
<br /> actual magnitude of the change in the radon flux depends upon the rate of change of
<br /> the barometric pressure and its duration. The effect of pressure changes to VOC
<br /> concentrations in soil gas is expected to be similar.
<br /> Rainfall Events
<br /> Surface flux
<br /> Kienbusch and Ranum(1986)evaluated the affects of rainfall on the collection of Flux
<br /> chamber measurements on open ground. In tests at a simulated landfill,water was
<br /> added to dry soil cells to simulate rainfall. Trace precipitation(0.01 inches)had no
<br /> effect on measured emission fluxes from the ground. Heavier rainfall(0.4 inches),
<br /> however,did have an effect. The emission Flux was decreased by 90 to 95 percent and
<br /> the reduction in emissions lasted for over eight days. These results are consistent with
<br /> other field observations(Radian Corporation,1984;Eklund,1992).
<br /> Soil Drainage
<br /> Gardner et al.(1970)derived approximate solutions for unsaturated flow following
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