1、Simulating the Effect of Aerobic Biodegradation on Soil Vapor Intrusion into BuildingsEvaluation of Low Strength Sources Associated with Dissolved Gasoline PlumesAPI PUBLICATION 4775APRIL 2009Simulating the Effect of Aerobic Biodegradation on Soil Vapor Intrusion into BuildingsEvaluation of Low Stre
2、ngth SourcesAssociated with Dissolved Gasoline PlumesRegulatory and Scientific Affairs DepartmentAPI PUBLICATION 4775APRIL 2009PREPARED UNDER CONTRACT BY:LILIAN D. V. ABREU, ROBERT ETTINGER, AND TODD MCALARYGEOSYNTEC CONSULTANTS, INC.Special NotesAPI publications necessarily address problems of a ge
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12、ctor of Regulatory Analysis and Scientific Affairs,API, 1220 L Street, NW, Washington, D.C. 20005.ContentsPageAbstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Introduc
13、tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14、 . . . . . . . . . . . . . 23 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.1 Conditions Simulated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Multi-Component Mixture Vapor Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.1 Effect of Source Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.2 Effect of First-Order Biodegradation Rate . . . . . . . . . . . . .
17、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124.3 Effect of Source Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124.4 Effect of Building Type . . . . . . . . . . . . . . . .
18、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.5 Results and Discussion for Multi-Component Gasoline Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 Evaluation of Additional Parameters . . . . . . . . . . . . . .
19、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265.1 Effect of Soil Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265.2 Effect of Foundation Crack Location . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295.3 Effect of a High Moisture-Content Soil Layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Discussion . . . . . . . . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326.1 Development of a Conceptual Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326.2 Preliminary Screening. .
22、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336.3 Site-Specific Assessments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347 Conc
23、lusions and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、. . . . 357.2 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、 . . . . . . . . . . . . . . . . . . . 36Appendix A Predicted Soil Gas Pressure Field and Air Flow Rate into the Building . . . . . . . . . . . . . . . . . . . 38Appendix B Plots of Attenuation Factors as a Function of Source Concentration, Depth and First-order Biodegradation Rates for Basement Sce
26、narios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Appendix C Plots of Attenuation Factors as a Function of Source Concentration, Depth and First-order Biodegradation Rates for Slab-on-grade Scenarios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、. . . . 49Figures1 Vertical cross section of sample model domain showing the grid refinement for basement scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Vertical cross section of sample model d
28、omain showing the grid refinement forslab-on-grade scenario. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Effect of low vapor source concentration (Cvs) on soil gas concentration distribution and vapor intrus
29、ion attenuation factors () for basement foundation scenarios and hydrocarbon biodegradation rate = 0.79 h-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Effect of low vapor source concentration (Cvs) on soil gas concentration distribution and va
30、por intrusion attenuation factors () for slab-on-grade foundation scenarios and hydrocarbon biodegradation rate = 0.79 h-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10ContentsPage5 Influence of soil vapor source concentration and first-order biode
31、gradation rates () on vapor intrusion attenuation factors () for basement scenarios, homogeneous sand soil and source depth (D) of 5 m bgs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Influence of soil vapor source concentration an
32、d first-order biodegradation rates () on vapor intrusion attenuation factors () for slab-on-grade scenarios, homogeneous sand soil and source depth (D) of 5 m bgs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Effect of biodegradatio
33、n rate ( on soil gas concentration distribution and vapor intrusion attenuation factors () for low vapor source concentration (4 mg/L) located at 4 m bgs (2 m below a basement foundation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34、138 Effect of biodegradation rate ( on soil gas concentration distribution and vapor intrusion attenuation factors () for low vapor source concentration (4 mg/L) located at 4 m bgs(4 m below the slab-on-grade foundation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35、 . . . . . . . . . . 149 Effect of source depth on the soil gas concentration distribution and vapor intrusion attenuation factors () for basement scenarios with a low vapor source concentration of 1 mg/L and biodegradation rate = 0.79 h-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36、 . . . . . . . . . . . . . . . . 1510 Effect of source depth on the soil gas concentration distribution and vapor intrusion attenuation factors () for slab-on-grade scenarios with a low vapor source concentration of 1 mg/L and biodegradation rate = 0.79 h-1. . . . . . . . . . . . . . . . . . . . . .
37、 . . . . . . . . . . . . . . . . . . . . . . . . . 16 11 Effect of source depth on the soil gas concentration distribution and vapor intrusion attenuation factors () for basement scenarios with a high vapor source concentration of 100 mg/L and biodegradation rate = 0.79 h-1. . . . . . . . . . . . .
38、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1712 Attenuation factors as a function of source depth below foundation and first-order biodegradation rate for basement scenarios with perimeter cracks and 10 mg/L vapor source concentration . . . . . . . 1813 Attenuation factors as a
39、function of source depth below foundation and first-order biodegradation rate for slab-on-grade scenarios with perimeter cracks and 10 mg/L vapor source concentration . . . . 1914 Effect of building type on soil gas concentration distribution for low vapor source concentration (4 mg/L) and biodegrad
40、ation rate = 0.79 h-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2015 Effect of building type on soil gas concentration distribution for high vapor source concentration(100 mg/L) and biodegradation rate = 0.79 h-1. . . . . . . . . . . . . . . . . .
41、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2116 Effect of multi-component source on soil gas distribution and oxygen consumption in the subsurface for dissolved groundwater source scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2317 Effect of mult
42、i-component source on soil gas distribution and oxygen consumption in thesubsurface for NAPL source scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2418 Normalized steady-state soil gas concentration distribution for oxygen and hyd
43、rocarbon with a vapor source concentration of 4 mg/L located at 5 m bgs (3 m below the foundation) . . . . . . . . 2719 Attenuation factors as a function of soil type and vapor source concentration for a source located at 5 m bgs (3 m below a basement foundation) . . . . . . . . . . . . . . . . . .
44、. . . . . . . . . . . . . . . 2820 Attenuation factors as a function of soil type and source depth below a basement foundation for a 10 mg/L source vapor concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2921 Effect of crack positioning (perimeter vs cen
45、ter of foundation) on attenuation factors as a function of vapor source concentration located 1 m below a basement foundation . . . . . . . . . . . . . . . . 3022 Effect of crack positioning (perimeter vs center of foundation) on attenuation factors as a function of vapor source concentration locate
46、d 3 m below a slab-on-grade foundation. . . . . . . . . . . . . 3023 Normalized steady-state soil gas concentration distribution for oxygen and hydrocarbon with a vapor source concentration of 1 mg/L located at 4 m bgs (2 m below a basement foundation) . . . . . 3124 Normalized steady-state soil gas
47、 concentration distribution for oxygen and hydrocarbon with a vapor source concentration of 10 mg/L located at 4 m bgs (2 m below a basement foundation) . . . . 32ContentsPageA1 Normalized steady-state disturbance pressure distribution for a homogeneous soil permeability field (Kg=10-11m2) surroundi
48、ng basement and slab-on-grade foundations with perimeter cracks and a lower boundary at depths of 3, 5 and 7 m bgs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39A2 Plan view of the foundation crack distribution: a) perimeter crack; b) center-of-foundation crac
49、ks . . . 40A3 Normalized steady-state disturbance pressure distribution for a homogeneous soil permeabilityfield (Kg=10-11m2) surrounding basement foundations with cracks located on perimeter and on center of the foundation slab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41A4 Normalized steady-state disturbance pressure distribution for a homogeneous soil permeability field (Kg=10-11m2) below slab-on-grade foundations with cracks located on perimeter and on center of the foundation slab.
