modeling of vapor intrusion and volatile organic compounds...
TRANSCRIPT
Modeling of Vapor Intrusion and Volatile
Organic Compounds Transport in the Soil – Review and Implementation
Xinyue Liu
Exchange student from South University of Science and Technology in China
CONTENTS
1 Conceptual model
3 Numerical model
2 Mathematical model
4 Results and discussion
5 Next step
1 Conceptual model
Some of the volatile organic compounds,
contained in contaminants of interest from
the subsurface, can enter the building
through soil gas transportation.
Vapor intrusion
Johnson, P. C., & Ettinger, R. A. (1991). Heuristic model for predicting the intrusion rate of contaminant vapors into buildings.
1 Conceptual model
• Sources: gas station, improper disposal,
accidental spillage, or leaking landfill liners
• Forms: can become bound to the soil matrix,
dissolved in groundwater (or soil water)
and/or exist as a separate, residual phase
known as a non-aqueous phase liquid
(NAPL)
• Two broad categories: chlorinated solvents
and petroleum hydrocarbons.
VOC contaminants
Johnson, P. C., & Ettinger, R. A. (1991). Heuristic model for predicting the intrusion rate of contaminant vapors into buildings.
1 Conceptual model
• Slab
• Crawl space
• Basement
Buildings
Yao, Y., Shen, R., Pennell, K. G., & Suuberg, E. M. (2013). A Review of Vapor Intrusion Models.
2 Mathematical model
1. Darcy’s law:
Governing equations
2. Convection-diffusion equation:
3. Millington and Quirk equation:
2 Mathematical model
1. Darcy’s law:
Boundary conditions
p=0
p=0
p=0
p=0
p=-5 [Pa]
p=0 p=0
Water table
symmetric infinity
atmosphere
slab
crack
slab
16 m * 3 m domain
3 Numerical model
• Comsol:
Simulation software;
especially for Multiphysics problems
• 229 codes:
Created by MIT Course 229 Staffs
1. Darcy’s law:
• parameters:
ϕg (air filled porosity) = 0.38
Kg (permeability) = 1e-12 [m^2]
3 Numerical model
• 229 codes:
1. Darcy’s law:
3 Numerical model
• 229 codes:
• Finite volume method
1. Darcy’s law:
Pierre F.J Lermusiaux. Lecture 15 notes
1
*
.
.
Nx Ny
p
p
p
=
( ) 0p
c pt
− =
( ) 0p
x y c p ndAt
− =
( ) ( ) 0face
faces
px y c p n A
t
− =
d pAp
dt=
CDS approximation
FV discretization of
Laplace operator
3 Numerical model
• 229 codes:
• Finite volume method
1. Darcy’s law:
Pierre F.J Lermusiaux. Lecture 15 notes
d pAp
dt=
FV discretization of
Laplace operator - Dfs
1 23 4_
2
n n nnp p p
Dfs p Dfs bcst
− −− += +
4 Results and discussion
• Pressure field:
• Time = 20 h
• Comsol:
• 229 codes:
4 Results and discussion
• Pressure field:
3 Numerical model
2. Convection-diffusion equation:
3. Millington and Quirk equation:
Advection of gasAdvection of water
Diffusion Reaction
Gas phase Liquid
phase
Solid
phase
Effective transport
porosity
Effective diffusion
coefficient
Gas
phase
Liquid
phase
chlorinated solvents
Porosity n = 0.38
Diffusion coefficient Di<0.01cm2/s
3 Numerical model
• Comsol:
2. Convection-diffusion equation:
3. Millington and Quirk equation:
Advection of gasAdvection of water
Diffusion Reaction
Gas phase Liquid
phase
Solid
phase
Gas
phase
Liquid
phase
3 Numerical model
• Comsol: Boundary conditions
c=0
c=1
c=0
c=0
c=0 c=0
Water table
symmetric infinity
atmosphere
slab
crack
slab
16 m * 3 m domain
4 Results and discussion
• Comsol:
T = 300h
T = 500h
Vapor intrusion
Path way is complete
T = 900h
Vapor intrusion becomes steady;
Risk maximum
References
[ 1 ] P i e r r e F. J L e r m u s i a u x . 2 2 9 L e c t u r e n o t e s
[ 2 ] J o h n s o n , P. C . , & E t t i n g e r , R . A . ( 1 9 9 1 ) . H e u r i s t i c m o d e l f o r p r e d i c t i n g t h e
i n t r u s i o n r a t e o f c o n t a m i n a n t v a p o r s i n t o b u i l d i n g s . E n v i r o n m e n t a l S c i e n c e &
Te c h n o l o g y, 2 5 ( 8 ) , 1 4 4 5 - 1 4 5 2
[ 3 ] Ya o , Y. , S h e n , R . , P e n n e l l , K . G . , & S u u b e r g , E . M . ( 2 0 1 3 ) . A R e v i e w o f
Va p o r I n t r u s i o n M o d e l s . E n v i r o n m e n t a l S c i e n c e & Te c h n o l o g y, 4 7 ( 6 ) , 2 4 5 7 -
2 4 7 0 .
[ 4 ] Ya o , Y. , S h e n , R . , P e n n e l l , K . G . , & S u u b e r g , E . M . ( 2 0 1 3 ) . A R e v i e w o f
Va p o r I n t r u s i o n M o d e l s . E n v i r o n m e n t a l S c i e n c e & Te c h n o l o g y, 4 7 ( 6 ) , 2 4 5 7 -
2 4 7 0 . d o i : 1 0 . 1 0 2 1 / e s 3 0 2 7 1 4 g
[ 5 ] I l l a n g a s e k a r e , T. ; P e t r i , B . ; F u č i k , R . ; S a u c k , C . ; S h a n n o n , L . ; S m i t s , K . ;
C i h a n , A . ; C h r i s t , J . ; S c h u l t e , P. ; P u t m a n , B . ; L i , Y. Va p o r I n t r u s i o n f r o m
E n t r a p p e d N A P L S o u r c e s a n d G r o u n d w a t e r P l u m e s : P r o c e s s U n d e r s t a n d i n g a n d
I m p r o v e d M o d e l i n g To o l s f o r P a t h w a y A s s e s s m e n t , S E R D P P r o j e c t E R - 1 6 8 7
F i n a l R e p o r t 2 0 1 4 .
Q&A?
Thank you: Pier re F.J Lermusiaux (MIT) ;
Wael Haj j Al i (MIT) ;
Enze Ma (SUSTech)