Air Flow Air Flow Optimization Optimization

for Remediation for Remediation using SPARGusing SPARG

Diane FinkDiane Fink

Liz HilkertLiz Hilkert

Significance and ObjectiveSignificance and Objective

Optimal airflow rates are important in Optimal airflow rates are important in remediation remediation – Ensure maximum contaminant volatilizationEnsure maximum contaminant volatilization– Prevent Prevent

channeling channeling Determine ideal Determine ideal

capillary pressurescapillary pressuresfor a one meter for a one meter soil column soil column – varying water varying water

table heightstable heights

SPARG InformationSPARG Information

Unix based program for one or two Unix based program for one or two dimensional column simulationsdimensional column simulations

Uses finite element-Galerkin's Uses finite element-Galerkin's formulation formulation

The airflow simulation model that is The airflow simulation model that is the basis for AirFixthe basis for AirFix– Includes contaminant transportIncludes contaminant transport

SPARG CalibrationSPARG Calibration

Only dependable data from Only dependable data from 2D model2D model

Capillary Capillary Head of Head of 10.15 m10.15 m

Calibration Calibration successfulsuccessful

Sensitivity Sensitivity AnalysisAnalysis

Sensitive Variables

Capillary Pressure Saturation

Atmospheric Pressure All

Soil Lambda  Porosity Ave Saturation

    

  Sensitivity

0.340 0.109 Min-Def 1.003

0.390 0.125 Def-Max 0.998

0.440 0.141  

 

Atmospheric Pressure

Capillary Pressure at Y =0.4

    

  Sensitivity

8.000 -0.524 Min-Def 29.032

10.000 0.276 Def-Max 6.509

12.000 1.076  

SPARG InputsSPARG Inputs Constant Inputs:Constant Inputs:

– Psubd: 0.2 mPsubd: 0.2 m– Soil Lambda: 3.4Soil Lambda: 3.4– Porosity: 0.39Porosity: 0.39– Grid: 1,10 Grid: 1,10 – Grid Division: 0.1 mGrid Division: 0.1 m– Atmospheric Atmospheric

Pressure: 10 mPressure: 10 m

20 elements

22 nodes

Varied SPARG InputsVaried SPARG Inputs

Water Table Height:Water Table Height:– Half of Sand Height: 0.33 mHalf of Sand Height: 0.33 m– Full Sand Height: 0.67 mFull Sand Height: 0.67 m

Airflow Entry Rate (nodes 1 and 2):Airflow Entry Rate (nodes 1 and 2):– Varied by increasing air entry pressureVaried by increasing air entry pressure– Minimum for half full: 10.53 mMinimum for half full: 10.53 m– Minimum for full: 10.87 mMinimum for full: 10.87 m

Effect of Air Entry Pressure at Full Effect of Air Entry Pressure at Full Water Table Height (0.67 m)Water Table Height (0.67 m)

Saturation

Capillary Pressure

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Capillary Pressure (m)

Hei

gh

t (m

)

10.8910.9310.97

0

2

4

6

8

10

12

14

16

18

20

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Saturation (m)

Ele

me

nt

(-)

10.8910.9310.97

Effect of Air Entry Pressure at Half Effect of Air Entry Pressure at Half Water Table Height (0.33 m)Water Table Height (0.33 m)

Capillary Pressure

Saturation0

2

4

6

8

10

12

14

16

18

20

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Saturation (m)

Ele

me

nt

(-)

10.531

10.55

10.570

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Capillary Pressure (m)

Hei

gh

t (m

)

10.531

10.55

10.57

Graphical TrendsGraphical Trends Capillary pressure:Capillary pressure:

– linear relationship linear relationship with column heightwith column height

– indirectly indirectly proportional to proportional to water table height water table height

– directly directly proportional to air proportional to air entry pressure at entry pressure at lower water table lower water table heightsheights

pressures converge as air pressures converge as air reaches the top of the reaches the top of the column, which is column, which is atmosphericatmospheric

Saturation:Saturation:– nonlinear nonlinear

relationship with relationship with column heightcolumn height

– directly proportional directly proportional to water table height to water table height

– indirectly indirectly proportional to air proportional to air entry pressure at entry pressure at lower water table lower water table heightsheights

saturation levels converge saturation levels converge as air reaches the top of the as air reaches the top of the column, which is column, which is atmosphericatmospheric

ConclusionsConclusions

Full Water Table Height (0.67 m):Full Water Table Height (0.67 m):– Air entry pressure range: 10.871 – 10.89 m Air entry pressure range: 10.871 – 10.89 m

Half Water Table Height (0.33 m):Half Water Table Height (0.33 m):– Air entry pressure range: 10.531 – 10.55 mAir entry pressure range: 10.531 – 10.55 m

Thank YouThank You

Questions?Questions?