1. Multiphase Field-scale Modeling: Brine Transport Ann Cook Per Per Hatlevik Jonathan Levine Brice Loose Keegan Roberts Amber Sallerson Katy Schulte Martina Vlckova Thomas Willingham

2. Introduction to DNAPLs Types Sources Behavior PCE, TCE, DCE, VC, CT, CF, DCM, TCA

3. Introduction to DNAPLs Long lived Difficult to remove Health Hazards –Liver problems –Increased risk of cancer –Nervous system, or circulatory problems 1 Density of Water (r w ) Density of DNAPL (r n ) ~1 g/mL~1.45-1.62 g/mL

4. Brine Treatment Technology How does it work? –Mobilization of the NAPL Increase Gravimetric Forces Decrease Capillary Trapping Forces

5. Brine Treatment Technology s n-a = NAPL-aqueous interfacial tension r = effective pore size r n = NAPL density r a =aqueous phase density g =gravitational acceleration l =characteristic length of NAPL pool in vertical direction

6. Brine Treatment Technology How does it work? –Closed system on 5 sides Area of RemediationSheet-piles Plan View Impermeable Layer (e.g., clay) Profile View

7. Brine Treatment Technology How does it work? No Flow Boundary No Flow Boundary

8. Brine Treatment Technology How does it work? Pump in Brine Layer

9. Brine Treatment Technology How does it work? Lower Water Table

10. Brine Treatment Technology Gravimetric Forces Removal of DNAPL

11. Brine Treatment Technology How does it work?

12. Brine Treatment Technology How does it work? Removal of DNAPL

13. Brine Treatment Technology How does it work?

14. Brine Treatment Technology How does it work? Remove Brine <1% Original DNAPL Mass

15. Brine Treatment Technology How does it work? <1% Original = Meet DNAPL Mass Standards

16. Brine Treatment Technology Why is it novel? –$$ Cheaper $$ –Higher rates of removal than current technologies Pump and Treat Natural Attenuation

17. Possible Instabilities in the System Physical –Density (changes and/or differences) –Excessive Surfactant Concentration  bypass –Pore Clogging Model –Fingering –Gravity - Rayleigh

18. Rayleigh-Taylor Instability Initial density stratified domain Unstable system (small perturbations) Occur in model and physical system Brine Ground Water

19. Rayleigh Number Dimensionless Number Ratio

20. Modified Rayleigh Number

21. SUTRA Code written by USGS Simulates single phase fluid flow and transport in the subsurface Uses a combination of finite-element and finite difference methods to solve a series of equations

22. Conservation Equations Species Balance Equation Species-Summed Flow Equation

23. SUTRA Transport Math Magic

24. SUTRA Fluid Flow Species Summed Flow Equation Darcy’s Law Math Magic

25. Requirements for SUTRA D L < 4a L Pe < 2 D L = local distance between sides of an element measured in the direction parallel to local flow a L = longitudinal dispersivity

26. SUTRA Goal To model a freshwater system where we inject brine –3D model –Relatively small in the y-direction Visualize system instabilities Removal of brine from system

27. Simulations Ran 1.Brine slumping model 2.Fully saturated fresh water system with brine injection 3.Unsaturated brine injection 4.Multiple well configurations

28. Example Problem: Slumping brine interface which admits an analytic solution in the case that the vertical scale is much less that the horizontal (H << R), and a constant hydraulic conductivity (K c ) High frequency spatial hydraulic conductivity

29. Homogenization permits approximation of K(x,z,t) as a constant that captures the variability Homogenized equations compare well with the accepted numerical solution. High frequency variations are absent.

30. Evaluate Instabilities Extraction Well Injection Wells

31. Fingering Fingering due to viscous instability

32. SUTRA MODELING BCs

33. SUTRA MODELING Initial Injection

34. SUTRA MODELING Brine Injection

35. Transport and Flow Equations AKA “The Magic”