# Presentation: 504951

## Recent Advances and Future Plans on Hanford 100H Numerical Modeling Studies

- Sumit Mukhopadhyay and Eric Sonnenthal
- Lawrence Berkeley National Laboratory
- October 2006

## Recapitulation

- In October 2005, preliminary numerical modeling approach was first presented
- Injection of LiBr through Borehole 699-96-45 and pumping through Borehole 699-96-44 were simulated
- A two-dimensional (2-D) numerical grid was generated for this purpose
- Saturated Hanford sand was assumed
- Permeability (6.4x10-12 m2) was assumed homogeneous. Equivalent hydraulic conductivity is 6.3x10-3

## Current Status

- Development of numerical grid
- The preliminary 2-D grid has since been modified
- In the plane of the aquifer (Hanford Formation) with a thickness of 1.0 m.
- This grid is ~24 m long and ~12 m wide
- The injection borehole (699-96-45) is at the centre
- The grid is radial near the injection and pumping wells, and rectangular away from them
- A new three-dimensional (3-D) grid has been created
- The 3-D grid was created by stacking five 2-D grids in the vertical direction
- At present, the 3-D grid represents the saturated Hanford formation (1.0 m thick).
- Unsaturated zone above and Ringold Formation below can be added, if needed

## Current Status

- Hydrological Considerations
- Geophysical monitoring
- Hydraulic conductivity distribution (Hubbard et al., 2005)

**Higher K**
**Lower K**

## Model Heterogeneous Hydraulic Conductivity Distribution

## 2-D Contours of Br Tracer

- At end
- Of 2nd
- Injection
- Pumping
- Rate: 0.54
*gpm*.

- 1st Injection:
- Br- 15.3 g/l
- 2nd Injection:
- Br- 8.2 g/l

## 3-D Contours of Br Tracer

## Breakthrough Curve: Data vs. Model

## Acid Injection

- Reactive transport associated with HRC injection cannot be simulated immediately
- Physical properties of Glycerol (tri) polylactate are not yet available
- Thermodynamic database corresponding to bioreduction of HRC is not yet ready
- To test the model, simulations were performed assuming HCl is injected into the Hanford Formation
- to demonstrate the reactive transport modeling capabailities
- To capture/investigate the physical/chemical processes associated with injection of ‘acid’

## Reactive Transport Simulation of HCl injection

- Test conditions were maintained similar to actual HRC injection conditions
- 40 Ibs of HCl solution (pH 5.2) was injected
- Injection happened over 30 minutes
- Pumping continued for 27 days
- Initial mineralogy (volume fraction)
- Calcite 0.01
- K-Feldspar 0.2724
- Albite 0.3964
- Quartz 0.2756

## Reactive Transport Simulation of HCl Injection

- Initial composition of groundwater
- (all numbers, except pH, are in ppm)
-         pH             7.92         ca2+          64.2         na+            26.6         k+             0.21         cl-              30.7        br-              ~0        hco3-         77.6       alo2-           0.62
-      so4(2-)        74.2       sio2(aq)      3.40
-       hfeo2(aq)    0.04         no3-(aq)      42.3

## Contours of Dissolved CO2

- 5 days

- 27 days

## 3-D Contours of pH

- 5 days

- 27 days

## 3-D Contours of TDS

- 5 days

- 27 days

## Chemical Process Model for Cr(VI) Remediation with HRC*

- Bacteria that produce
- H2 from Lactic Acid (B2)
- Bacteria that produce
- Lipase for polylactate cleavage (B3)
- Bacteria that changes Cr(VI) (B1)

- * *Farone et al., 1999*

## Bioreduction of Cr(VI)*

- * *J. Dommer, personal communication, 2006.*

- Enumerate possble Cr6+
- reduction pathways
- Develop balance equations
- for each of those reactions
- For example,

- Develop a thermodynamic
- database for these reactions
- and the relevant parameters

## Next Stages

- Hydrology
- Further modification of the 3D grid, including addition of Ringold Formation and the unsaturated zone
- Incorporate flow properties of HRC (viscosity, capillary characteristics, etc.)
- Update hydraulic conductivity heterogeneity data
- Geochemistry
- Add important mineral phases, Cr and Fe species, thermodynamic and kinetic data
- Evaluate all pre-HRC injection mineral-water-gas reactions to set up geochemical model for the region of HRC injection
- Set up and run model for HRC injection, comparing to geophysical measurements