1. Anthropogenic Induced Redox Disequilibrium in Uranium Ore Zones
Richard Abitz, Savannah River National Laboratory Bruce Darling, Southwest Groundwater Consulting, LLC
Please extend my regrets for absence at the meeting, due to a conflict with work travel to the UK.
GSA 2010, Denver, Colorado

2. Drilling Issues Related to Redox Disequilibrium
Physical change to the ore minerals
Chart assumes constant volume based on a 1000 um diameter particle

3. Drilling Issues Related to Redox Disequilibrium
Chemical reactions in the ore zone
7/2O2 + H2O + FeS2 → 2H+ + Fe++ + 2SO4--
½O2 + 2H+ + UO2 → H2O + UO2++
Airlift purge and pump adds O2
Introduction of oxygen from drilling fluids and airlift purge during well development.
Arsenic release from pyrite oxidation.

4. Mineral Dissolution Rates
General form of rate law (Lasaga, 1995)1:
Rate = k0*Amin*e-Ea/RT*anH+*g(I)*Πiani*f(ΔGr)
Increase in both surface area (Amin) and
O2 activity (anO2) will increase dissolution rate.
1 Lasaga, A.C., 1995, Fundamental Approaches in Describing Mineral
Dissolution and Precipitation Reactions, in Reviews in Mineralogy,
Volume 31, Chemical Weathering Rates of Silicate Minerals,
Mineralogical Society of America.
Introduction of oxygen from drilling fluids and airlift purge during well development.
Arsenic release from pyrite oxidation.

5. Goliad Project about 130 mi SW of Houston
12 mi N of Goliad
15 mi E of Victoria

6. UEC Permit UR03075 Cartoon of Goliad section at the proposed ISL site
About 350 to 400 ft of sand with gravel, silt, clay
Target sand horizons 50 to 80 feet thick
Fluvial deposits exposed in area, change to deltaic down dip
UEC Permit UR03075

7. UEC Permit UR03075 Initial ISL target is B Sand, yellow pattern
Permit Area about 3 km E-W
First ore body proposed to develop; Sand B (yellow pattern)
Proposed aquifer exemption zone is black dashed line surrounding proposed production sands
Private water wells within 1 km of permit boundary (blue dots)
Note 44 (Abrameit Windmill) located within PA

8. Production Test Wells (PTW), Sand B
URANIUM: Apr 2008: to mg/L
July 2009: <0.003 to mg/L
Nov 2009: <0.003 to mg/L
Variation due to redox instability, and not natural variation of ion concentrations (see F plot slide).
April 2008 sampling round after initial well development
All November results below EPA DW std of mg/L
Low U results in line with reducing conditions for uranium ore body
One-half detection limit plotted

9. Production Test Wells (PTW), Sand B
ARSENIC: Apr 2008: to mg/L
July 2009: <0.010 mg/L
Nov 2009: <0.010 mg/L
Indication of oxidation in some wells.
Other wells have no source for As?
Lower values for Round 1 are an artifact of a lower reported detection limit for round 1

10. Production Test Wells (PTW), Sand B
FUORIDE: Apr 2008: 0.50 to 0.79 mg/L
July 2009: 0.50 to 0.54 mg/L
Nov 2009: 0.50 to 0.69 mg/L
F results show U variation is not due to natural fluctuations in ion concentrations.
All rounds show similar results

11. Production Test Wells (PTW), Sand B
RADIUM: Apr 2008: 10 to 1,680 pCi/L
July 2009: 17 to 2,000 pCi/L
Nov 2009: 10 to 1,590 pCi/L
Similar results for all 3 rounds…exception is PTW 13 (low first round)
After ore has been disturbed, radium will not return to low values (not redox sensitive and mobilized by chloride ion)

12. B Monitor Wells (BMW), Sand B
URANIUM: Apr 2008: <0.001 to mg/L
July 2009: <0.003 to mg/L
Nov 2009: <0.003 mg/L
April 2008 sampling round after initial well development
All July and November results below EPA DW std of mg
One-half detection limit plotted

13. B Monitor Wells (BMW), Sand B
ARSENIC: Apr 2008: to mg/L
July 2009: <0.010 mg/L
Nov 2009: <0.010 mg/L
Indication of oxidation in some wells.
Other wells have no source for As?
Lower values for Round 1 are an artifact of a lower reported detection limit for round 1

14. B Monitor Wells (BMW), Sand B
RADIUM: Apr 2008: 0.90 to 41 pCi/L
July 2009: 1.3 to 48 pCi/L
Nov 2009: 0.10 to 40 pCi/L
Similar results for all 3 rounds
After ore has been disturbed, radium will not return to low values (not redox sensitive and mobilized by chloride ion)
BMW 10, 11, 14, 15 have similar uranium results…no significant U ore or no significant oxidation. Radium is less than 5 pCi/L in these wells.

15. Overlying Monitor Wells (OMW), Sand A
URANIUM: Apr 2008: to mg/L
July 2009: to mg/L
Nov 2009: to mg/L
Similar variation of U over all three rounds
No uranium ore to oxidize

16. Overlying Monitor Wells (OMW), Sand A
ARSENIC: Apr 2008: to mg/L
July 2009: to mg/L
Nov 2009: to mg/L
Reduction of As in Rounds 2 & 3

17. Overlying Monitor Wells (OMW), Sand A
RADIUM: Apr 2008: 0.5 to 6.0 pCi/L
July 2009: 0.2 to 3.2 pCi/L
Nov 2009: 0.4 to 1.0 pCi/L

18. Uranium solubility as a function of Eh
Boxes show range of concentration and Eh for sampling rounds
Note boxes shift to lower Eh range as one progresses from round 1 to round 3.
Implies concentration control by redox decrease and uranium solubility.