Uranium Resources

Restoration

La Rosita Mine

Duval County, Texas

Mark S. Pelizza

Uranium Resources, Inc.

NRC/NMA Uranium Recovery Workshop

May 27, 2010

Uranium Resources

Uranium Resources

LA ROSITA ISR MINE HISTORY

PA1 production from October 1990 through March

1992 1,073,000 pounds of U3O8. Restoration August

2005 through May 2008.

PA2 production from June 1995 through June 1999

1,569,000 pounds of U3O8. Restoration May 2001

through March 2005.

Discovered and

drilled in the mid-

1970's by Union

Carbide Corp.

Chevron Resources

Company purchased

in 1980.

URI acquired 1985.

Uranium Resources

Uranium Resources

IN-SITU URANIUM RECOVERY

In-situ recovery (“ISR”) is an non-

destructive mining process where

uranium is extracted from sandstone

aquifers by reversing the natural process

which deposited the uranium. Existing

groundwater fortified with oxygen is used

to leach the uranium from sands.

The uranium is then recovered by

passing the leach solution over ion

exchange resin, much like in a domestic

water softener. The loaded resin is then

processed. Finally, the groundwater is

restored consistent with is previous

quality and use.

Uranium Resources

O2 INJECTION/CARBONATE COMPLEX

U4 to U6

2UO2 + O2 → 2UO3

UO3 + 2NaHCO3 → NA2UO2(CO3)2 + H2O

Uranium Resources

INCREASE TRACE ELEMENTS/SALINITYOxidation, pH↓ and Ion Exchange

Oxidation of iron sulfides – Fe (ppt) SO4 ↑ pH ↓ FeS2 + 15/4 O2 + 7/2 H2O → Fe(OH)3 [ppt] + 4 H

+ + 2 SO4

=

Oxidation of ferroselite – Fe (ppt) Se ↑ pH ↓ FeSe2 + 11/4 O2 + 7/2 H2O → Fe(OH)3 [ppt] + 4 H

+ + 2 SeO3

=

Oxidation of molybdenum sulfide – Mo ↑ S ↑ pH ↓ 2 MoS2 + 9/2 O2 + 2 H2O → Mo2O5 + 4 H

+ + 2 S2O3

=

Thiosulfate

Dissolution of calcium carbonate from lowered pH caused by oxidation of one mole of FeS2 – CaSO4 (ppt) HCO3 ↑ pH ↑ [Ca ↑ further lowers CaSO4 & HCO3 solubility]

2 H2SO4 + 4 CaCO3 + 4NaCl → 4NaHCO3 +2 CaSO4 [ppt] +2 Ca ++

+ 2 Cl –

Ion Exchange Na2UO2(CO3)2 + 2RCl → R2 UO2(CO3)2 + 2NaCl

Uranium Resources

GROUNDWATER RESTORATION

Uranium Resources

1,000,000,000 gal.

6.8 Pore Volumes

Uranium Resources

LA ROSITA ISR – GROUNDWATER

RESTORATION STABILITY SUMMARY

PRODUCTION AREA 1

Below RT Below MCL No Standard Above RT & MCL

Parameter Units

EPA

Primary

MCL

EPA

Secondary

MCL

PA BL Well

Low

PA BL Well

High

PA

Restoration

Table

Lixiviant

5-15-1992

Stability

Sample 1

Dec. 2008

Stability

Sample 2

May 2009

Stability

Sample 3

Aug. 2009

Stability

AverageCODE

Calcium mg/l 116 205 155 826 112 134 129 125

Magnesium mg/l 32 76 53 177 22 27 28 26

Sodium mg/l 353 502 422 668 193 205 212 203

Potassium mg/l 17 42 26 42 17 18 19 18

Carbonate mg/l 0 8 0 0 0 0 0 0

Bicarbonate mg/l 10 278 204 504 204 167 201 191

Sulfate mg/l 250 122 318 196 1,730 153 211 233 199

Chloride mg/l 250 705 1,037 866 1,513 356 373 381 370

Nitrate mg/l 10 0.53 1.30 1.79 0.67 0.13 0.64 0.65 0.47

Fluoride * mg/l 4 2 <.01 5.50 0.81 0.67 0.66 0.80 0.73 0.73

Silica mg/l 23 67 50 31 24 23 25 24

TDS (180 c) mg/l 500 1,590 2,310 1,933 5,450 998 1,231 1,193 1,141

EC (25 c) μmho 2,950 3,990 3,388 6,900 1,596 1,876 1,890 1,788

ALK as CaCO3 mg/l 26 228 169 413 167 140 165 157

pH 6.5-8.5 7.52 9.15 7.45 7.49 7.33 7.46 7.43

Arsenic * mg/l 0.01 <.001 0.059 0.009 0.007 0.005 0.006 0.004 0.005

Cadmium * mg/l 0.005 0.0001 0.0015 0.0005 0.0007 0.0020 0.0020 0.0020 0.0020

Iron mg/l 0.3 0.010 0.480 0.105 0.510 0.018 0.013 0.010 0.014

Lead * mg/l 0.015 <.001 0.008 0.002 <0.001 0.004 0.004 0.004 0.004

Manganese mg/l 0.05 <.01 0.47 0.06 0.67 0.10 0.11 0.11 0.11

Mercury mg/l 0.002 <.0001 0.0020 0.0003 0.0001 0.0001 0.0001 0.0001 0.0001

Molybdenum mg/l 1.0 <.01 0.17 0.05 0.20 0.25 0.24 0.18 0.23

Selenium * mg/l 0.05 <.001 0.430 0.008 0.160 0.033 0.032 0.034 0.033

Uranium μg/l 30 42 1,200 350 17,400 576 637 639 617

Ammonia-N * mg/l 0.10 1.10 0.38 0.05 0.13 0.18 0.15

Radium 226 pCi/l 5.0 0.4 595.0 183.0 196.0 89.1 90.1 81.3 86.9

Uranium Resources

LA ROSITA ISR – GROUNDWATER

RESTORATION STABILITY SUMMARY

PRODUCTION AREA 2

Below RT Below MCL No Standard Above RT & MCL

Parameter Units

EPA

Primary

MCL

EPA

Secondary

MCL

PA BL Well

Low

PA BL Well

High

PA

Restoration

Table

Lixiviant

5-15-1992

Stability

Sample 1

Dec. 2008

Stability

Sample 2

May 2009

Stability

Sample 3

Aug. 2009

Stability

AverageCODE

Calcium mg/l 68 239 170 725 173 177 170 173

Magnesium mg/l 21 88 62 175 48 50 51 50

Sodium mg/l 285 638 420 515 285 268 297 283

Potassium mg/l 17 65 28 40 22 21 23 22

Carbonate mg/l 0 1 0 0 0 0 0

Bicarbonate mg/l 27 279 216 434 242 245 226 238

Sulfate mg/l 250 62 533 248 1,370 235 225 221 227

Chloride mg/l 250 663 1,032 870 1,290 606 633 631 623

Nitrate mg/l 10 0.50 1.40 1.30 0.22 1.22 1.38 0.96 1.19

Fluoride * mg/l 4 2 <.01 5.30 0.77 0.67 0.56 0.60 0.60 0.59

Silica mg/l 29 76 53 40 38 34 34 35

TDS (180 c) mg/l 500 1,430 2,600 2,045 4,640 1,546 1,837 1,753 1,712

EC (25 c) μmho 2,620 4,320 3,519 6,020 2,543 2,738 2,647 2,643

ALK as CaCO3 mg/l 24 229 177 356 198 203 186 196

pH 6.5-8.5 7.19 8.39 7.0-8.0 7.00 7.26 7.20 7.19 7.22

Arsenic * mg/l 0.01 <.001 0.061 0.014 0.006 0.004 0.004 0.004 0.004

Cadmium * mg/l 0.005 <.0001 0.0053 0.0002 0.0004 0.002 0.003 0.002 0.002

Iron mg/l 0.3 <.01 0.090 0.020 0.020 0.023 0.044 0.016 0.027

Lead * mg/l 0.015 <.001 0.006 0.001 0.001 0.004 0.005 0.005 0.005

Manganese mg/l 0.05 <.01 0.14 0.03 0.75 0.24 0.17 0.14 0.18

Mercury mg/l 0.002 <.0001 0.0001 0.0001 <.0001 0.0001 0.0001 0.0001 0.0001

Molybdenum mg/l 1.0 <.01 0.64 0.06 2.90 0.14 0.13 0.15 0.14

Selenium * mg/l 0.05 <.001 0.045 0.006 0.041 0.034 0.037 0.031 0.034

Uranium μg/l 30 12 2,890 547 23,700 650 933 680 755

Ammonia-N * mg/l <.01 0.56 0.08 <.01 0.13 0.13 0.13

Radium 226 pCi/l 5.0 1.0 642.0 130.3 463.0 64.17 56.04 62.11 60.78

Uranium Resources

POST RESTORATION

WATER QUALITY

↑ salinity from ion exchange fully mitigated. RO is

highly effective in that dissolved salts are reduced

below baseline mean.

↑ calcium and carbonates due to pH drop are

effectively mitigated. RO is effective with affected

parameters restored to baseline mean.

↑ uranium, trace elements due to oxidation are

greatly reduced but not eliminated. RO is partially

effective and residual concentrations may remain.

Parameters typically affect use quality of the water

similarly before mining and after restoration.

Uranium Resources

NELAC IMPLICATIONS

* For these parameters, today's TCEQ required

NELAC accredited and certified analytical methods

result in greater concentration LLD's than the

historic baseline analytical method provided for.

Rather than use zero (0) in the calculations, the LLD

values were used as the default measured value in

both the baseline and restoration stability statistical

calculations, resulting in a post restoration stability

averages that are greater than baseline simply

because the LLD is a greater concentration.

Uranium Resources

RESTORATION TABLE VALUES

NOT ACHIEVED - 331TAC107 (g)(1)

uses for which the groundwater was suitable at baseline levels

actual existing use of groundwater in the area prior to and during

mining

potential future use of baseline quality groundwater and of

proposed restoration quality

the effort made by the permittee to restore the groundwater to

baseline

technology available to restore groundwater for particular

parameters

the ability of existing technology to restore groundwater to

baseline quality in the area under consideration

the cost of further restoration efforts

the consumption of groundwater resources during further

restoration

the harmful effects of levels of particular parameter

Uranium Resources

RESTORATION PROGRESS ILLUSTRATION

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

PORE VOLUMES

PP

M U

RA

NIU

M

Baseline

EPA Primary MCL

Uranium

0

1000

2000

3000

4000

5000

6000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

PORE VOLUMES

PP

M T

DS

Baseline

TDS

LA ROSITA ISR

1,000,000,000 gal. or

6.8 PV treated and

circulated

Uranium Resources

BASELINE WATER QUALITY

Naturally - uranium

and its decay

products, radium and

radon, cause

groundwater to

become radioactive

and to exceed federal

and state drinking

water limits making

the natural

groundwater present

near uranium ore

suitable only for

industrial purposes.

Exempt USDW

“Baseline”

“Background”

“Background”

Uranium Resources

LA ROSITA ISR PRE-MINING U-NATURAL

0

200

400

600

800

1,000

1,200

1,400

1

mic

ro

gra

ms

/L U

PA1 Restoration Table

PA2 Restoration Table

141 BL Well Average

EPA Primary MCL

Uranium Resources

LA ROSITA ISR PRE-MINING 226Ra

0

50

100

150

200

1

pic

oc

urie

s/L

Ra

PA1 Restoration Table

PA2 Restoration Table

141 BL Well Average

EPA Primary MCL

Uranium Resources

URANIUM ROLL FRONT DEPOSITION =

NATURAL ATTENUATION

Uranium Resources

MANGANESE

“Iron and manganese tend to be relatively

immobile under oxidizing conditions and more

mobile under reducing conditions.”

“The presence of significant concentrations of iron

and manganese in solution is generally a good

indicator of reducing conditions.”

FATE AND TRANSPORT OF POST-RESTORATION

GROUNDWATER CONSTITUENTS AT IN-SITU

URANIUM LEACH FACILITIES, May 10 2006,

Demuth & Schramke, (Petrotek Engineering

Corporation & Enchemica LLC), p29-30. Prepared

for Uranium Resources, Inc.

Uranium Resources

THE PUBLIC CONCERN

“To date, no remediation of an ISR operation in the

United States has successfully returned the aquifer

to baseline conditions.”

J.T. Otton, S. Hall, U.S. Geological Survey, In-Situ

Recovery Uranium Mining in the United States:

Overview of Production and Remediation Issues.

IAEA 2009.

Uranium Resources

331TAC107(a)(2)

Achievement of restoration shall be determined

using one of the following methods:

(A) When all sample measurements from

groundwater samples from all baseline wells for

a restoration parameter are equal to or below the

restoration table value…; or

(B) A statistical analysis of information from

groundwater samples from baseline wells

proposed by the owner or operator and

approved by the executive director that

demonstrates that the groundwater quality is

representative of the restoration table values.

Uranium Resources

UTL Calculation MethodsThe Rosita data set was used to calculate Upper Tolerance Limits

(UTL95-95) for most constituents in PA1 and PA2. For large data sets

following normal distributions, this factor can be roughly estimated as

the mean plus two standard deviations.

ProUCL 4.00.04 (Singh et al., 2009)[1], an EPA-sponsored statistical

program is ideally suited for this purpose. ProUCL first determines if

the data for a given constituent follows a normal, gamma, or

logarithmic distribution. If the data follow one of these statistical

distributions, a relevant UTL is calculated. If the data follow no

discernible distribution a non-parametric UTL is calculated. In the

case of data with non-detects, the Kaplan-Meier non-parametric

method is used. Non-detect data are entered as the MDL with a

qualifier code indicating non-detect status. The K-M method is

deemed superior to simple substitution methods (MDL, MDL/2;Singh

et al., 2009).

[1] Singh, Anita, Maichle, R., Singh, A., Lee, S.E., and Armbya, N., 2009,

ProUCL Version 4.00.04 User Guide, Draft, prepared for the U.S.

Environmental Protection Agency, EPA/600/R-07/038

Uranium Resources

LANL MEAN vs. 95% UTL ANALYSIS

ValueDistribution

TypeValue

Distribution

Type

Calcium mg/l 155 235 Normal 125 170 264 Normal 173

Magnesium mg/l 53 85 Normal 26 62 103 Normal 50

Sodium mg/l 422 680 Nonparametric 203 420 580 Normal 283

Potassium mg/l 26 29 Nonparametric 18 28 45 Normal 22

Bicarbonate mg/l 204 344 Normal 191 216 260 Nonparametric 238

Sulfate mg/l 196 261 Normal 199 248 533 Nonparametric 227

Chloride mg/l 866 1,141 Normal 370 870 1,095 Normal 623

Nitrate mg/l 1.79 3.24 Gamma 0.47 1.30 5.55 Normal 1.19

Fluoride mg/l 0.81 1.35 Normal 0.73 0.77 1.01 Normal 0.59

Silica mg/l 50 58 Normal 24 53 70 Normal 35

TDS (180 c) mg/l 1,933 2,172 Normal 1,141 2,045 2,622 Normal 1,712

EC (25 c) μmho 3,388 3,818 Normal 1,788 3,519 4,383 Normal 2,643

ALK as CaCO3 mg/l 169 296 Normal 157 177 213 Nonparametric 196

Arsenic mg/l 0.009 0.023 Normal 0.005 0.014 0.261 Log normal 0.004

Cadmium mg/l 0.0005 0.0618 Normal 0.0020 0.0002 0.0012 Log normal 0.0022

Iron mg/l 0.105 0.48 Nonparametric 0.014 0.020 0.036 KM UTL 0.027

Lead mg/l 0.002 0.071 Log normal 0.004 0.001 Insf. Detects 0.005

Manganese mg/l 0.06 0.26 Log normal 0.11 0.03 0.03 KM UTL 0.18

Mercury mg/l 0.0003 Insf. Detects 0.0001 0.0001 Insf. Detects 0.0001

Molybdenum mg/l 0.05 0.16 Normal 0.23 0.06 0.2440 Log normal 0.14

Selenium mg/l 0.008 Insf. Detects 0.033 0.006 0.078 Log normal 0.034

Uranium μg/l 0.350 7.500 Log normal 0.617 0.547 8.418 Log normal 0.755

Uranium μg/l 0.350 1.200 Nonparametric 0.617 0.547 2.890 Nonparametric 0.755

Ammonia-N mg/l 0.38 0.80 Nonparametric 0.15 0.08 0.43 Nonparametric 0.13

Radium 226 pCi/l 183.0 617.1 Normal 86.9 130.3 1907.0 Log normal 60.8

Radium 226 pCi/l 130.3 548.0 Nonparametric 60.8

CODE

BL 95% UTL

CODE

PA

Restoration

Table

Stability

Average

Parameter UnitsPA

Restoration

Table

Stability

Average

PA1 PA2

BL 95% UTL

Below RT Below MCL No Standard Above RT & MCL Below 95% UTL

Uranium Resources

Uranium Resources

Uranium Resources

ACKNOWLEDGEMENTS

Ardyth Simmons, Ph.D.

Jeff Heikoop, Ph.D.

Liz Miller, Ph.D.

Los Alamos National Laboratory