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Report by hydrogeologist finds Texas in-situ uranium mines have been unable to restore ground water aquifers to premining water quality

State regulators routinely approve leaving higher uranium levels in ground water; author questions mine operators' scientific understanding of aquifers

Posted October 24, 2008, Updated March 30, 2009



Note:  Upon the request of Dr. Darling, his report was removed from this website on March 28, 2009.  Evidently, another hydrogeologist with close ties to uranium mining attempted to file an anonymous complaint with the Texas Board of Licensure for Professional Geoscientists that an unsigned/unsealed version of Dr. Darling's report had been publicly released.  A signed and sealed version was posted below on March 30, 2009.  As of this date, no one has published a rebuttal to Dr. Darling's report.  JW



A groundbreaking report by hydrogeologist Bruce K. Darling, PhD, P.G. for the first time provides data from the Texas Commission on Environmental Quality (TCEQ) documenting the failure of Texas in-situ uranium mine operators to clean up ground water aquifers following mining.  Darling concludes that Texas mining regulators have routinely granted requests for relaxed restoration standards at in-situ uranium mining sites and that no evidence has been found that Texas authorities have ever denied such a request.


He further claims that such relaxed restoration standards are an admission that the mine operators are unable to meet the original restoration standards and that "this calls into question the operators' understanding of the geochemistry of the hydrogeologic systems that they are exploiting."


The report was commissioned by Blackburn & Carter, a Houston law firm.


Dr. Darling is well-qualified to review these data, according to his bio published in the journal of the American Institute of Professional Geologists:

He has served as a hydrogeologist with the University of Texas Bureau of Economic Geology and Law Engineering and Environmental Services, and as a minerals economist with the US Bureau of Mines. Mr. Darling has extensive experience in water-resource development and management projects. He has completed site-characterization studies of low-level radioactive waste disposal facilities in Texas and North Carolina. His background encompasses supervising geological field reconnaissance, development of geochemical and analytic transport models, groundwater exploration and development programs, exploration geology, and mineral resource economics. Mr. Darling holds a Ph.D. degree in hydrology and an MA degree in mineral economics from the University of Texas at Austin. He also earned an MS in geology and a BA in philosophy from the University of Southwestern Louisiana. He is a member of the American Institute of Professional Geologists, the Association of Groundwater Scientists and Engineers, the Austin Geological Society, and the West Texas Geological Society. He is a licensed professional geologist in six states.

Darling used internal paper documents and spreadsheets from the Underground Injection Control office of the TCEQ to prepare the report.  The original source documents are on microfiche and microfilm records located in the Central Records office of the TCEQ.  Darling's work was hampered because TCEQ staff were reluctant to certify their own paper and digital documents as official records, and Darling found the microfiche and microfilm records to be poorly organized and difficult to search. 


Darling found 27 permitted in-situ uranium mines in south Texas, including roughly 80 authorized production areas.  Mine operations date from the 1980s through the present day. 


Under Texas law, ground water restoration standards for 26 water quality indicators are established when production areas are permitted.  Following mining, if the operator is unable to clean up the water to the original restoration standards, the operator may request that the standards be amended.  Darling found 51 production areas where such ground water restoration amendments had been approved.  With respect to uranium, mine operators were granted permission to leave higher levels of the radioactive metal in 43 different production areas. 


In one area (Zamzow PAA-1) the acceptable level of uranium in the ground water was increased by an astounding 29,900%.  The original restoration standard was 0.01 mg/l; the amended standard was 3.0 mg/l.  For comparison, the federal maximum contaminant level (MCL) for uranium in drinking water is 0.03 mg/l.  Zamzow is one of five ISL mines cited by Powertech as evidence that aquifers can be cleaned up after ISL mining.  From Powertech's web page titled "Groundwater Protection":

The groundwater restoration, or cleanup of an aquifer impacted by in-situ uranium solution mining has been shown to be technically, physically and economically achievable. (Ref. NRC NUREG/CR 6870) Some recent successful ISR mine closures include the O'Hern, Hobson, Zamzow, Pawlik, and Longoria mines in South Texas, all owned by different companies. There are no historical cases in the United States where ISR has made a long-term negative impact on public health or the environment.

TCEQ data paint a different picture.  For all five mines, uranium restoration values were amended in response to requests by the mines' operators.  Amended restoration values were increased from 291% (O'Hern PAA-4) to 29,900% (Zamzow PAA-1).  Although "last sample values" for uranium are not available for all five mines, three production areas showed significant increases in uranium levels after restoration efforts ceased: 213% for O'Hern PAA-4, 4,765% for Longoria PAA-2, and 10,538% for Longoria PAA-1.


Using Powertech's logic, an aquifer is successfully cleaned up even if the level of uranium in the ground water is 29,900% higher than the premining water quality, as long as a government agency approves the change.  And this enormous increase in uranium contamination does not constitute "a long-term negative impact on public health or the environment." 


The table below was compiled from data contained in Dr. Darling's report.  Mine production areas in red are those cited by Powertech as examples of mines that have been successfully cleaned up.





Restoration History of Texas In-Situ Uranium Mines
  Original Amended     Last  
  Uranium Uranium     Uranium  
Production Restoration Restoration     Sample  
Mine Area (PAA) Value (mg/l) Value (mg/l) % Change   Value (mg/l) % Change
Benavides  1 0.083 2.000 2310%   1.040 1153%
Benavides  2 0.078 2.000 2464%   0.279 258%
Benavides  3 0.120 3.000 2400%   1.500 1150%
Benavides  4 2.000       0.950 -53%
Brelum  1 0.037 2.000 5305%   0.025 -32%
Brelum  2 0.031 2.000 6394%   0.013 -58%
Bruni 1 0.461 5.000 985%   1.185 157%
Bruni 5-2 0.461 4.000 768%   3.020 555%
Burns/Moser 2 0.050 1.700 3300%   no data no data
Burns/Moser 3 0.082 1.250 1424%   no data no data
Burns/Moser 4 0.020 0.200 900%   no data no data
Clay West 1 0.400 0.800 100%   no data no data
El Mesquite  2 0.085 1.350 1488%   no data no data
El Mesquite  3 0.840 2.700 221%   2.530 201%
El Mesquite  4 0.062 1.950 3045%   no data no data
Hobson 1 0.025 0.290 1060%   no data no data
Holiday  2 0.200 0.500 150%   no data no data
Holiday  3 1.600 2.000 25%   no data no data
Holiday  4 0.036 2.550 6983%   no data no data
Holiday  5 0.063 1.095 1638%   no data no data
Holiday  6 0.368 2.300 525%   no data no data
Lamprecht  1 0.160 0.757 373%   no data no data
Las Palmas  1 2.913 7.000 140%   no data no data
Las Palmas  2 0.566 2.000 253%   no data no data
Las Palmas  3 2.400 5.000 108%   no data no data
Longoria  1 0.047 2.000 4155%   5.000 10538%
Longoria  2 0.037 3.000 8008%   1.800 4765%
McBryde 1 0.831 4.000 381%   no data no data
Mt Lucas 1 0.293 0.550 88%   no data no data
Mt Lucas 2 0.076 0.500 558%   no data no data
Mt Lucas 3 0.770 1.750 127%   no data no data
Mt Lucas 4 0.097 1.600 1549%   no data no data
Mt Lucas 5 0.258 1.500 481%   no data no data
Mt Lucas 6 0.125 2.000 1500%   no data no data
Mt Lucas 7 0.047 1.000 2028%   no data no data
Mt Lucas 8 0.334 1.250 274%   no data no data
Nell 1 0.041 2.000 4778%   no data no data
O'Hern 1 0.280 1.550 454%   no data no data
O'Hern  4 0.307 1.200 291%   0.960 213%
Pawlik 1A 0.002 0.020 900%   no data no data
Rosita  1 2.000 4.000 100%   0.672 -66%
Tex-1 1 0.050 1.000 1900%   no data no data
Trevino 1 0.015 2.000 13233%   no data no data
Trevino 2a 0.036 2.000 5456%   no data no data
West Cole 1 0.169 2.750 1527%   no data no data
West Cole 2 0.662 2.500 278%   no data no data
West Cole 3 1.660 3.150 90%   no data no data
Zamzow  1 0.010 3.000 29900%   no data no data
1.  Only mine production areas with original uranium restoration values and amended values and/or 
     last sample values are included.          
2.  Data are from the Texas Commission on Environmental Quality.        
3.  The federal maximum contaminant level for uranium in drinking water is 0.03 milligrams per liter (mg/l).



Report on Findings Related to the Restoration of In-Situ Uranium Mines in South Texas - Bruce K. Darling, Ph.D., P.G. - SOUTHWEST GROUNDWATER CONSULTING, LLC - September 29, 2008 (PDF 982 KB)  Note: This is the "official" signed and sealed version.


Resume - Bruce K. Darling (PDF 88KB)


"Most comprehensive report ever compiled" on ISL uranium mine restoration shows water is worse than before mining started at most mines - Texas County sues mining company over threat to ground water; county attorney claims baseline water testing is faulty - Posted September 23, 2008


Texas in-situ leach uranium mines failed to restore ground water to premining condition - Texas Natural Resource Conservation Commission agendas from 1990s reveal that relaxing water cleanup standards is routine - Posted September 7, 2008


After in-situ uranium leaching, ground water cannot be returned to the way it was - Nuclear Regulatory Commission official and uranium mining executive acknowledge restoration of aquifer to baseline is unachievable - Posted September 3, 2008


Consideration of Geochemical Issues in Groundwater Restoration at Uranium In-Situ Leach Mining Facilities (NUREG/CR-6870)

U.S. Nuclear Regulatory Commission and U.S. Geological Survey - January 2007 (PDF 2.0MB)