Upload
others
View
10
Download
0
Embed Size (px)
Citation preview
Resin hauling truck and trailer at Hobson Processing Plant Zero Emission vacuum dryer at Hobson Processing Plant
1
Successful Legacy of In-Situ Recovery 2014 Uranium Recovery Workshop – Denver - June 19, 2014 Harry L. Anthony, IV P.E. – Senior Advisor, UEC Presenter
Craig Holmes, Regulatory Advisor, UEC Co-Author
Reverse Osmosis Water Processing Equipment
Reclaimed ISR Wellfield
Reverse Osmosis Water Treatment Reclaimed In-Situ Wellfield
Successful Legacy of In-Situ Recovery One of the best kept secrets in Texas is that uranium has been continually mined since the late
1950s. Uranium mining was initially conducted by open-pit mining followed by conventional milling to produce “yellowcake” which is harnessed to produce electrical energy in nuclear power plants.
In the early 1970s, a new environmentally sensitive means of extraction was developed in South Texas addressing concerns about the disturbance of the surface of the land, dewatering portions of the aquifer to enable men and equipment to work beneath the surface, and later forming vast areas of mill tailings from the processing of ores. It was at this time that South Texas gave birth to In-Situ Recovery (ISR) and has ever since been the ISR capital of the western world.
The following images were compiled from archived and recent photographs, as well as satellite imagery over a decade of licensed ISR operations in South Texas. In each case, groundwater was restored consistent with baseline quality and approved by the Texas Commission of Environmental Quality (TCEQ). Subsequently each wellfield and all associated physical structures and equipment were reclaimed and the land returned to the surface owner for “unrestricted use.” Surface reclamation was regulated and final approval was overseen and approved by the TCEQ and ultimately the NRC. The illustrations presented show either cleared land supporting cattle operations and/or reclaimed brush suitable for nature habitat to populate.
Unless you were intimately associated with one of the projects illustrated in the following pages and knew its original location, the existence of prior mining in all these examples is non-detectable.
These are successful mining legacies that are quietly unheralded, and optically undetected for all the obvious reasons.
Today's Discussion Outline 1. Discussion addressing groundwater restoration.
a. Typical Baseline Water Quality in Ore b. Review of Primary and Secondary EPA Standards c. Using USGS Study on Groundwater Restoration, review data. d. TX HB 1079 – Range Tables e. Restoration Conclusion
2. Pictorial of Reclaimed Texas ISR Sites. a. Reclamation - Land returned to unrestricted use.
Uranium Depositional Process
Uranium is ubiquitous and is easily dissolved in the presence of water, oxygen, and
carbon dioxide. The source of the uranium is from volcanic actions eons ago originating
from the Big Bend area. Tuffaceous soil containing trace amounts of uranium were
deposited throughout South Texas and constitute the source. Over geologic time, meteoric
rains mix with oxygen and carbon dioxide in the atmosphere and solubilize trace amounts
of uranium in the soils . The oxidized waters now containing dissolved uranium flow down-
dip through the aquifer until contacting areas where high levels of sulfur in the water is
encountered. At this interface the uranium precipitates as a coating on sand grains. After
millions of years of this process a uranium ore body is formed.
The Wellfield
Localize “ sink ” with groundwater flowing into the center.
Groundwater Restoration
After mining, groundwater will be flushed and disposed from the mine area
into the operation’s non hazardous disposal well at an approved rate. This
action together with treating a significant portion of the recovered water via
Reverse Osmosis treatment, will further enhance the quality of the water
being returned to the mine.
Water will continue to be pumped from the mine area which will undergo
further polishing using Reverse Osmosis (RO) treatment. RO is essentially
an ion filter. Filtering out Sulfate (SO4-2), Calcium (Ca+2), Chloride (Cl-1),
Uranyl Oxide (UO3+2), Bicarbonate (HCO4-1), and essentially all (98%)
dissolved salts, the water produced by this equipment is of drinking water
quality.
This produced water will be blended with the circulating groundwater until
the groundwater quality meets or exceeds the pre-mining use category.
Element EPA Drinking Water
Standards Typical Pre-mining
Water Conc.
Uranium 0.03 ppm 0.1-1.0 ppm
Arsenic 0.01 ppm 0.03-0.1 ppm
Radium 226 5 picocuries/liter
25-380 picocuries/liter
Radon 4,000 picocuries/liter 2000-20,000 picocuries/liter
National Primary Drinking Water Regulations (NPDWRs or primary standards) are legally enforceable standards that apply to public water systems. Primary standards protect public health by limiting the levels of contaminants in drinking water. National Secondary Drinking Water Regulations (NSDWRs or secondary standards) are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards.
26 Element Baseline List Primary and Secondary Standards
Parameter Units
Standard
1 Calcium mg/l
2 Magnesium mg/l
3 Sodium mg/l
4 Potassium mg/l
5 Carbonate mg/l
6 Bicarbonate mg/l
7 Sulfate 250 mg/l Secondary
8 Chloride 250 mg/l Secondary
9 Fluoride 2.0 mg/l Secondary
10 Nitrate-N 10 mg/l Primary
11 Silica mg/l Secondary
12 pH std. units Secondary
13 TDS 500 mg/l Secondary
14 Conductivity µmhos Secondary
15 Alkalinity mg/l
16 Ammonia-N mg/l Primary
17 Arsenic 0.01 mg/l Primary
18 Cadmium 0.005 mg/l Primary
19 Iron 0.3 mg/l Secondary
20 Lead Zero mg/l Primary
21 Manganese 0.05mg/l Secondary
22 Mercury 0.002 mg/l Primary
23 Molybdenum mg/l
24 Selenium 0.05mg/l Primary
25 Uranium 0.03 mg/l Primary
26 Radium-226 5.0 pCi/l Primary
The 22 sites examined in the USGS report can be used as a good indicator of whether groundwater was restored to levels consistent with the pre-mining use category. The data and the prevailing regulatory rules are substantial enough to show that restoration effectiveness successfully addressed important issues such as the return to pre—mining use class, conservation of groundwater resources and protection of human health.
Factors influencing baseline water values.
1. Laboratory accuracy. National Environmental Laboratory Accreditation Program (NELAP) was established in 2005.
2. Sampling Air-jetting versus pumping. Pumping is now the accepted method in harvesting baseline samples.
3. Baseline values are an average of all the samples. On the chemically reduced side of the front uranium values will be low; on the oxidized side of the front they will be higher. Selecting sample locations is important.
4. Large ranges of values within one parameter (U and Ra) is indicative that a fairly robust set of samples need to be harvested to get a good statistical baseline value. These values are typically reported in parts per billion (U) and parts per trillion (Ra). Other constituents are reported in parts per million and parts per thousand. A factor that that is always overlooked.
5. Human error. Data entry, dilution, transposing numbers.
Total Dissolved Solids Secondary Standard
Uranium Primary Std
Radium Primary Std
1 Curie = 1 gram Ra226
Pico = 10-12
picoCurie/liter = parts per trillion
Arsenic Primary Std
Selenium Primary Std
Chloride Secondary Std
Silica No Health Std
Potassium No HealthStd
1. With the passage of Texas HB-1079 in 2013, came the recognition of the fact that groundwater has a natural range for each of the constituents that it contains. In contrast to the past, current-day regulations require that a Restoration Range Table (RRT) be developed showing the low and high values. The new RRT is somewhat akin to the consistent with baseline term in the sense that if water is restored to values within its pre-mining natural range its use class will not have changed and its quality will therefore be consistent with baseline.
Texas HB-1079
Conclusions 1. Of the Primary Drinking Water Standards that comprise the 26 species
analyzed, most are below baseline values and oftentimes below drinking water standard with the exception of uranium. However on average the uranium concentration was brought back to within less than 0.4 ppm of baseline.
2. Amended Baseline Tables Values are typically always higher than Restored Values.
3. Achieving baseline consistent with each of the 26 ions in a restoration table developed by the regulatory agency, has always been industry’s goal. Regrettably, some have translated “consistent with baseline” into rigid black and white terms that were applied to each ion.
4. The data and the prevailing regulatory rules are substantial enough to show that restoration effectiveness successfully addressed important issues such as the return to pre—mining use class, conservation of groundwater resources and protection of human health.
Palangana 1995
Plant Site Wellfield
BEFORE
Palangana 2008
Plant Site Wellfield
AFTER
UCC, Palangana 1976 Plant Site Wellfield
BEFORE
UEC, Palangana 2010 Plant Site Wellfield
CURRENT
Holiday El-Mesquite 1995
Plant Site Wellfield
BEFORE
Holiday El-Mesquite 2008
Plant Site Wellfield
AFTER
Holiday El-Mesquite 1990 Plant Site Wellfield
BEFORE
Holiday El-Mesquite 2010 Plant Site Wellfield
CURRENT
Holiday El-Mesquite 2010 Plant Site Wellfield
CURRENT
Holiday El-Mesquite 2010 Plant Site Wellfield
CURRENT
US Steel, Operations 1995
Clay West
Burns
Moser
Plant Site Wellfield
BEFORE
US Steel, Operations 2008
Clay West
Burns
Moser
Plant Site Wellfield
AFTER
US Steel, Burns Wellfield 2010 Plant Site Wellfield
CURRENT
US Steel, Clay West Processing Plant 2010
Plant Site Wellfield
CURRENT
Conclusions: ISR Mining is an environmentally sensitive means to mine.
a. No disturbance to land surface b. No dewatering of aquifer c. Restoration of groundwater consistent with baseline. d. Surface reclaimed for “unrestricted use” and returned to
landowner. e. A carbon free, inexpensive, abundant energy is produced for
millions to use and enjoy. Green Energy f. Jobs, tax-base, Jobs