AC : VALIDITY OF THE METHODOLOGY FOR ESTABLISH- ING BASELINE WATER QUALITY FOR URANIUM

Transcription

1 AC : VALIDITY OF THE METHODOLOGY FOR ESTABLISH- ING BASELINE WATER QUALITY FOR URANIUM Mrs. Marisa Hamilton, Riviera Kaufer High School Dr. Lee Clapp, Texas A&M University, Kingsville Lee Clapp is an Associate Professor in environmental engineering. Prof. Mohamed Abdelrahman, Texas A&M University, Kingsville Mohamed Abdelrahman received the B.S. and M.S. degrees in electrical engineering and engineering physics from Cairo University, Egypt in 1988 and 1992, respectively. He received an M.S. and a Ph.D. in measurement and control and nuclear engineering from Idaho State University in 1994 and 1996, respectively. He is currently the Associate Dean of Engineering at Texas A&M University, Kingsville. Abdelrahman s research focus is industrial applications of sensing and control with major research funding from the U.S. Department of Energy, National Science Foundation, and industry. He has also focused on collaborative and innovative educational research. Abdelrahman is passionate about outreach activities for popularizing engineering research and education. His activities in that arena included NSF funded sites for research experience for undergraduates and research experience for Teachers. He has published his research results in more than 90 papers in refereed journals and conference proceedings and 30+ technical reports. c American Society for Engineering Education, 2012 Page

2 Validity of the Methodology for Establishing Baseline Water Quality for Uranium In Situ Recovery (ISR) Mining Abstract This paper examines the research a teacher completed during the Research Experience for Teachers in Manufacturing for Competitiveness in the United States (RETainUS) summer project and the implementation of the research in a high school science classroom. The research involved the importance of establishing a baseline water quality level prior to in situ recovery mining for uranium. Water is the life line of many and the quality of that water is being questioned by many. In South Texas there is a clash between private citizen groups and uranium mining companies regarding ground water quality in uranium mining sites. Private citizens groups are claiming that uranium mining companies are contaminating the ground water with drilling and uranium production processes and that the baseline well locations and averages are not randomly selected. However, research findings show that the drilling process is similar to that of other drilling processes. There is not a clear variation between drilling for baseline water wells and drilling for identification and production of uranium deposits. The claims that uranium companies are polluting the ground water may be valid but the phenomenon needs to be better understood before conclusions can be made on the causes of uranium contamination in ground water. There are many improvements that can be made by private citizens, uranium companies, and the regulatory agencies to maintain better water quality. Using this research experience, the teacher created a thematic unit using the question of Is your water safe to drink? for a high school aquatic science class following the legacy cycle format. Students will explore what makes water safe to drink, where well water comes from, drilling water well practices, and the uranium mining process. Students will test their own water samples for basic water contaminants. Student learning will be gauged by a scenario of the student working at an environmental lab and lastly sharing their new found knowledge with local publications. Students in this community are aware of uranium in the ground water, as the area has been plagued with water quality problems. This legacy cycle will give the students information need to become informed citizens. Summer Research With a summer experience at Texas A&M University-Kingsville s Research Experience for Teachers (RET) project, the teacher conducted research on baseline water quality prior to in situ recovery (ISR) mining for uranium. This research was instrumental to the understanding of water quality in our community, both personally and professionally. The teacher moved to an area that has been riddled with ground water quality and uranium mining controversy. Prior to this research, the teacher knew nothing of the importance water quality. The teacher was one of many that will drink water; as long as it tastes, looks, and smells good. After this research, that is no longer the case. There is much more than aesthetic qualities when it comes to quality water. Most of the summer included finding water standards, learning drilling standards and uranium mining processes via computer research, and interviewing professionals in the field. Practical Page

3 field experience was gained collecting water samples from a well. Visits to ISR uranium mining sites in various stages provided even more insight to this process. Aquifers Different materials allow different fluids to travel through them at different rates. If the substance does not allow a fluid to travel though it, the substance is known as impermeable. If a substance allows a fluid to travel through it, the substance is known as permeable. These different properties can be applied to underground sediments, creating areas ideal for fluids (i.e. water, oil, and gas) to collect. An underground layer of porous rock, sand, or gravel, makes an excellent storage space for ground water; while, clay and shale do not retain water very well. If layers of impermeable and permeable of sediment form, water may become embedded between these layers. The water and porous sediment become known a confined aquifer, as seen in Figure 1. The water reaches a maximum level, which is referred to as the water table. The water is not stagnant, but moves due to the pressure of the rock formation itself. The water table will rise and fall depending on the rate of ground water recharge. Figure 1: Anatomy of an aquifer 1 Uranium Deposits Formation of Uranium Deposits Approximately 48 million years ago, South Texas underwent an enormous amount of volcanic activity, leaving the area rich in dispersed uranium. 2 As precipitation filtered through the soil, uranium dissolved and eventually mixed with groundwater, which flowed downgradient. When the ground water came into contact with a reducing environment containing chemical compounds such as coal, oil, natural gas or sulfides, the uranium precipitated out of solution and deposited in an ore body known as a roll front as seen in Figure 2. The uranium then concentrated in these roll fronts trapped between oxidized and reducing. 3 Page

4 Figure 2: Uranium ore roll front 3 Drilling of a private water well Private land owners may have a water well drilled on their property. The private owner contracts with a drilling company to drill the water well. The driller will bring a drilling rig onto the property and begins drilling several feet into the ground. At this point, a casing then follows the drill bit to prevent the hole from collapsing. The rod that is connected to the drill bit is hollow, allowing for a lubricant to be added to the drill bit. This minimizes friction, prevents overheating, and lifts rock cuttings to the surface. Figure 3 shows the circulation of mud during the drilling process. This lubricant is commonly known as drilling mud. This mud is a mixture of water, clay, weighting material and chemicals. 4 During the drilling process samples of the formation are taken and analyzed. 5 Figure 3: Mud circulation in the hole 4 When the well is completed, the drilling company will submit a report detailing the description of the formation materials. There is a section in the report on water quality that indicates if any of the drilling samples contained undesirable constituents. If the answer is no, then no water quality testing is needed. If the answer is yes, then a Report of Undesirable Water must be submitted. The original report contains a section with a question asking if a chemical analysis of the water was completed and is answered by a checked yes or no. Once this is completed, the well is ready for private use. 6 Page

5 Private Well Regulations There are no regulations in the State of Texas that regulate the quality of water from a private water well (Texas Groundwater Protection Committee, no date). The quality of the water could be tested using the guidelines set by the United States Environmental Protection Agency s (U.S. EPA) Safe Drinking Water Act (SWDA). However, the SDWA rules only applies to public drinking water systems; that is governmental or privately run companies that supply water to more than 25 people or 15 service connections. It is at the discretion of the private land owner to have the water sample tested to see if it meets current SWDA standards. 6 Uranium Mining In-situ Mining Uranium is first located by exploratory drilling which involves the drilling of boreholes. The drilling of these boreholes is similar to that of drilling personal water wells. The difference is that you are not drilling to hit water, but drilling to take soil samples. The soil samples are examined for different levels of oxidation and reduction. The soil samples will be different colors, as shown in Figure 4. The process is continued until it is determined whether the amounts of uranium detected make it economically feasible to recover. The operation then goes from exploration to the beginning of ISR mining. 3 Figure 4: Soil samples 3 The first stage of ISR begins with establishing groundwater quality that will be deemed the baseline values. These baseline values are an important part of the restoration process after mining has been completed. After the wells are drilled, oxygenated water is pumped into the aquifer formation containing the insoluble uranium deposits. The uranium undergoes a chemical oxidation reaction allowing it to become soluble in water. The water, now containing soluble uranium, is pumped to the surface and transferred to an ion exchange column, as shown in Figure 5. Here the water is pumped through resin beads that exchange the uranium for chloride ions. The water now depleted of most uranium (but enriched in chloride) is returned to the aquifer to start the cycle again. The resin is then shipped to the processing plant to be stripped of uranium to make yellow cake and the resin is recycled. 3 Page

6 Figure 5: ISR mining process 7 ISR Mining Regulations The uranium mining process is regulated by several governmental agencies. Exploration for uranium deposits is governed by the Texas Railroad Commission (RRC). An RRC exploration permit consists of maps, descriptions of drillings methods, the estimated number of boreholes, and the methods for marking the drilled boreholes. The methods for well construction and plugging of the well, once exploration is completed, must also be noted. Samples from the bore wells are examined to determine if uranium recovery mining is feasible. This will also give the geologist an idea of where to drill for the uranium once the recovery process begins. 8 Once the recovery of uranium is deemed viable, a new permit must be obtained from the Texas Commission of Environmental Quality (TCEQ) and its Underground Injection Control (UIC) program. Some included items are: the core data report, a map of the area, financial assurance, and a technical report. The map must denote the lease boundaries, the proposed production areas (PAAs), and the location of baseline wells, along with the location of existing wells within a quarter of a mile of the PAA and their purposes. 11 The technical report of the application focuses on the PAAs. Groundwater analyses for each baseline well in both production and non-production aquifers must be submitted. A summary page for the analysis of the ground water must also be submitted as part of the required report. 11 The aquifer to be drilled (i.e., for production purposes) must also qualify for an aquifer exemption from the U.S. EPA. An aquifer may be exempted if it is not currently being used and will not be used in the future as a drinking water source, or it is not reasonably expected to supply a public water system due to a high total dissolved solids content. 10 If the aquifer does not meet the qualifications for an exemption, then uranium mining will not be allowed. If the aquifer does meet the exemption qualifications, meaning it does not meet SWDA standards, then the aquifer is granted an exemption. Once an aquifer is granted an exemption, Page

7 the exemption cannot be revoked. The water is deemed as unsafe forever. However, only parts of an aquifer may be classified as unsafe, while other areas of the aquifer are safe to drink from. This could happen around an ore deposit. The water will also have a different taste depending upon which side of the ore deposit you are on. On the oxidized side of the ore body, the water will have a much nicer taste. On the reduced side of the ore body, the water may have the smell of rotten eggs, due to the presence of sulfides. Figure 6 exhibits this situation. Figure 6: Water quality surrounding ore body 11 Baseline Water Quality To establish baseline levels, water samples are taken from baseline wells in the production zone in PAA. 12 The water is tested for 26 constituents are listed in Table 1 below. There are standards for collecting, preserving, and analyzing the samples. Table 1: Baseline Groundwater Sample Constituents 12 Nitrate as in N Calcium Alkalinity Fluoride Magnesium ph Silica Sodium Arsenic Total Dissolve Solids Potassium Cadmium Molybdenum Carbonate Iron Uranium Bicarbonate Lead Ammonia as N Sulfate Manganese Radium-226 Chloride Mercury Selenium Conductivity Page

8 Placement of Baseline Wells The placement of baseline wells is not determined or regulated by the TCEQ. Baseline wells are installed in areas of ore bodies. 13 In the production area, a minimum of five baseline wells or one baseline well for every four acres is needed. The location of these wells must be noted on the map of the production area that is to be included with the application. 12 Creating the Restoration Table A restoration table is a list of ground water quality parameter values that companies must return the aquifer to after ISR mining is completed. This table is based upon the baseline ground water analysis that was submitted with the application. It is calculated by using the mean concentrations for the 26 parameters based on all groundwater samples collected from baseline wells prior to mining, or by an alternative statistical analysis approved by the executive director that yields representative baseline ground water quality. 12 Amending the Restoration Table If a company has been trying to restore the ground water to pre-mining values and has stabilized reduced concentrations, the company will seek an amendment to the restoration table. There are various factors that are considered in determining whether the restoration table should be amended. They include the uses of groundwater at baseline levels, existing use of groundwater, future use of groundwater at baseline quality and proposed restoration quality, effort made to reach baseline quality, technology available, ability of technology to restore the groundwater, cost, consumption of groundwater resources, and the harmful effects of levels of a particular parameter. More specifically an amendment may be made if a reasonable effort has been taken to restore the groundwater quality, the value for the parameter has been stabilized for one year, the water is currently suited for the same use as it was prior to mining, and further efforts would consume energy, water, and other natural resources without providing benefit to the state. Once an amendment is made to the table, monitoring must continue for a time period of two years. 14 Criticism of ISR Mining Some argue that the water needed to drill test wells liberates these two radioactive elements (uranium and radium). 15 Or that it [oxygen] can be introduced by human activities (oxygenrich groundwater used to drill exploratory boreholes in situ mining activities that introduce oxygen into the deposit ). 16 In Uranium Mining in Texas: Why Is It Done That Way, it is mentioned that during the recovery phase of the pump test 99% of the amount of water was returned to the formation, thus allowing the introduction of large quantities of oxygenated water, resulting in the elevated values of uranium observed shortly after the pump test. 17 The water in the PAA may have met SWDA standards prior to the drilling and testing of the water, but now fail due to the methods used. Baseline wells are drilled to establish the quality of the groundwater prior to the recovery mining, but the placement of the baseline wells is not prescribed, as are monitor well placements. The location of these wells is being criticized. Opposition groups are stating that results of the boreholes, completed during exploration, could influence where the baseline wells are drilled Page

9 yielding higher levels of uranium allowing the mining companies to cherry-pick the locations 18, 19 of the baseline wells. When submitting baseline water samples, companies are required to submit a report with water quality information. This report asks for the high, low, and average measurement of 26 constituents. The Coastal Bend Sierra Club commented on TCEQ s Draft Rules for Uranium Mining in Texas that calculating the average for the restoration table must be scrutinized more closely. Using an arithmetic mean based is not legitimate if there are outlier values, meaning the numerical value is very different than the other numbers. The second concern is the use of a statistical mean. For this to be valid, the sample set must be randomly chosen, whereas in reality the sample sets are not random. 18 Others are criticizing companies for not returning their groundwater to pre-mining conditions. 20 Dr. Richard Abitz conducted a workshop for the Coastal Bend Sierra Club and the South Texas Opposes Pollution organization on May 17, 2008, during which he said that I have never seen mining companies even come close to pre-mining levels. 20 A report by the Unites States Geological Society recently stated that All PAAs in Texas have received amended restoration goals for at least one element 21 Findings The argument that the drilling process alone is contaminating the water source is a reasonable argument. However that argument cannot be made true for only drilling with regards to ISR uranium mining. The same process is used for the drilling of other types of wells, private drinking wells, public drinking wells, oil and gas wells, and ISR uranium wells. If the water is being contaminated for baseline values for ISR mining, then the groundwater could also become contaminated during drilling of public and private drinking wells. More specifically, if uranium is present then it will be liberated in all locations, not just at uranium mining fields. According to the Uranium Exploration in the Côte-Nord Region website there is not enough volume of material mobilized during exploration work to significantly increase this natural contamination rate. The amount of oxygen that may be added during drilling is minimal and may influence a radius of about three feet. 13 This quantity of oxygen is not comparable to the amount of oxygen that is added to the well once it is in production. It may take as long as a week for the uranium to peak. 14 Some private citizens have had water wells on their private property for years, and point out that this water has been used by people for years. 25 However, it must be recognized that, although these water wells have been used for years, the water quality has been unregulated. Unless the water is tested, no one can say for certain that the water meets current drinking water standards. Uranium was not regulated under the SDWA until 2000 and changed to its current standard of 30 mg/l in December of Prior to this date, uranium had a recommendation level. Uranium cannot be detected by smell, taste, or sight. As long as the water smells good, tastes good, and looks good, people drink it. The only way to detect uranium in the water is to have the water tested. The costs of the tests can be expensive and the ramifications of the test could be Page

10 significant. One EPA-certified company would test for uranium at a cost of $ If test results reveal undesirable results, the land owner would have to disclose that fact if the property were ever sold. For this reason, many land owners are not going to have the water tested after a well is drilled. The Texas Mining and Reclamation Association (TMRA) researched a database from the National Uranium Resource Evaluation (NURE) program. The NURE program was established in the 1970 s to identify uranium resources in the United States. As shown in Figure 7, TMRA found 108 South Texas wells with levels of uranium higher than the EPA standards. These wells were tested from 1975 to 1980 and prior to uranium ISR mining. 29 Figure 7: Historic water wells in South Texas that contained uranium above the EPA drinking water standard 29 During the staging of the well field, pump tests are conducted to establish hydraulic communication between wells. More specifically pump tests are used to define the hydrological characteristics of the ore zone, obtain information about the ground water flow, and to determine if the surrounding strata are suitable to prevent movement of the recovery solution into the underlying or overlying aquifers. 30 There are no standards on conducting pump tests or when these pump tests are to be conducted. Pumps tests involve the pumping of water out of the aquifer to ensure that the water is going to flow in the correct direction. Well types can be modified, meaning an injector well becomes an extractor well or the reverse. This ensures that the next phase of the process, circulating oxygenated water, remains in the mining field. At no time during the pump test is oxygenated water introduced to the aquifer. The water table is allowed to rise naturally, filling in with surrounding ground water. Page

11 The question then becomes the location of a well. Some wells are naturally going to show a higher level of uranium than others. That has more to do with the geology of the well, not the methodology of the drilling or mining. The mining companies are in the business of making money by recovering uranium. Legally the mining companies are following the procedures set forth by the TCEQ and the UIC program. However, there are going to be differences in the amount of uranium found in baseline water samples, simply because of the geology of the aquifer and the uranium roll front. The mining companies are going to want areas of high uranium. Uranium concentrations found in a baseline well in a hot spot can dramatically alter an average. One suggestion given by Scheurich was to have samples obtained from wells that are located on a systemic grid across the entire mining area surrounded by the monitor well ring or randomly selected with an appropriate statistical procedure. 18 Water samples are typically taken from existing well sites. Questions are raised concerning how close the wells have to be and whether baseline wells really provide representative statistical data if they are not systematic in location but are rather drilled as a means to locate pockets of uranium. Lastly is the problem of the restoration of the aquifer to the baseline quality. A company will ask for an amendment to the restoration table. How much work does a company need to do to return the levels to pre-mining conditions? I should be noted that if an amendment is granted the company must monitor that well for an additional two years. Maybe the answer is not in just monitoring and reaching a consistent level, but what other techniques can be employed to lower the current level to the original baseline levels. Conclusions of Summer Research Private citizens should have their water tested for health and safety reasons. This testing should be independent of uranium mining or uranium exploration. Merely stating that drilling wells during uranium exploration is causing contamination of the water supply is not justified. If the drilling process contaminates water with uranium then the same would have to be true for all contaminants that behave similarly and all wells that are drilled in areas rich with uranium deposits. The quality of water has to do more with the location than the drilling process. Unfortunately, it appears that the selection of wells for establishing baseline groundwater quality is governed by the uranium exploration process, as opposed to a more rational geostatistical approach. Groundwater in a uranium ore body will naturally differ from groundwater quality that is not in a uranium ore body. The two types of groundwater quality are currently not clearly segregated when establishing baseline groundwater quality and they should be distinguished. There is also the problem of calculating the average constituent concentration that is site specific since each site is different with respect to well spacing and aquifer characteristics. Each ore body and mine field must be examined closely to determine which statistical method is best suited for the site. Geology is also plays a large role in baseline concentration values and some areas are going to have a naturally higher concentration than others. Page

12 Legacy Cycle Mrs. Hamilton, the teacher-researcher, teaches in a rural community of approximately 2,000 people. Schools in the surrounding school districts only enroll students up to either grades six or eight. At the time of implementation, the high school enrollment was 240 students, including transfer students from surrounding communities. The lesson cycle was implemented with 21 students. With the exception of one tenth grader, all the students are seniors. The demographics of the students are split between 11 Hispanics and 10 Caucasians, with 14 males and 7 females. The learner abilities vary greatly as the class is an elective course. Students range from gifted and talented to modified-curriculum due to special needs. Five students are identified as At-Risk and 11 students are economically disadvantaged. With this new wealth of information and the importance of what was learned from the research, a lesson cycle was developed for the teacher s students to share in this new perspective of water quality. The implementation of the legacy cycle will have meaning to students in this community, as many families have private water wells and know of the uranium controversy occurring in their own backyard. The students will go through the learning process of the legacy cycle. The legacy cycle is comprised of six stages: challenge question, generate ideas, multiple perspectives, research and revise, test your mettle, and go public. Students will be challenged with the question of is your water safe to drink? Students will have to determine what makes water safe to drink. During class discussions, students will bring up the topic of uranium in the ground water. At this point, the teacher will integrate her experience from the RET summer experience. Students will then research how wells are drilled, how aquifers work, how to mine uranium using in situ recovery mining, and how it affects ground water quality. Students will hear different perspectives from various people dealing with ground water quality. Students will test their own well s water using various test strips and hand-held data collectors. Students will determine whether their own drinking water meets standards, based on the constituents that were tested. Students will share this information by writing articles for the school newspaper and local newspaper. Finally, students will test their understanding of the project by taking on the task of being employed by an environmental lab that tests water quality. Each group of students will be given different water samples. Each group must create a report to submit to clients summarizing the water quality. The report must be consumer-friendly and easily deciphered. Conclusions and Summary With the implementation of this legacy cycle a greater understanding of water quality should be gained by those that need it most. Providing a community with the knowledge of the geology and science behind their drinking water source will alleviate many misconceptions. Student will become informed consumers and will not perpetuate false science. In a community where uranium mining has occurred to the north and may also begin to the south, the knowledge of scientific principles is vital. The town has had its problems with uranium in the water. Therefore the community needs to be educated so that decisions are made based on science rather than fear. This lesson was designed to give a basic understanding of uranium and water quality. The greater result will be an understanding of asking the right questions and seeking answers to those questions. Page

13 Acknowledgement This material is based upon work supported by the National Science Foundation under Grant No. EEC , Research Experience for Teachers in Manufacturing for Competitiveness in the United States (RETainUS). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Bibliography 1. University of Georgia, River Basin Center (no date). Georgia s Aquifers. Retrieved January 8, 2012, from aquifers.htm. 2. Brain, M., & Lamb, R. (2000, October 9). How Nuclear Power Works. Retrieved July 6, 2011, from 3. Texas Mining and Reclamation Association [TMRA] (no date). In-Situ Recovery Technology. Retrieved June 7, 2011, from 4. Freudenrich, C.C. (no date). How Oil Drilling Works. ELS and Company. Retrieved January 8, 2012, from 5. R. Carrillo personal communication, June 13, United States Environmental Protection Agency [U.S.EPA]. (2002, January). Drinking Water from Household Wells, EPA 816-K Curnamona Energy (no date). Production of Uranium by In Situ Leaching. Retrieved January 8, 2012, from 8. Caudle, J.E. (no date). Railroad Commission Update on Uranium Exploration Regulations. Railroad Commission of Texas, Surface Mining and Reclamation Division. Retrieved January 8, 2012, from 9. Texas Commission on Evironmental Quaility [TCEQ]. (2011, January 25). Class III Injection Well Area Permit Application to Conduct In Situ Mining of Uranium. Retrieved from January 8, 2012, from U.S. EPA. (2010, December 10). Water: Underground Injection Control Glossary. Retrieved June 23, 2011, from: Uranium Resources Inc. (no date). Uranium ISR 101 Graphic Fact Sheet. Retrieved January 8, 2012, from: Texas Adminstrative Code (2009). Establishment of Baseline and Control Parameters for Excursion Detection. Subchapter F: Standards for Class III Well Production Area Development, 30 Tex. Admin. Code Texas Commision on Environmental Quality, Underground Injection Control (UIC) Program. 13. Rice, G. (2006). Effects of URI's Kingsville Dome Mine on Groundwater Quality. Kleberg County URI Citizen Review Board. 14. D. McCoig and A Kurus, personal communication, July Sass, R. (2011, April 8). Environmental Friendly mining not as benign as it seems. Message posted to Abitz, D. (2009, May 3). TMRA Propaganda is Shameful. Kingsville Record. Page

14 17. Sass, R. (2011). Uranium Mining In Texas: Why is it done That Way? James A. Baker III Institute for Public Policy. Rice University. Retrieved January 8, 2012, from: Scheurich, V. (2009). Coastal Bend Sierra Club's Comments on TCEQ's Draft Rules for Uranium Mining in Texas. Retrieved June 24, 2011, from Suter, P., & Scheurich, V. (2009b). South Texas Uranium News, October 5, Retrieved June 6, 2011, from Walsh, M. M. (2008, June 3). Uranium mining: Is it really safe? Corpus Christi Caller Times. 21. Hall, S. (2009). Groundwater Restoration at Uranium In-Situ Recovery Mines, South Texas Coastal Plain. USGS Open-File Report Ressources Naturelies et Fauna Quebec (2009). Uranium Exploration in the Côte-Nord Region. Retrieved June 24, 2011, from S. Talbott personal communication, July 12, H. Fels personal communication, July 12, Reese, A. (2009, May 4). Mining: Uranium proposal draws challenge from Texas county. E&E Publishing, LLC. Retrieved January 8, 2012, from United States Environmental Protection Agency [U.S. EPA]. (2011, Updated May 4). Drinking Water Contaminants. Retrieved June 16, 2011, from index.cfm#radionuclides. 27. University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources. (2008, November). Drinking Water: Uranium. Retrieved July 7, 2011, from publicationd.jsp?publicationid= D. Grunstra personal communication, July 7, Texas Mining and Reclamation Association [TMRA]. (2009, April 1). Historic Database Shows High Concentrations of Naturally Occurring Uranium in South Texas Water Wells. Retrieved July 6, 2011 from: Colorado Mining Association (no date). Uranium In-Situ Recovery. Retrieved July 5, 2011, from Page