Browsing by Subject "waste disposal"

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Analysis of Unsaturated Flow Based on Physical Data Related to Low Level Radioactive Waste Disposal Chihuahuan Desert, Texas
(1990) Scanlon, Bridget R.; Wang, Fred P.; Richter, Brend C.
Unsaturated flow in arroyos and fissures in the Hueco Bolson of West Texas was studied to determine if downward fluxes are higher beneath these features relative to other geomorphic settings. Soil samples collected from five boreholes in two arroyos and in and adjacent to a fissure were analyzed for moisture content, water potential, and chloride content to evaluate moisture flux. In addition, three neutron-probe access tubes were installed in and adjacent to a fissure to monitor moisture content over time. A ponding test with CaBr2 as a tracer was conducted at a fissure to compare moisture movement in the fracture fill with movement in the surrounding sediments. The arroyos are floored by a shallow (~2-m [~6.6-ft]) layer of surficial gravel underlain by clays. Moisture content was low in the gravel (~4%) and much higher in the clay (21% to 33%). Water potentials decreased with depth, which indicates a potential for downward flux. A sharp increase in chloride concentrations below the contact between the shallow gravels and deeper clays is attributed to a larger mass of water influenced by evaporation from the low-permeability clay material. Soil texture and moisture content in the fissure were similar to that in surrounding sediments. Water potentials were close to 0 at depth in the fissure as well as in surrounding sediments and decreased toward land surface, which suggests a potential for upward liquid water flow. Chloride concentrations were approximately two orders of magnitude lower in the fissure than in the clays of the arroyos. These low chloride concentrations indicate that chloride is being flushed downward in the region of the fissures. The ponding test showed that the downward flux of chloride and bromide was greater in the fracture fill than in surrounding sediments. Water potentials in the fissures and arroyos are higher than those found in the ephemeral stream and interstream settings, and the higher potentials are attributed to wetter conditions in the former geomorphic settings. The upward decrease in water potentials in the fissures is similar to that found in the stream/interstream settings and suggests upward liquid water movement. These water-potential gradients contrast with those found in the arroyos, which are downward and indicate a potential for downward water movement. Chloride concentrations in the arroyos are similar to those found in the stream/interstream sediments; however, chloride concentrations in the fissure sediments are an order of magnitude lower than those in other geomorphic settings. These comparisons suggest that the downward flux of water is greater in the fissures than in other geomorphic settings.
Chemical Wastes Disposed of by Deep Well Injection and Their Subsurface Reactions
(1988) Capuano, Regina M.; Kreitler, Charles W.
More than 8.6 billion gallons of liquid industrial waste are disposed of by deep-well injection each year (Mankin and Moffett, 1987). This constitutes more than half of the approximately 15 billion gallons of liquid hazardous waste that must be disposed. About 90 percent of these wastes are injected into deep aquifers in the Gulf Coast Region (Gordon and Bloom, 1986). In recent years, the proportion of waste managed by deep well injection has increased because of the limitations on other methods of disposal such as landfills, surface impoundments, and mixing with surface soil. Therefore, until methods of waste minimization adequately limit the production of liquid hazardous waste, deep well injection is a much-needed method for disposal. Recent legislation limits deep well injection unless the injector demonstrates that there will be no migration of hazardous constituents from the injection zone for as long as the waste remains hazardous (Federal Register 40 FR 146). To prove that injected waste does not migrate from the vicinity of the wellbore, it must be shown that the fluid or chemical constituents in the fluid are immobile or that the hazardous material degrades to a nonhazardous form before the fluid migrates from the area. It is unlikely that fluids are immobile in deep Texas aquifers, as indicated by the large gradients in fluid potential produced around injection zones (Kreitler et al., 1988). In addition, improperly sealed abandoned wells and deep growth faults, which are both common in the Gulf Coast area, can provide unexpected pathways to the surface. Instead, it needs to be shown that the hazardous chemicals are immobilized through reactions with the sediments or are transformed into nonhazardous substances.
Deep Well Injection: Chemical Wastes Disposed and Their Subusrface Reactions
(1989) Capuano, Regina M.; Kreitler, Charles W.
More than half of the liquid hazardous waste disposed of annually in the United States is disposed of by deep well injection. Little is known, however, about the chemical compositions of these wastes or about the subsurface reactions that could degrade hazardous compounds within them. This study presents the compositions of waste streams disposed of into Class I wells in Texas and their degradation processes. These Texas waste streams, which constitute 60 percent of the industrial waste disposed of annually by deep well injection in the United States, are probably representative of such injection nationwide. Phenols, chlorinated organics, cyanide, nickel, nitriles, and ketones-aldehydes compose 92 to 95 percent of the acute hazardous and toxic wastes disposed of annually. Biodegradation, if it occurs in deep injection aquifers, is probably the most effective degradation process because it causes nearly complete consumption of the organic nutrient and can degrade the widest range of hazardous organic compounds. Hydrolysis, chemical interactions, sorption, and oxidation-reduction are other possible degradation processes. Degradation in the deep subsurface probably changes with distance from the wellbore. Oxidation and hydrolysis are likely near the wellbore, where solutions are oxidized and have extremely low or high pH values, whereas anaerobic microbial activity probably dominates in an outer zone where toxic compounds are more dilute, the solution is reduced, and pH conditions are near neutral. All compounds in the waste solution must be considered when waste degradation processes are predicted. For example, generally nonhazardous carboxylic acids and their derivatives, present in 30 of the 98 waste streams studied, are highly reactive, and their presence in solution significantly affects the solution pH and hydrolysis and sorption reactions of hazardous compounds. Because carboxylic acids are generally favored as a primary substrate, their presence may either inhibit biodegradation of other primary substrates in the waste solution or enhance degradation of secondary substrates. Another common component in the organic waste streams, cyanide, is generally toxic to microbes and therefore inhibits biodegradation of other hazardous compounds. Field experiments backed up by laboratory experiments and numerical simulations are the best method for verification of waste degradation reactions. Waste-stream compositions could be altered before injection to enhance degradation and discourage unfavorable reactions using the relationships predicted from this type of experiment. This report was submitted in fulfillment of Cooperative Agreement CA-814056-01-0 by the Bureau of Economic Geology under the sponsorship of the U.S. Environmental Protection Agency. This report covers a period from August 1, 1987, to July 31, 1988, and work was completed as of July 31, 1988.
Effects of pharmaceutical wastes on growth of microalgae
(1970) Van Baalen, C. (Chase), 1925-1986; Batterton, John
The purpose of this work was to assay samples of waste material from Puerto Rican pharmaceutical industries for inhibition of growth of algae. Two samples (noted as I and II) supplied to us were tested for toxicity to six microalgae. The test organisms, two blue-green algae, two green algae, and two diatoms [r]epresent three major divisions of algae.
Electrical Resistivity Studies Related to the Proposed Low Level Radioactive Waste Repository, Hudspeth County, Texas
(1990) Keller, G. R.; Baker, Mark R.
As part of the site characterization effort for the proposed low-level nuclear waste disposal site north of Fort Hancock, Texas, the University of Texas at El Paso conducted an electrical resistivity survey of the area. This survey was contracted by the Texas Low-Level Radioactive Waste Authority. The intent is to repeat this survey annually if the site is licensed in order to monitor leachate migration. A series of soundings were made, and profile readings were taken around the entire perimeter of the proposed site. The locations of these measurements are shown in Figure 1. The procedures outlined in Draft Regulatory Guide 6.7 of the Texas Department of Health were followed. A Price array configuration was used to make the measurements, and the Barnes layer method (Barnes, 1953) was used to calculate apparent subsurface resistivities. The voltage readings were generally the average of 4 measurements, but in a few cases, 16 measurements were averaged. Repeatability was excellent (1 or 2%) for a specific placement of the electrodes. However, movement of any electrode by 1 m created variations in readings of up to 100%, and variations of 50% were common. These results are to be expected considering the near-surface variability in terms of soil composition and water saturation, but they must be kept in mind if the survey is repeated in the future.
Evaluating the Potential of East Texas Interior Salt Domes for Isolation of Nuclear Wastes
(1977) Brown, Jr., L. F
At least as early as 1960, the U.S. Atomic Energy Commission was contracting studies of the suitability of salt (halite) as repositories for waste nuclear products. Underground disposal offers the most favorable means of ensuring confinement of a growing volume of nuclear waste products. The chemical and physical properties of salt, either in domes or in bedded layers, have focused principal attention on the potential nature of salt repositories. Bedded salt deposits of various ages occur as strata within numerous sedimentary basins in the United States. In Texas, parts of the Permian Basin, the Palo Duro and Dalhart basins, are currently under investigation to determine waste isolation potential by the Bureau of Economic Geology, The University of Texas at Austin. Texas also contains at least 78 on-land salt domes that are sufficiently shallow to identify by conventional geophysical and drilling/subsurface mapping methods. Of these 78 domes, 20 domes occur within the interior East Texas Basin. Previous workers have considered coastal domes to be unstable and have also rejected about two-thirds of the Texas interior domes for various reasons (to be discussed later). Consequently, using a variety of criteria and data, approximately a half dozen interior Texas salt domes are currently "unrejected" by studies to date. At this time, it is necessary to reassess the earlier studies of East Texas interior domes, review the potential of the domes for nuclear waste isolation, and undertake intensive analysis of selected, high-priority candidate domes. This thorough evaluation must precede any decision concerning the actual use of the domes for nuclear waste disposal. Every conceivable natural factor must be considered and tested if necessary. Principal research effort should be focused very quickly on specific domes. We believe, however, that along with site-specific studies, continuing analysis of regional geohydrologic systems and salt-basin tectonics should be integrated with site-specific evaluations.
Evaluating the Potential of East Texas Salt Domes for Isolation of Nuclear Waste
(1978) Kreitler, Charles W.
Since January 1978, the Bureau of Economic Geology has been evaluating the potential for using a salt dome in the East Texas Basin as a repository for nuclear waste isolation. This report is a brief summary of work accomplished within Year I. Using the dome selection criteria of Brunton and others (1977), Kreitler and others (1978) selected Oakwood, Keechi, and Palestine salt domes as possible sites for a nuclear waste repository. The problem of depositing nuclear wastes into an East Texas salt dome contains two critical questions: (1) Are the domes still growing (tectonic stability)? (2) Are the domes dissolving, and what is the rate of dissolution (hydrologic stability)? These two questions are being asked on a dome-specific and regional scale. The long-term suitability of a dome cannot be ascertained until it is placed in a regional context. This necessitates regional as well as site-specific studies. The approach includes three subprograms: (1) subsurface geology, (2) hydrogeology, and (3) surficial geology and remote sensing. The subsurface geology program investigates dome size and shape, the geology immediately around the dome, and the infilling of the East Texas Basin over geologic time and how this basin filling affected the growth of the domes. The surficial geology and remote sensing program addresses the problem of potential dome growth during the Quaternary. Typical questions examined in this program include: have Pleistocene terraces been uplifted or warped, has there been any fault movement in the Pleistocene, and are there any movements reflected in lineation patterns around domes anomalous to regional patterns or indicated by drainage networks? The hydrogeology program evaluates the hydrologic stability of the domes with the following objectives: What are the rates and directions of regional groundwater flow? What are the ages of these groundwaters? How does groundwater flow around a salt dome? What are the rates of salt solution? Does the caprock prevent salt dissolution? This document represents a progress report and is not a final statement on the Bureau of Economic Geology's position on the suitability of salt domes in the East Texas Basin for waste isolation. The observations and ideas presented in this document therefore represent a status report and may be subject to change as more information and concepts are developed.
Final report : NOAA Puerto Rico pharmaceutical wastes, January 11, 1980
(1980) Van Baalen, C. (Chase), 1925-1986
Individual pharmaceutical wastes from operations in Puerto Rico were examined for toxicity towards representative types of microalgae.
Final Report for the Texas Low-Level Radioactive Waste Disposal Authority:Preliminary Geologic and Hydrologic Studies of Selected Areas in Culberson and Hudpseth Counties, Texas
(1986) Kreitler, Charles W.
In December 1985, the Bureau of Economic Geology (BEG) was tasked by the Texas Low-level Radioactive Waste Disposal Authority to conduct a preliminary study of the geology and hydrology of sites being considered for the construction of a low-level radioactive waste repository. The potential sites are located in Culberson and Hudspeth Counties, Texas. The potential host rocks under consideration for the repository include the Permian evaporites in Culberson County and the Cenozoic gravels and silty clays of the Hueco Bolson in Hudspeth County. The repository is intended to be constructed within the unsaturated zone. The geologic investigations aim to provide data for evaluating the general geologic framework of the proposed sites. Additionally, they provide site-specific data for evaluating the physical and structural characteristics of the units, as well as for understanding active geomorphic processes.
Geologic Analogs of Engineered Barriers: Natural Examples of Very Long- Term Performance of Layered Geologic Materials
(1997) Hovorka, Susan D.
Materials in the vadose zone are modified through time by a number of processes. These processes have the potential to adversely affect the performance of engineered barriers capping waste disposal facilities. In this study, the alteration of layered natural materials from 10 sites was described. In order for the materials to serve as partial analogs for typical arid-region engineered barriers, sites were selected to (1) have a difference between mean annual evaporation and rainfall greater than 40 inches rainfall and less than 50 days continuously below freezing; (2) be multilayered with maximum grain size contrasts (fine-grained materials overlying gravel); (3) be well-dated with ages less than 500,000 years. Site access and quality of exposure were also critical variables. The selected sites are composed of fluvial and lacustrine deposits and range in age from 500 to 22,000 years. Fine-grained materials include clay, silty clay, diatomite, and calcareous lake deposits. Coarse-grained materials include gravel, gravel with sand matrix, and gravel with mud matrix. Modification of sediments includes penetration by roots, cracking of fine-grained materials in response to shrink/swell, infiltration of fines into gravel, precipitation of carbonate, limonite, manganese oxides and hydroxides, gypsum and halite, and oxidation and reduction of iron associated with fines. The two main variables that can be related to intensity of alteration are (1) geomorphic setting and (2) composition of fine materials. The most alteration was observed in deposits now in topographic lows; deposits on hillsides underwent the least alteration. Clayey deposits showed more evidence of shrink-swell and cracking than diatomites. Topographic effects and mineralogy have more influence on the amount of alteration than the age of the deposits. Infiltration of fine materials into gravels is common but little can be deduced about the rates and processes driving this type of alteration. Relationships to constrain the timing of infiltration could not be developed. It is probable that much or all of the infiltration of fine material into gravel occurred in the depositional environment.
Geologic Factors in the Isolation of Nuclear Waste: Evaluation of Long-Term Geomorphic Processes and Catastrophic Events
(1980) Mara, Susan J.
Associated with commercial nuclear power production in the United States is the generation of potentially hazardous radioactive waste products. The Department of Energy (DOE), through the National Waste Terminal Storage (NWTS) Program and the Office of Nuclear Waste Isolation (ONWI), is seeking to develop nuclear waste isolation systems in geologic formations. These underground waste isolation systems will prevent contact between waste radionuclides and the biosphere, ensuring they don't reach concentrations harmful to humans or the environment. Comprehensive analyses of specific isolation systems are needed to assess their long-term effectiveness. The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program has been established to develop the capability of making those analyses. Among the analyses required for system evaluation is the detailed assessment of the post-closure performance of nuclear waste repositories in geologic formations. This assessment focuses on aspects of the nuclear program that have not been previously addressed. The nature of the isolation systems (e.g., potential for breaches and transport through the geosphere) and the extremely long time periods over which the wastes must be controlled necessitate the development, demonstration, and application of novel assessment capabilities. The assessment methodology must be thorough, flexible, objective, and scientifically defensible. Furthermore, the data utilized must be accurate, documented, reproducible, and based on sound scientific principles.
Geology and Geohydrology of the Palo Duro Basin, Texas Panhandle - A Report on the Progress of Nuclear Waste Isolation Feasibility Studies (1983)
(1987) Gustavson, Thomas C.
The sixth year of investigations was highlighted by analyses of structures and topographic features related to dissolution and collapse; studies of the relationship of fractures to structural trends; stratigraphic analyses of Mississippian, Pennsylvanian, Permian, Triassic, and Quaternary strata; analyses of organic carbon and vitrinite in Ordovician, Mississippian, and Pennsylvanian rocks; studies of evaporite cyclicity; analyses of core to determine sedimentary structures, diagenetic modifications, fabric, water content, clay mineral assemblages, and bromine content; studies of geophysical logs to estimate porosity distribution; isotopic analyses of water from the dissolution zone, saline springs, and the Dockum Group; hydrologic testing of the San Andres Formation; studies of pressure-depth relationships and vertical groundwater flow; the development of a regional vertical groundwater flow model; and studies of eolian processes and rates of denudation.
Geology and Hydrogeology of the Palo Duro Basin, Texas Panhandle A Synthesis of Nuclear Waste Isolation Feasibility Studies, 1977-1987
(1988) Dutton, Alan R.; DuBar, Jules R.; Gustavson, Thomas C.
Detailed studies of the geology and hydrogeology of Permian salt beds and adjacent strata in the Palo Duro Basin, Texas Panhandle, began in 1977 when the U.S. Department of Energy (DOE) initiated investigations to consider the salt beds as potential host rocks for a high-level radioactive waste repository. Studies continued until 1987 when the U.S. Congress directed that repository siting focus solely on Yucca Mountain in Nevada. Knowledge of the geology and hydrogeology of the large and complex Palo Duro Basin was minimal in 1977, in large part because of the previously limited success of hydrocarbon exploration in the basin. The ensuing decade of research produced significant new knowledge of stratigraphy, regional tectonics, geomorphology, hydrocarbon potential, geochemistry, hydrogeologic properties, and ground-water flow in the basin. This report synthesizes and examines the extensive results of these geologic and hydrogeologic studies of the Palo Duro Basin and identifies the perceived scientific issues that remain to be addressed and answered before high-level nuclear waste could be buried in the Texas Panhandle in any future program. Some geologic and hydrogeologic aspects of the Palo Duro Basin still are not well defined where geologic and hydrogeologic data are sparse and where interpretations differ. Principal among these scientific issues are questions pertaining to the timing of tectonic and diagenetic events affecting Permian sediments and host-rock stability; thermal maturity of hydrocarbon source rocks and the potential for additional discoveries of oil and gas in the basin; recharge rates and the relative significance of different sources of recharge to the High Plains aquifer and to the aquifer in the Triassic Dockum Group; ground-water flow velocity through the evaporite section and deep-basin aquifers, influence of fractures on flow velocity, and whether to treat flow as a steady-state phenomenon; origin and age of brine in deeply buried formations beneath the salt section; origin, paleoenvironment, and rate of formation of playa-lake and other lacustrine basins during the Cenozoic Era; Quaternary and present rates of salt dissolution; and the varying local extent of salt dissolution beneath the Southern High Plains.
Geomorphology of the Hueco Bolson in the Vicinity of the Proposed Low-Level Radioactive Waste Disposal Site, Hudspeth County, Texas
(1990) Baumgardner, Jr., Robert W.
The Fort Hancock study area is located 40 mi (65 km) southeast of El Paso, Texas, in the Hueco Bolson on an alluvial slope between the Diablo Plateau and the Rio Grande. The study area spans the drainage divide between Alamo and Camp Rice Arroyos. Since deposition of bolson fill ceased, the arroyos have incised, cutting down to expose the Fort Hancock and Camp Rice Formations in their floors and valley walls. Quaternary strata younger than the Camp Rice Formation underlying the study area can be divided into four units: a basal gravel, a middle sand, a petrocalcic horizon (Stage IV), and an upper sand. The petrocalcic horizon is interpreted to be the upper surface of the Madden Gravel, and, on the basis of its dense, laminated character, took 25,000 to 75,000 years to form. These Quaternary sediments range in thickness from 20 to 60 ft (6 to 18 m), thinning to the southwest across the study area and toward the edges of arroyos.
Geophysical Studies Related to the Proposed Low Level Readioactive Waste Repository Hudspeth County, Texas
(1990) Keller, G. R.; Doser, Diane I.; Baker, Mark R.
Geologic characterization of sites for low-level radioactive waste repositories generally requires qualitative and quantitative estimates of variations in rock properties between test wells. Seismic reflection surveys are an accepted technique for providing a qualitative picture of structural and/or stratigraphic variation when tied closely to control information from wells. Reflection surveys also are useful in identifying areas where additional well control may be needed to adequately characterize geologic variations. Ten miles (16 km) of reconnaissance seismic data were collected and interpreted by Phillips et al. (1986) in the vicinity of the proposed repository site near Fort Hancock, Hudspeth County, Texas. Three lines were collected perpendicular to the major structural trends, and a fourth line tied these three together. These data typically resolve variations in stratigraphic thickness that are more than 20 ft (6 m) thick, one-fourth the dominant time wavelength, and that are more than 90 ft (27 m) deep. These data can image horizontal variations greater than 110 ft (34 m), with 8 common depth point samples per wavenumber.
Hydrochemical Characterization of Saline Aquifers of the Texas Gulf Coast Used for Disposal of Industrial Waste
(1986) Kreitler, Charles W.; Richter, Brend C.
Disposal of toxic chemical wastes into geologic formations in the deep subsurface and the number of disposal wells used have increased sharply during the last 30 years. In Texas, permits for more than 200 waste disposal wells, which accept approximately 16 percent of the chemical wastes generated in the United States, were issued by the Texas Department of Water Resources (TDWR) during this period (Knape, 1984). Most waste disposal wells use porous, saline sandstone aquifers along the Texas Gulf Coast (fig. 1). Simultaneously, fresh groundwater is recovered from shallower, updip sections of these aquifers. Therefore, integrity of disposal zones is of importance both on a statewide and on a nationwide level. Waste injected into subsurface formations may react with formation fluid or formation material, depending on the chemical and physical nature of the phases involved. Aquifer material may dissolve or mineral matter may precipitate, thus changing original compositions of disposal zones. It is desirable to predict these changes to assure successful operation of injection practices. To satisfactorily evaluate the suitability of deep-well injection into Gulf Coast formations, hydrochemical and hydrogeological parameters of these aquifers are currently under study by the Bureau of Economic Geology, The University of Texas at Austin. This report represents the first stage of the characterization of saline aquifers in the Gulf Coast that are used for industrial waste disposal and summarizes geochemical parameters of disposal zones.
Hydrogeologic Characterization of the Saline Aquifers, East Texas Basin- Implications to Nuclear Waste Storage in East Texas salt Domes
(1983) Kreitler, Charles W.; Collins, Edward W.; Fogg, Graham E.; Jackson, M. P. A.; Seni, Steven J.
Groundwaters in the deep aquifers (Nacatoch to Travis Peak) range in salinity from 20,000 to over 200,000 mg/L. Based on their isotopic compositions, they were originally recharged as continental meteoric waters. Recharge probably occurred predominantly during the Cretaceous time; therefore, the waters are very old. Because the basin has not been uplifted, there are no extensive recharge or discharge zones. The flanks of domes and radial faults associated with domes may function as localized discharge points. Both the water chemistry and the hydraulic pressures for the aquifers suggest that the basin can be subdivided into two major aquifer systems: (1) the upper Cretaceous aquifers (Woodbine and shallower) which are hydrostatic and (2) the deep lower Cretaceous and deeper formations (Glen Rose, Travis Peak, and older units), which are slightly overpressured. The source of sodium and chloride in the saline waters is considered to be from salt dome dissolution. Most of the dissolution occurred during the Cretaceous. Chlorine-36 analyses suggest that dome solution is not presently occurring. Salinity cross sections across individual domes do not indicate that ongoing solution is an important process. The major chemical reactions in the saline aquifers are dome dissolution, albitization, and dedolomitization. Albitization and dedolomitization are important only in the deeper formations. The high Na concentrations in the deeper aquifer system result in the alteration of plagioclase to albite and the release of Ca into solution. The increase in Ca concentrations causes a shift in the calcite/dolomite equilibrium. The increase in Mg results from dissolution of dolomite.
Hydrogeologic Characterization of the Saline Aquifers, East Texas Basin-Implications to Nuclear Waste Storage in East Texas Salt Domes
(1987) Kreitler, Charles W.; Collins, Edward W.; Fogg, Graham E.
Groundwaters in the deep aquifers (Nacatoch to Travis Peak) range in salinity from 20,000 to over 200,000 mg/l. Based on their isotopic compositions, they were originally recharged as continental meteoric waters. Recharge probably occurred predominantly during Cretaceous time; therefore, the waters are very old. Because the basin has not been uplifted and faulting of the northern and western sides, there are no extensive recharge or discharge zones. The flanks of domes and radial faults associated with domes may function as localized discharge points. Both the water chemistry and the hydraulic pressures for the aquifers suggest that the basin can be subdivided into two major aquifer systems: (1) the upper Cretaceous aquifers (Woodbine and shallower) which are hydrostatic to subhydrostatic and (2) the deep lower Cretaceous and deeper formations (Glen Rose, Travis Peak, and older units), which are slightly overpressured. The source of sodium and chloride in the saline waters is considered to be from salt dome dissolution. Most of the dissolution occurred during the Cretaceous. Chlorine-36 analyses suggest that dome solution is not presently occurring. Salinity cross sections across individual domes do not indicate that ongoing solution is an important process. The major chemical reactions in the saline aquifers are dome dissolution, albitization, and dedolomitization. Albitization and dedolomitization are important only in the deeper formations. The high Na concentrations in the deeper aquifers system result in the alteration of plagioclase to albite and the release of Ca into solution. The increase in Ca concentrations causes a shift in the calcite/dolomite equilibrium. The increase in Mg results from dissolution of dolomite. The critical hydrologic factors in the utilization of salt domes for disposal of high-level nuclear waste are whether the wastes could leak from a candidate dome and where they would migrate. The following conclusions are applicable to the problem of waste isolation in salt domes: (1) Salt domes in the East Texas Basin have extensively dissolved. The NaCl in the saline aquifers is primarily from this process. Major dissolution, however, probably occurred in the Cretaceous time. There is little evidence for ongoing salt dome dissolution in the saline aquifers. (2) If there was a release to a saline aquifer, waste migration would either be along the dome flanks or laterally away from the dome. If there is a permeability conduit along the dome flanks, then contaminants could migrate to the fresh-water aquifers, provided an upward hydraulic gradient exists. Calculation of performance assessment scenarios must take into account whether there is potential for upward flow between saline aquifers at repository level and the fresh water aquifers. If an upward flow potential exists, upward leakage along the dome flanks should be used as the worst-case scenario.
Hydrogeology of Formations Used for Deep-Well Injection, Texas Gulf Coast
(1988) Kreitler, Charles W.; Akhter, M. Saleem; Donnelly, Andrew C. A.; Wood, Warren Theodore, 1962-
This research program was conducted to investigate fluid migration potential, fluid direction, and velocities in the regional hydrologic environment of the Texas Gulf Coast Tertiary formations in the context of deep-well injection of hazardous chemical wastes. The study focused on the Frio Formation due to its significant waste injection and the availability of a large database on formation pressures and water chemistry in the Frio. Pressure data collected from drill-stem tests and bottomhole pressure measurements in onshore oil and gas wells were used to evaluate pressure regimes. Pressure-depth profiles and potentiometric surfaces constructed from this data revealed three hydrologic regimes: a shallow section with fresh to moderately saline water in the upper 3,000-4,000 ft, an essentially saline hydrostatic section 4,000-5,000 ft thick, and a deeper overpressured section with moderate to high salinities. The hydrologic complexity is further compounded by extensive depressurization in the 4,000-8,000 ft depth interval, likely resulting from the production of over 10 billion barrels of oil equivalent and associated brines over the past 50 years. It was not possible to construct a composite potentiometric surface of the entire Frio to determine "natural" flow gradients or "natural" points of discharge. Potentiometric surfaces representing discrete depth intervals were mapped, and these values, along with flow gradients determined from potentiometric surfaces and published permeability and porosity data, were used to compute linear fluid flow velocities ranging from 0.01 ft/year to 105 ft/year in the lateral direction. The potential for vertical fluid migration was investigated using equivalent environmental hydraulic head maps. The presence of widespread pockets of depressured formations significantly affects the direction and value of fluid gradients, as these depressured oil and gas fields may become potential sinks for the injected chemical wastes. Published water chemistry data were supplemented by field sampling of waters from 32 oil fields. Active recharge of the Frio by continental waters does not seem to be occurring. All sampled waters appear to be in isotopic equilibrium with the rock matrix. Salt dome dissolution is the primary reaction controlling water chemistry in the northern section, while brines from the deeper geopressured section may be leaking into the hydrostatic section of the central and southern Gulf Coast Frio. The absence of organic acids and the alteration of Frio oils from samples shallower than approximately 7,000 ft suggest biodegradation, which has useful implications for the degradation of injected chemical wastes. A detailed analysis of the localized hydrodynamics in Victoria County, Texas, as a case study demonstrates the applicability of the developed techniques to injection facility siting and monitoring processes, particularly where depressurization was observed on a local, county-size scale.
Locating Field Confirmation Study Areas for Isolation of Nuclear Waste in the Texas Panhandle
(1977) Galloway, William E.; Gustavson, Thomas C.
Early in 1977, the Bureau of Economic Geology was invited to assemble and evaluate geologic data on several salt-bearing basins within the State as a contribution to the national nuclear repository program. In response to this request, the Bureau, acting as a technical research unit of The University of Texas at Austin and the State of Texas, initiated a long-term program to assemble and interpret all geologic and hydrologic information necessary for the delineation, description, and evaluation of salt-bearing strata and their environments in the Panhandle area. The technical effort has, to date, been divided between two research groups. A basin analysis group has assembled the regional stratigraphic and structural framework of the total basin fill, initiated an evaluation of natural resources, and selected stratigraphic core sites for sampling the salt and associated beds. Two drilling sites have provided nearly 8,000 feet of core material for analysis and testing of the various lithologies overlying and interbedded with salt units. Concurrently, a surface studies group has collected ground and remotely sensed data toward describing surficial processes, including carbonate and evaporate solution, geomorphic evolution, and fracture system development. A newly formed basin geohydrology group will evaluate both shallow and deep circulation of fluids within the basins. This paper is a summary report of progress to date. It reviews principal conclusions and illustrates methodologies utilized and the types of data and displays generated. Several topical reports will be forthcoming as various phases of the study are completed and will discuss in detail various geological aspects of the Palo Duro and Dalhart Basins.