Publications

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Downhole sonar surveys from the four active U.S. Strategic Petroleum Reserve sites have been modeled and used to generate a four-volume sonar atlas, showing the three-dimensional geometry of each cavern. This volume 1 focuses on the Bayou Choctaw SPR site, located in southern Louisiana. Volumes 2, 3, and 4, respectively, present images for the Big Hill SPR site, Texas, the Bryan Mound SPR site, Texas, and the West Hackberry SPR site, Louisiana. The atlas uses a consistent presentation format throughout. The basic geometric measurements provided by the down-cavern surveys have also been used to generate a number of geometric attributes, the values of which have been mapped onto the geometric form of each cavern using a color-shading scheme. The intent of the various geometrical attributes is to highlight deviations of the cavern shape from the idealized cylindrical form of a carefully leached underground storage cavern in salt. The atlas format does not allow interpretation of such geometric deviations and anomalies. However, significant geometric anomalies, not directly related to the leaching history of the cavern, may provide insight into the internal structure of the relevant salt dome.

Downhole sonar surveys from the four active U.S. Strategic Petroleum Reserve sites have been modeled and used to generate a four-volume sonar atlas, showing the three-dimensional geometry of each cavern. This volume 4 focuses on the West Hackberry SPR site, located in southwestern Louisiana. Volumes 1, 2, and 3, respectively, present images for the Bayou Choctaw SPR site, Louisiana, the Big Hill SPR site, Texas, and the Bryan Mound SPR site, Texas. The atlas uses a consistent presentation format throughout. The basic geometric measurements provided by the down-cavern surveys have also been used to generate a number of geometric attributes, the values of which have been mapped onto the geometric form of each cavern using a color-shading scheme. The intent of the various geometrical attributes is to highlight deviations of the cavern shape from the idealized cylindrical form of a carefully leached underground storage cavern in salt. The atlas format does not allow interpretation of such geometric deviations and anomalies. However, significant geometric anomalies, not directly related to the leaching history of the cavern, may provide insight into the internal structure of the relevant salt dome.

Downhole sonar surveys from the four active U.S. Strategic Petroleum Reserve sites have been modeled and used to generate a four-volume sonar atlas, showing the three-dimensional geometry of each cavern. This volume 3 focuses on the Bryan Mound SPR site, located in southeastern Texas. Volumes 1, 2, and 4, respectively, present images for the Bayou Choctaw SPR site, Louisiana, the Big Hill SPR site, Texas, and the West Hackberry SPR site, Louisiana. The atlas uses a consistent presentation format throughout. The basic geometric measurements provided by the down-cavern surveys have also been used to generate a number of geometric attributes, the values of which have been mapped onto the geometric form of each cavern using a color-shading scheme. The intent of the various geometrical attributes is to highlight deviations of the cavern shape from the idealized cylindrical form of a carefully leached underground storage cavern in salt. The atlas format does not allow interpretation of such geometric deviations and anomalies. However, significant geometric anomalies, not directly related to the leaching history of the cavern, may provide insight into the internal structure of the relevant salt dome.

Downhole sonar surveys from the four active U.S. Strategic Petroleum Reserve sites have been modeled and used to generate a four-volume sonar atlas, showing the three-dimensional geometry of each cavern. This volume 2 focuses on the Big Hill SPR site, located in southeastern Texas. Volumes 1, 3, and 4, respectively, present images for the Bayou Choctaw SPR site, Louisiana, the Bryan Mound SPR site, Texas, and the West Hackberry SPR site, Louisiana. The atlas uses a consistent presentation format throughout. The basic geometric measurements provided by the down-cavern surveys have also been used to generate a number of geometric attributes, the values of which have been mapped onto the geometric form of each cavern using a color-shading scheme. The intent of the various geometrical attributes is to highlight deviations of the cavern shape from the idealized cylindrical form of a carefully leached underground storage cavern in salt. The atlas format does not allow interpretation of such geometric deviations and anomalies. However, significant geometric anomalies, not directly related to the leaching history of the cavern, may provide insight into the internal structure of the relevant salt dome.

The Stratton Ridge salt dome is a large salt diapir located only some ten miles from the currently active Strategic Petroleum Reserve Site at Bryan Mound, Texas. The dome is approximately 15 miles south-southwest of Houston. The Stratton Ridge salt dome has been intensively developed, in the desirable central portions, with caverns for both brine production and product storage. This geologic technical assessment indicates that the Stratton Ridge salt dome may be considered a viable, if less-than-desirable, candidate site for potential expansion of the Strategic Petroleum Reserve (SPR). Past development of underground caverns significantly limits the potential options for use by the SPR. The current conceptual design layout of proposed caverns for such an expansion facility is based upon a decades-old model of salt geometry, and it is unacceptable, according to this reinterpretation of salt dome geology. The easternmost set of conceptual caverns are located within a 300-ft buffer zone of a very major boundary shear zone, fault, or other structural feature of indeterminate origin. This structure transects the salt stock and subdivides it into an shallow western part and a deeper eastern part. In places, the distance from this structural boundary to the design-basis caverns is as little as 150 ft. A 300-ft distance from this boundary is likely to be the minimum acceptable stand-off, from both a geologic and a regulatory perspective. Repositioning of the proposed cavern field is possible, as sufficient currently undeveloped salt acreage appears to be available. However, such reconfiguration would be subject to limitations related to land-parcel boundaries and other existing infrastructure and topographic constraints. More broadly speaking, the past history of cavern operations at the Stratton Ridge salt dome indicates that operation of potential SPR expansion caverns at this site may be difficult, and correspondingly expensive. Although detailed information is difficult to come by, widely accepted industry rumors are that numerous existing caverns have experienced major operational problems, including salt falls, sheared casings, and unintended releases of stored product(s). Many of these difficulties may be related to on-going differential movement of individual salt spines or to lateral movement at the caprock-salt interface. The history of operational problems, only some of which appear to be a matter of public record, combined with the potential for encountering escaped product from other operations, renders the Stratton Ridge salt dome a less-than-desirable site for SPR purposes.

The Chacahoula salt dome, located in southern Louisiana, approximately 66 miles southwest of New Orleans, appears to be a suitable site for a 160-million-barrel-capacity expansion facility for the U.S. Strategic Petroleum Reserve, comprising sixteen 10-million barrel underground storage caverns. The overall salt dome appears to cover an area of some 1800 acres, or approximately 2.8 square miles, at a subsea elevation of 2000 ft, which is near the top of the salt stock. The shallowest known salt is present at 1116 ft, subsea. The crest of the salt dome is relatively flatlying, outward to an elevation of -4000 ft. Below this elevation, the flanks of the dome plunge steeply in all directions. The dome appears to comprise two separate spine complexes of quasi-independently moving salt. Two mapped areas of salt overhang, located on the eastern and southeastern flanks of the salt stock, are present below -8000 ft. These regions of overhang should present no particular design issues, as the conceptual design SPR caverns are located in the western portion of the dome. The proposed cavern field may be affected by a boundary shear zone, located between the two salt spines. However, the large size of the Chacahoula salt dome suggests that there is significant design flexibility to deal with such local geologic issues.

Technical assessment and remodeling of existing data indicates that the Richton salt dome, located in southeastern Mississippi, appears to be a suitable site for expansion of the U.S. Strategic Petroleum Reserve. The maximum area of salt is approximately 7 square miles, at a subsurface elevation of about -2000 ft, near the top of the salt stock. Approximately 5.8 square miles of this appears suitable for cavern development, because of restrictions imposed by modeled shallow salt overhang along several sides of the dome. The detailed geometry of the overhang currently is only poorly understood. However, the large areal extent of the Richton salt mass suggests that significant design flexibility exists for a 160-million-barrel storage facility consisting of 16 ten-million-barrel caverns. The dome itself is prominently elongated from northwest to southeast. The salt stock appears to consist of two major spine features, separated by a likely boundary shear zone trending from southwest to northeast. The dome decreases in areal extent with depth, because of salt flanks that appear to dip inward at 70-80 degrees. Caprock is present at depths as shallow as 274 ft, and the shallowest salt is documented at -425 ft. A large number of existing two-dimensional seismic profiles have been acquired crossing, and in the vicinity of, the Richton salt dome. At least selected seismic profiles should be acquired, examined, potentially reprocessed, and interpreted in an effort to understand the limitations imposed by the apparent salt overhang, should the Richton site be selected for actual expansion of the Reserve.

Subsurface geological investigations have been conducted at two large playa lakes at the Tonopah Test Range in central Nevada. These characterization activities were intended to provide basic stratigraphic-framework information regarding the lateral distribution of ''hard'' and ''soft'' sedimentary materials for use in defining suitable target regions for penetration testing. Both downhole geophysical measurements and macroscopic lithilogic descriptions were used as a surrogate for quantitative mechanical-strength properties, although some quantitative laboratory strength measurements were obtained as well. Both rotary (71) and core (19) holes on a systematic grid were drilled in the southern half of the Main Lake; drill hole spacings are 300 ft north-south and 500-ft east-west. The drilled region overlaps a previous cone-penetrometer survey that also addressed the distribution of hard and soft material. Holes were drilled to a depth of 40 ft and logged using both geologic examination and down-hole geophysical surveying. The data identify a large complex of very coarse-grained sediment (clasts up to 8 mm) with interbedded finer-grained sands, silts and clays, underlying a fairly uniform layer of silty clay 6 to 12 ft thick. Geophysical densities of the course-grained materials exceed 2.0 g/cm{sup 2}, and this petrophysical value appears to be a valid discriminator of hard vs. soft sediments in the subsurface. Thirty-four holes, including both core and rotary drilling, were drilled on a portion of the much larger Antelope Lake. A set of pre-drilling geophysical surveys, including time-domain electromagnetic methods, galvanic resistivity soundings, and terrain-conductivity surveying, was used to identify the gross distribution of conductive and resistive facies with respect to the present lake outline. Conductive areas were postulated to represent softer, clay-rich sediments with larger amounts of contained conductive ground water. Initial drilling, consisting of cored drill holes to 100-ft (33-m) depth, confirmed both the specific surface geophysical measurements and the more general geophysical model of the subsurface lake facies. Good agreement of conductive regions with drill holes containing little to no coarse-grained sediments was observed, and vice-versa. A second phase of grid drilling on approximately 300-ft (100-m) centers was targeted a delineating a region of sufficient size containing essentially no coarse-grained ''hard'' material. Such a region was identified in the southwestern portion of Antelope Lake.

Natural gas is a clean fuel that will be the most important domestic energy resource for the first half the 21st centtuy. Ensuring a stable supply is essential for our national energy security. The research we have undertaken will maximize the extractable volume of gas while minimizing the environmental impact of surface disturbances associated with drilling and production. This report describes a methodology for comprehensive evaluation and modeling of the total gas system within a basin focusing on problematic horizontal fluid flow variability. This has been accomplished through extensive use of geophysical, core (rock sample) and outcrop data to interpret and predict directional flow and production trends. Side benefits include reduced environmental impact of drilling due to reduced number of required wells for resource extraction. These results have been accomplished through a cooperative and integrated systems approach involving industry, government, academia and a multi-organizational team within Sandia National Laboratories. Industry has provided essential in-kind support to this project in the forms of extensive core data, production data, maps, seismic data, production analyses, engineering studies, plus equipment and staff for obtaining geophysical data. This approach provides innovative ideas and technologies to bring new resources to market and to reduce the overall environmental impact of drilling. More importantly, the products of this research are not be location specific but can be extended to other areas of gas production throughout the Rocky Mountain area. Thus this project is designed to solve problems associated with natural gas production at developing sites, or at old sites under redevelopment.

The West Hackberry salt dome, in southwestern Louisiana, is one of four underground oil-storage facilities managed by the U. S. Department of Energy Strategic Petroleum Reserve (SPR) Program. Sandia National Laboratories, as the geotechnical advisor to the SPR, conducts site-characterization investigations and other longer-term geotechnical and engineering studies in support of the program. This report describes the conversion of two-dimensional geologic interpretations of the West Hackberry site into three-dimensional geologic models. The new models include the geometry of the salt dome, the surrounding sedimentary layers, mapped faults, and a portion of the oil storage caverns at the site. This work provides a realistic and internally consistent geologic model of the West Hackberry site that can be used in support of future work.

The geologic model implicit in the original site characterization report for the Bayou Choctaw Strategic Petroleum Reserve Site near Baton Rouge, Louisiana, has been converted to a numerical, computer-based three-dimensional model. The original site characterization model was successfully converted with minimal modifications and use of new information. The geometries of the salt diapir, selected adjacent sedimentary horizons, and a number of faults have been modeled. Models of a partial set of the several storage caverns that have been solution-mined within the salt mass are also included. Collectively, the converted model appears to be a relatively realistic representation of the geology of the Bayou Choctaw site as known from existing data. A small number of geometric inconsistencies and other problems inherent in 2-D vs. 3-D modeling have been noted. Most of the major inconsistencies involve faults inferred from drill hole data only. Modem computer software allows visualization of the resulting site model and its component submodels with a degree of detail and flexibility that was not possible with conventional, two-dimensional and paper-based geologic maps and cross sections. The enhanced visualizations may be of particular value in conveying geologic concepts involved in the Bayou Choctaw Strategic Petroleum Reserve site to a lay audience. A Microsoft WindowsTM PC-based viewer and user-manipulable model files illustrating selected features of the converted model are included in this report.

This report summarizes recent reviews, observations, and analyses believed to be imperative to our understanding of the recent two million cubic feet salt fall event in Big Hill Cavern 103, one of the caverns of the Strategic Petroleum Reserve (SPR). The fall was the result of one or more stress driven mechanical instabilities, the origins of which are discussed in the report. The work has lead to important conclusions concerning the engineering and operations of the caverns at Big Hill. Specifically, Big Hill, being the youngest SPR site, was subjected to state-of-the-art solutioning methods to develop nominally well-formed, right-circular cylindrical caverns. Examination of the pressure history records indicate that operationally all Big Hill SPR caverns have been treated similarly. Significantly, new three-dimensional (3-D) imaging methods, applied to old (original) and more recent sonar survey data, have provided much more detailed views of cavern walls, roofs, and floors. This has made possible documentation of the presence of localized deviations from ''smooth'' cylindrical cavern walls. These deviations are now recognized as isolated, linear and/or planar features in the original sonar data (circa early 1990s), which persist to the present time. These elements represent either sites of preferential leaching, localized spalling, or a combination of the two. Understanding the precise origin of these phenomena remains a challenge, especially considering, in a historical sense, the domal salt at Big Hill was believed to be well-characterized. However, significant inhomogeneities in the domal salt that may imply abnormalities in leaching were not noted. Indeed, any inhomogeneities were judged inconsequential to the solution-engineering methods at the time, and, by the same token, to the approaches to modeling the rock mass geomechanical response. The rock mass was treated as isotropic and homogeneous, which in retrospect, appears to have been an over simplification. This analysis shows there are possible new opportunities regarding completing an appropriate site characterization for existing operating cavern fields in the SPR, as well as expansion of current sites or development of new sites. Such characterization should first be consistent with needs identified by this report. Secondly, the characterization needs to satisfy the input requirements of the 3-D solutioning calculational methods being developed, together with 3-D geomechanical analyses techniques which address deformation of a salt rock mass that contains inhomogeneities. It seems apparent that focusing on these important areas could preclude occurrence of unexpected events that would adversely impact the operations of SPR.

The Big Hill salt dome, located in southeastern Texas, is home to one of four underground oil-storage facilities managed by the U. S. Department of Energy Strategic Petroleum Reserve (SPR) Program. Sandia National Laboratories, as the geotechnical advisor to the SPR, conducts site-characterization investigations and other longer-term geotechnical and engineering studies in support of the program. This report describes the conversion of two-dimensional geologic interpretations of the Big Hill site into three-dimensional geologic models. The new models include the geometry of the salt dome, the surrounding sedimentary units, mapped faults, and the 14 oil storage caverns at the site. This work provides a realistic and internally consistent geologic model of the Big Hill site that can be used in support of future work.

Existing paper-based site characterization models of salt domes at the four active U.S. Strategic Petroleum Reserve sites have been converted to digital format and visualized using modern computer software. The four sites are the Bayou Choctaw dome in Iberville Parish, Louisiana; the Big Hill dome in Jefferson County, Texas; the Bryan Mound dome in Brazoria County, Texas; and the West Hackberry dome in Cameron Parish, Louisiana. A new modeling algorithm has been developed to overcome limitations of many standard geological modeling software packages in order to deal with structurally overhanging salt margins that are typical of many salt domes. This algorithm, and the implementing computer program, make use of the existing interpretive modeling conducted manually using professional geological judgement and presented in two dimensions in the original site characterization reports as structure contour maps on the top of salt. The algorithm makes use of concepts of finite-element meshes of general engineering usage. Although the specific implementation of the algorithm described in this report and the resulting output files are tailored to the modeling and visualization software used to construct the figures contained herein, the algorithm itself is generic and other implementations and output formats are possible. The graphical visualizations of the salt domes at the four Strategic Petroleum Reserve sites are believed to be major improvements over the previously available two-dimensional representations of the domes via conventional geologic drawings (cross sections and contour maps). Additionally, the numerical mesh files produced by this modeling activity are available for import into and display by other software routines. The mesh data are not explicitly tabulated in this report; however an electronic version in simple ASCII format is included on a PC-based compact disk.

Abstract not provided.

Portions of the SmartSampling{trademark} analysis methodology have been applied to the evaluation of radioactive contaminated landscape soils at Brookhaven National Laboratory. Specifically, the spatial, volumetric distribution of cesium-137 ({sup 137}Cs) contamination within Area of Concern 16E-1 has been modeled probabilistically using a geostatistical methodology, with the purpose of identifying the likelihood of successfully reducing, with respect to a pre-existing, baseline remediation plan, the volume of soil that must be disposed of offsite during clean-up. The principal objective of the analysis was to evaluate the likelihood of successful deployment of the Segmented Gate System (SGS), a novel remediation approach that emphasizes real-time separation of clean from contaminated materials during remediation operations. One primary requirement for successful application of the segmented gate technology investigated is that a variety of contaminant levels exist at the deployment site, which would enable to the SGS to discriminate material above and below a specified remediation threshold value. The results of this analysis indicate that there is potential for significant volume reduction with respect to the baseline remediation plan at a threshold excavation level of 23 pCi/g {sup 137}Cs. A reduction of approximately 50%, from a baseline volume of approximately 1,064.7 yd{sup 3} to less than 550 yd{sup 3}, is possible with acceptance of only a very small level of engineering risk. The vast majority of this volume reduction is obtained by not excavating almost all of levels 3 and 4 (from 12 to 24 inches in depth), which appear to be virtually uncontaminated, based on the available data. Additional volume reductions related to soil materials on levels 1 (depths of 0--6 inches) and 2 (6--12 inches) may be possible, specifically through use of the SGS technology. Level-by-level evaluation of simulation results suggests that as much as 26 percent of level 1 and as much as 65% of level 2 soils may actually be uncontaminated. Additionally, numerical experiments have been conducted to investigate the effects of selective excavation on the volume and average activity of the remediated materials. These numerical experiments indicate that nonselective excavation may result in mixing of contaminated and uncontaminated materials such that the total volume of material above the threshold excavation level of 23 pCi/g may exceed the baseline volume, thus defeating volume-reduction efforts.

This report describes the creation of three-dimensional numerical models of selected rock-matrix properties for the region of the potential high-level nuclear waste repository site at Yucca Mountain, which is located in southern Nevada. The models have been generated for a majority of the unsaturated and shallow saturated zone within an area referred to within the Yucca Mountain Site Characterization project as the site area. They comprise a number of material properties of importance both to detailed process-level modeling activities and to more summary-style performance assessment modeling. The material properties within these models are both spatially variable (heterogeneous) and spatially correlated, as the rocks are understood from data obtained from site-characterization drill holes widely scattered across the site area.

Drill hole USW SD-12 is one of several holes drilled under Site Characterization Plan Study 8.3.1.4.3.1, also known as the {open_quotes}Systematic Drilling Program,{close_quotes} as part of the U.S. Department of Energy characterization program at Yucca Mountain, Nevada, which has been proposed as the potential location of a repository for high-level nuclear waste. The SD-12 drill hole is located in the central part of the potential repository area, immediately to the west of the Main Test Level drift of the Exploratory Studies Facility and slightly south of midway between the North Ramp and planned South Ramp declines. Drill hole USW SD-12 is 2166.3 ft (660.26 m) deep, and the core recovered essentially complete sections of ash-flow tuffs belonging to the lower half of the Tiva Canyon Tuff, the Pah Canyon Tuff, and the Topopah Spring Tuff, all of which are part of the Miocene Paintbrush Group. A virtually complete section of the Calico Hills Formation was also recovered, as was core from the entire Prow Pass Tuff formation of the Crater Flat Group.

Drill hole USW SD-9 is one of several holes drilled under Site Characterization Plan Study as part of the characterization program at Yucca Mountain, Nevada, which has been proposed as the potential location of a repository for high-level nuclear waste. The SD-9 drill hole is located in the northern part of the potential repository area. Quantitative and semiquantitative data are included in this report for cover recovery, rock-quality designation (RQD), lithophysal cavity abundance, and fracturing. These data are spatially variable, both within and among the major formational-level stratigraphic units. Nonwelded intervals in general exhibit higher recoveries and more intact (higher) RQD values than welded intervals. The most intact, highest-RQD materials encountered within the Topopah Spring belong to the lower 33.3 ft of the middle nonlithophysal zone. This report includes quantitative data for the framework material properties of porosity, bulk and particle density, and saturated hydraulic conductivity. Graphical analysis of variations in these laboratory hydrologic properties indicates first-order control of material properties by the degree of welding and the presence of zeolite minerals. Many major lithostratigraphic contacts are not well expressed in the material-property profiles; contacts of material-property units are related more to changes in the intensity of welding. Approximate in-situ saturation data of samples preserved immediately upon recovery from the hole are included in the data tabulation.

The USW SD-7 drill hole is one of several holes drilled under Site Characterization Plan Study 8.3.1.4.3.1, also known as the Systematic Drilling Program, as part of the U.S. Department of Energy characterization program at Yucca Mountain, Nevada. The Yucca Mountain site has been proposed as the potential location of a repository for high-level nuclear waste. The SD-7 drill hole is located near the southern end of the potential repository area and immediately to the west of the Main Test Level drift of the Exploratory Studies Facility. The hole is not far from the junction of the Main Test Level drift and the proposed South Ramp decline. Drill hole USW SD-7 is 2675.1 ft (815.3 m) deep, and the core recovered nearly complete sections of ash-flow tuffs belonging to the lower half of the Tiva Canyon Tuff, the Pah Canyon Tuff, and the Topopah Spring Tuff, all of which are part of the Miocene Paintbrush Group. Core was recovered from much of the underlying Calico Hills Formation, and core was virtually continuous in the Prow Pass Tuff and the Bullfrog Tuff. The SD-7 drill hole penetrated the top several tens of feet into the Tram Tuff, which underlies the Prow Pass and Bullfrog Tuffs. These latter three units are all formations of the Crater Flat Group, The drill hole was collared in welded materials assigned to the crystal-poor middle nonlithophysal zone of the Tiva Canyon Tuff; approximately 280 ft (85 m) of this ash-flow sheet was penetrated by the hole. The Yucca Mountain Tuff appears to be missing from the section at the USW SD-7 location, and the Pah Canyon Tuff is only 14.5 ft thick. The Pah Canyon Tuff was not recovered in core because of drilling difficulties, suggesting that the unit is entirely nonwelded. The presence of this unit is inferred through interpretation of down-hole geophysical logs.

The US Department of Energy conducted the 1994 Fernald (Ohio) field characterization demonstration project to evaluate the performance of a group of both industry-standard and proposed alternative technologies in describing the nature and extent of uranium contamination in surficial soils. Detector stability and measurement reproducibility under actual operating conditions encountered in the field is critical to establishing the credibility of the proposed alternative characterization methods. Comparability of measured uranium activities to those reported by conventional, US Environmental Protection Agency (EPA)-certified laboratory methods is also required. The eleven (11) technologies demonstrated included (1) EPA-standard soil sampling and laboratory mass-spectroscopy analyses, and currently-accepted field-screening techniques using (2) sodium-iodide scintillometers, (3) FIDLER low-energy scintillometers, and (4) a field-portable x-ray fluorescence spectrometer. Proposed advanced characterization techniques included (5) alpha-track detectors, (6) a high-energy beta scintillometer, (7) electret ionization chambers, (8) and (9) a high-resolution gamma-ray spectrometer in two different configurations, (10) a field-adapted laser ablation-inductively coupled plasma-atomic emission spectroscopy (ICP-AES) technique, and (11) a long-range alpha detector. Measurement reproducibility and the accuracy of each method were tested by acquiring numerous replicate measurements of total uranium activity at each of two ``standard sites`` located within the main field demonstration area. Meteorological variables including temperature, relative humidity. and 24-hour rainfall quantities were also recorded in conjunction with the standard-sites measurements.

The 1994 Fernald field characterization demonstration program, hosted by Fernald Environmental Management Project, was established to investigate technologies that are applicable to the characterization and remediation of soils contaminated with uranium. An important part of this effort was evaluating field-screening tools potentially capable of acquiring high-resolution information on uranium contamination distribution in surface soils. Further-more, the information needed to be obtained in a cost- and time-efficient manner. Seven advanced field-screening technologies were demonstrated at a uranium-contaminated site at Fernald, located 29 kilometers northwest of Cincinnati, Ohio. The seven technologies tested were: (1) alpha-track detectors, (2) a high-energy beta scintillometer, (3) electret ionization chambers, (4) and (5) two variants of gamma-ray spectrometry, (6) laser ablation-inductively coupled plasma-atomic emission spectroscopy, and (7) long-range alpha detection. The goals of this field demonstration were to evaluate the capabilities of the detectors and to demonstrate their utility within the US Department of Energy`s Environmental Restoration Program. Identical field studies were conducted using four industry-standard characterization tools: (1) a sodium-iodide scintillometer, (2) a low-energy FIDLER scintillometer, (3) a field-portable x-ray fluorescence detector, and (4) standard soil sampling coupled with laboratory analysis. Another important aspect of this program was the application of a cost/risk decision model to guide characterization of the site. This document is a compilation of raw data submitted by the technologies and converted total uranium data from the 1994 Fernald field characterization demonstration.

Rock properties in volcanic units at Yucca Mountain are controlled largely by relatively deterministic geologic processes related to the emplacement, cooling, and alteration history of the tuffaceous lithologic sequence. Differences in the lithologic character of the rocks have been used to subdivide the rock sequence into stratigraphic units, and the deterministic nature of the processes responsible for the character of the different units can be used to infer the rock material properties likely to exist in unsampled regions. This report proposes a quantitative, theoretically justified method of integrating interpretive geometric models, showing the three-dimensional distribution of different stratigraphic units, with numerical stochastic simulation techniques drawn from geostatistics. This integration of soft, constraining geologic information with hard, quantitative measurements of various material properties can produce geologically reasonable, spatially correlated models of rock properties that are free from stochastic artifacts for use in subsequent physical-process modeling, such as the numerical representation of ground-water flow and radionuclide transport. Prototype modeling conducted using the GSLIB-Lynx Integration Module computer program, known as GLINTMOD, has successfully demonstrated the proposed integration technique. The method involves the selection of stratigraphic-unit-specific material-property expected values that are then used to constrain the probability function from which a material property of interest at an unsampled location is simulated.

A stochastic representation of the lithologic units and associated hydrogeologic parameters of the potential high-level nuclear waste repository are developed for use in performance-assessment calculations, including the Total-System Performance Assessment for Yucca Mountain-SNL Second Iteration (TSPA-1993). A simplified lithologic model has been developed based on the physical characteristics of the welded and nonwelded units at Yucca Mountain. Ten hydrogeologic units are developed from site-specific data (lithologic and geophysical logs and core photographs) obtained from the unsaturated and saturated zones. The three-dimensional geostatistical model of the ten hydrogeologic units is based on indicator-coding techniques and improves on the two-dimensional model developed for TSPA91. The hydrogeologic properties (statistics and probability distribution functions) are developed from the results of laboratory tests and in-situ aquifer tests or are derived through fundamental relationships. Hydrogeologic properties for matrix properties, bulk conductivities, and fractures are developed from existing site specific data. Extensive data are available for matrix porosity, bulk density, and matrix saturated conductivity. For other hydrogeologic properties, the data are minimal or nonexistent. Parameters for the properties are developed as beta probability distribution functions. For the model units without enough data for analysis, parameters are developed as analogs to existing units. A relational, analytic approach coupled with bulk conductivity parameters is used to develop fracture parameters based on the smooth-wall-parallel-plate theory. An analytic method is introduced for scaling small-core matrix properties to the hydrogeologic unit scales.

Two-dimensional, heterogeneous, spatially correlated models of thermal conductivity and bulk density have been created for a representative, east-west cross section of Yucca Mountain, Nevada, using geostatistical simulation. The thermal conductivity models are derived from spatially correlated, surrogate material-property models of porosity, through a multiple linear-regression equation, which expresses thermal conductivity as a function of porosity and initial temperature and saturation. Bulk-density values were obtained through a similar, linear-regression relationship with porosity. The use of a surrogate-property allows the use of spatially much-more-abundant porosity measurements to condition the simulations. Modeling was conducted in stratigraphic coordinates to represent original depositional continuity of material properties and the completed models were transformed to real-world coordinates to capture present-day tectonic tilting and faulting of the material-property units. Spatial correlation lengths required for geostatistical modeling were assumed, but are based on the results of previous transect-sampling and geostatistical-modeling work.

Indicator geostatistical techniques have been used to produce a number of fully three-dimensional stochastic simulations of large-scale lithologic categories at the Yucca Mountain site. Each realization reproduces the available drill hole data used to condition the simulation. Information is propagated away from each point of observation in accordance with a mathematical model of spatial continuity inferred through soft data taken from published geologic cross sections. Variations among the simulated models collectively represent uncertainty in the lithology at unsampled locations. These stochastic models succeed in capturing many major features of welded-nonwelded lithologic framework of Yucca Mountain. However, contacts between welded and nonwelded rock types for individual simulations appear more complex than suggested by field observation, and a number of probable numerical artifacts exist in these models. Many of the apparent discrepancies between the simulated models and the general geology of Yucca Mountain represent characterization uncertainty, and can be traced to the sparse site data used to condition the simulations. Several vertical stratigraphic columns have been extracted from the three-dimensional stochastic models for use in simplified total-system performance assessment exercises. Simple, manual adjustments are required to eliminate the more obvious simulation artifacts and to impose a secondary set of deterministic geologic features on the overall stratigraphic framework provided by the indictor models.

Exhaustive characterization of a contaminated site is a physical and practical impossibility. Descriptions of the nature, extent, and level of contamination, as well as decisions regarding proposed remediation activities, must be made in a state of uncertainty based upon limited physical sampling. The probability mapping approach illustrated in this paper appears to offer site operators a reasonable, quantitative methodology for many environmental remediation decisions and allows evaluation of the risk associated with those decisions. For example, output from this approach can be used in quantitative, cost-based decision models for evaluating possible site characterization and/or remediation plans, resulting in selection of the risk-adjusted, least-cost alternative. The methodology is completely general, and the techniques are applicable to a wide variety of environmental restoration projects. The probability-mapping approach is illustrated by application to a contaminated site at the former DOE Feed Materials Production Center near Fernald, Ohio. Soil geochemical data, collected as part of the Uranium-in-Soils Integrated Demonstration Project, have been used to construct a number of geostatistical simulations of potential contamination for parcels approximately the size of a selective remediation unit (the 3-m width of a bulldozer blade). Each such simulation accurately reflects the actual measured sample values, and reproduces the univariate statistics and spatial character of the extant data. Post-processing of a large number of these equally likely statistically similar images produces maps directly showing the probability of exceeding specified levels of contamination (potential clean-up or personnel-hazard thresholds).

A set of detailed geostatistical simulations of porosity has been produced for a layered stratigraphic sequence of welded and nonwelded volcanic tuffs at Yucca Mountain, Nevada. The simulations are produced using a composite. model of spatial continuity and they are highly conditioned to abundant drill hole (core) information. A set of derivative simulations of saturated hydraulic conductivity has been produced, in the absence of conditioning data, using a cross-variable relationship developed from similar data elsewhere. The detailed simulations reproduce both the major stratigraphic units and finer scale layering indicated by the drill hole data. These simulations have been scaled up several order of magnitude to represent block-scale effective hydrologic properties suitable for use in numerical modeling of groundwater flow and transport. The upscaling process involves the reformulation of a previously reported method that iteratively adapts an initial arbitrary grid to ``homogenize`` the detailed hydraulic properties contained within the adjusted cell limits and to minimize the size of cell in highly heterogeneous regions. Although the computation of the block-effective property involves simple numerical averaging, the blocks over which these averages are computed are relatively homogeneous, which reduces the numerical difficulties involved in averaging non-additive properties, such as permeability. The entire process of simulation and upscaling is rapid and computationally efficient compared with alterative techniques. It is thus suitable for the Monte Carlo evaluation of the uncertainty in site characterization as it affects the results of groundwater flow and transport calculations.

Hydrologic properties have been measured on outcrop samples taken from a detailed, two-dimension grid covering a 1.4 km outcrop exposure of the 10-m thick non-welded-to-welded, shardy base microstratigraphic unit of the Tiva Canyon Member of the Miocene Paintbrush Tuff at Yucca Mountain, Nevada. These data allow quantification of spatial trends in rock matrix properties that exist in this important hydrologic unit. Geologic investigation, combined with statistical and geostatistical analyses of the numerical data, indicates that spatial variability of matrix properties is related to deterministic geologic processes that operated throughout the region. Linear vertical trends in hydrologic properties are strongly developed in the shardy base microstratigraphic unit, and they are more accurately modeled using the concept of a thickness-normalized stratigraphic elevation within the unit, rather than absolute elevation. Hydrologic properties appear to be correlated over distances of 0.25 to 0.3 of the unit thickness after removing the deterministic vertical trend. The use of stratigraphic elevation allows scaling of identified trends by unit thickness which may be of particular importance in a basal, topography-blanketing unit such as this one. Horizontal changes in hydrologic properties do not appear to form obvious trends within the limited lateral geographic extent of the ash-flow environment that was examined. Matrix properties appear to be correlated horizontally over distances between 100 and 400 m. The existence and quantitative description of these trends and patterns of vertical spatial continuity should increase confidence in models of hydrologic properties and groundwater flow in this area that may be constructed to support the design of a potential high-level nuclear waste repository at Yucca Mountain.

The spatial correlation structure of volcanic tuffs at and near the site of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada, is estimated using samples obtained from surface outcrops and drill holes. Data are examined for four rock properties: porosity, air permeability, saturated hydraulic conductivity, and dry bulk density. Spatial continuity patterns are identified in both lateral and vertical (stratigraphic) dimensions. The data are examined for the Calico Hills tuff stratigraphic unit and also without regard for stratigraphy. Variogram models fitted to the sample data from the tuffs of Calico Hills indicate that porosity is correlated laterally over distances of up to 3000 feet. If air permeability and saturated conductivity values are viewed as semi-interchangeable for purposes of identifying spatial structure, the data suggest a maximum range of correlation of 300 to 500 feet without any obvious horizontal to vertical anisotropy. Continuity exists over vertical distances of roughly 200 feet. Similar variogram models fitted to sample data taken from vertical drill holes without regard for stratigraphy suggest that correlation exists over distances of 500 to 800 feet for each rock property examined. Spatial correlation of rock properties violates the sample-independence assumptions of classical statistics to a degree not usually acknowledged. In effect, the existence of spatial structure reduces the ``equivalent`` number of samples below the number of physical samples. This reduction in the effective sampling density has important implications for site characterization for the Yucca Mountain Project.