8 research outputs found
Recommended from our members
Hydraulic testing around Room Q: Evaluation of the effects of mining on the hydraulic properties of Salado Evaporites
Room Q is a 109-m-long cylindrical excavation in the Salado Formation at the Waste Isolation Pilot Plant (WIPP) site. Fifteen boreholes were drilled and instrumented around Room Q so that tests could be conducted to determine the effects of room excavation on the hydraulic properties of the surrounding evaporate rocks. Pressure-buildup and pressure-pulse tests were conducted in all of the boreholes before Room Q was mined. The data sets from only eight of the boreholes are adequate for parameter estimation, and five of those are of poor quality. Constant-pressure flow tests and pressure-buildup tests were conducted after Room Q was mined, producing eleven interpretable data sets, including two of poor quality. Pre-mining transmissivities interpreted from the three good-quality data sets ranged from 1 x 10{sup -15} to 5 x 10{sup -14} m{sup 2}/s (permeability-thickness products of 2 x 10{sup -22} to 9 x 10{sup -21} m{sup 3}) for test intervals ranging in length from 0.85 to 1.37 m. Pre-mining average permeabilities, which can be considered representative of undisturbed, far-field conditions, were 6 x 10{sup -20} and 8 x 10{sup -20} m{sup 2} for anhydrite, and 3 x 10{sup -22} m{sup 2} for halite. Post-mining transmissivities interpreted from the good-quality data sets ranged from 1 x 10{sup -16} to 3 x 10{sup -13} m{sup 2}/s (permeability-thickness products of 2 x 10{sup -23} to 5 x 10{sup -20} m{sup 3}). Post-mining average permeabilities for anhydrite ranged from 8 x 10{sup -20} to 1 x 10{sup -19} m{sup 2}. The changes in hydraulic properties and pore pressures that were observed can be attributed to one or a combination of three processes: stress reduction, changes in pore connectivity, and flow towards Room Q. The effects of the three processes cannot be individually quantified with the available data
Recommended from our members
Design, modeling, and current interpretations of the H-19 and H-11 tracer tests at the WIPP site
Site-characterization studies at the Waste Isolation Pilot Plant (WIPP) site in southeastern New Mexico, US identified ground-water flow in the Culebra Dolomite Member of the Rustler Formation as the most likely geologic pathway for radionuclide transport to the accessible environment in the event of a breach of the WIPP repository through inadvertent human intrusion. The results of recent tracer tests, as well as hydraulic tests, laboratory measurements, and re-examination of Culebra geology and stratigraphy, have led to a significant refinement of the conceptual model for transport in the Culebra. Tracer test results and geologic observations suggest that flow occurs within fractures, and to some extent within interparticle porosity and vugs connected by microfractures. Diffusion occurs within all connected porosity. Numerical simulations suggest that the data from the tracer tests cannot be simulated with heterogeneous single-porosity models; significant matrix diffusion appears to be required. The low permeability and lack of significant tracer recovery from tracers injected into the upper Culebra suggest that transport primarily occurs in the lower Culebra
Recommended from our members
Hydrology and Hydraulic Properties of a Bedded Evaporite Formation
The Permian Salado Formation in the Delaware Basin of New Mexico is an extensively studied evaporite deposit because it is the host formation for the Waste Isolation Pilot Plant, a repository for transuranic wastes. Geologic and hydrologic studies of the Salado conducted since the mid-1970's have led to the development of a conceptual model of the hydrogeology of the formation that involves far-field permeability in anhydrite layers and at least some impure halite layers. Pure halite layers and some impure halite layers may not possess an interconnected pore network adequate to provide permeability. Pore pressures are probably very close to lithostatic pressure. In the near field around an excavation, dilation, creep, and shear have created and/or enhanced permeability and decreased pore pressure. Whether flow occurs in the far field under natural gradients or only after some threshold gradient is reached is unknown. If far-field flow does occur, mean pore velocities are probably on the order of a meter per hundreds of thousands to tens of millions of years. Flow dimensions inferred from most hydraulic-test responses are subradial, which is believed to reflect channeling of flow through fracture networks, or portions of fractures, that occupy a diminishing proportion of the radially available space, or through percolation networks that are not ''saturated'' (fully interconnected). This is probably related to the directional nature of the permeability created or enhanced by excavation effects. Inferred values of permeability cannot be separated from their associated flow dimensions. Therefore, numerical models of flow and transport should include heterogeneity that is structured to provide the same flow dimensions as are observed in hydraulic tests. Modeling of the Salado Formation around the WIPP repository should also include coupling between hydraulic properties and the evolving stress field because hydraulic properties change as the stress field changes
Recommended from our members
Interpretations of Tracer Tests Performed in the Culebra Dolomite at the Waste Isolation Pilot Plant Site
This report provides (1) an overview of all tracer testing conducted in the Culebra Dolomite Member of the Rustler Formation at the Waste Isolation Pilot Plant (WPP) site, (2) a detailed description of the important information about the 1995-96 tracer tests and the current interpretations of the data, and (3) a summary of the knowledge gained to date through tracer testing in the Culebra. Tracer tests have been used to identify transport processes occurring within the Culebra and quantify relevant parameters for use in performance assessment of the WIPP. The data, especially those from the tests performed in 1995-96, provide valuable insight into transport processes within the Culebra. Interpretations of the tracer tests in combination with geologic information, hydraulic-test information, and laboratory studies have resulted in a greatly improved conceptual model of transport processes within the Culebra. At locations where the transmissivity of the Culebra is low (< 4 x 10{sup -6} m{sup 2}/s), we conceptualize the Culebra as a single-porosity medium in which advection occurs largely through the primary porosity of the dolomite matrix. At locations where the transmissivity of the Culebra is high (> 4 x 10{sup -6} m{sup 2}/s), we conceptualize the Culebra as a heterogeneous, layered, fractured medium in which advection occurs largely through fractures and solutes diffuse between fractures and matrix at multiple rates. The variations in diffusion rate can be attributed to both variations in fracture spacing (or the spacing of advective pathways) and matrix heterogeneity. Flow and transport appear to be concentrated in the lower Culebra. At all locations, diffusion is the dominant transport process in the portions of the matrix that tracer does not access by flow
Recommended from our members
Hydraulic Testing of Salado Formation Evaporites at the Waste Isolation Pilot Plant Site: Final Report
This report presents interpretations of hydraulic tests conducted in bedded evaporates of the Salado Formation from May 1992 through May 1995 at the Waste Isolation Pilot Plant (WIPP) site in southeastern New Mexico. The WIPP is a US Department of Energy research and development facility designed to demonstrate safe disposal of transuranic wastes from the nation's defense programs. The WIPP disposal horizon is located in the lower portion of the Permian Salado Formation. The hydraulic tests discussed in this report were performed in the WIPP underground facility by INTERA inc. (now Duke Engineering and Services, Inc.), Austin, Texas, following the Field Operations Plan and Addendum prepared by Saulnier (1988, 1991 ) under the technical direction of Sandia National Laboratories, Albuquerque, New Mexico
Recommended from our members
Sandia Corporation Report SAND86-0611
From abstract: Drillhole DOE-2 was drilled to investigate a structural depression marked by the downward
displacement of stratigraphic markers in the Salado Formation ~ 2 mi north of the center of
the WIPP site. This depression was named informally after the shallow borehole FC-92 in
which the structure was described. The presence of the depression was confirmed by drilling
Recommended from our members
WIPP Case Study - Compliance Monitoring, Passive Institutional Controls, and Record Keeping
The WIPP Case Study describes the compliance monitoring program, record keeping requirements, and passive institutional controls that are used to help ensure the Waste Isolation Pilot Plant (WIPP) will safety contain radioactive waste and indicate dangers and location of the wastes. The radioactive components in the waste are regulated by the U.S. Environmental Protection Agency (EPA) while the hazardous components in the waste are regulated by the New Mexico Environment Department (NMED). This paper addresses monitoring relating to radionuclide containment performance, passive institutional controls, and record keeping over a 10,000-year time frame. Monitoring relating to the hazardous components and the associated regulator are not addressed in this paper. The WIPP containment performance is mandated by release limits set by regulation. Regulations also require the radioactive waste containment performance of the WIPP to be predicted by a ''Performance Assessment.'' The EPA did not base the acceptance of the WIPP solely on predicted containment but included additional assurance measures. One such assurance measure is monitoring, which may be defined as the on-going measurement of conditions in and around the repository. This case study describes the evolution of the WIPP monitoring program as the WIPP project progressed through the planning, site characterization, regulatory promulgation, and eventual operational stages that spanned a period of over 25 years. Included are discussions of the regulatory requirements for monitoring, selection of monitoring parameters, trigger values used to identify unexpected conditions, assessment of monitoring data against the trigger values, and plans for post-closure monitoring. The United EPA established the requirements for Passive Institutional Controls (PICs) for disposal sites. The requirements state the a disposal site must be designated by the most permanent markers, records, and other passive institutional controls practicable to indicate the dangers of the wastes and their location. The PIC Task Force assessed the effectiveness of PICs in deterring inadvertent human intrusion and developed a conceptual design for permanently marking the Waste Isolation Pilot Plant (WIPP), establishing records, and identifying other practicable controls to indicate the dangers of the wastes and their location. The marking system should provide information regarding the location, design, contents, and hazards associated with WIPP. This paper discuss these controls including markers, records, archives, and government ownership and land-use restrictions