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D.A. Webster

Publications and source records attributed to D.A. Webster.

14 recordsLinked to original sources
USGS1996

Results of ground-water tracer tests using tritiated water at Oak Ridge National Laboratory, Tennessee

Ground-water tracer tests were conducted at two sites in the radioactive-waste disposal area of Oak Ridge National Laboratory from 1977 to 1982. The purpose of the tests was to determine if the regolith beds had weathered sufficiently to permit the substantial flow of water across them. Regolith of the sites has developed on the Pumpkin Valley Shale and the Nolichucky Shale of the Conasauga Group, both of Cambrian age. About 50 curies of tritium dissolved in water were used as the tracer at one site, and about 100 curies at the other. Distances from the injection wells to a semi-circle of observation wells were 12 and 30 feet, respectively. Results demonstrated that ground water is able to flow through joints in the weathered bedding and that the direction of the water-table gradient is the primary factor governing flow direction. Nevertheless, the substantial lateral spread of the plume as it developed showed that bedding-plane openings, important in controlling flow in the deeper rock, can still exert a significant secondary influence on flow direction in the weathered rock. About 3,500 water samples from the injection and observation wells were analyzed for tritium during the test period. Concentrations detected spanned 11 orders of magnitude. Measurable concentrations were still present in the two injection wells and most observation wells 5 years after the tracer was introduced. Matrix diffusion may have played a significant role in these tests. The process would account for the sustained concentrations of tritium at many of the observation wells, the long-term residual concentrations at the injection and observation wells, and the apparent slow movement of the centers of mass across the two well fields. The process also would have implications regarding aquifer remediation. Other tracer tests have been conducted in the regolith of the Conasauga Group. Results differ from the results described in this report.

Tennessee↗
USGS1993

Ground-water hydrology of the lower Wolftever Creek basin, with emphasis on the Carson Spring area, Hamilton County, Tennessee

An investigation of the ground-water-flow system that supplies Carson Spring and the surrounding lower Wolftever Creek basin northeast of Chattanooga, Tennessee, was conducted from September 1986 through December 1989. About two-thirds of the lower basin is underlain by the Chepultepec Dolomite of Ordovician age. Test drilling within a few miles of the spring showed that numerous solution cavities have developed in this formation; many are partly or completely plugged with cherty gravels and mud. In the recharge area to the spring, the formation can provide yields of 100 to perhaps 600 gallons of water per minute to bedrock wells. A well that penetrated a well-integrated cavity system underlying Carson Spring was tested at 2,000 gallons per minute. From May 1987 through December 1989, mean daily withdrawals from four wells at Carson Spring ranged from 4.78 to 5.83 cubic feet per second; mean daily spring discharge, which includes withdrawals, ranged from 5.53 to 5.79 cubic feet per second. For a 16-month drought period during 1987 and 1988, withdrawals from these wells exceeded natural spring discharge, and demonstrates that for a period of many consecutive months, the aquifer supplying the spring is capable of yielding more water than the spring would have discharged under natural conditions. Although the lower basin encompasses 17 square miles, the Carson Spring recharge area probably is not greater than 9 square miles. Most water not captured by cavities supplying the spring is discharged to Wolftever Creek. In the lower basin, the rate of ground-water discharge to the creek is about twice the average rate of discharge (0.25 cubic foot per second per square mile of drainage area) to area streams. Principal constituents in ground water in the lower basin are calcium and bicarbonate, or calcium, magnesium, and bicarbonate. Specific conductance commonly ranges from 100 to 700 microsiemens per centimeter, and pH usually ranges from about 7 to 8. Overall, the ground water is of good quality and suitable for most uses. Several potential sources of degradation are present and arise from industrial, municipal, and domestic activities.

Tennessee↗
USGS1993

Water quality, organic chemistry of sediment, and biological conditions of streams near an abandoned wood-preserving plant site at Jackson, Tennessee

An investigation of water quality, organic sediment chemistry, and biological conditions of streams near an abandoned wood-preserving plant site at Jackson, Tennessee, was conducted during December 1990. The study was designed to assess the extent of possible contamination of water and biota in the streams from creosote-related discharge originating at this Superfund site. Central Creek, adjacent to the plant, had degraded water quality and biological conditions. Water samples from the most downstream station on Central Creek contained 30 micrograms per liter of pentachlorophenol, which exceeds the State's criterion maximum concentrations of 9 micrograms per liter for fish and aquatic life. Bottom-sediment samples from stations on Central Creek contained concentrations of acenaphthene, napthalene, and phenanthrene ranging from 1,400 to 2,500 micrograms per kilogram. Chronic or acute toxicity resulted during laboratory experiments using test organisms exposed to creosote-related contaminants. Sediment elutriate samples from Central Creek caused slightly to highly toxic effects on Ceriodaphnia dubia. Pimephales promelas, and Photobacterium phosphoreum. Fish-tissue samples from this station contained concentrations of naphthalene. dibenzofuran, fluorene, and phenanthrene ranging from 1.5 to 3.9 micrograms per kilogram Blue-green algae at this station represented about 79 percent of the organisms counted, whereas diatoms accounted for only 11 percent. Benthic invertebrate and fish samples from Central Creek had low diversity and density. Sediment samples from a station on the South Fork Forked Deer River downstream from its confluence with Central Creek contained concentrations of acenaphthene, anthracene, chrysene, fluoranthene, fluorene, pyrere, and phenanthrene ranging from 2,800 to 69,000 micrograms per kilogram. Sediment elutriate samples using water as elutriate from this station contained concentrations of extractable organic compounds ranging from an estimated 43 to 420 micrograms per liter. Sediment elutriate samples were toxic to Ceriodaphnia dubta, Pimephales promelas, Photobacterium phosphoreum, and Salenastrum capricornulum.

Water-Resources Investigations Report↗
USGS1988

Hydrology of the Melton Valley radioactive-waste burial grounds at Oak Ridge National Laboratory, Tennessee

Burial grounds 4, 5, and 6 were used sequentially from 195 1 to the present for the disposal of solid, low-level radioactive waste by burial in shallow trenches and auger holes. Abundant rainfall, a generally thin unsaturated zone, geologic media of inherently low permeability, and the operational practices employed have contributed to partial saturation of the buried waste, leaching of radionuclides, and transport of dissolved matter from the burial areas. Two primary methods of transport from these sites are by dissolution in circulating ground water, and the overflow of fluids in trenches and subsequent flow across land surface. The waste-disposal areas are underlain by the Conasauga Group (Cambrian age), a complex sequence of mudstone, siltstone, and limestone interbeds grading from one lithotype to the other, both laterally and vertically. Compressional forces that caused regional thrust faulting also caused much internal deformation of the beds. Folds, bedding-plane faults, and joints are widespread. Small solution openings have developed in some areas where the structurally-related openings have provided ingress to ground water. Both the regolith and bedrock sections of the aquifer are anisotropic, but anisotropy is more pronounced in the bedrock. The lower practical limit of ground-water circulation probably occurs at about 200 to 250 feet depth. A conceptual model of flow is described wherein the primary control on direction of ground-water flow changes from the water-table gradient in the regolith to the hydraulic head distribution within the secondary openings of the bedrock and the three-dimensional geometry of those openings. Locally, the direction of flow in the regolith also is controlled by gradients within openings in certain relatively resistant beds and structurally-related features. Hydraulic conductivities as measured by slug tests of wells range from 2.9 x 10m3 to 6.7 feet per day in the regolith, and 1.5 x 10s4 to 1.9x 10-l feet per day in bedrock at depths of 100 to 200 feet. Whiteoak Creek and its tributaries receive all overland flow from trench spillage, surface runoff from each site, and discharge of ground water from the regolith of each site. Potentiometric data indicate that this drainage system also receives ground water discharged from the bedrock of burial ground 5. By projection of the bedrock flow patterns characteristic of this site to other areas of Melton Valley, it is inferred that discharge from the bedrock underlying burial grounds 4 and 6 also is to the same drainage system. The differences in potentiometric heads and a comparatively thin saturated zone in bedrock do not favor the development of deep flow through bedrock from one river system to another. Hydraulic potentials, hydraulic conductivities, and hydrochemical data indicate that most ground water in the aquifer flows through the regolith. A smaller amount of water flows through the bedrock, where the flow paths are longer in distance and the time of travel is considerably greater. In burial ground 5 the regolith section of the aquifer has widespread contamination, principally by iron, tritium, and strontium-90. Contamination decreases substantially with increasing depth in bedrock, particularly below 100 feet. The sites have received little monitoring because they have not been considered a hazard. As improvements in plant facilities have reduced the discharge of radionuclides to the Whiteoak Creek system, the discharge of contaminants from the burial grounds has become relatively more significant. The burial grounds are now a principal source of 3H and a major contributor of 90 Sr in the discharge of Whiteoak Creek to the Clinch River.

Tennessee↗
USGS1982

Precipitation data for burial grounds 5 and 6, Oak Ridge National Laboratory, Tennessee, 1976-1980

As part of a hydrogeologic investigation, precipitation data were collected at two stations, one each in Burial Grounds 5 and 6 at the Oak Ridge National Laboratory, Tennessee. Daily, monthly, and annual values are reported herein for the period from January 1976 through December 1980. During this period, annual values ranged from about 25 percent above to about 25 percent below the calculated mean of 51.96 inches at Burial Ground 5 and 49.60 inches at Burial Ground 6.

Tennessee↗
USGS1980

Water-level data for wells in Burial Ground 6, Oak Ridge National Laboratory, Tennessee, 1975-1979

At Oak Ridge National Laboratory, Tenn., solid waste materials contaminated by low levels of radioactivity are disposed of in shallow trench burial areas termed ' burial grounds'. Data pertaining to wells in Burial Ground 6 are presented for the period 1975 to 1979. Included are an inventory of wells, measurements of water levels, well hydrographs, and a map showing the location of the wells. (USGS)

Open-File Report↗
USGS1976

A review of hydrologic and geologic conditions related to the radioactive solid-waste burial grounds at Oak Ridge National Laboratory, Tennessee

Solid waste contaminated by radioactive matter has been buried in the vicinity of Oak Ridge National Laboratory since 1944. By 1973, an estimated six million cubic feet of such material had been placed in six burial grounds in two valleys. The practice initially was thought of as a safe method for permanently removing these potentially hazardous substances from man's surroundings, but is now que.3tionable at this site because of known leaching of contaminants from the waste, transport in ground water, and release to the terrestrial and fluvial environments. This review attempts to bring together in a single document information from numerous published and unpublished sources regarding the past criteria used for selecting the Oak Ridge burial-ground sites, the historical development and conditions of these facilities as of 1974, the geologic framework of the Laboratory area and the movement of water and water-borne contaminants in that area, the effects of sorption and ion exchange upon radionuclide transport, and a description and evaluation of the existing monitoring system. It is intended to assist Atomic Energy Commission (now Energy Research and Development Administration) officials in the formulation of managerial decisions concerning the burial grounds and present monitoring methods. Sites for the first three burial grounds appear to have been chosen during and shortly after World War II on the basis of such factors as safety, security, and distance from sources of waste origin. By 1950, geologic criteria had been introduced, and in the latter part of that decade, geohydrologic criteria were considered. While no current criteria have been defined, it becomes evident from the historical record that the successful containment of radionuclides below land surface for long periods of time is dependent upon a complex interrelationship between many geologic, hydrologic, and geochemical controls, and any definition of criteria must include consideration of these factors. For the most part, the burial grounds have been developed by a simple cut and fill procedure similar to the operation of a municipal landfill. Low permeability of the residuum, high rainfall, shallow depth to ground water, the excavation of trenches below the water table, and other practices, have contributed to a condition of waste leaching in probably all of the burial grounds. Despite these conditions, only very small concentrations of radionuclides have been found in wells or otherwise attributed to the initial three, small sites in Bethel Valley. This fact, however, may be due in part to the scant extent of site monitoring of those burial grounds for transport of radionuclides in ground water, and to the discharge of liquid radioactive waste to the drainage in concentrations that probably would have masked the presence of contaminants derived from these burial grounds. In comparison to the Bethel Valley sites, larger amounts of radioactive contaminants have been found in wells, seeps, trench overflow, and the drainages that drain Burial Grounds 4 and 5 in Melton Valley. The movement of radionuclides from the trenches to the drainages show that the latter sites are not suitable for the retention of all contaminants under existing conditions, and invalidates the operational concept of long-term or permanent retention of all radionuclides in the geologic environment. The transport of many radioactive ions leached from the waste has been retarded by the very high sorptive and ion exchange capacity of the residuum with which the radionuclides have had contact. Not all radionuclides, though, will be retained in the subsurface by adsorption, absorption, or ion exchange. Among those radioactive contaminants that may be problematical with respect to trench burial at Oak Ridge are tritium and other negatively-charged nuclides, positively-charged radionuclides included in some of the complexed molecules, radioactive ions that have chemical properties si

Open-File Report↗
USGS1972

Map showing ranges in probable maximum well yield from water-bearing rocks in the San Francisco Bay region, California

This map presents generalized information regarding the probable maximum yields of wells in the rocks of the San Francisco Bay region. It is intended to serve the needs of planners and other persons seeking general information on potential yields from water wells. Four ranges in probable yield, based on adequacy of the range in yield for major beneficial uses of water, are given. The ranges are related to the concept of normal probability; that is, well yields are expressed in terms of the 68- and 95-percent levels of chance. For example, there is a 68-percent chance that wells in areas designated A will yield from 0.5 to 5 gpm (gallons per minute) and a 95-percent chance that wells in such areas will yield from 0.1 to 10 gpm. assuming operation without excessive drawdown. Thus, it can be expected that most wells drilled in area A will obtain water supplies marginal to adequate for domestic purposes, that most wells will yield fewer than 10 gpm, and that some wells will be virtually dray.

California↗