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D.A. Webster

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

8 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↗
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↗
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↗