Sediment chemistry of the Colorado River delta of Lake Powell, Utah, 2001
No abstract available.
Utah↗
Geology topics
D. D. Graham
Publications and source records attributed to D. D. Graham.
Trichloroethylene and 1,1-dichloroethylene concentrations in ground water after temporary shutdown of the reclamation well field at Air Force Plant 44, Tucson, Arizona, 1999
Industrial activities beginning in the early 1940s resulted in extensive contamination of ground water near the Tucson International Airport, Tucson, Arizona, including an area around Air Force Plant 44, an industrial facility located on land owned by the U.S. Air Force and operated by a defense contractor. Principal ground-water contaminants are volatile organic compounds, primarily trichloroethylene (also called trichloroethene) and 1,1-dichloroethylene (also called 1,1-dichloroethene). A ground- water reclamation system was put into operation in 1987 to extract and treat contaminated ground water at Air Force Plant 44 and the downgradient area that is south of Los Reales Road. The ground- water reclamation system consists of 25 extraction wells, 22 recharge wells, and a water-treatment facility. Soil-vapor extraction techniques are being used to remove volatile organic compounds from the unsaturated zone. More than 120,000 pounds of volatile organic compounds have been removed from the regional aquifer and overlying unsaturated zone at Air Force Plant 44 and adjacent downgradient areas south of Los Reales Road. Air Force Plant 44 and adjacent areas being remediated by the ground-water reclamation system are about 7 square miles. To assess ground-water cleanup progress at Air Force Plant 44 and surrounding areas south of Los Reales Road, and possibly to identify areas that are resistant to cleanup attempts, ground-water samples were collected and analyzed after water levels had returned to near-equilibrium conditions following a 3-week shutdown of extraction and recharge wells. Modifications of the standard ground-water sampling procedures used at the site also were tested. The modifications included tests of a reduced-flow purging and sampling method in six monitoring wells and vertical- profile sampling in five extraction wells at the reclamation well field. The water treatment facility and all extraction and recharge wells at the reclamation well field were shut down on April 15, 1999, and water levels were allowed to recover for about 3 weeks before samples of ground water were obtained from 102 wells at Air Force Plant 44 and surrounding areas. Concentrations of trichloroethylene and 1,1-dichloroethylene were determined for samples obtained during the sitewide sampling effort. Data for 101 wells sampled in February 1999 before shutdown were compared with data obtained for wells sampled in May 1999 after shutdown. Concentrations of trichloroethylene increased in 36 wells, remained the same in 32 wells, and decreased in 33 wells. Increases in concentrations of trichloroethylene of as much as 1,476 micrograms per liter and decreases of as much as 2,292 micrograms per liter were reported after shutdown. Concentrations of trichloroethylene remained the same for the two sampling periods in wells that had concentrations that were at, or close to, the lower reporting limit (0.5 micrograms per liter) before shutdown. Net change in concentrations of trichloroethylene after shutdown on a percentage basis ranged from an increase of 1,300 percent to a decrease of 100 percent. Increases in concentrations of 1,1-dichloroethylene after shutdown of the reclamation well field of as much as 66 micrograms per liter and decreases of as much as 411.6 micro- grams per liter were reported. Concentrations of 1,1-dichloroethylene remained the same for the two sampling periods in wells that had concentrations that were at, or close to, the lower reporting limit (0.5 micrograms per liter) before shutdown. Net change in concentrations of 1,1-dichloroethylene after shutdown on a percentage basis ranged from an increase of 660 percent to a decrease of 100 percent. Data obtained from the water samples indicate that the largest changes in concentrations of trichloroethylene and 1,1-dichloroethylene occurred in samples collected from wells completed in the upper zone of the regional aquifer, along the axis of the contaminant plume, in close proximity to previously identified historical disposal areas. Changes in contaminant concentrations observed after shutdown of the well field probably were the result of changes in ground-water flow directions under nonpumping conditions compared with those present when the extraction and recharge wells were operating. Minimal changes occurred at the perimeter of the plume, which suggests that operation of the reclamation well field has been successful at containing the spread of the plume. New contaminant-source areas were not identified within the perimeter of the plume. A modification of the standard sampling technique used at Air Force Plant 44 was tested in six wells. In these wells, greatly reduced flow rates were used for well purging and sampling. Results indicate no distinct pattern of change of contaminant concentrations compared with concentrations in samples subsequently obtained using the standard technique, and no advantage was evident for using this method in routine sampling of the monitoring wells at Air Force Plant 44. Temperature profiles obtained before vertical-profile sampling of selected wells indicate little temperature variation with depth. The temperature-profile information suggests that under nonpumping conditions, most of the water enters these wells near the top of the screened interval and moves downward in response to a hydraulic gradient in the regional aquifer. Samples at depths below the top of the screened interval probably do not accurately represent water from the adjacent sediments. Vertical-profile samples were obtained in five wells and analyzed for concentrations of trichloroethylene. None of the wells showed large enough variation of contaminant concentrations with depth to indicate that a major improvement in extraction efficiency could be obtained by pumping selectively from a restricted interval. The largest variation in concentrations of trichloroethylene with depth that was observed ranged from 62 micrograms per liter near the top of the screened interval to 42 micrograms per liter near the bottom of the screened interval of one of the wells. The lack of large variation is probably the result of downward water flow in the casing of these wells.
Arizona↗
Overview of environmental and hydrogeologic conditions at three Federal Aviation Administration facilities near Anchorage International Airport, Anchorage, Alaska
Explore the source record for details and available documents.
Open-File Report↗
Methodology, results, and significance of an unsaturated-zone tracer test at an artificial-recharge facility, Tucson, Arizona
A tracer test conducted in 1987 at an artificial-recharge facility in Tucson, Arizona, indicates that solute movement through the poorly sorted stratified alluvial sediments in the unsaturated zone beneath a recharge basin takes place along preferential-flow paths. Movement of a tracer-laced pulse of reclaimed wastewater was monitored using pressure-vacuum lysimeters installed at depths that range from 11 to 45 ft below the bottom of the recharge basin. Tracer-breakthrough curves do not indicate a consistent relation between maximum tracer concentration and depth or between time of tracer breakthrough and depth. Apparent dispersion, as indicated by the slope of the rising leg of the tracer-breakthrough curve, shows no apparent relation with depth. In some cases, the tracer arrived earlier at deep sampling locations than at shallow ones. Velocity of solute flow ranged from 1.9 to 9.0 ft/day. Less interaction between recharge water and solid-phase materials in the unsaturated zone occurs under preferential-flow conditions than if flow occurred as a uniform wetting front. Flow of water through the unsaturated zone is concentrated into fingers or channels under preferential-flow conditions, and the renovating capability of soil is reduced because of the reduced surface area and reduced contact time in the biologically active part of the unsaturated profile. Chemical substances that normally would be decomposed by microbial activity or sorbed by sediment particles can move through the unsaturated zone and cause groundwater contamination under preferential-flow conditions. (USGS)
Water-Resources Investigations Report↗
Flow in the unsaturated zone, Tucson, Arizona
Field studies in Tucson, Arizona were conducted based on the discovery of contaminants in groundwater from a substantial number of municipal and private wells, and evidence that the presence of a thick unsaturated zone does not prevent the eventual migration of contaminants to regional groundwater systems. A pulse of water containing a tracer was monitored as it passed through the unsaturated zone by using six soil-moisture samplers (lysimeters) that were installed at depths of 11 to 45 ft, 10 ft apart, beneath a shallow, manmade, 3/4-acre recharge basin. The tracer was allowed to infiltrate into the ground for seven days, and water was collected from samplers at 12-hr intervals for about 30 days. Well defined tracer peaks, presented graphically as tracer breakthrough curves, were observed for all but one of the lysimeters installed at the site. Maximum tracer concentration showed no consistent relation with depth; tracer breakthrough sometimes occurred earlier in deep sampling locations than in shallow ones. Rather than moving straight down, water movement occurred along preferential flow paths, referred to as bypass or macropore flow, probably at low soil tension which occurs when the soil is near saturation. Under such conditions, contaminant arrival times can occur sooner than would be expected if flow was assumed to occur as a uniform wetting front that pushes ahead of it the water previously stored in the pores of the unsaturated sediments. Much of the water stored in the soil profile is not involved under conditions of bypass flow, and less interaction occurs between the recharge water and the solid matrix of the unsaturated zone. Therefore certain substances such as chlorinated hydrocarbons (trichloroethylene, pesticides) , other refractory organic compounds (detergents, humic acid), and microorganisms (bacteria) could pass into the underlying groundwater. Results of this study have applicability throughout the southwestern United States as well as in other parts of the country where the practice of artificial recharge is being considered. (Lantz-PTT)
Open-File Report↗
Potential for leakage among principal aquifers in the Memphis area, Tennessee
The principal aquifers in the Memphis area consist primarily of sand or sand and gravel, and the confining beds consist of clay, silt, sand, and lignite. The Jackson Formation and upper part of the Claiborne Group serve as the confining bed separating the water table aquifers from the Memphis Sand; the Flour Island Formation separates the Memphis Sand from the Fort Pillow Sand. Differences in total hydraulic head among the principal aquifers in the Memphis urban area result in vertical hydraulic gradients which create a potential for inter-aquifer exchange of water. Throughout this area, the gradient is downward from the water table aquifers to the Memphis Sand. In the central part of the Memphis urban area, the vertical hydraulic gradient is upward from the Fort Pillow Sand to the Memphis Sand, and in the eastern and western parts, it is downward from the Memphis Sand to the Fort Pillow Sand. The vertical distribution of carbon-14 data for water from the fluvial deposits, Memphis Sand, and Fort Pillow Sand shows an increase in the relative age of the water with depth. The areal distribution of carbon-14 data for water from the upper part of the Memphis Sand indicates that relatively recent water has been brought into the major cone of depression in the potentiometric surface of the Memphis Sand, either by horizontal movement or from downward vertical leakage. The normal, near-surface geothermal gradient in the Memphis area was determined to be 0.6 C/100 ft. Deviations from the normal geothermal gradient, in areas affected by intense pumping from the Memphis Sand, indicate that downward vertical leakage occurs from the water table aquifers through the Jackson-upper Claiborne confining bed to the Memphis Sand. The velocity of downward vertical leakage of water from the Memphis Sand through the Flour Island confining bed to the Fort Pillow Sand was determined to be 0.0066 ft/day by analysis of borehole temperature data from an observation well in the northeastern part of the Memphis area. From this velocity and the head difference between the Memphis Sand and the Fort Pillow Sand at this locality, the hydraulic conductivity of the Flour Island confining bed was determined to be 0.00114 ft/day. (Lantz-PTT)
Tennessee↗
Preliminary assessment of ground-water resources of Lauderdale County, Tennessee
The ground-water resource in Lauderdale County is in a rudimentary stage of development. The principal shallow aquifers are the Mississippi alluvial deposits of Quaternary age and the Cockfield Formation, Memphis Sand, and Fort Pillow Sand of Tertiary age. Water levels fluctuate seasonally. High water levels generally occur in the winter, spring, or early summer, and low water levels occur in the fall or early winter. Water from the Mississippi alluvial deposits, Cockfield Formation, and Memphis Sand is a calcium bicarbonate type and is generally of good quality. Undesirable parameters from the standpoint of use are hardness and concentrations of dissolved iron and dissolved solids. The Fort Pillow Sand, as yet untapped, has potential to yield a sodium bicarbonate type of water of somewhat better quality than is available from the shallow aquifers. Estimated values of transmissivity from single-well pumping tests are highest for the Mississippi alluvial deposits and lowest for the Cockfield. Several north-northeast and west-northwest trending faults cross the country.
Tennessee↗
Test well installation and water quality, Hollywood Dump area, Memphis, Tennessee
The Hollywood Dump in north Memphis, Tennessee is known to contain hazardous wastes. Monitor wells were installed and sampled to determine if contaminants have entered the underlying Wolf River alluvium and concentrated near the base of this unconfined aquifer. Four water-quality samples were collected from each of nine monitor wells screened in the Wolf River alluvium at the Hollywood Dump between June 1982 and June 1983. Also sampled during this period was one well screened in the fluvial (terrace) deposits, about one-half mile upgradient from the dump, and three nearby wells screened in the Memphis Sand artesian aquifer. Low levels of several organic compounds, including heptachlor, chlordane and chlordene, were detected in water from the Wolf River alluvium. High concentrations of barium and arsenic were also detected. Water from the Memphis Sand showed no traces of synthetic organic compounds. Other constituents and properties were found to be at levels that are normal for that aquifer. Five of the Wolf River alluvium wells sampled were newly installed. Geophysical logs made in these wells, supplemented by drillers logs and split spoon samples, show that clay underlies the alluvial aquifer at the well locations. (USGS)
Water-Resources Investigations Report↗
Installation and sampling of observation wells and analyses of water from the shallow aquifer at selected waste-disposal sites in the Memphis area, Tennessee
Observation wells were installed and sampled at six abandoned waste-disposal sites in the Memphis area that have been identified as having received unknown quantities and types of industrial wastes. These sites are: (1) Bellevue Dump, (2) Brooks Road Dump, (3) Hollywood Dump, (4) Jackson Pit Dump, (5) Millington Dump-Landfill, and (6) Old Ordnance Dump. Ten wells were installed adjacent to and downgradient from these sites in the shallow water-table aquifer. This aquifer is made up chiefly of the alluvium and fluvial (terrace) deposits of Quaternary age, but locally may include sand in the uppermost part of the Jackson Formation and Claiborne Group of Tertiary age. Water samples were collected from these 10 wells and from two other wells in the shallow water-table aquifer at the Hollywood Dump. Most wells were sampled twice --initially in the early summer when water levels were high and again in the fall when water levels were low. Other wells were sampled only once in either summer or fall. The water was analyzed for common constituents, selected trace constituents, and selected organic compounds.
Tennessee↗
Effects of urban development on the aquifers in the Memphis area, Tennessee
Ground-water withdrawals from aquifers in the Memphis area average about 190 Mgal/d. Potential problems associated with increases in pumpage and urban development are lowered water levels, contamination of the aquifers, and land subsidence. Long-term water-level declines in the Memphis Sand, the principal artesian aquifer of the area, range from less than 0.1 ft per year near the outcrop area to about 1.8 ft per year near the center of pumping. A 1980 map of the potentiometric map surface shows that small cones of depression around major pumping centers are superimposed on a regional cone. Except for increased pumping lift, few problems are expected from water level declines in the Memphis Sand. At present, there is very little pumpage from other aquifers in the area--the alluvium, the fluvial deposits and the Fort Pillow Sand--and no long-term water level declines are expected unless pumpage is increased significantly. Low concentrations of leachates from waste-disposal sites in the area have been detected in the water table aquifers near these sites, but no indication of contamination of the underlying artesian aquifers has yet been found. Seasonal land-surface elevation changes of less than 0.03 ft have been recorded by an extensometer near the center of the major cone of depression of the Memphis Sand. These changes correlate with seasonal changes in artesian pressure in the Memphis Sand. Over the period of record no significant net change in land-surface elevation has been recorded. (USGS)
Water-Resources Investigations Report↗
Chemical character of ground water in the shallow water-table aquifer at selected localities in the Memphis area, Tennessee
The City of Memphis depends solely on ground water for its water supply. About 97 percent of inventoried pumpage in the Memphis area, which totaled about 194 Mgal/d in 1979, is from the Memphis Sand. This aquifer generally has been believed to be separated from the shallow water-table aquifer (alluvium and fluvial deposits) by a relatively thick and wide-spread confining bed consisting chiefly of clay. Studies by the Geological Survey in recent decades, however, have indicated that part of the recharge to the Memphis Sand probably is derived by vertical leakage from the shallow water-table aquifer through the confining bed and that locally "windows" of sand exist in the confining bed through which any contaminants in the shallow water-table aquifer could enter the Memphis Sand (See Criner and others, 1964, p. 30; Bell and Nyman, 1968, p. 7-8; Parks and Lounsbury, 1976, p. 26-27). More recently, additional evidence of vertical leakage being a component of recharge to the Memphis Sand was provided during the calibration of a digital computer model of the aquifers in the Memphis area. For this calibration a leakage factor, averaging about 20 percent over the Memphis area, had to be applied to the model in order to simulate known historic water levels in the Memphis Sand (J. V. Brahana, 1980, oral commun. ). This discovery has heightened concern about the possibility of contaminants being in the shallow water table aquifer, and thus, the potentiality for any contaminants to enter the Memphis Sand. Areas where the shallow water-table aquifer is most susceptible to contamination are those that have been or are being used for waste disposal. Historically, Memphis and Shelby County along with private concerns and industries have used dumps and landfills in two geologically and topographically different areas -- the flood plains of nearby streams and abandoned gravel pits in upland areas. These dumps and landfills have received a large variety of wastes including ashes, construction and demolition materials, garbage, rubbish, street refuse, and chemical and industrial wastes. Most of these dumps and landfills were closed in the early 1970's at the beginning of state regulation of waste disposal practices. Nevertheless, leachates from these waste disposal facilities presumably have been and are entering the shallow water-table aquifer.
Tennessee↗