Geology topics

Clifton C. Casey

Publications and source records attributed to Clifton C. Casey.

9 recordsLinked to original sources

USGS2010

Groundwater Hydrology and Chemistry in and near an Emulsified Vegetable-Oil Injection Zone, Solid Waste Management Unit 17, Naval Weapons Station Charleston, North Charleston, South Carolina, 2004-2009

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated the hydrology and groundwater chemistry in the vicinity of an emulsified vegetable-oil injection zone at Solid Waste Management Unit (SWMU) 17, Naval Weapons Station Charleston, North Charleston, South Carolina. In May 2004, Solutions-IES initiated a Phase-I pilot-scale treatability study at SWMU17 involving the injection of an edible oil emulsion into the aquifer near wells 17PS-01, 17PS-02, and 17PS-03 to treat chlorinated solvents. The Phase-I injection of emulsified vegetable oil resulted in dechlorination of trichloroethene (TCE) to cis-1,2-dichloroethene (cDCE), but the dechlorination activity appeared to stall at cDCE, with little further dechlorination of cDCE to vinyl chloride (VC) or to ethene. The purpose of the present investigation was to examine the groundwater hydrology and chemistry in and near the injection zone to gain a better understanding of the apparent remediation stall. It is unlikely that the remediation stall was due to the lack of an appropriate microbial community because groundwater samples showed the presence of Dehalococcoides species (sp.) and suitable enyzmes. The probable causes of the stall were heterogeneous distribution of the injectate and development of low-pH conditions in the injection area. Because groundwater pH values in the injection area were below the range considered optimum for dechlorination activity, a series of tests was done to examine the effect on dechlorination of increasing the pH within well 17PS-02. During and following the in-well pH-adjustment tests, VC concentrations gradually increased in some wells in the injection zone that were not part of the in-well pH-adjustment tests. These data possibly reflect a gradual microbial acclimation to the low-pH conditions produced by the injection. In contrast, a distinct increase in VC concentration was observed in well 17PS-02 following the in-well pH increase. Adjustment of the pH to near-neutral values in well 17PS-02 may have made that well relatively favorable to VC production compared with much of the rest of the injection zone, possibly accounting for acceleration of VC production at that well. Following a Phase-II injection in which Solutions-IES, Inc., injected pH-buffered emulsified vegetable oil with an improved efficiency injection approach, 1,1-dichloroethene, TCE, and cDCE rapidly decreased in concentration and are now (2009) undetectable in the injection zone, with the exception of a low concentration (43 micrograms per liter, August 2009) of cDCE in well 17PS-01. In August 2009, VC was still present in groundwater at the test wells in concentrations ranging from 150 to 640 micrograms per liter. The Phase-II injection, however, appears to have locally decreased aquifer permeability, possibly resulting in movement of contamination around, rather than through, the treatment area.

North Carolina↗

USGS2007

Investigation of Ground-Water Contamination at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound ground-water contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina. The primary contaminants of interest are tetrachloroethene, 1,1,1-trichloroethane, trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,1-dichloroethane, and 1,1-dichloroethene. In general, the hydrogeology of Solid Waste Management Unit 12 consists of a surficial aquifer, composed of sand to clayey sand, overlain by dense clay that extends from about land surface to a depth of about 8 to 10 feet and substantially limits local recharge. During some months in the summer, evapotranspiration and limited local recharge result in ground-water level depressions in the forested area near wells 12MW-12S and 12MW-17S, seasonally reflecting the effects of evapotranspiration. Changes in surface-water levels following Hurricane Gaston in 2004 resulted in a substantial change in the ground-water levels at the site that, in turn, may have caused lateral shifting of the contaminant plume. Hydraulic conductivity, determined by slug tests, is higher along the axis of the plume in the downgradient part of the forests than adjacent to the plume, implying that there is some degree of lithologic control on the plume location. Hydraulic conductivity, hydraulic gradient, sulfur-hexafluoride measurements, and historical data indicate that ground-water flow rates are substantially slower in the forested area relative to upgradient areas. The ground-water contamination, consisting of chlorinated volatile organic compounds, extends eastward in the surficial aquifer from the probable source area near a former underground storage tank. Engineered remediation approaches include a permeable reactive barrier and phytoremediation. The central part of the permeable reactive barrier along the main axis of the contaminant plume appears to be actively removing contamination; however, ground-water contamination is moving around the southern end of the permeable reactive barrier. Changes in the contaminant concentrations along the path of ground-water transport reflect a complex variety of influences. Potential influences include dechlorination, sorption and desorption, transpirative removal by trees, lateral shifting of the plume, and the presence of zones of differing concentrations possibly reflecting one or more pulse releases of contamination from the source area. Near the source area at well 12MW-10S, volatile organic compound concentrations of cis-1,2-dichlorothene, vinyl chloride, 1,1-dichloroethane, and 1,1,1-trichloroethane continued an irregular decline, while tetrachloroethene and 1,1-dichloroethene showed marked fluctuations in concentration during 2005 and 2006. Volatile organic compound concentrations at well 12MW-03S continued to show decreasing concentrations with the June 2006 concentrations being the lowest yet recorded at that well for several volatile organic compounds. Concentration and delta carbon 13 data indicate that in the upgradient part of the plume, tetrachloroethene is being degraded to trichloroethene, which is being degraded to cis-1,2-dichloroethene, and cis-1,2-dichloroethene is accumulating faster than it is being depleted. Ground-water volatile organic compound concentrations also changed in some wells in the forested area in the midpart of the plume. Increasing tetrachloroethene and decreasing trichloroethene and 1,1-dichloroethene concentrations were observed at wells 12MW-05S and 12MW-29S, possibly reflecting a lateral shift in the axis of the contamination plume or an advancing contamination pulse. Substantial decreases in contamination occur in the forested area downgradient from well 12MW-05S. Probable major loss mechanisms in this area include evapotranspiration and sorption.

North Carolina, South Carolina↗

USGS2007

Evaluation of pore-water samplers at a drainage ditch, Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, 2005–06

The U.S. Geological Survey, in cooperation with the Naval Facilities Engineering Command Southeast, used innovative sampling methods to investigate ground-water contamination by chlorobenzenes beneath a drainage ditch on the southwestern side of Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, during 2005-06. The drainage ditch, which is a potential receptor for ground-water contaminants from Installation Restoration Site 4, intermittently discharges water to Corpus Christi Bay. This report evaluates a new type of pore-water sampler developed for this investigation to examine the subsurface contamination beneath the drainage ditch. The new type of pore-water sampler appears to be an effective approach for long-term monitoring of ground water in the sand and organic-rich mud beneath the drainage ditch.

Texas↗

USGS2007

Investigation of ground-water contamination at a drainage ditch, Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, 2005–06

The U.S. Geological Survey, in cooperation with the Naval Facilities Engineering Command Southeast, used newly developed sampling methods to investigate ground-water contamination by chlorobenzenes beneath a drainage ditch on the southwestern side of Installation Restoration Site 4, Naval Air Station Corpus Christi, Corpus Christi, Texas, during 2005-06. The drainage ditch, which is a potential receptor for ground-water contaminants from Installation Restoration Site 4, intermittently discharges water to Corpus Christi Bay. This report uses data from a new type of pore-water sampler developed for this investigation and other methods to examine the subsurface contamination beneath the drainage ditch. Analysis of ground water from the samplers indicated that chlorobenzenes (maximum detected concentration of 160 micrograms per liter) are present in the ground water beneath the ditch. The concentrations of dissolved oxygen in the samples (less than 0.05-0.4 milligram per liter) showed that the ground water beneath and near the ditch is anaerobic, indicating that substantial chlorobenzene biodegradation in the aquifer beneath the ditch is unlikely. Probable alternative mechanisms of chlorobenzene removal in the ground water beneath the drainage ditch include sorption onto the organic-rich sediment and contaminant depletion by cattails through uptake, sorption, and localized soil aeration.

Texas↗

USGS2006

Influence of In-Well Convection on Well Sampling

Convective transport of dissolved oxygen (DO) from shallow to deeper parts of wells was observed as the shallow water in wells in South Carolina became cooler than the deeper water in the wells due to seasonal changes. Wells having a relatively small depth to water were more susceptible to thermally induced convection than wells where the depth to water was greater because the shallower water levels were more influenced by air temperature. The potential for convective transport of DO to maintain oxygenated conditions in a well was diminished as ground-water exchange through the well screen increased and as oxygen demand increased. Convective flow did not transport oxygen to the screened interval when the screened interval was deeper than the range of the convective cell. The convective movement of water in wells has potential implications for passive, or no-purge, and low-flow sampling approaches. Transport of DO to the screened interval can adversely affect the ability of passive samplers to produce accurate concentrations of oxygen-sensitive solutes, such as iron. Other potential consequences include mixing the screened-interval water with casing water and potentially allowing volatilization loss at the water surface. A field test of diffusion samplers in a convecting well during the winter, however, showed good agreement of chlorinated solvent concentrations with pumped samples, indicating that there was no negative impact of the convection on the utility of the samplers to collect volatile organic compound concentrations in that well. In the cases of low-flow sampling, convective circulation can cause the pumped sample to be a mixture of casing water and aquifer water. This can substantially increase the equilibration time of oxygen as an indicator parameter and can give false indications of the redox state. Data from this investigation show that simple in-well devices can effectively mitigate convective transport of oxygen. The devices can range from inflatable packers to simple baffle systems.

Scientific Investigations Report↗

USGS2004

Use of borehole radar methods and borehole geophysical logs to monitor a field-scale vegetable oil biostimulation pilot project at Fridley, Minnesota

Cross-hole and surface-to-borehole radar and conventional borehole geophysical logs were used to monitor subsurface injections of vegetable oil emulsion conducted as part of a field-scale biostimulation pilot project at the Anoka County Riverfront Park (ACP), located downgradient of the Naval Industrial Reserve Ordnance Plant (NIROP), in Fridley, Minnesota. The pilot project was undertaken to evaluate biostimulation using emulsified vegetable oil for treatment of ground water contaminated with chlorinated hydrocarbons. The objectives of the geophysical investigations were to delineate the distribution of vegetable oil injected at NIROP, and evaluate the utility of adding geophysical tracers to the vegetable oil emulsions. Geophysical data were acquired by the U.S Geological Survey in five site visits over 1.5 years. This paper presents (1) level-run radar traveltime and amplitude data; (2) radar cross-hole traveltime tomograms; (3) vertical-radar profile diffraction tomograms; and (4) borehole electromagnetic induction logs. Based on comparison of pre- and postinjection data sets, a conceptual model was developed to define the distribution of emulsified vegetable oil and the extent of ground water having altered chemistry resulting from injections and, possibly, enhanced microbial degradation of chlorinated hydrocarbons. Radar slowness (reciprocal velocity) anomalies indicate that the emplaced oil emulsion remained close to the injection wells, whereas attenuation anomalies indicate changes in ground-water chemistry downgradient of all three injections.

Minnesota↗

USGS2003

Methodology for estimating times of remediation associated with monitored natural attenuation

Natural attenuation processes combine to disperse, immobilize, and biologically transform anthropogenic contaminants, such as petroleum hydrocarbons and chlorinated ethenes, in ground-water systems. The time required for these processes to lower contaminant concentrations to levels protective of human health and the environment, however, varies widely between different hydrologic systems, different chemical contaminants, and varying amounts of contaminants. This report outlines a method for estimating timeframes required for natural attenuation processes, such as dispersion, sorption, and biodegradation, to lower contaminant concentrations and mass to predetermined regulatory goals in groundwater systems. The time-of-remediation (TOR) problem described in this report is formulated as three interactive components: (1) estimating the length of a contaminant plume once it has achieved a steady-state configuration from a source area of constant contaminant concentration, (2) estimating the time required for a plume to shrink to a smaller, regulatoryacceptable configuration when source-area contaminant concentrations are lowered by engineered methods, and (3) estimating the time needed for nonaqueous phase liquid (NAPL) contaminants to dissolve, disperse, and biodegrade below predetermined levels in contaminant source areas. This conceptualization was used to develop Natural Attenuation Software (NAS), an interactive computer aquifers. NAS was designed as a screening tool and requires the input of detailed site information about hydrogeology, redox conditions, and the distribution of contaminants. Because NAS is based on numerous simplifications of hydrologic, microbial, and geochemical processes, the program may introduce unacceptable errors for highly heterogeneous hydrologic systems. In such cases, application of the TOR framework outlined in this report may require more detailed, site-specific digital modeling. The NAS software may be downloaded from the Web site http://www.cee.vt.edu/NAS/ Application of NAS illustrates several general characteristics shared by all TOR problems. First, the distance of stabilization of a contaminant plume is strongly dependent on the natural attenuation capacity of particular ground-water systems. The time that it takes a plume to reach a steady-state configuration, however, is independent of natural attenuation capacity. Rather, the time of stabilization is most strongly affected by the sorptive capacity of the aquifer, which is dependent on the organic matter content of the aquifer sediments, as well as the sorptive properties of individual contaminants. As a general rule, a high sorptive capacity retards a plume.s growth or shrinkage, and increases the time of stabilization. Finally, the time of NAPL dissolution depends largely on NAPL mass, composition, geometry, and hydrologic factors, such as ground-water flow rates. An example TOR analysis for petroleum hydrocarbon NAPL was performed for the Laurel Bay site in South Carolina. About 500 to 1,000 pounds of gasoline leaked into the aquifer at this site in 1991, and the NAS simulations suggested that TOR would be on the order of 10 years for soluble and poorly sorbed compounds, such as benzene and methyl tertiary-butyl ether (MTBE). Conversely, TOR would be on the order of 40 years for less soluble, more strongly sorbed compounds, such as toluene, ethylbenzene, and xylenes (TEX). These TOR estimates are roughly consistent with contaminant concentrations observed over 10 years of monitoring at this site where benzene and MTBE concentrations were observed to decrease rapidly and are approaching regulatory maximum concentration limits, whereas toluene, ethylbenzene, and xylene concentrations decreased at a slower rate and have remained relatively high. An example TOR analysis for petroleum hydrocarbon NAPL was performed for the Laurel Bay site in South Carolina.

South Carolina↗

USGS2001

Evaluation of passive diffusion bag samplers in selected wells at the Naval Surface Warfare Center, Louisville, Kentucky, July 1999 to January 2000

Passive diffusion bag samplers were tested in 11 wells at the Naval Surface Warfare Center, Louisville, Kentucky, by comparing the volatile organic compound concentrations obtained from passive diffusion bag samplers to volatile organic compound concentrations obtained by pumping the wells. The wells were screened in poorly permeable formations, including overburden, shale, and limestone. In five of the tested wells containing detectable volatile organic compound contamination, the data suggest that the diffusion samplers accurately reflected ambient contaminant concentrations (wells 1-NEC-15-P, 1-NEC-MW17-S, 1-NEMW23-S, 1-NW-MW24-S, and 1-NW-MW24-P). Comparison of a third well (1-NEC-MW34-S), in which the passive diffusion bag samplers produced higher concentrations than the pumped sample, is less certain because the passive diffusion bag sampler had passed through a layer of light non-aqueous phase liquid during deployment, suggesting the possibility of carryover contamination. In two wells (1-NE-MW23-P and 1-NEC-MW15-S), it was unclear whether concentrations obtained by using the passive diffusion bag samplers adequately represented in situ concentrations because the comparison of concentrations obtained by using the samplers and the pump was inconsistent between sampling events and/or between volatile organic compounds. In one well (1-NEC-MW34-P), the methodologies matched poorly, with volatile organic compound concentrations obtained by using the passive diffusion bag sampler substantially lower than those obtained by using the pump. Two of the tested wells (1-NW-MW6-I and 1-SE-MW13-I) contained no detectable contaminants in water obtained from either method. Data from wells where multiple passive diffusion bag samplers were deployed showed the lowest volatile organic compound concentrations adjacent to the vuggy limestone and higher volatile organic compound concentrations deeper in the limestone, supporting colloidal-borescope data that indicate the vuggy limestone is not a zone that supplies water to the wells.

Water-Resources Investigations Report↗

USGS2001

Biodegradation potential of chlorinated solvents in ground water at the Naval Surface Warfare Center, Louisville, Kentucky, July 1999 to February 2000

The U.S. Geological Survey, in cooperation with the U.S. Department of the Navy, Southern Division Naval Facilities Engineering Command, investigated the potential for biodegradation of chlorinated solvents in ground water at the Naval Surface Warfare Center (also known as the Naval Ordnance Station, or the station), Louisville, Kentucky. The subsurface down to at least 100 feet at the station is characterized, from shallowest to deepest, by overburden deposits, a shale layer, and limestone. In general, all of the strata are poorly permeable. The permeable zones of the overburden and the limestone make up the overburden aquifer and the bedrock aquifer, respectively. Observed concentrations of redox-sensitive solutes suggest that the predominant anaerobic terminal electron accepting process in the overburden aquifer can shift between iron reduction and sulfate reduction, possibly as a result of rainfall-induced oxidation events. Daughter-product concentrations and laboratory experiments indicate that a variety of mechanisms, including reductive dechlorination and cometabolic oxidation, appear to be actively

Kentucky↗