The objective of this study was to investigate the need for domestic wastewater to receive secondary treatment when being applied to the soil by subsurface drip irrigation (SDI). SDI uniformly distributes wastewater into the soil, which optimizes the soil’s chemical, physical, and biological capacity to remove waste constituents. Because of these advantages, many regulatory jurisdictions are allowing SDI at sites that previously were prohibited from using conventional trench-based soil application systems because of shallow soil restrictions. However, most of these regulatory agencies also require that the wastewater receives secondary treatment (dissolved organic carbon reduction) before the SDI system. At issue is whether the enhanced soil-based renovation provided by SDI should eliminate the necessity for secondary treatment before SDI. Two SDI systems were installed and monitored at two sites in Tennessee. These locations were residential developments served by a septic tank effluent pump (STEP) collection system, a recirculating media filter (fine gravel media), and SDI dispersal. At both locations, SDI plots were established to receive primary treated (septic tank effluent) and secondary treated (recirculating media filter effluent) wastewater. In close proximity to randomly selected SDI emitters, soil samples were extracted. Soil cores were analyzed to determine saturated hydraulic conductivity (Ksat), and pore water samples were analyzed for nitrate, total nitrogen, total carbon, and total phosphorus. Results indicate that the primary-treated sites had lower Ksat values, higher nitrate and higher total nitrogen levels than the secondary-treated side and the background soil. Interestingly, the primary treated side had less total carbon and the background phosphorus concentration was twice that of the primary and secondary treated sides. Primary effluent showed a decrease in concentration for all constituents with increased depth. Secondary treatment does result in a higher quality effluent but is not needed when applying effluent with a SDIS.

In the last decade, a significant amount of research has been performed to characterize the microstructure of unsheared and sheared triaxial sand specimens to advance the understanding of the engineering behavior of soils. However, most of the research has been limited to two-dimensional (2-D) image analysis of section planes that resulted in loss of information regarding the skeleton of the soil (pore structure) and other attributes of the three-dimensional (3-D) microstructure. In this research, the 3-D microstructures of triaxial test specimens were, for the first time, characterized. A serial sectioning technique was developed for obtaining 3-D microstructure from 2-D sections of triaxial test specimens. The mosaic technique was used to get high-resolution large field of view images. Various 3-D characterization parameters were used to study the microstructures of the specimens. To study the preparation method induced variation in soil microstructure, two specimens prepared with air pluviation and moist tamping methods were preserved with epoxy impregnation. A coupon was cut from the center of each specimen, and following a serial sectioning and image capture process, the 3-D structure was reconstructed. To study the evolution of structure during shearing tests, two additional specimens prepared to the same initial conditions with the same methods were subjected to axial compression loading under constant confining pressure up to an axial strain level of 14%. After shearing, the structure of these specimens were also preserved and analyzed following the same procedures as the unsheared specimens. The evolution of the pore structures was investigated accordingly. It was found that generally, moist tamped specimens were initially less uniform but had a more isotropic structure than air pluviated specimens. The standard deviations of 2-D local void ratio and 3-D pore size in dilated regions of sheared air pluviated and moist-tamped specimens were found to be smaller than those of as-consolidated specimens at a given void ratio. Tortuosity decreased with increasing pore size. It was also evident that the soil structures evolved differently depending on the initial structure. Comparison between 2-D and 3-D results indicated that it is not sufficient to use 2-D section information for characterizing some microstructural features.

Die Arbeit befasst sich mit der Untersuchung des Kernformstofffließens als nichtnewtonsche Fluidströmung. Dazu werden verschiedene Formgrundstoffe und Kernformstoffe rheologisch untersucht. Als Bindersysteme kommen PUR Coldbox und Wasserglas zum Einsatz. Für diese Untersuchungen wird ein eigens für diesen Zweck entwickeltes Messgerät verwendet. Die gewonnenen Daten werden in ein numerisches Modell implementiert, welches mit den Methoden der numerischen Strömungsmechanik den Kernschießvorgang abbildet. Dabei kommt der Open Source CFD Code OpenFOAM zum Einsatz. Der Kernschießvorgang wird mit verschiedenen Kernkastengeometrien numerisch und experimentell untersucht und die Ergebnisse verglichen. Die Ergebnisse der rheologischen Untersuchungen zeigen deutlich den Einfluss der Beschaffenheit des Formgrundstoffes und des Bindersystems auf die Fließfähigkeit des Kernformstoffes. Der Vergleich zwischen Experiment und Simulation zeigt gute Übereinstimmung. Das formulierte Modell gibt die Möglichkeit, Probleme in der Kernqualität vorherzusagen.

The objective of this study was to investigate the need for domestic wastewater to receive secondary treatment when being applied to the soil by subsurface drip irrigation (SDI). SDI uniformly distributes wastewater into the soil, which optimizes the soil’s chemical, physical, and biological capacity to remove waste constituents. Because of these advantages, many regulatory jurisdictions are allowing SDI at sites that previously were prohibited from using conventional trench-based soil application systems because of shallow soil restrictions. However, most of these regulatory agencies also require that the wastewater receives secondary treatment (dissolved organic carbon reduction) before the SDI system. At issue is whether the enhanced soil-based renovation provided by SDI should eliminate the necessity for secondary treatment before SDI.Two SDI systems were installed and monitored at two sites in Tennessee. These locations were residential developments served by a septic tank effluent pump (STEP) collection system, a recirculating media filter (fine gravel media), and SDI dispersal. At both locations, SDI plots were established to receive primary treated (septic tank effluent) and secondary treated (recirculating media filter effluent) wastewater. In close proximity to randomly selected SDI emitters, soil samples were extracted. Soil cores were analyzed to determine saturated hydraulic conductivity (Ksat), and pore water samples were analyzed for nitrate, total nitrogen, total carbon, and total phosphorus. Results indicate that the primary-treated sites had lower Ksat values, higher nitrate and higher total nitrogen levels than the secondary-treated side and the background soil. Interestingly, the primary treated side had less total carbon and the background phosphorus concentration was twice that of the primary and secondary treated sides. Primary effluent showed a decrease in concentration for all constituents with increased depth. Secondary treatment does result in a higher quality effluent but is not needed when applying effluent with a SDIS.

Understanding specific pathways for sand transport in the lower reaches of large rivers, particularly the Mississippi, is the key to addressing multiple significant geologic problems and for environmental restoration efforts. Field studies were performed in the Mississippi River 75-100 km upstream of the Gulf of Mexico outlet in April 2010 (water discharge: 23,000 m³ s⁻¹), May 2010 (18,500-20,500 m³ s⁻¹), and March 2011 (27,000 m³ s⁻¹) to examine sediment transport phenomena in the river channel. Methods comprised multibeam sonar bathymetric surveys, acoustic Doppler current profiler measurements of current velocity and acoustic backscatter, point-integrated isokinetic suspended sediment sampling, and channel-bed grab sampling. Channel morphology surveys revealed a 30-60 m deep thalweg, alternating between banks every 2-3 km, opposite bedform-covered lateral sand bars. Dune sizes nearest the thalweg ranged from 7 m wavelength and 0.3 m height to over 100 m wavelength and 2.3 m height as a function of water discharge, with decreasing dune sizes towards shallow water. Material comprising the dunes was well-sorted, 125-500 [mu]m sand. Bedload transport rates increased exponentially with water discharge in April 2010 and March 2011 comparable to previous studies in this reach, though rates in May 2011 were well below predicted values for a site (Myrtle Grove) immediately downriver of a sand-mining project. Average water velocities ranged from 1.3 m s⁻¹ in May 2010 to 2 m s⁻¹ in March 2011. Skin-friction shear stress increased with water discharge, but varied over an order of magnitude at all measured discharges. Suspended sand concentration and grain size increased with proximity to the bed during all study periods, and was most pronounced in March 2011. Suspended sand concentrations were greatest over the center of lateral bars, and lowest in the thalweg, indicating that sand transport downstream occurs primarily over lateral sand bars where there is a combination of high shear stress and available bed material. Total bed-material discharge increased exponentially with water discharge. Bedform-induced turbulence may be responsible for the bed material suspension. These results are relevant to coastal restoration efforts by river diversion which seek to distribute sand from the upper water column to deltaic interdistributary wetlands. / text

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Frac-pack design is still done on conventional hydraulic fracturing models that employ linear elastic fracture mechanics. However it has become evident that the traditional models of fracture growth are not applicable to soft rocks/unconsolidated formations due to elastoplastic material behavior and strong coupling between flow and stress model. Conventional hydraulic fracture models do not explain the very high net fracturing pressures reported in field and experiments and predict smaller fracture widths than expected. The key observations from past experimental work are that the fracture propagation in poorly consolidated sands is a strong function of fluid rheology and leak off and is accompanied by large inelastic deformation and shear failure leading to higher net fracturing pressures. In this thesis a numerical model is formulated to better understand the mechanisms governing fracture propagation in poorly consolidated sands under different conditions. The key issues to be accounted for are the low shear strength of soft rocks/unconsolidated sands making them susceptible to shear failure and the high permeabilities and subsequently high leakoff in these formations causing substantial pore pressure changes in the near wellbore region. The pore pressure changes cause poroelastic stress changes resulting in a strong fluid/solid coupling. Also, the formation of internal and external filtercakes due to plugging by particles present in the injected fluids can have a major impact on the failure mechanism and observed fracturing pressures. In the presented model the fracture propagation mechanism is different from the linear elastic fracture mechanics approach. Elastoplastic material behavior and poroelastic stress effects are accounted for. Shear failure takes place at the tip due to fluid invasion and pore pressure increase. Subsequently the tip may fail in tension and the fracture propagates. The model also accounts for reduction in porosity and permeability due to plugging by particles in the injected fluids. The key influence of pore pressure gradients, fluid leakoff and the elastic and strength properties of rock on the failure mechanisms in sands have been demonstrated and found to be consistent with experimental observations. / text

Multiphase flow is the simultaneous flow of two or several phases through a system such as a pipe. This common phenomenon can be found in the petroleum and chemical engineering industrial fields. Transport of sand particles in multiphase production has attracted considerable attention given sand production is a common problem especially to the oil and gas industry. The sand production causes loss of pipe wall thickness which can lead to expensive failures and loss of production time. Build-up of sand in the system can result in blockage and further hamper production. Monitoring of multiphase flow is a process that has been established over several decades. This thesis reports an assessment of the application of Acoustic Emission (AE) technology as an alternative online technique to monitoring of sand particles under multiphase flow conditions in a horizontal pipe. The research was conducted on a purpose built test rig with the purpose of establishing a relation between AE activity and sand concentration under different multiphase flow conditions. The investigation consisted of five experimental tests. The initial experiment was performed to provide a basis for the application of AE technology to detect sand particle impact prior to performing tests in multiphase flow conditions. Further investigations are reported on two phase air-sand, water-sand and air- water-sand three-phase flows in a horizontal pipe for different superficial gas velocities (VSG), superficial liquid velocities (VSL) and sand concentrations (SC). The experimental findings clearly showed a correlation exists between AE energy levels and multiphase flow parameters, such as superficial liquid velocity (VSL), superficial gas velocity (VSG), sand concentration and sand minimum transport condition (MTC).

The study which was carried out around gravel pits at Stanton Harcourt (Oxfordshire) and Rinwood (Hampshire) falls into three sections. The first involves an analysis of the groundwater character- istics of the gravels. This includes an estimation of the permeability of the gravels (using single-well dilution methods) and an analysis of the recharge mechanisms operating in them. The latter is based upon observed relationships between groundwater fluctuations and hydrometeorological factors. Secondly, the hydrological effects of gravel extraction and dewatering are analysed. By monitoring groundwater levels, the nature and extent of the zone of drav/dcvm around the gravel pits is determined. Induced recharge from rivers and recirculation of water from surface ditches into the pits, as a result of dewatering, is identified. Estimates of the proportion of induced recharge in groundwater are then made using chemical evidence. A mathematical model of gravel pit dewatering is developed. The influence of hydraulic conductivity and the initial pumping rate in determining the effects of dewatering is established by a series of sensitivity analyses using this model. As a practical example, the model is used to predict the effects of dewatering a new site near Stanton Harcourt. The extent of the drawdown around each stage in its development is determined, and this is used to evaluate the effects on private sources and agriculture in the surrounding area. Thirdly, the effects of one type of rehabilitation project (i.e. lake formation) are investigated. A method for predicting the final lake level is explained. Deviation of the observed lake levels from those predicted is explained in terms of the sealing effect of fine sediment plus chemical and biological processes. The effects of lake formation on groundwater levels and flow are described, and the changes in water quality produced by the flow of groundwater through a lake are examined.

Thesis (doctoral)--Université de Paris, 1919. / Vol. 2 has title: Le Berry dans l'œuvre de George Sand. Vol. 1 has subtitle: Nohant, 1808-1876. Includes indexes. Includes bibliographical references (v. 1, p. [632]-657; v. 2, p. [356]-366).