The objective of this study is to develop guidelines for the analysis of storm water retention ponds in Central Florida. Development of a combined seepage analysis considering both unsaturated and saturated groundwater flow incorporation into a systematic approach for storm water retention pond design will result in safer and more economical storm water management practices. The research was conducted in four phases: 1) A literature review. 2) A review of mathematical and empirical analysis of transient – unsaturated/saturated groundwater flow. 3) Construction and testing of a downscaled storm water pond model. 4) Incorporation of full scale percolation pond test data from ponds constructed and tested in Central Florida. The literature review was undertaken to research mathematical and empirical equations for both unsaturated and saturated groundwater seepage to be incorporated into the modelling and development of final system analysis. The review was concentrated on seepage studies conducted in subsoil conditions similar to those in Central Florida. It was found in the early review of literature that separate studies and modelling for unsaturated and saturated seepage are widespread and relatively well documented. However, documentation of combined groundwater seepage model, since the majority of storm water retention ponds in Central Florida experience both seepage condition (unsaturated/saturated) during the design storm event. Inspection of operational seepage ponds and interviews with regulatory agencies and consulting firms in Central Florida indicated that successful design of storm water retention ponds greatly depends on the accurate definition of the subsoil conditions and the seepage characteristics during a specific design storm event. Interviews with those responsible for pond design revealed that there is currently no widespread accepted design method, and most of the designs are based on mostly local experience. Also, history indicates that even though the unsteady seepage analysis is a complex phenomenon, there is usually very little money I the budget for its analysis and design. However, due to continuous increase of property values and the need to optimize pond sizing, the trend of under budgeting for seepage bond design is reversing. Application of the research results will yield a more accurate analysis which accounts for unsaturated and saturated seepage for sizing of storm water retention ponds in Central Florida. The analytical solutions developed from this research are a combination of acceptable mathematical and empirical groundwater seepage equations or dimensionless graphs modified for the purpose of storm water retention pond analysis.

A three-dimensional finite element model for the analysis of steady state seepage has been presented in this study. The theory of unsaturated flow has been used in the analysis of steady state seepage. The model applies the invariant mesh procedure in the finite element analysis. Galerkin's method is used in the formulation of the finite element equations. The pre and the post processor developed in the generation and viewing of the finite element mesh and the free surface has also been discussed in this study. The study presents the comparison of results obtained from the three-dimensional model with a previously validated two-dimensional model. / Master of Science

The events of Hurricane Katrina in 2005 prompted the US Army Corps of Engineers (USACE) to commission studies to identify the failure mechanisms of levees and I-walls. This involves updating of the current USACE Engineering Manual (EM) 1110-2-1913, "Design and Construction of Levees," which uses Blanket Theory for seepage analysis. Blanket Theory entails analytical methods for calculating seepage pressures and flows beneath levees. The revision of the manual will address the design seepage criteria for levees, with a focus on incorporating new seepage analysis procedures besides Blanket Theory. Finite element analysis is one such method that has more recently become the method of choice for general seepage analyses in geotechnical engineering. The focus of this research is mainly on underseepage analyses of levees in the lower Mississippi valley using numerical modeling, with a goal of helping engineers in making the transition from current Corps methods to finite element analysis. General guidelines are provided to conduct seepage analysis using finite element analysis for pre-defined Blanket Theory cases as well as for the design of seepage berms. In addition, the 3D finite element modeling is conducted for a full-scale field load test involving complex geometry and stratigraphy, which is useful in better understanding the response of levees and I-walls. / Ph. D.

The US Army Corps of Engineers is responsible for regular dredging of shipping channels which produces about 300 million yd³ of dredged sediments annually. Many of these sediments have to be contained within confined disposal facilities (CDFs) due to the presence of heavy metals, PCB’s and other harmful constituents within the pore water of the dredge soils. However, these contaminants frequently seep back into the water from which the dredge was removed. The primary objective of this research was to modify the existing finite element program POLUT2D to evaluate the rate and quantity of contaminant transport through CDFs. Two actual field problems were evaluated using the modified program. One of these problems was a new CDF to be located along the US coast and the other was the existing Buffalo Harbor Dike facility located on Lake Erie in Buffalo, New York. The analyses of the coastal facility indicated that a cumulative quantity of about 43 kilograms of arsenic will seep back into the bay at the end of 50 years following filling of the CDF with arsenic contaminated dredge. Analyses of the Buffalo Harbor facility indicated that about 45 kilograms of chlorobenzene seeps annually into Lake Erie from the dredge material contained within this structure. Sensitivity analyses were also performed to evaluate the effect of soil properties, boundary conditions, etc. on contaminant transport through CDFs. The results indicated that some soil properties such as unit weight, molecular diffusion, and transverse dispersivity have little impact on contaminant transport. Other properties, such as the distribution coefficient and the longitudinal dispersivity, have only a slight to moderate impact on contaminant transport, while the coefficient of hydraulic conductivity can have a significant impact on contaminant transport though CDFs. Analyses also indicated that tidal fluctuations and infiltration from precipitation impact contaminant transport and must be modeled. Additional studies indicated that a slurry trench may provide better containment than a soil liner, and that a combination of a slurry trench and soil cover can reduce contaminant loading by a factor of about 4 depending on the thickness of the soil cover. / Ph. D.

Fyllningsdammar har alltid ett naturligt läckage då jordmaterialet som används har en viss permeabilitet. Detta acceptabla naturliga läckage är viktigt att övervaka för att kontrollera att läckageflödet håller sig inom förväntade värden. Om läckaget blir för stort, kan det leda till felmoder som i sin tur leder till dammbrott. Damminstrumentering som möjliggör övervakning av läckage i fyllningsdammar är ett krav enligt RIDAS. På nedströmssidan av fyllningsdammar finns det dränagerör som samlar upp och leder läckagevatten till platser där läckaget mäts med något slags instrument. Detta mätinstrument mäter inte endast läckaget genom fyllningsdammar, utan påverkas även av yttre faktorer såsom nederbörd och evapotranspiration. Detta examensarbete syftar därför att utveckla en generell metod för läckageövervakning vid fyllningsdammar, för att erhålla det normala läckaget. Hur det normala läckaget kan erhållas allmängiltigt för fyllningsdammar har presenterats. Det normala läckaget genom dammkroppen kan antingen erhållas med hjälp av fysikalisk läckageberäkning (qD1,Fysikalisk) eller från läckagemätning (qD1,Läckagemätning). Fysikalisk läckageberäkning bygger på en genomströmningsmodell baserat på fysikaliska samband. Läckage från läckagemätning baseras på en vattenbalansekvation där läckageflödet är en term av flera, som uppmätt läckage nedströms dammen, nederbörd och avdunstning. En fallstudie har genomförts för en av Vattenfalls dammanläggningar för att testa den metodik som framtagits för erhållande av det normala läckaget. De fysikaliska läckageberäkningarna har modellerats fram med hjälp av COMSOL Multiphysics och läckaget från läckagemätningarna har beräknats fram med hjälp av vattenbalansekvationen och indata på hydrologi. Resultatet visar att det är viktigt att ta hänsyn till de yttre faktorerna från vattenbalansekvationen eftersom dessa kan ha en betydande påverkan på det läckageflöde som faktiskt mäts. Vidare bedöms det betydande att modellera läckage baserat på en fysikalisk baserad strömningsmodell eftersom detta värde sällan finns idag. Då kan en jämförelse av läckage från läckagemätningar jämföras med det fysikaliska läckaget. Det bedöms att beräkning av läckage från läckagemätningar med hjälp av vattenbalansekvationen är en bra metod för att beräkna läckaget genom dammar. Dock behöver den studerade dammanläggningen en djupare analys för att senare kunna tillsätta gränsvärden. Detta genom att även undersöka läckage under dammkroppen och magasinsförändringar vid beräkning av läckage från läckagemätningar. Det fysikaliska läckaget genom att modellera genomströmningen för hela geometrin och genom att utföra en tidsberoende modellering. / Embankment dams are not completely impervious as its core materials has a certain permeability. This seepage is important to monitor to follow-up to ascertain that it stays as expected. If the seepage increase above design, failure modes could occur and ultimately a dam failure. The Swedish dam safety guideline RIDAS deals with this safety aspect by requirements on instrumentation to measure seepage. Downstream embankment dams, drainage leads seepage water to an outflow point where seepage can be measured. However, at these points the measured flow also is impacted by external factors such as precipitation and evapotranspiration. The aim of this report is to propose a method where the measured flow by post-processing can exclude the impact of these external factors. The normal seepage through a dam can either be obtained by modelling (where the physical seepage has been obtained based on physical relationships) or by a water balance equation (where the seepage from measurement downstream a dam is a part of the water balance equation, including the impact by precipitation and evapotranspiration. A case study has been carried out on a dam operated by Vattenfall, as a means to assess the proposed methodology. The seepage has been modelled using the COMSOL Multiphysics software, and the seepage from measurements has been calculated by the water balance equation. The results show that it is important to take into account external factors as it clearly affects the measured seepage flow. Furthermore, it is of great importance to calculate the theoretical design seepage, which is a threshold value level that is rarely modelled today. If both the seepage from measurements and theoretical seepage is obtained, a comparison of these can be made. The seepage from measurements (with the help of the water balance equation) is a good method to obtain embankment dam seepages. However, the results from the case study implies that further work is needed to be able to set relevant limit values.

Non-overflow flow-through rockfill structures are river engineering elements used to attenuate and delay inflow hydrographs. They represent expedient places to deposit rather enormous quantities of waste rock at mountainous mine sites. Their application has become so common that matters of safety regarding their design have been laid out in Section 8.5 of the Canadian Dam Safety Guidelines (CDA 2007). The research described herein was directed at investigating the different aspects of the hydraulics of these flow-through rockfill structures. In order to assess the potential for an unraveling failure of flow-through rockfill dams, a systematic study of the hydraulic design of these structures was conducted and the non-linear nature of flow through these structures was dealt with using a p-LaPlacian-like partial differential equation. Subsequently, factors of safety against this type of failure are presented for a range of downstream slopes, thus showing the unsafe combinations of embankment slope and particle diameter. Three different index gradients within the toe of such structures were investigated. In this regard, the gradient most suitable for independently computing the height of the point of first flow emergence on the downstream face is examined and a method for independently computing the variation in hydraulic head within that vertical (which allows for the toe of the structure to be isolated) is presented. An additional gradient that allows for the independent estimation of the default tailwater depth is proposed. In order to provide better tools to assess the behavior of these embankments at the toe, laboratory and analytical studies were undertaken. In this regard, the hydraulics associated with the zone of the downstream toe were studied. The depth variation of the seepage-face was computationally modeled, and two approaches for solving the spatially varied flow (SVF) condition problem within the toe region undertaken. The results show that a dual linear variation in depth can be used to good accuracy, without inducing any unrealistic exit gradients in the zone of primary concern with respect to unraveling. It is hoped that these techniques and computational tools provided herein will aid in facilitating the design and assessment of these flow-through rockfill structures.

Many environmental studies of water transport through the vadose zone require a field determination of saturated hydraulic conductivity. The purpose of this dissertation is to analyze the reliability of existing methods to determine saturated hydraulic conductivity, K(s), in the vadose zone from constant head borehole infiltration test data. In methods developed by the U. S. Bureau of Reclamation [USBRI, and in lesser known ones, K(s) is computed knowing the height of water in the borehole, length open to the formation, borehole radius, distance above the water table, and steady flow rate. The mathematical formulas on which these methods rest are derived on the basis of numerous simplifying assumptions. The free surface approach is used as the conceptual model of flow from a borehole. Results of numerical simulations are used to compare with the analytical solutions. Simulations with a steady-state finite element computer program, FREESURF, show that the Nasberg-Terletskata solution most closely approximates flow from a borehole with the free surface approach. The influence of capillarity is simulated for saturated-unsaturated porous media in four soils using a finite element computer program, FLUMP, and an integrated finite difference program, TRUST. Contrary to what one finds with the free surface approach, only a small portion of the flow field near the borehole is saturated at steady-state and the cross sectional area normal to the flow path increases with depth below the borehole. For deep water table conditions in fine textured soils, values of K(s) computed using the USBR open-hole equations may be more than 160% greater than the true values; and in coarse sands the USBR solutions may under-estimate the actual value by more than 35%. Mostly because of the influence of unsaturated soil properties there is no unique relationship between K(s), borehole conditions, and steady flow rate, as implied in the analytical solutions. Steady-state simulations demonstrate that existing solutions for borehole infiltration tests in anisotropic or nonuniform soils may also lead to significant errors. Time dependent simulations show that the time to reach a steady flow rate may be more than several days in very dry, low-permeable soils. The time to reach a steady flow rate can be significantly reduced by decreasing the open area between the borehole and formation while increasing the height of water in the borehole. Two methods are proposed to minimize the time, water volume requirements, and cost of conducting constant head borehole infiltration tests. Simulations show that a plot of the inverse of flow rate versus logarithm of time departs from a straight line after about 80% of the steady rate is achieved for various soil and borehole conditions; the steady rate is approximately 0.8 times the rate at the break in slope. In the second method flow rate is plotted versus the inverse of the square root of time and the steady rate is estimated within about 10% by linear extrapolation of early time measurements. USBR field data generally support this linear relationship. Two empirical equations are proposed to compute K(s). The first is applicable for a range of borehole conditions and approximately accounts for capillary effects with a single parameter. The second applies if the height of water in the borehole is I meter, and is based on the time to reach 80% of the steady rate and saturation deficit of the field soil.

A construção de barragens de terra sobre formações geológicas permeáveis constitui um dos mais sérios desafios da engenharia de barragens. Neste tipo de projeto, as principais variáveis que devem ser analisadas são a vazão, o gradiente de saída e a subpressão, todas decorrentes da percolação de água pela fundação. Este trabalho apresenta um estudo acerca da eficácia dos dispositivos de controle da percolação a partir de análises paramétricas realizadas em uma barragem típica utilizando o método dos elementos finitos através do programa SEEP/W. Nestas análises foram variadas as características dos dispositivos e a anisotropia hidráulica do maciço de fundação. Verificou-se que a trincheira de vedação parcial é extremamente ineficaz, que o tapete impermeável à montante apresenta cerca de 60% de eficácia para relações entre o comprimento do tapete e a largura da base da barragem da ordem de 1,70 e que a trincheira de vedação total associada aos dispositivos de drenagem constitui a solução mais eficaz no controle das variáveis vazão, gradiente de saída e subpressão. / The construction of earth dams on pervious geologic formations constitutes one of the most serious problems of the engineering of dams. In this type of project, the main variables that must be analyzed are the discharge, the exit gradient and the uplift pressure, all decurrent ones of the water seepage for the foundation. This work presents a study on the effectiveness of devices of control of the seepage from parametric analyses carried through in a typical dam using the method of the finite elements through program SEEP/W. In these analyses the characteristics of the devices and the hydraulic anisotropy of the foundation mass had been varied. It was verified that the cut-off trench of partial is extremely inefficacious, that the impermeable blanket to the sum presents about 60% of effectiveness for relations between the blanket length and the width of the base of the dam of the order of 1.70 and that the cut-off trench of associated to the drainage devices constitues the solution most effective in the control of the variables discharge, exit gradient and the uplift pressure.

A construção de barragens de terra sobre formações geológicas permeáveis constitui um dos mais sérios desafios da engenharia de barragens. Neste tipo de projeto, as principais variáveis que devem ser analisadas são a vazão, o gradiente de saída e a subpressão, todas decorrentes da percolação de água pela fundação. Este trabalho apresenta um estudo acerca da eficácia dos dispositivos de controle da percolação a partir de análises paramétricas realizadas em uma barragem típica utilizando o método dos elementos finitos através do programa SEEP/W. Nestas análises foram variadas as características dos dispositivos e a anisotropia hidráulica do maciço de fundação. Verificou-se que a trincheira de vedação parcial é extremamente ineficaz, que o tapete impermeável à montante apresenta cerca de 60% de eficácia para relações entre o comprimento do tapete e a largura da base da barragem da ordem de 1,70 e que a trincheira de vedação total associada aos dispositivos de drenagem constitui a solução mais eficaz no controle das variáveis vazão, gradiente de saída e subpressão. / The construction of earth dams on pervious geologic formations constitutes one of the most serious problems of the engineering of dams. In this type of project, the main variables that must be analyzed are the discharge, the exit gradient and the uplift pressure, all decurrent ones of the water seepage for the foundation. This work presents a study on the effectiveness of devices of control of the seepage from parametric analyses carried through in a typical dam using the method of the finite elements through program SEEP/W. In these analyses the characteristics of the devices and the hydraulic anisotropy of the foundation mass had been varied. It was verified that the cut-off trench of partial is extremely inefficacious, that the impermeable blanket to the sum presents about 60% of effectiveness for relations between the blanket length and the width of the base of the dam of the order of 1.70 and that the cut-off trench of associated to the drainage devices constitues the solution most effective in the control of the variables discharge, exit gradient and the uplift pressure.

Karst bedrock conditions and deterioration of the lock and dam structures have resulted in significant leakage through, underneath, and around Lock and Dam No. 8 on the Kentucky River. During severe droughts, the water surface in Pool No. 8 has been observed to drop below the crest of the dam, resulting in water supply shortages and water quality issues for surrounding communities reliant on the pool. Presently, the primary purpose of Lock and Dam No. 8 is water supply. Pool No. 8 is currently where the cities of Nicholasville (Jessamine County, KY) and Lancaster (Garrard County, KY) draw their water. Due to the age and condition of the structures, and the criticality of the retained water supply, the project Owner commissioned a replacement dam to be built. One major component of the replacement dam was a foundation improvement program. The foundation improvement program was designed to address the karst bedrock conditions at the site. The foundation improvements included a secant pile cutoff wall and a double-row grout curtain. The grout curtain at Lock and Dam No. 8 was evaluated based on the metrics presently available.