Ao redor do canal de Jurubatuba, no município de São Paulo, a água subterrânea do Aquífero Cristalino apresentou elevadas concentrações de Compostos Orgânicos Voláteis (VOC), levando à proibição do seu uso nessa região. No Brasil, são raros os estudos sobre áreas intensamente contaminadas, principalmente, em meios heterogêneos como os aquíferos fraturados. Nesse contexto, o presente trabalho foi realizado com o objetivo de elaborar um modelo conceitual da rede de fraturas, indicando os caminhos preferênciaisda água subterrânea.Uma detalhada investigação da geologia estrutural foi realizada, a partir dos seguintes métodos: 1) análise de lineamentos traçados em escala local e regional; 2) levantamento de fraturas, segundo scanlinese pontos, em afloramentos; 3) aplicação conjunta de diferentes perfilagens geofísicas (cáliper, radiação gama, temperatura, condutividade elétrica, imageamento óptico e acústico - OTV e ATV - e flowmeter) em quatro poços profundos;. Os resultados estruturais obtidos, levaram à caracterização dos principais grupos de fraturas, quanto às suas direções, mergulhos, comprimentos e espaçamentos. Foi verificado que os principais grupos de fraturas identificados nos poços, podem ser correlacionados com os grupos identificados nos afloramentos. Foram eles: (1) NW a NNW, subvertical;(2) E-W a ENE, subvertical; (3) NE, subvertical; (4) E-W a WNW, com mergulho entre 30° e 60°; (5) NNE e NE, com mergulho entre 10° e 40°. As fraturas NW, bastante frequentes nos afloramentos, foram subamostradas nos poços, onde, por sua vez, predominam as fraturas NNW. Outra diferença foi observada com relação ao grupo NNE e NE de baixo ângulo de mergulho, que enquanto nos poços as fraturas estão muitas vezes associado à foliação, nos afloramentos esta associação não ocorre. Os espaçamentos obtidos nos afloramentos para os grupos subverticais e de médio ângulo são mais representativos do que aqueles obtidos através das perfilagens. No entanto, o oposto ocorre para o grupo de baixo ângulo.Os grupos foram ordenados em ordem decrescente de espaçamento daseguinte forma: NNE a NE/ baixo ângulo, E-W a ENE/vertical, NW a NNW/vertical, E-W a WNW/médio e NE/vertical. Os grupos também foram classificados de acordo com a sua importância para o fluxo, sendo que: o grupo E-W a WNW e mergulho médio, apresentou menor importância; os três grupos subverticais (E-W a ENE, NE e NW a NNW) apresentaram importância intermediária, não sendo possível identificar a hierarquia entre eles; e o grupo de direção NNE a NE e baixo ou médio ângulo, com a maior importância. As de baixo ângulo são compatíveis com um dos camposde esforços atuais proposto pela literatura, tendo \'sigma\'1 de direção NE em regime compressivo, ou seja, com \'sigma\'3 vertical. / In the surroundings of the Jurubatuba channel, São Paulo, the ground water of the Crystalline Aquifer has elevated concentrations of VolatileOrganic Compounds (VOC), which led to its prohibition to usage. In Brazil, the studies about highly contaminated areas are scarce, and especially in heterogeneous environments like the fractured aquifers. Therefore, in this context, this work\'s main purpose is to elaborate a conceptual model of the fracture net in the Crystalline Aquifer, indicating the preferential ways of ground water flow and, consequently, of its contaminants. A detailed investigation of the structural geologyof the area was conducted, using the following methods: 1)analysis of lineaments in local and regional scale; 2) measurements of fractures in outcrops utilizing scanlinesand observation points; 3) integrated geophysical logging (calipers, gamma radiation, temperature, electrical conductivity, optical and acoustic imaging - OTV and ATV - and flowmeter) in four deep wells. The results obtained led to the characterization of strike, dip, length and spacing of all fractures and its subsequent division in groups. The main fracture groups identified in the wells can be correlated to the ones observed in the outcrops. The groups are: (1) NW to NNW, subvertical; (2) E-W to ENE, subvertical; (3) NE, subvertical; (4) E-W to WNW, with dips between 30º and 60º; (5) NNE and NE, with dips between 10ºand 40º. The fractures with direction NW, which are very common in outcrops, were subsampled in the wells - dominated by fractures NNW. Another difference observed was related to the low dip NNE and NE fractures; in the wells it is clear thatthey are associated with the rock foliation, but they don\'t occur in outcrops. The spacing obtained for the subvertical and medium angle groups in outcrops are more representative than the ones obtained through logging. However, the opposite is observed for the low angle group. The groups were then ordered following the spacing criteria. They are, in a decrescent order: NNE to NE/low angle, E-W to ENE/vertical, NW to NNW/vertical,E-W to WNW/medium angle and NE/vertical. The groups were also classified according to its importance of flow path, being: group E-W to WNW/medium dip was the least importance; the three subvertical groups had intermediate importance - not being possible to hierarchize between them; the most important group is NNE to NE and low to medium dip angle. This result is in agreement with one of the stress fields proposedin the literature, \'sigma\'1 with NE direction and in a compressive regimen, where the fractures that favor the flow are of low angle.

Com o aumento da crise hídrica aumentou a perfuração de poços tubulares e consequentemente a procura de métodos para se identificar aquíferos. Para esta finalidade, a geofísica aplicada tem sido cada vez mais procurada. Neste trabalho, utilizando a técnica geoelétrica de imageamento elétrico multi-eletrodos à geometria variável, visou-se localizar lineamentos estruturais nas rochas em subsuperfície, aptas a armazenarem água. Analisou-se quatro casos de aquíferos em rochas cristalinas: i) três deles em metassedimentos e corpos graníticos do Grupo Araxá; ii) e outro nos domos gnáissicos-migmatíticos da Formação Itabaiana Simão Dias. Os dados adquiridos foram processados e interpretados de acordo com informações geológicas de cada região. Para avaliar a resposta geofísica, em todas as situações os poços foram perfurados de acordo com o resultado do imageamento elétrico e em todas elas os poços perfurados apresentaram vazão de água. / With increasing water crisis also increased the drilling wells and therefore the demand for methods to identify aquifers. For this purpose, geophysics has been increasingly demanded. In this work, using the geoelectric technique of electric imaging with multi-electrode and variable geometry aimed to locate structural lineaments on the rocks in the subsurface, able to store water. It analyzed four cases of aquifers in crystalline rocks: i) three of them in the metasediments and granitic bodies of the Araxá Group; ii) and the other in the gneiss-migmatitic domes of Formation Itabaiana - Simão Dias. The acquired data were processed and interpreted in accordance with geological information of each region. To evaluate geophysical response, in all situations the wells were drilled in accordance with the result of the electric imaging and in all of them the drilled wells showed water flow.

The ability to extract accurately the stress intensity factor and the T-Stress for fractured engineering materials is very significant in the decision-making process for in-service engineering components, mainly for their functionality and operating limit. The subject of computational fracture mechanics in engineering make this possible without resulting to expensive experimental processes. In this thesis, the Finite Block Method (FBM) has been developed for the meshless study of interface stationary crack under both static and dynamic loading in bi-materials. The finite block method based on the Lagrangian interpolation is introduced and the various mathematical constructs are examined. This includes the use of the mapping technique. In a one-dimensional and a two-dimensional case, numerical studies were performed in order to determine the interpolation error. The finite block method in both the Cartesian coordinate and the polar coordinate systems is developed to evaluate the stress intensity factors and the T-stress for interface cracks between bi-materials. Using the William's series for bi-material, an expression for approximating the stress and displacement at the interface crack tip is established. In order to capture accurately the stress intensity factors and the T-stress at the crack tip, the asymptotic expansions of the stress and displacement around the crack tip are introduced with a singular core technique. The accuracy and capability of the finite block method in evaluating interface cracks is demonstrated by several numerical assessments. In all cases, comparisons have been made with numerical solutions by using the boundary collocation method, the finite element method and the boundary element method, etc.

Resumo: Os aqüíferos subterrâneos são reservas estratégicas de recursos hídricos, devendo haver um planejamento adequado para o seu uso e conservação. As zonas de recarga e de concentração de água subterrânea são de suma importância na dinâmica dos sistemas aqüíferos, sendo responsáveis, respectivamente, pelo reabastecimento e pelo armazenamento do recurso. Técnicas de fotointerpretação a partir de produtos de sensoriamento remoto podem ser muito úteis aos estudos hidrológicos, fornecendo informações relevantes a respeito do meio físico, principalmente em escala de reconhecimento. Assim, esta pesquisa tem como objetivo identificar e caracterizar as zonas de captura e concentração de águas subterrâneas em rochas cristalinas, a partir de técnicas de fotointerpretação em produtos de sensoriamento remoto. Para tal, foram estabelecidas unidades geoambientais, a partir da compartimentação do meio físico e posterior classificação de suas propriedades geotécnicas, e foi realizado também um mapeamento morfoestrutural de feições rúpteis e dúcteis. A combinação do Mapa de Unidades Geoambientais e do Mapa Morfoestrutural resultou no Mapa de Zonas de Captura e Concentração de Águas Subterrâneas, onde a convergência de evidências favoráveis à infiltração, percolação e concentração de águas indica as potenciais zonas de recarga, circulação e concentração de águas subterrâneas, colaborando com a prospecção e com o planejamento do uso deste recurso. As principais zonas de recarga e de concentração de recursos hídricos identificadas pelo mapeamento foram o Alto Estrutural de Natividade da Serra, potencialmente uma excelente zona de recarga, e o Baixo Estrutural de Lagoinha/São Luis do Paraitinga, com grande potencial à concentração de recursos hídricos. Estudos de maior detalhe nas áreas potenciais identificadas pelo mapeamento podem confirmar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The fractured aquifers are strategic reserves of water resources, and there should be proper planning for its use and conservation. Areas of concentration and recharge of groundwater is of paramount importance in the dynamics of aquifer systems, responsible respectively for storage and replenishment of the resource. Photointerpretation techniques from remote sensing products can be very useful for hydrological studies, providing relevant information about the physical environment, especially in wide recognition. Thus, this research aims to identify and characterize areas of capture and concentration of groundwater in crystalline rocks, from photointerpretation techniques in remote sensing products. For such geoenvironmental units were established from the partitioning of the physical environment and subsequent classification of their geotechnical properties, and was also performed a morphostructural mapping of brittle and ductile features. The combination of the Geoenvironmental Units Map and the Morphostructural Map resulted in the Groundwater Capture and Concentration Map, where the convergence of evidence favorable to infiltration, percolation and water concentration indicates potential areas of recharge, movement and concentration of groundwater, collaborating with the prospecting and planning of the use of this resource. The main areas of recharge and concentration of water resources were identified by mapping the High Structural of Natividade Sierra, potentially an excellent recharge area, and the Lower Structural of Lagoinha/São Luis do Paraitinga, with great potential to the concentration of water resources. Studies in greater detail of the potential areas identified by the mapping can confirm whether or not the presence of water resource, directing the actions of environmental planning and exploitation of water / Orientador: Juércio Tavares de Mattos / Coorientador: Jairo Roberto Jiménez-Rueda / Banca: Sérgio dos Anjos Ferreira Pinto / Banca: Tomoyuki Ohara / Mestre

Cette thèse présente l'étude du procédé de combustion in situ (CIS) dans un réservoir carbonaté fracturé. Afin de modéliser et de simuler les processus à grande échelle, deux axes principaux sont distinguées, qui correspondent aux petites et grandes échelles. Pour traiter les problèmes à petite échelle, un simulateur commercial de réservoir est utilisé afin d’étudier le processus à l'échelle de la carotte. Tout d'abord, le simulateur est validé pour des procédés simples pour lesquels des solutions analytiques sont disponibles. La validation plus poussée est effectuée en utilisant des résultats expérimentaux publiés dans la littérature. Puis, quelques simulations du système fracturé à l'échelle de la carotte sont effectuées. Le but de ces simulations est d'aborder, la faisabilité du processus CIS dans le système fracturé et de distinguer l'importance relative des divers mécanismes de production pétrolière. Dans l'étape suivante, les tests de tube de combustion et de cellule cinétique sont réalisés, afin de mieux comprendre la physique du processus mais aussi la cinétique de combustion dans un système carbonaté fracturé. Les simulations sont également menées à échelle d'un bloc métrique. Afin d'obtenir la connaissance nécessaire pour le changement d'échelle, des simulations sur plusieurs bloc sont menées et les moyenne des certains paramètres sont estimées. Dans la dernière partie, les conclusions sont présentées et la technique de prise de moyenne est utilisée sur un processus simple (combustion du solide-gaz) afin de donner quelques pistes quant aux enjeux futurs de ce genre de problème. / The aim of the present work is to study the in situ combustion (ISC) process at inter-well scale in a fractured reservoir. Due to the complexity associated with the ISC process, highly heterogeneous nature of the fractured reservoirs and some unsuccessful attempts in the past to put the process into practice, the subject of ISC in fractured systems has been receiving little interest and there are still many essential open questions in this area. It is very challenging to answer the question whether the ISC process could be applied in a heavy oil fractured reservoir or not. And if the answer is positive, what is (are) the dominant oil recovery mechanism(s) and finally, how can we model and simulate this process, at least, at inter-well scale. This work tries to give answers to some of these questions. In this regard, we followed a step by step procedure. In the first step, general literature concerning the combustion process in porous media and particularly that related to the combustion process in an oil reservoir was reviewed. Some other references about the modeling of fracture reservoirs were also reviewed. This led us to distinguish some of the main challenges in this area and define a methodology for the rest of the work. Based on this methodology, the first target was to understand and to characterize the behavior of a combustion front at small (Darcy) scale. The second target was to apply the knowledge of the first part to propose a suitable model for ISC at larger scale. To this end, a commercial thermal reservoir simulator (STARS) was used. The simulator was validated for both simple process for which an analytical solution is available and for a more complex process where the laboratory results are on hand. Then, after the validation part, the numerical tool has been used to widely investigate the conditions where a reaction front can propagate in a fractured core. This allowed us to understand some of the leading mechanisms (oxygen diffusion coefficient for extinction/ propagation of combustion front and matrix permeability for oil production). Some other numerical studies provided us with some understanding about the most important mechanism(s) of oil production. Thereafter, some single block simulations were done to investigate the two-dimensional behavior of the ISC process, based on which the underlying process was found to be diffusion dominated both for heat and mass transfers. These results also helped us to distinguish the characteristic length scale of some important parameters (temperature, coke concentration, combustion front, etc.) which can give useful information about the large scale model. After that, an experimental part has been performed to find propagation conditions of ISC at laboratory scale. This was done by varying both the operational conditions (flowrate, pressure and oxygen concentration) and the characteristics of the fractured system (aperture, surface area, permeability). This permitted us to find that in some suitable conditions there is a possibility to generate a combustion front in a fractured system containing heavy oil. To give an idea about the modeling of the process at larger scale, some fine grid simulations are also performed using a multi-block model. By analyzing the results of this model some guidelines are proposed for the large scale model. At the end, a short discussion about the upscaling of an easy system (solid-gas combustion using an Arrhenius law as a function for the mass sink term in a conductive system) is presented based on an upscaling using the volume averaging method.

Este trabalho buscou avaliar a existência de diferentes padrões hidroquímicos e isotópicos dos aquíferos fraturados do Sistema Aquífero Serra Geral (SASG), relacionando esses padrões com as profundidades das entradas de água. O estudo foi desenvolvido a partir do inventário e cadastramento de poços tubulares existentes na região do município de Carlos Barbosa - RS, do levantamento e interpretação de dados geológicos e hidrogeológicos, além da coleta e análise de amostras de água de poços tubulares que estão em operação e são utilizados pela companhia de abastecimento CORSAN. Para este trabalho foram utilizadas informações hidroquímicas e isotópicas da água de 12 poços tubulares e 3 fontes, além de análise isotópica mensal da água da chuva. A análise dos resultados foi realizada através dos diagramas de Piper, Schoeller e Stiff, além de análise estatística de agrupamento a fim de verificar padrões semelhantes entre os pontos amostrados. Os resultados obtidos permitiram evidenciar que a maioria dos poços apresentam profundidade de até 150 metros com vazões médias que variam de 5 a 20 m³/h, localizados em zonas de média e alta densidade de fraturas, as quais possuem orientação preferencial para noroeste. Quanto à hidroquímica, as águas que circulam por esses aquíferos são do tipo bicarbonatadas cálcicas ou magnesianas, predominando as águas bicarbonatadas mistas e cálcicas, com pequenas variações em relação à concentração dos íons e suas razões iônicas. Essas características hidroquímicas são típicas de águas que circulam por estruturas de rochas vulcânicas ácidas e indicam um baixo tempo de residência, sendo as concentrações variáveis com as profundidades das entradas da água. A avaliação entre a correlação de padrões hidroquímicos com a profundidade das entradas de água permitiu a identificação de dois grupos. O primeiro grupo é caracterizado por poços que apresentam entradas de água localizadas em profundidades inferiores a 30 metros e águas com baixa concentração de íons. No segundo grupo estão inseridos poços cujas entradas de água estão localizadas entre 50 e 112 metros e apresentam águas com uma maior concentração de íons como cálcio, sódio, bicarbonatos e maiores valores de condutividade e sólidos totais dissolvidos. A explicação dessas diferenças está relacionada com a circulação de água e com tempo de interação água-rocha que ocorre de forma diferente dependendo da profundidade das entradas de água. A análise de isótopos das águas de poços, fontes e da água da chuva apresentam semelhanças isotópicas indicando que água subterrânea pode ser caracterizada como originada por infiltração da precipitação nas áreas de recarga. Por fim, a caracterização hidroquímica e isotópica indicam que as águas subterrâneas dessa região apresentam baixo grau de mineralização e baixo tempo de residência, sendo que as exceções foram encontradas em poços que possuíam entradas de água mais profundas. / This study aimed to evaluate the existence of different hydrochemical and isotopic patterns of fractured aquifers of Serra Geral Aquifer System (SGAS), relating these patterns with depths of water intakes. The study was developed from the inventory and registration of wells in the region of Carlos Barbosa - RS, the survey and interpretation of geological and hydrogeological data, and the collection and analysis of samples of water from wells that are in operation and are used by the supply company CORSAN. Hydrochemical and isotopic information from 12 wells and 3 water sources were used for this work, in addition to monthly isotopic analysis of rainwater. The analysis was performed using diagrams as Piper, Schoeller and Stiff, and statistical cluster analysis to verify similar patterns between the sampling points. The results have highlighted that most wells have depths up to 150 meters with average flow rates ranging from 5 to 20 m³/h, located in areas of medium and high density of fractures, which have preferential orientation to the northwest. As for hydrochemistry, water circulating through these aquifers are the calcic or magnesian bicarbonate type , predominantly mixed and calcic bicarbonate waters, with minor variations in the concentration of ions and their ionic reasons. These hydrochemical characteristics are typical of waters that circulate structures and acidic volcanic rocks indicate a low residence time, and the varying concentrations with depths of water inputs. The evaluation of the correlation between patterns hydrochemical with water entry's depth allowed the identification of two groups. The first group is characterized by wells that have water intakes located bellow than 30 meters and waters with low concentration of ions. In the second group are inserted into wells whose water inlets are located between 50 and 112 meters and water present in a higher concentration of ions such as calcium, sodium, bicarbonates and higher values of conductivity and dissolved solids. The explanation of these differences are related to the circulating water and water - time interaction rock occurs differently depending of water entry's depth. Analysis of isotopes of water wells and sources of rainwater present isotopic similarities indicating that groundwater can be characterized as caused by infiltration of rainfall areas recharging. Finally, the hydrochemical and isotopic characterization indicate that the groundwater in this region have low grade mineralization and low residence time, with the exceptions were found in wells that had water intakes deeper.

abstract: Given the profound influence that schools have on students’ genders and the existing scholarly research in the field of education studies which draws clear implications between practices of schooling and sanctioning and promoting particular gender subjectivities, often in alignment with traditional norms, I conduct a critical ethnography to examine the practices of gender in one eighth grade English language arts (ELA) classroom at an arts-missioned charter school. I do this to explore how ELA instruction at an arts charter school may provide opportunities for students to do gender differently. To guide this dissertation theoretically, I rely on the process philosophy of Erin Manning (2016, 2013, 2007) to examine the processual interactions among of student movement, choreography, materiality, research-creation, language, and art. Thus, methods for this study include field notes, student assignments, interviews and focus groups, student created art, maps, and architectural plans. In the analysis, I attempt to allow the data to live on their own, and I hope to give them voice to speak to the reader in a way that they spoke to me. Some of them speak through ethnodrama; some of them speak through autoethnography, visual art and cartography, and yet others through various transcriptions. Through these modes of analysis, I am thinking-doing-writing. The analysis also includes my thinking with fields – the fields of gender studies, qualitative inquiry, educational research, English education, and critical theory. In an attempt to take to the fields, I weave all of these through each other, through Manning and other theorists and through my ongoing perceptions of event-happenings and what it means to do qualitative research in education. Accordingly, this dissertation engages with the various fields to reconsider how school practices might conceive the ways in which they produce gender, and how students perceive gender within the school space. In this way, the dissertation provides ways of thinking that may unearth what was previously cast aside or uncover possibilities for what was previously unthought. / Dissertation/Thesis / Doctoral Dissertation Educational Leadership and Policy Studies 2019

This thesis is aimed to calculate the effective permeability tensor and to simulate the fluid flow in naturally fractured reservoirs. This requires an understanding of the mechanisms of fluid flow in naturally fractured reservoirs and the detailed properties of individual fractures and matrix porous media. This study has been carried out to address the issues and difficulties faced by previous methods; to establish possible answers to minimise the difficulties; and hence, to improve the efficiency of reservoir simulation through the use of properties of individual fractures. The methodology used in this study combines several mathematical and numerical techniques like the boundary element method, periodic boundary conditions, and the control volume mixed finite element method. This study has contributed to knowledge in the calculation of the effective permeability and simulation of fluid flow in naturally fractured reservoirs through the development of two algorithms. The first algorithm calculates the effective permeability tensor by use of properties of arbitrary oriented fractures (location, size and orientation). It includes all multi-scaled fractures and considers the appropriate method of analysis for each type of fracture (short, medium and long). In this study a characterisation module which provides the detail information for individual fractures is incorporated. The effective permeability algorithm accounts for fluid flows in the matrix, between the matrix and the fracture and disconnected fractures on effective permeability. It also accounts for the properties of individual fractures in calculation of the effective permeability tensor. The second algorithm simulates flow of single-phase fluid in naturally fractured reservoirs by use of the effective permeability tensor. This algorithm takes full advantage of the control volume discretisation technique and the mixed finite element method in calculation of pressure and fluid flow velocity in each grid block. It accounts for the continuity of flux between the neighbouring blocks and has the advantage of calculation of fluid velocity and pressure, directly from a system of first order equations (Darcy???s law and conservation of mass???s law). The application of the effective permeability tensor in the second algorithm allows us the simulation of fluid flow in naturally fractured reservoirs with large number of multi-scale fractures. The fluid pressure and velocity distributions obtained from this study are important and can considered for further studies in hydraulic fracturing and production optimization of NFRs.

<p>The aim of this study was to test whether one could use the same methods as used for sampling heavy metals and apply them to radioactive elements. Furthermore a sampling protocol was developed, the first of its kind, for the sampling of radioactive elements in fractured rock aquifers. This was achieved by initially examining local as well as international manuals and methods. The aforementioned was done in conjunction with a literature review of the movement of radioactive elements in these fractured rock aquifers. Beaufort West was utilised as a study area and the geology, hydrogeology and topography was outlined. Background radioactivity was generally acceptable except for two samples which were anomalously high. Taking cognisance of the methods used, as well as those previously applied in the area and abroad, a sampling protocol for radioactive elements in fractured rock aquifers was developed and attached as an appendix. In conclusion it was suggested that multiple methods be tested on one well in order to check whether similar results would occur. This would thus determine the best applicable methods. Also it was proposed that a new method, called DGT sampling, be applied in order to gain a time weighted average of the heavy metals and radioactive elements in groundwater. It could also be clearly seen, by comparing historical data and the current data, that the methods used for sampling heavy metal can be applied to radioactivity.</p>

Much is known about natural attenuation of contaminants in granular aquifers because many contaminant plumes in these aquifers have been intensively monitored with detailed sampling along cross sections positioned across the plumes (i. e. transects). However, little is known about natural attenuation of contaminant plumes in fractured rock. In this thesis study, strong natural attenuation of a persistent co-mingled plume of trichloroethylene (TCE) and an herbicide (metolachlor) in a 100 <em>m</em> thick dolostone aquifer used for municipal water supply in Cambridge, Ontario is shown based on detailed delineation of groundwater contaminant concentrations along a single transect located 150 <em>m</em> downgradient from the area where the metolachlor entered the dolostone and 300 <em>m</em> downgradient from the TCE source area. This delineation was accomplished using depth-discrete, multilevel groundwater monitoring systems in five cored holes and detailed analyses of contaminant concentration in rock cores. The maximum metolachlor concentration on the transect is a factor of 20 below the maximum concentration in the metolachlor source area and the maximum TCE concentration on the transect is lower by a factor of 100 from the TCE source area. <br /><br /> Matrix diffusion and strong temporal variability of the groundwater flow system caused by pumping of nearby municipal wells have likely caused strong natural attenuation of metolachlor and TCE and degradation has likely contributed to even stronger TCE attenuation. The transect shows rock core concentrations much higher than the groundwater concentrations in the multilevel systems at the same locations and in the conventional monitoring wells, which indicates that plume persistence is likely maintained by back diffusion from the rock matrix, which has very low hydraulic conductivity but substantial porosity, into the active groundwater flow in the fractures. <br /><br /> Metolachlor has been observed at very low concentrations and has persisted at these concentrations in the nearest municipal pumping well located approximately 780 <em>m</em> downgradient of the transect, however this well shows no detectable TCE. The relatively low concentrations along the transect and the replenishment of the plume by back diffusion suggests that a substantial increase of metolachlor or TCE in the municipal well is unlikely.