The Hampton Roads Sanitation District is heading a Managed Aquifer Recharge project designed to build water resiliency for the district as well as meet recent regulations concerning effluent released into the Chesapeake Bay. The Sustainable Water Initiative for Tomorrow (SWIFT) project will include five injection well fields across the Virginian Coast. The first of these fields to be implemented is the James River site, scheduled to begin in 2025. A model of the Virginia Coastal Plain region was created in 2009 and has been used to simulate the combined impact of the full-scale SWIFT project. This study estimated the change in hydraulic head in the Potomac Aquifer System caused by the proposed James River recharge well field at a regional and local level. That estimation required the use of a widely accepted model of the Virginia Coastal Plain developed in 2009 which was subjected to a limited validation using USGS monitoring well data for comparison. That model was then used to establish boundary conditions for a local scale model surrounding the James River site, after which each model was used to run four pumping scenarios with varying rates of recharge. The validation of the Virginia Coastal Plain model found it to be satisfactory for the scope of this work, and it was therefore used to interpolate boundary conditions for the developed local model. The regional and local model both showed an increase in the simulated head values of the Potomac Aquifer System. The regional model simulated a sharper initial increase than the local model, however, long term the local model simulated a greater impact to the groundwater levels from the proposed recharge. / Master of Science / The Potomac Aquifer System (PAS) is a main water source for most of eastern Virginia and high pumping rates have caused notable drawdown in several areas. The Hampton Roads Sanitation District (HRSD) has initiated the Sustainable Water Initiative for Tomorrow (SWIFT) project that is designed to alleviate the stress on the PAS by artificially recharging the PAS through injection well. A regional groundwater model, built in 2009, has been used to estimate the impact of the proposed recharge for the SWIFT project at full capacity. This work validated the use of the regional model within the region of the first proposed SWIFT well field at the James River Site. Once the validation was complete, the regional model provided a framework to develop a more detailed model on a smaller scale. That model was then used to simulate the proposed injection well field at varying rates to estimate the effect of the James River Site. This study has shown that the regional model provides an adequate framework to build local scale models. The simulations run in both the regional and local models found that the proposed recharge increases the water levels in the PAS immediately surrounding the well field and that the impact is felt to distances exceeding 50 miles after 10 years.

No description available.

Water managers must balance the need for clean and safe drinking water with ever-increasing amounts of waste-water. A technique for treating and storing surface water called “managed aquifer recharge” (MAR) is frequently used to help maintain this balance. When MAR is used to produce drinking water, water managers must ensure that disease-causing microbial contaminants are removed from the water prior to its distribution. This thesis examined the processes responsible for removing a specific class of microbial contaminants called “enteric viruses” during MAR. Viruses are naturally removed in groundwater through adsorption and inactivation mechanisms. This thesis investigated how these virus removal mechanisms were affected by ionic strength (IS), dissolved organic carbon (DOC), and the age of the sand used in a MAR infiltration basin. This was done using batch and flow-through column experiments designed to mimic conditions characteristic of a basin infiltration MAR scheme in Uppsala, Sweden. Bacteriophage MS2 was used as a proxy for enteric viruses. All of the experiments were conducted at 4°C. Experimental data were modeled to describe the fate and transport of viruses in the infiltrated groundwater. Conventional least-squares optimization and generalized likelihood uncertainty estimation (GLUE) were compared as model fitting-approaches in order to determine how data uncertainty affects parameter estimates and model predictions. Results showed that the sand used in the infiltration basins accumulates adsorbed organic matter as it is exposed to infiltrating surface waters. This reduced the amount of MS2 that was removed due to adsorption and inactivation. Results from GLUE indicated that MS2 is more likely to inactivate in a time-dependent manner when in the presence of sand with high concentrations of organic matter. Both model fitting techniques indicated that virus attachment rates were significantly lower for sand with high organic carbon content. Neither methodology was capable of adequately capturing the kinetics of virus adsorption. Uncertainties in the experimental data had a large effect on the conclusions that could be drawn from fitted models. This study showed that the presence of natural organic matter reduces the value of the infiltration basin as a microbial barrier.

Região Metropolitana de São Paulo, onde a disponibilidade hídrica foi classificada como \"Crítica\", durante os anos de 2014 e 2015 ocorreu um período de seca que originou a denominada \"crise hídrica\", agravando a situação dos mananciais que abastecem a região. Os estudos sobre mudanças climáticas demonstram não ser um fenômeno isolado e, diante disso, a adoção de tecnologias para reúso de água é essencial para aumentar a disponibilidade hídrica de locais que enfrentam cenários de escassez, como a RMSP. A recarga de aquíferos com efluentes tratados para reúso de água é uma técnica que, se adotada corretamente, pode trazer benefícios como o aumento do volume de água subterrânea disponível para a população. Para estudo da tecnologia, buscou-se como referência as plantas de Shafdan (Israel), Atlantis (África do Sul), Sabadell (Espanha), Adelaide (Austrália), avaliando principalmente os processos de tratamento, métodos de recarga e características qualitativas dos efluentes utilizados para recarga de aquíferos. Foram consultadas as legislações de Estados Unidos e da Espanha sobre o assunto e, com base nestas referências, foram adotados os seguintes requisitos de qualidade do efluente para recarga de aquíferos: sólidos suspensos (35 mg/L), carbono orgânico dissolvido (125,0 mg/L), DBO5,20 (25,0 mg/L), nitrato (25,0 mg/L) e Escherichia coli (1000 UFC/100 mL). A partir dos estudos de caso e das legislações, foi definido que o requisito mínimo de tratamento para recarga é o tratamento terciário para remoção de nitrogênio. Foi avaliada a replicabilidade desta técnica na Região Metropolitana de São Paulo através de comparativos entre os requisitos definidos e as características do efluente e da água de reúso produzida na RMSP em quatro cenários: legislação aplicável ao lançamento de efluentes tratados, características do efluente tratado a nível secundário de uma das ETEs da RMSP, características da água de reúso produzida na RMSP para usos urbanos e características da água de reúso produzida para uso industrial na planta Aquapolo. Verificou-se que atualmente apenas a água de reúso produzida no Aquapolo é submetida a tratamento terciário e atende aos requisitos qualitativos para recarga adotados neste trabalho. O custo de operação de um sistema de produção de água de reúso e recarga de aquíferos foi estimado em US$ 1,41/m³, valor superior à tarifa de água potável comercializada para residências na RMSP, atualmente US$ 0,75/m³. Concluiu-se que há potencial para adoção da tecnologia de recarga de aquíferos com água de reúso na RMSP, visto que há tecnologia disponível para produzir água de reúso na qualidade requerida. Ainda assim, é necessária a avaliação da hidrogeologia local antes de praticar a recarga. Em relação ao custo, o valor da tarifa de água potável vigente é expressivamente menor quando comparado ao valor caso a tecnologia proposta nesse trabalho fosse implantada. Entretanto, deve-se avaliar a importância da adoção de alternativas para disponibilização de água para a população. Ou seja, mesmo que em primeira vista seja mais onerosa, esta técnica é uma oportunidade para obtenção de água para diversos usos em situações de extrema seca, quando o valor da água passa a ser inestimável. / In the São Paulo metropolitan region, where water availability was classified as \"critical\", during the years of 2014 and 2015 there was a period of drought that led to the \"water crisis\", aggravating the situation of the water sources that supply the region. Studies on climate change demonstrate not be an isolated phenomenon and, given this, the adoption of technologies for reuse of water is essential to increase the water availability in areas facing drought situations, like SPMR. The aquifer recharge with treated wastewater to water reuse is a technics that, if properly implemented, can bring benefits as increasing the volume of groundwater available to the population. For the study of the technology, the reference plants were Shafdan (Israel), Atlantis (South Africa), Sabadell (Spain), Adelaide (Australia), survey the treatment processes, recharge methods and qualitative characteristics of effluents to aquifer recharge. The legislation of the United States and Spain was consulted and, based on these references, the following aquifer recharge effluent quality requirements were adopted: suspended solids (35 mg/L), organic solved carbon (125,0 mg/L), BOD5,20 (25,0 mg/L), nitrate (25,0 mg/L) e Escherichia coli (1000 UFC/100 mL). From the case studies and legislation, it was defined that the minimum treatment requirement for recharge is the tertiary treatment for nitrogen removal. The replicability of this technics in the Metropolitan Region of São Paulo was survey through comparisons between the defined requirements and the characteristics of the effluent and the reuse water produced in the RMSP in four scenarios: applicable legislation to treated effluents discharge, effluent characteristics at secondary level treated, reuse water produced in the SPMR for urban uses and characteristics of the reuse water produced for industrial use in Aquapolo. It was verified that currently only the reuse water produced in Aquapolo is subjected to tertiary treatment and meets the qualitative requirements for recharge adopted in this study. The operating cost of a reuse and aquifer recharge water production system was estimated at US$ 1,41 / m³, which is higher than the drinking water tariff traded for residences in the RMSP, currently US$ 0,75 / m³. It was concluded that there is potential for the adoption of recharge water reuse technology in the RMSP, because the technology is available there to produce reuse water in the required quality. Nevertheless, it is necessary to study the local hydrogeology before the recharge. About cost, the value of the current drinking water tariff is significantly lower when compared to the value in case the technology proposed in this work was implemented. However, the importance of adopting alternatives for water availability to the population should be study. That is, even if it is more expensive at first sight, this technique is an opportunity to obtain water for various uses in situations of extreme drought, when the water value becomes inestimable.

Este trabalho visa avaliar a recarga e o sistema de fluxo do aqüífero Guarani com o auxílio de um modelo numérico, aplicado à área delimitada pelas bacias hidrográficas dos rios Jacaré-Guaçú e Jacaré-Pepira (sub-bacias do rio Tietê, na região central do Estado de São Paulo, Brasil). Com este fim, foi estabelecido um modelo conceitual para o sistema de escoamento subterrâneo. Técnicas em SIG foram utilizadas no armazenamento, processamento e análise de dados levantados em intensa revisão bibliográfica, bem como, gerados mapas com as características dimensionais e hidrogeológicas. Os fenômenos hidrológicos mais significativos foram selecionados, resultando na construção do modelo conceitual para estimativa de fluxo e recarga do aqüífero, que possui na área de estudo significativa extensão de afloramento. Foram atribuídas seis zonas de recarga correspondentes a formações e estruturas geológicas que compõem o aqüífero semiconfinado e livre. O modelo foi calibrado pelas vazões de base, obtidas de hidrogramas diários, e pelos níveis estáticos de poços. Uma análise de sensibilidade foi realizada envolvendo os parâmetros de ajuste da calibração. Os resultados mostram existir interação entre as recargas do aqüífero, provenientes das duas bacias, e indicam que o aqüífero essencialmente drena a sua recarga através dos rios. Os fluxos laterais (fluxo subterrâneo entre bacias), a descarga profunda e a explotação por poços representam pequenas saídas em comparação à recarga total, contudo, a ação dos poços apresenta efeitos com alguma tendência regional no entorno dos maiores centros urbanos da área de estudo. A determinação das vazões de base identificou os trechos ao longo dos rios nos quais o aqüífero os carrega e é carregado. Apesar do aqüífero essencialmente abastecer os rios, os trechos nos quais os rios o carregam são significativos e importantes por serem trechos nas quais o aqüífero é potencialmente mais vulnerável. / This work aims to assess the recharge and flow system of the Guarani aquifer with the aid of a numeric model, applied to the area delimited for the hydrographic basins of the rivers Jacaré-Guaçú and Jacaré-Pepira (sub-basin of the Tietê river, in the central region of São Paulo State, Brazil). Thus, a conceptual model for groundwater flow system was established. GIS based tools was used in the storage, processing and analysis of data raised in intense bibliographical revision as well as generated maps with the dimensional and hydrogeologic characteristics. Main hydrologic phenomena were selected, leading to a groundwater conceptual model for evaluation of recharge and groundwater flow, taking into account the significant outcrop region in the study area. The geologic formations and structures were attributed to six corresponding zones of recharge that compose the semi-confined and free aquifer. The model was calibrated by the baseflow from daily hydrograms and by the static level from wells. It was carried out a sensitivity analysis including the calibration parameter set. The results show that there is interaction between aquifer recharge from the two basins and that the aquifer mainly drain its recharge into the rivers. The lateral flows (groundwater flows between basins), the deep discharge and the groundwater exploitation from wells represent small exits in comparison to the total recharge; however, the action of the wells presents effect with some regional trend in the vicinity of the biggest urban centers of the study area. The determination of the baseflows identified the stretches to long of the rivers in which the aquifer loads and is loaded. Despite the aquifer essentially supplying the rivers, the stretches in which the rivers load it are significant and important for being stretches in which the aquifer is potentially more vulnerable.

Região Metropolitana de São Paulo, onde a disponibilidade hídrica foi classificada como \"Crítica\", durante os anos de 2014 e 2015 ocorreu um período de seca que originou a denominada \"crise hídrica\", agravando a situação dos mananciais que abastecem a região. Os estudos sobre mudanças climáticas demonstram não ser um fenômeno isolado e, diante disso, a adoção de tecnologias para reúso de água é essencial para aumentar a disponibilidade hídrica de locais que enfrentam cenários de escassez, como a RMSP. A recarga de aquíferos com efluentes tratados para reúso de água é uma técnica que, se adotada corretamente, pode trazer benefícios como o aumento do volume de água subterrânea disponível para a população. Para estudo da tecnologia, buscou-se como referência as plantas de Shafdan (Israel), Atlantis (África do Sul), Sabadell (Espanha), Adelaide (Austrália), avaliando principalmente os processos de tratamento, métodos de recarga e características qualitativas dos efluentes utilizados para recarga de aquíferos. Foram consultadas as legislações de Estados Unidos e da Espanha sobre o assunto e, com base nestas referências, foram adotados os seguintes requisitos de qualidade do efluente para recarga de aquíferos: sólidos suspensos (35 mg/L), carbono orgânico dissolvido (125,0 mg/L), DBO5,20 (25,0 mg/L), nitrato (25,0 mg/L) e Escherichia coli (1000 UFC/100 mL). A partir dos estudos de caso e das legislações, foi definido que o requisito mínimo de tratamento para recarga é o tratamento terciário para remoção de nitrogênio. Foi avaliada a replicabilidade desta técnica na Região Metropolitana de São Paulo através de comparativos entre os requisitos definidos e as características do efluente e da água de reúso produzida na RMSP em quatro cenários: legislação aplicável ao lançamento de efluentes tratados, características do efluente tratado a nível secundário de uma das ETEs da RMSP, características da água de reúso produzida na RMSP para usos urbanos e características da água de reúso produzida para uso industrial na planta Aquapolo. Verificou-se que atualmente apenas a água de reúso produzida no Aquapolo é submetida a tratamento terciário e atende aos requisitos qualitativos para recarga adotados neste trabalho. O custo de operação de um sistema de produção de água de reúso e recarga de aquíferos foi estimado em US$ 1,41/m³, valor superior à tarifa de água potável comercializada para residências na RMSP, atualmente US$ 0,75/m³. Concluiu-se que há potencial para adoção da tecnologia de recarga de aquíferos com água de reúso na RMSP, visto que há tecnologia disponível para produzir água de reúso na qualidade requerida. Ainda assim, é necessária a avaliação da hidrogeologia local antes de praticar a recarga. Em relação ao custo, o valor da tarifa de água potável vigente é expressivamente menor quando comparado ao valor caso a tecnologia proposta nesse trabalho fosse implantada. Entretanto, deve-se avaliar a importância da adoção de alternativas para disponibilização de água para a população. Ou seja, mesmo que em primeira vista seja mais onerosa, esta técnica é uma oportunidade para obtenção de água para diversos usos em situações de extrema seca, quando o valor da água passa a ser inestimável. / In the São Paulo metropolitan region, where water availability was classified as \"critical\", during the years of 2014 and 2015 there was a period of drought that led to the \"water crisis\", aggravating the situation of the water sources that supply the region. Studies on climate change demonstrate not be an isolated phenomenon and, given this, the adoption of technologies for reuse of water is essential to increase the water availability in areas facing drought situations, like SPMR. The aquifer recharge with treated wastewater to water reuse is a technics that, if properly implemented, can bring benefits as increasing the volume of groundwater available to the population. For the study of the technology, the reference plants were Shafdan (Israel), Atlantis (South Africa), Sabadell (Spain), Adelaide (Australia), survey the treatment processes, recharge methods and qualitative characteristics of effluents to aquifer recharge. The legislation of the United States and Spain was consulted and, based on these references, the following aquifer recharge effluent quality requirements were adopted: suspended solids (35 mg/L), organic solved carbon (125,0 mg/L), BOD5,20 (25,0 mg/L), nitrate (25,0 mg/L) e Escherichia coli (1000 UFC/100 mL). From the case studies and legislation, it was defined that the minimum treatment requirement for recharge is the tertiary treatment for nitrogen removal. The replicability of this technics in the Metropolitan Region of São Paulo was survey through comparisons between the defined requirements and the characteristics of the effluent and the reuse water produced in the RMSP in four scenarios: applicable legislation to treated effluents discharge, effluent characteristics at secondary level treated, reuse water produced in the SPMR for urban uses and characteristics of the reuse water produced for industrial use in Aquapolo. It was verified that currently only the reuse water produced in Aquapolo is subjected to tertiary treatment and meets the qualitative requirements for recharge adopted in this study. The operating cost of a reuse and aquifer recharge water production system was estimated at US$ 1,41 / m³, which is higher than the drinking water tariff traded for residences in the RMSP, currently US$ 0,75 / m³. It was concluded that there is potential for the adoption of recharge water reuse technology in the RMSP, because the technology is available there to produce reuse water in the required quality. Nevertheless, it is necessary to study the local hydrogeology before the recharge. About cost, the value of the current drinking water tariff is significantly lower when compared to the value in case the technology proposed in this work was implemented. However, the importance of adopting alternatives for water availability to the population should be study. That is, even if it is more expensive at first sight, this technique is an opportunity to obtain water for various uses in situations of extreme drought, when the water value becomes inestimable.

Este trabalho visa avaliar a recarga e o sistema de fluxo do aqüífero Guarani com o auxílio de um modelo numérico, aplicado à área delimitada pelas bacias hidrográficas dos rios Jacaré-Guaçú e Jacaré-Pepira (sub-bacias do rio Tietê, na região central do Estado de São Paulo, Brasil). Com este fim, foi estabelecido um modelo conceitual para o sistema de escoamento subterrâneo. Técnicas em SIG foram utilizadas no armazenamento, processamento e análise de dados levantados em intensa revisão bibliográfica, bem como, gerados mapas com as características dimensionais e hidrogeológicas. Os fenômenos hidrológicos mais significativos foram selecionados, resultando na construção do modelo conceitual para estimativa de fluxo e recarga do aqüífero, que possui na área de estudo significativa extensão de afloramento. Foram atribuídas seis zonas de recarga correspondentes a formações e estruturas geológicas que compõem o aqüífero semiconfinado e livre. O modelo foi calibrado pelas vazões de base, obtidas de hidrogramas diários, e pelos níveis estáticos de poços. Uma análise de sensibilidade foi realizada envolvendo os parâmetros de ajuste da calibração. Os resultados mostram existir interação entre as recargas do aqüífero, provenientes das duas bacias, e indicam que o aqüífero essencialmente drena a sua recarga através dos rios. Os fluxos laterais (fluxo subterrâneo entre bacias), a descarga profunda e a explotação por poços representam pequenas saídas em comparação à recarga total, contudo, a ação dos poços apresenta efeitos com alguma tendência regional no entorno dos maiores centros urbanos da área de estudo. A determinação das vazões de base identificou os trechos ao longo dos rios nos quais o aqüífero os carrega e é carregado. Apesar do aqüífero essencialmente abastecer os rios, os trechos nos quais os rios o carregam são significativos e importantes por serem trechos nas quais o aqüífero é potencialmente mais vulnerável. / This work aims to assess the recharge and flow system of the Guarani aquifer with the aid of a numeric model, applied to the area delimited for the hydrographic basins of the rivers Jacaré-Guaçú and Jacaré-Pepira (sub-basin of the Tietê river, in the central region of São Paulo State, Brazil). Thus, a conceptual model for groundwater flow system was established. GIS based tools was used in the storage, processing and analysis of data raised in intense bibliographical revision as well as generated maps with the dimensional and hydrogeologic characteristics. Main hydrologic phenomena were selected, leading to a groundwater conceptual model for evaluation of recharge and groundwater flow, taking into account the significant outcrop region in the study area. The geologic formations and structures were attributed to six corresponding zones of recharge that compose the semi-confined and free aquifer. The model was calibrated by the baseflow from daily hydrograms and by the static level from wells. It was carried out a sensitivity analysis including the calibration parameter set. The results show that there is interaction between aquifer recharge from the two basins and that the aquifer mainly drain its recharge into the rivers. The lateral flows (groundwater flows between basins), the deep discharge and the groundwater exploitation from wells represent small exits in comparison to the total recharge; however, the action of the wells presents effect with some regional trend in the vicinity of the biggest urban centers of the study area. The determination of the baseflows identified the stretches to long of the rivers in which the aquifer loads and is loaded. Despite the aquifer essentially supplying the rivers, the stretches in which the rivers load it are significant and important for being stretches in which the aquifer is potentially more vulnerable.

Managed aquifer recharge (MAR) is widely applied for sustainable groundwater management. Despite its apparent simplicity, the evaluation of MAR schemes can be challenging especially with regard to feasibility assessment, planning but also operation. The absence of proper evaluation methods hinders the optimal operational management, reduces the level of public trust and raises questions about the impact of MAR on the affected ecosystem. The development of appropriate tools could help water utilities to maximize the use of groundwater while satisfying physical, financial, and sustainability constraints. As overall objective, the application of new and advanced tools can increase the understanding of the underlying processes and in that way increase the confidence in MAR and foster the successful implementation of MAR schemes. The thesis consists of three main parts which objectives are to: 1) understand the role of modelling in MAR and identify information gaps by a review of available modelling studies; 2) increase the availability of efficient database and analytical tools including their development and web-based implementation; and 3) improve and contribute to new advances in numerical modelling of MAR. A survey of conducted modelling studies, mainly based on numerical methods, revealed that groundwater flow models are most frequently applied to assess MAR schemes. Modelling objectives comprise the planning and optimization of the design and operation of a MAR facility as well as its impact on the groundwater system. Simulations help to assess the achievable recovery efficiency and occurring geochemical processes to minimize the risk of failure of a planned facility, also with regard to long-term impacts. Furthermore, site-selection and the influence of MAR on seawater intrusion are frequently analysed by modelling. The literature review served as a basis for the MAR model selection tool which enables, dependent on objectives, methods and model types, to extract suitable models and case studies. Based on analytical equations to determine groundwater mounding, saltwater intrusion or the pumping-induced river drawdown, further tools were developed and compiled on a web-based platform for easy access and utilization. The web-based applications can be used as screening tools to assess MAR-related issues. For a more detailed analysis, numerical models represent useful instruments to analyse MAR schemes on various scales. On regional scale, the feasibility of MAR implementation at proposed locations is often a challenging question due to the lack of detailed knowledge of the local groundwater system and its response to MAR. Consequently, an approach combining numerical groundwater flow modelling and GIS-based multi-criteria decision-analysis (MCDA) was formulated and subsequently tested for the city centre of Hanoi, Vietnam. The results indicate that MAR could help to reduce the local overexploitation of groundwater and stop land subsidence. For existing MAR schemes on local scale, the residence time in the subsurface is a critical parameter determining e.g. the removal of pathogens. As the influence of viscosity on the seasonal residence time is not fully clear, a numerical groundwater flow and heat transport model was set up for a MAR scheme in Berlin, Germany to evaluate the seasonal impact of viscosity. The results suggest that the consideration of viscosity in the numerical modelling scheme has an influence on the subsurface travel time and results in shorter residence times. At point scale, clogging represents a critical issue with regard to the long-term viability of a MAR scheme which is frequently neglected in numerical models. The numerical unsaturated flow model HYDRUS-1D/2D was enhanced to enable the simulation of time-variable hydraulic conductivities as an approximation of clogging. With the help of the time-variable scaling factor in combination with the reservoir boundary condition, the increasing water head in the laboratory aquifer well and infiltration basin due to clogging was reproduced. The presented tools and numerical modelling approaches are useful to assess a wide range of MAR-specific issues, to manage the risks associated with implementation and operation and improve the overall performance and reliability of MAR schemes. Through the application of suitable data-based, analytical and numerical tools, the thesis contributes to the perception of MAR as a suitable and reliable technique for water resource management.:1 INTRODUCTION 1 2 ASSESSMENT OF MANAGED AQUIFER RECHARGE THROUGH MODELLING 11 3 WEB-BASED EMPIRICAL AND ANALYTICAL TOOLS FOR INITIAL MAR-RELATED ASSESSMENT 29 4 MANAGED AQUIFER RECHARGE FEASIBILITY ASSESSMENT USING GIS-BASED SUITABILITY MAPPING AND NUMERICAL MODELLING 53 5 INFLUENCE OF VISCOSITY ON THE SEASONAL RESIDENCE TIME DURING MAR OPERATION 73 6 SIMULATION OF HYDRAULIC CONDUCTIVITY CHANGES OVER TIME DURING MAR OPERATION 91 7 SCIENTIFIC IMPLICATIONS AND RESEARCH PERSPECTIVES...113 Bibliography 117 A Appendix 143 / Grundwasseranreicherung (engl. Managed Aquifer Reharge, MAR) wird oftmals für ein nachhaltiges Grundwassermanagement eingesetzt. Trotz der scheinbaren Einfachheit von MAR, kann die Bewertung insbesondere in Bezug auf Machbarkeitsstudien, Planung, aber auch Betrieb herausfordernd sein. Das Fehlen geeigneter Bewertungsmethoden hindert ein optimales Betriebsmanagement, reduziert das Vertrauen der Öffentlichkeit und wirft Fragen über die Auswirkungen von MAR auf das betroffene Ökosystem auf. Die Entwicklung geeigneter Instrumente könnte daher Wasserversorgern helfen, die Nutzung des Grundwassers zu maximieren und gleichzeitig physische, finanzielle und nachhaltige Bedingungen einzuhalten. Als übergeordnetes Ziel kann die Anwendung neuer und fortschrittlicher Instrumente das Verständnis für die zugrunde liegenden Prozesse verbessern und so das Vertrauen in MAR stärken und die erfolgreiche Umsetzung von MAR-Anlagen fördern. Die Arbeit besteht aus drei Hauptteilen, deren Ziele es sind: 1) die Rolle der Modellierung von MAR zu verstehen und Informationslücken durch eine Überprüfung der verfügbaren Modellierungsstudien zu identifizieren; 2) die Verfügbarkeit effizienter datenbankbasierter und analytischer Instrumente einschließlich ihrer Entwicklung und webbasierten Implementierung zu erhöhen; und 3) mit Hilfe von neuen Fortschritten die numerische Modellierung von MAR-Anlagen zu verbessern und zu unterstützen. Eine Literaturrecherche bereits durchgeführter Modellierungsstudien, die vor allem auf numerischen Modellen beruhen, ergab, dass Grundwasserströmungsmodelle am häufigsten zur Beurteilung von MAR-Anlagen eingesetzt werden. Die Modellierungsziele umfassen die Planung und Optimierung des Aufbaus und des Betriebs einer MAR-Anlage sowie deren Auswirkungen auf das Grundwassersystem. Simulationen helfen, die erreichbare Rückgewinnungseffizienz und die auftretenden geochemischen Prozesse zu beurteilen, um das Ausfallrisiko einer geplanten Anlage auch im Hinblick auf langfristige Auswirkungen zu minimieren. Darüber hinaus wird die Standortauswahl und der Einfluss von MAR auf das Eindringen von Meerwasser häufig durch Modellierung analysiert. Die Literaturrecherche diente als Grundlage für das MAR-Modellauswahl-Tool, bei dem in Abhängigkeit von Zielen, Methoden und Modelltypen geeignete Modelle und Fallstudien extrahiert werden können. Weitere Werkzeuge, die auf analytischen Gleichungen zur Bestimmung von Grundwasseraufwölbung, Salzwasserintrusion oder der pumpinduzierten Durchflussreduzierung im Fließgewässer basieren, wurden entwickelt und auf der webbasierten INOWAS-Plattform für einen einfachen Zugang und Nutzung zusammengestellt. Die webbasierten Anwendungen können als Screening-Instrumente zur Beurteilung von MAR-bezogenen Problemen eingesetzt werden. Für eine detailliertere Analyse stellen numerische Modelle nützliche Instrumente zur Analyse von MAR-Anlagen auf verschiedenen Skalen dar. Auf regionaler Ebene ist die Machbarkeit der Umsetzung von MAR an den vorgeschlagenen Standorten oft eine schwierige Frage, da das lokale Grundwassersystem und seine Reaktion auf die Anwendung von MAR nicht hinreichend bekannt sind. Dazu wurde ein Ansatz entwickelt, der numerische Grundwasserströmungsmodellierung und GIS-basierte multikriterielle Entscheidungsanalyse (MCDA) kombiniert, um die Machbarkeit und mögliche Auswirkungen der MAR-Implementierung zu bewerten. Der kombinierte Ansatz wurde im Stadtzentrum von Hanoi, Vietnam, getestet, wo die Ergebnisse darauf hindeuten, dass MAR dazu beitragen könnte, die lokale Übernutzung zu reduzieren und die Bodensenkung zu stoppen. Auf lokaler Ebene bei bestehenden MAR-Systemen ist die Verweilzeit im Untergrund ein kritischer Parameter, der z.B. die Entfernung von Krankheitserregern bestimmt. Da der Einfluss von Viskosität auf die saisonale Verweildauer nicht eindeutig ist, wurde für eine MAR-Anlage in Berlin ein numerisches Grundwasserströmungs- und Wärmetransportmodell erstellt, um die saisonalen Auswirkungen des Prozesses zu bewerten. Die Ergebnisse deuten darauf hin, dass Viskosität einen Einfluss auf die unterirdische Verweilzeit hat und zu einer Verkürzung der Aufenthaltszeiten führt. Auf kleiner Skala stellt die Kolmatierung ein wichtiges Thema dar, das den Erfolg eines MAR-Systems erheblich bestimmt, jedoch in numerischen Modellen häufig vernachlässigt wird. Das numerische ungesättigte Strömungsmodell HYDRUS-1D/2D wurde erweitert, um die Simulation von zeitlich variablen hydraulischen Leitfähigkeiten als vereinfachte Näherung von Kolmatierung zu ermöglichen. Mit Hilfe des zeitlich variablen Skalierungsfaktors in Kombination mit der Speicherrandbedingung konnte der im Labor gemessene, durch Kolmatierung verursachte, ansteigende Wasserspiegel im Brunnen und Infiltrationsbecken reproduziert werden. Die vorgestellten Werkzeuge und numerischen Modellierungsansätze sind nützlich, um eine breite Palette von MAR-spezifischen Fragen zu bewerten, um die mit der Implementierung und dem Betrieb verbundenen Risiken zu managen und die Gesamtleistung und Zuverlässigkeit von MAR-Anlagen zu verbessern. Durch den Einsatz geeigneter empirischer, analytischer und numerischer Werkzeuge trägt die Arbeit dazu bei, dass MAR als eine geeignete und zuverlässige Technik für das Wasserressourcenmanagement angesehen wird.:1 INTRODUCTION 1 2 ASSESSMENT OF MANAGED AQUIFER RECHARGE THROUGH MODELLING 11 3 WEB-BASED EMPIRICAL AND ANALYTICAL TOOLS FOR INITIAL MAR-RELATED ASSESSMENT 29 4 MANAGED AQUIFER RECHARGE FEASIBILITY ASSESSMENT USING GIS-BASED SUITABILITY MAPPING AND NUMERICAL MODELLING 53 5 INFLUENCE OF VISCOSITY ON THE SEASONAL RESIDENCE TIME DURING MAR OPERATION 73 6 SIMULATION OF HYDRAULIC CONDUCTIVITY CHANGES OVER TIME DURING MAR OPERATION 91 7 SCIENTIFIC IMPLICATIONS AND RESEARCH PERSPECTIVES...113 Bibliography 117 A Appendix 143

Soil aquifer treatment (SAT), the removal of contaminants during percolation through soil, is a strategy employed in managed aquifer recharge (MAR), one method of indirect potable water reuse. As part of Hampton Roads Sanitation District's (HRSD) MAR project, The Sustainable Water Initiative for Tomorrow (SWIFT), a soil column study was performed using four columns filled with sand taken from the Potomac Aquifer System (PAS) as well as water from various stages in SWIFT's 1MGD demonstration facility. Two pairs of two columns were operated in series, simulating 3 days and 1 month of travel time through aerobic to anaerobic conditions. During Phase 1 of testing, each pair of columns was fed from different stages in the SWIFT treatment process. During Phase 2 of testing, one set of columns was spiked with a conservative tracer bromide, and several contaminants of emerging concern (CECs). The contaminants monitored during both phases included total organic carbon (TOC), nitrogen species, and the disinfection byproducts bromate and NDMA. During Phase 2 of testing, CECs, iron, arsenic, bromide, and sulfate were monitored in addition to those monitored during Phase 1. About 50% of the TOC was removed within 3 days of travel time, with no additional removal observed in 1 month. Nitrate was conserved in the 3-day columns, but completely removed after 1 month, indicating denitrification. Bromate and NDMA were reduced significantly in the 3-day columns and mostly non-detect in the 1-month effluent. Many of the spiked CECs were reduced significantly in the 3-day column indicating degradation. Three compounds exhibited some retardation through both columns but were not degraded. A few compounds, notably perfluorooctanoic acid (PFOA), showed no retardation or degradation. / Master of Science / In order to continue to meet the water demands of the future, potable reuse is a necessary and effective solution. HRSD's SWIFT project aims to create a sustainable source of drinking water through advanced treatment of its wastewater effluent and subsequent recharge of the Potomac Aquifer in a process known as managed aquifer recharge (MAR). During MAR, chemical and biological contaminants are attenuated or removed through a process known as soil aquifer treatment (SAT). HRSD installed pilot-scale soil columns at their 1MGD SWIFT demonstration facility to evaluate the potential removal of contaminants. During the study, removal of contaminants, both regulated and unregulated, was observed. This study demonstrated that SAT provides an effective environmental barrier against many contaminants and helped to inform the level of treatment necessary to protect public health during MAR potable reuse projects.

Soil aquifer treatment (SAT) during managed aquifer recharge has been studied as a method of providing additional environmental barriers to pathogens and contaminants in indirect potable reuse (IPR) applications. A soil column study was conducted by Hampton Roads Sanitation District in order to evaluate the effectiveness of SAT, as a component of its IPR project involving the replenishment of the Potomac Aquifer System (PAS), in providing a sustainable source of drinking water. Four packed soil columns were constructed with sand from the PAS and were designed to simulate the travel time of 3 days and 30 days. The tests conducted aimed at evaluating pathogen removal (MS2, E. coli and Cryptosporidium oocysts); evaluating attenuation of regulated (nitrate, nitrite, bromate, trihalomethane (THM), haloacetic acids (HAA), organic carbon) and unregulated contaminants of concern that affect drinking water quality. Effective pathogen removal was observed with 6 to 7-log removals of MS2 and E. coli and 3 to 5-log removals of microbeads, used as a surrogate for Cryptosporidium. Removal across 3 day columns was comparable to 30-day columns but the potential to achieve higher removal with longer retention time was acknowledged. Nitrate, bromate, THMs and HAAs were completely reduced in 30-day columns. Total organic carbon was removed at 25 – 35% in all four columns. Seven out of the 106 contaminants of emerging concern (CEC) tested were consistently detected in the column feed and effluent at concentrations greater than 100 ng/L; some compounds showed potential for removal while no conclusive results were drawn for the remaining compounds. / MS / Potable reuse is a sustainable solution to the increasing water demands of the present and more so the future. Hampton Road Sanitation District (HRSD) aims to treat effluent from its wastewater treatment plants using advanced treatment process for direct recharge of the Potomac aquifer system. This is a method of indirect potable reuse termed as managed aquifer recharge (MAR). MAR can provide additional environmental barriers to contaminants present in water through a process of natural attenuation called soil aquifer treatment (SAT). A soil column study was conducted at HRSD’s pilot scale facility in order to asses SAT under controlled conditions at a meaningful scale. Attenuation of pathogens; regulated contaminants (nitrate, nitrite, bromate, etc.) and contaminants of emerging concern was evaluated through the soil columns. The results showed effective removal of most contaminants of interest which demonstrated that SAT potentially improves water quality and meets public health standards in potable reuse applications.