Petroleum leakage from storage tanks, underground pipelines during exploration and production facilities is the reason of hydrocarbon migration into the groundwater. Petroleum companies use various LNAPL (Light Non-Aqueous Phase Liquids) recovery techniques to prevent lateral migration of hydrocarbon through the offsite of a facility. A petroleum refinery facility in the Gulf Coast region of South Texas was selected to evaluate ongoing LNAPL recovery system. Three analyses were carried out in this study. First, hydrogeologic conditions were determined using DGP (Diagnostic Gauge Plots). The concept of why ANT (Apparent LNAPL Thickness) is not a good metric to estimate recovery rates was explained based on hydrogeologic conditions of LNAPL. LNAPL and groundwater surface contour maps were built to have information about the direction of flow. All map illustrations were created using ArcGIS software. Well configurations were used to determine hydrogeologic condition in case of lack sufficient data for DGP. Second, LNAPL transmissivity were estimated using API (American Petroleum Institute) LNAPL Transmissivity Workbook. LNAPL condition was required in estimating LNAPL transmissivity values with API workbook, where methods of analysis are dependent of LNAPL condition. Total fluids recovery data were also used to estimate transmissivity values in the study wells. 0.08 ft2/d transmissivity value was arbitrarily chosen to determine the endpoint of recovery. Third, LNAPL recovery rates were predicted using LDRM (LNAPL Distribution and Recovery Model) for 11 recovery wells in the study region. Single phase –water- extraction method was used for LNAPL recovery under atmospheric conditions. Soil and fluid properties along with recovery system data were required for LNAPL recovery estimation. Some of these data were available from the dataset provided by oil company and some of them were estimated using API and Rosetta databases. Soil properties, radius of recovery values, and water production rates were calibrated in order to fit the LDRM recovery and transmissivity results with the actual field data. The modeled recovery rates and transmissivity values were consistent with actual data. Projections for future in a well were made. The model can be used for the endpoint of recovery projections. / text

The presence of light non-aqueous phase liquid (LNAPL) in the subsurface constitutes a long-term source of pollution for groundwater. Hence understand the movement of NAPL in the subsurface is essential in order to design effective remediation technology. Their movement in the subsurface is so complex that researchers have been using different media, different NAPLs, and conducted experiments in 1-D column, 2-D tank and 3-D tank in order to study the phenomenon. To solve the problem of limitation in flow boundaries in 1-D researchers have used two dimensional (2-D) tanks made of glass and plexiglass. However there have been some questions concerning the possible impact of NAPL wettability on materials use to construct the tank. This wettability may influence the flow of fluids at the visual interface. A representative LNAPL (dodecane) was released in the vadose zone of an Ottawa sand. Two external constant head reservoirs were used to maintain a constant water table in the tank. Time-series digital images of plume were used to analyze the geometry and position of the plume in the tanks regarding to the water table. Then relative geometry of the LNAPL was compared to Pantazidou and Sitar's equation. In both the sand and the glass tank, water is the wetting fluid, whereas dodecane (LNAPL) is the non-wetting fluid. However, on the plexiglass the LNAPL is the wetting fluid. As a result 40% and 70% difference were observed between glass and plexiglass tanks regarding the length and the thickness, and the area was twice the size of the plume in the glass tank. This demonstrates that the tank material is an important parameter to be considered on flow visualization of NAPL. Moreover, the influence of ethanol on dodecane was tested on a 2-D tank in glass. The results showed that the presence of ethanol appears to influence on the size and position of the plume in the subsurface.

No / Accidental spills of hydrocarbons, such as Light Non-Aqueous Phase Liquids (LNAPLs), are one of the most common sources of subsurface contamination. Migration of LNAPL in a porous medium is influenced by various factors such as the number of fluids present in the unsaturated/saturated zones and the proportion of pores occupied by each fluid. The results for relationship between matric suction and degree of saturation are presented in this paper for water¿air, water¿LNAPL and LNAPL¿air systems in a sand. A simple and reliable setup using Buchner funnel was designed to obtain these relations. It was found that the relationship between matric suction head and degree of saturation is hysteretic for all the fluid systems (water¿air, water¿LNAPL and LNAPL¿air). Furthermore, the amount of hysteresis depended upon the fluid system, with the maximum hysteresis occurring for water¿air system. The results suggest that the amount of trapped air depends upon the reversal degree of saturation from drying to wetting.

In this field-scale study, air sparging (AS) system was applied at a petroleum-hydrocarbon spill site to remediate contaminated soil and groundwater in situ. The objective of this study was to evaluate the effectiveness of the AS system on volatile organic compounds (VOC) removal via the volatilization mechanism. Moreover, the AS system would also enhance the in situ bioremediation process due to the increased oxygen concentration in the subsurface. Results from the preliminary site characterization show that high concentrations of benzene and toluene were present in the subsurface in the western part of the site. Up to 15.62 and 30,957 mg/Kg of benzene and toluene were detected in soil samples, respectively. Moreover, up to 0.068 and 4.8 mg/L of benzene and toluene were observed in groundwater samples, respectively. The following remediation activities were conducted during the one-year investigation and remediation period: 1. Construction of four recovery wells were for light non-aqueous phase liquid (LNAPL) and contaminated groundwater extraction to prevent the expansion of VOC plume. The extracted groundwater was delivered to the wastewater treatment plant for treatment before discharge. 2. Installation of ten air sparging wells to enhance the removal of VOC through volatilization and biodegradation processes. 3. Conduction of (1) soil gas survey, (2) soil and groundwater sampling and analyses, and microbial enumeration periodically to evaluate the effectiveness of AS on VOC removal. Results from the field-scale study indicate that the AS system is able to effectively contain the plume. This can be confirmed by the following findings: (1) decrease in VOC concentrations in both soil and groundwater, (2) increase in carbon dioxide and increase in oxygen concentrations in the soil gas samples, and (3) increase in bacterial population in soil samples. Results from this study indicate that AS system can effectively contain the plume and manage this petroleum hydrocarbon spill site.

Neste trabalho foi realizado um levantamento GPR 4D em laboratório no qual foi simulado o vazamento de óleo de uma ETD - Estação de Transmissão e Distribuição de Energia Elétrica. Os estudos consistiram em derramar 15 litros de óleo em três experimentos: tanque contendo areia seca, tanque contendo areia úmida mais gradiente hidráulico e tanque contendo areia úmida. Em todos os experimentos o objetivo foi detectar a pluma de contaminação e avaliar a migração desse óleo com o tempo. Os dados GPR 4D foram adquiridos utilizando-se uma antena blindada de 400 MHz modelo SIR-3000 equipamento da GSSI. O monitoramento no tempo de aquisição dos dados variou de 2 minutos até 12 dias. No experimento com o tanque preenchido com areia seca não foi possível determinar a pluma de contaminação devido ao baixo contraste entre as propriedades físicas do meio e a pluma contaminante. No experimento em que o tanque foi preenchido com areia úmida e havia a presença de um gradiente hidráulico, foi possível determinar a migração da pluma de contaminação a partir do 5º dia. Para finalizar, o 3º experimento onde o tanque estava cheio de areia úmida também não foi possível identificar a pluma, devido ao baixo contraste entre as propriedades físicas. Nesta pesquisa também foram realizadas modelagens numéricas 2D utilizando o método FDTD, onde foram simulados os três experimentos, considerando posições intermediárias da pluma de contaminação em função do tempo. Os resultados das modelagens foram concordantes com os resultados obtidos com dados reais e ajudaram a definir o padrão de reflexão da pluma contaminante. Os promissores resultados indicam que a determinação efetiva da pluma contaminante de óleo numa ETD é possível desde o meio que esteja saturado com água. Portanto, para garantir o sucesso das pesquisas GPR para fins de mapeamento e delineamento de plumas de contaminação em ETDs recomenda-se que a aquisição dos dados seja feita após um período de chuvas. / In this work a 4D GPR survey was accomplished in a laboratory in which a oil leak from a ETD Estação de Transmissão e Distribuição of electric energy was simulated. The studies consisted in an oil spill (15 liters) in three different experiments: i) tank containing dry sand, ii) tank containing wet sand with a hydraulic gradient and iii) tank containing wet sand. In all experiments the objective was detect the contamination plume and evaluate the migration of the oil with the time. The 4D GPR data was acquired using a shielded antenna of 400 MHz model SIR-3000 of the GSSI equipment. The time monitoring of the data acquisition ranged from 2 minutes up to 12 days. In the experiment-1 with the tank filled with dry sand wasnt possible to determine the plume contamination due to the low contrast of the physical properties between the environment and the plume. In the experiment-2 where the tank filled with the dry sand in the presence of a hydraulic gradient, was possible to determine the migration of the plume from the fifth day. Finally, the experiment-3 where the tank was filled with wet sand wasnt possible to identify the plume, due to the low contrast between the physical properties. This research also conducted 2D numerical modeling using the FDTD method, where the three experiments were simulated, considering intermediary positions of the contamination plume with respect with time. The results of the modeling were consistent with the results obtained with real data and helped to define a pattern of reflection of the contamination plume. The promising results indicate that the effective determination of the contaminating plume of oil in an ETD is possible provided that the environment be saturated with water. Therefore, to guarantee the success of researches with GPR for mapping and delineation of contamination plumes in ETDs its recommended that the data acquisition be realized in the rainy season.

Neste trabalho foi realizado um levantamento GPR 4D em laboratório no qual foi simulado o vazamento de óleo de uma ETD - Estação de Transmissão e Distribuição de Energia Elétrica. Os estudos consistiram em derramar 15 litros de óleo em três experimentos: tanque contendo areia seca, tanque contendo areia úmida mais gradiente hidráulico e tanque contendo areia úmida. Em todos os experimentos o objetivo foi detectar a pluma de contaminação e avaliar a migração desse óleo com o tempo. Os dados GPR 4D foram adquiridos utilizando-se uma antena blindada de 400 MHz modelo SIR-3000 equipamento da GSSI. O monitoramento no tempo de aquisição dos dados variou de 2 minutos até 12 dias. No experimento com o tanque preenchido com areia seca não foi possível determinar a pluma de contaminação devido ao baixo contraste entre as propriedades físicas do meio e a pluma contaminante. No experimento em que o tanque foi preenchido com areia úmida e havia a presença de um gradiente hidráulico, foi possível determinar a migração da pluma de contaminação a partir do 5º dia. Para finalizar, o 3º experimento onde o tanque estava cheio de areia úmida também não foi possível identificar a pluma, devido ao baixo contraste entre as propriedades físicas. Nesta pesquisa também foram realizadas modelagens numéricas 2D utilizando o método FDTD, onde foram simulados os três experimentos, considerando posições intermediárias da pluma de contaminação em função do tempo. Os resultados das modelagens foram concordantes com os resultados obtidos com dados reais e ajudaram a definir o padrão de reflexão da pluma contaminante. Os promissores resultados indicam que a determinação efetiva da pluma contaminante de óleo numa ETD é possível desde o meio que esteja saturado com água. Portanto, para garantir o sucesso das pesquisas GPR para fins de mapeamento e delineamento de plumas de contaminação em ETDs recomenda-se que a aquisição dos dados seja feita após um período de chuvas. / In this work a 4D GPR survey was accomplished in a laboratory in which a oil leak from a ETD Estação de Transmissão e Distribuição of electric energy was simulated. The studies consisted in an oil spill (15 liters) in three different experiments: i) tank containing dry sand, ii) tank containing wet sand with a hydraulic gradient and iii) tank containing wet sand. In all experiments the objective was detect the contamination plume and evaluate the migration of the oil with the time. The 4D GPR data was acquired using a shielded antenna of 400 MHz model SIR-3000 of the GSSI equipment. The time monitoring of the data acquisition ranged from 2 minutes up to 12 days. In the experiment-1 with the tank filled with dry sand wasnt possible to determine the plume contamination due to the low contrast of the physical properties between the environment and the plume. In the experiment-2 where the tank filled with the dry sand in the presence of a hydraulic gradient, was possible to determine the migration of the plume from the fifth day. Finally, the experiment-3 where the tank was filled with wet sand wasnt possible to identify the plume, due to the low contrast between the physical properties. This research also conducted 2D numerical modeling using the FDTD method, where the three experiments were simulated, considering intermediary positions of the contamination plume with respect with time. The results of the modeling were consistent with the results obtained with real data and helped to define a pattern of reflection of the contamination plume. The promising results indicate that the effective determination of the contaminating plume of oil in an ETD is possible provided that the environment be saturated with water. Therefore, to guarantee the success of researches with GPR for mapping and delineation of contamination plumes in ETDs its recommended that the data acquisition be realized in the rainy season.

Com a finalidade de estudar o comportamento de fluidos aquosos não miscíveis em água no solo, foram executados ensaios de laboratório, a construção de um modelo físico e a comparação dos dados com a simulação numérica com o programa HSSM. Os ensaios de laboratório tiveram a finalidade de obter os parâmetros do solo utilizado no modelo físico e numérico. Foram obtidas curvas de retenção do solo com concentrações de 2, 5, 10 e 15% de óleo e somente com água, para comparar o comportamento das curvas. Para o modelo físico, foi construído um tanque experimental para simular o derramamento de óleo no solo e, assim, obter uma pluma de contaminação de óleo de maneira controlada. Foram executados três ensaios com o tanque experimental, primeiro com o solo na umidade higroscópica, o segundo com um nível dágua definido, e o terceiro com o solo úmido, mas sem um nível dágua. Destes ensaios no tanque, foram coletadas amostras para a análise em laboratório das concentrações de óleo de cada parte do tanque. A partir dos resultados das curvas características foi possível observar que o óleo influencia principalmente na umidade residual. E a análise das amostras coletadas do tanque experimental indica que a concentração de óleo na pluma estava constante, com concentração de 2% de óleo. Juntando os dados colhidos dos ensaios de laboratório e do tanque experimental, foram executadas simulações da evolução da pluma de contaminação de NAPL para os três casos simulados no tanque experimental. A simulação numérica foi coerente com o modelo físico, mas foi observado que subestima a velocidade de expansão da pluma, principalmente quando o solo está com a umidade baixa. / In order to study the behavior of non-aqueous phased liquids in the soil, laboratory tests were performed, and the construction of a physical model and comparison of data obtained with the numerical simulation with the program HSSM. Laboratory tests are designed to obtain the soil parameters used in the physical and numerical model. Retention curves of soil with concentrations of 2, 5, 10 and 15% of oil and water only were obtained to compare the curves. For the physical model, an experimental tank was built to simulate the oil spill on the ground and have a contamination plume of oil with controlled conditions. Were performed three experiments with the tank, first with the hygroscopic soil moisture, the second with a defined water table, and the third with natural soil moisture, but without a water table. From these tests in the tank, samples were collected for laboratory analysis of concentrations of each part of the oil tank. From the results of the retention curves it was observed that the major oil influence was on residual moisture. And the analysis of samples collected from the experimental tank indicates that the oil concentration in the plume was constant at the concentration of 2% of oil. Combining the data collected in laboratory testing and experimental tank, numerical simulations were performed of the evolution of NAPL contamination plume for the three cases simulated in the experimental tank. The numerical simulation was consistent with the physical model, but it was observed that underestimates the rate of expansion of the contamination plume, especially when the moisture of soil is low.

Com a finalidade de estudar o comportamento de fluidos aquosos não miscíveis em água no solo, foram executados ensaios de laboratório, a construção de um modelo físico e a comparação dos dados com a simulação numérica com o programa HSSM. Os ensaios de laboratório tiveram a finalidade de obter os parâmetros do solo utilizado no modelo físico e numérico. Foram obtidas curvas de retenção do solo com concentrações de 2, 5, 10 e 15% de óleo e somente com água, para comparar o comportamento das curvas. Para o modelo físico, foi construído um tanque experimental para simular o derramamento de óleo no solo e, assim, obter uma pluma de contaminação de óleo de maneira controlada. Foram executados três ensaios com o tanque experimental, primeiro com o solo na umidade higroscópica, o segundo com um nível dágua definido, e o terceiro com o solo úmido, mas sem um nível dágua. Destes ensaios no tanque, foram coletadas amostras para a análise em laboratório das concentrações de óleo de cada parte do tanque. A partir dos resultados das curvas características foi possível observar que o óleo influencia principalmente na umidade residual. E a análise das amostras coletadas do tanque experimental indica que a concentração de óleo na pluma estava constante, com concentração de 2% de óleo. Juntando os dados colhidos dos ensaios de laboratório e do tanque experimental, foram executadas simulações da evolução da pluma de contaminação de NAPL para os três casos simulados no tanque experimental. A simulação numérica foi coerente com o modelo físico, mas foi observado que subestima a velocidade de expansão da pluma, principalmente quando o solo está com a umidade baixa. / In order to study the behavior of non-aqueous phased liquids in the soil, laboratory tests were performed, and the construction of a physical model and comparison of data obtained with the numerical simulation with the program HSSM. Laboratory tests are designed to obtain the soil parameters used in the physical and numerical model. Retention curves of soil with concentrations of 2, 5, 10 and 15% of oil and water only were obtained to compare the curves. For the physical model, an experimental tank was built to simulate the oil spill on the ground and have a contamination plume of oil with controlled conditions. Were performed three experiments with the tank, first with the hygroscopic soil moisture, the second with a defined water table, and the third with natural soil moisture, but without a water table. From these tests in the tank, samples were collected for laboratory analysis of concentrations of each part of the oil tank. From the results of the retention curves it was observed that the major oil influence was on residual moisture. And the analysis of samples collected from the experimental tank indicates that the oil concentration in the plume was constant at the concentration of 2% of oil. Combining the data collected in laboratory testing and experimental tank, numerical simulations were performed of the evolution of NAPL contamination plume for the three cases simulated in the experimental tank. The numerical simulation was consistent with the physical model, but it was observed that underestimates the rate of expansion of the contamination plume, especially when the moisture of soil is low.

Remediation of contaminated groundwater remains a high-priority national goal in the United States. Water is essential to life, and new sources of water are needed for an expanding population. Groundwater remediation remains a significant technical challenge despite decades of research into this field. New approaches are needed to address the most severely-polluted aquifers, and cost-effective solutions are required to meet remediation objectives that protect human health and the environment. Source reduction combined with Monitored Natural Attenuation (MNA) is a remediation strategy whereby the source of contamination is aggressively treated or removed and the residual groundwater plume depletes due to natural processes in the subsurface. The USEPA requires long-term performance monitoring of groundwater at MNA sites over the remediation timeframe, which often takes decades to complete. Presently, computational tools are lacking to adequately integrate source remediation with economic models. Furthermore, no framework has been developed to highlight the tradeoff between the degree of remediation versus the level of benefit within a cost structure. Using the Natural Attenuation Software (NAS) package developed at Virginia Tech, a set of formulae have been developed for calculating the TOR for petroleum-contaminated aquifers (specifically tracking benzene and MTBE) through statistical techniques. With the knowledge of source area residual saturation, groundwater velocity, and contaminant plume source length, the time to remediate a site contaminated with either benzene or MTBE can be determined across a range of regulatory maximum contaminant levels. After developing formulae for TOR, an integrated and interactive decision tool for framing the decision analysis component of the remediation problem was developed. While MNA can be a stand-alone groundwater remediation technology, significant benefits may be realized by layering a more traditional source zone remedial technique with MNA. Excavation and soil vapor extraction when applied to the front end of a remedial action plan can decrease the amount of time to remediation and while generally more expensive than an MNA-only approach, may accrue long-term economic advantages that would otherwise be foregone. The value of these research components can be realized within the engineering and science communities, as well as through government, business and industry, and communities where groundwater contamination and remediation are of issue. Together, these tools constitute the Sâ ªEâ ªEâ ªPâ ªAGE paradigm, founded upon the concept of sound science for an environmental engineering, effectual economics, and public policy agenda. The TOR formulation simplifies the inputs necessary to determine the number of years that an MNA strategy will require before project closure and thus reduces the specialized skills and training required to perform a numerical analysis that for one set of conditions could require many hours of simulation time. The economic decision tool, that utilizes a life cycle model to evaluate a set of feasible alternatives, highlights the tradeoffs between time and economics can be realized over the lifetime of the remedial project. / Ph. D.

Made available in DSpace on 2014-12-17T14:09:17Z (GMT). No. of bitstreams: 1 AdrianaMSR_TESE.pdf: 15407461 bytes, checksum: 9724571238317c177c2fdb4b02772cad (MD5) Previous issue date: 2013-05-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Activities that have fuel subterranean storage system are considered potentially polluting fuels by CONAMA Resolution 273, due to the possibility of leak, outpouring and overflow of fuel into the ground. Being even more worrying when contaminate groundwater for public supply, as the case of Natal City. For this reason, the Public Ministry/RN, in partnership with UFRN, developed the project environmental suitability of Gas stations in Natal, of which 36% showed evidence of contamination. This paper describes the four stages of the management of contaminated areas: preliminary assessment of environmental liabilities, detailed confirmatory investigation of the contamination, risk analysis to human health (RBCA), as well as the remediation plan of degraded areas. Therefore it is presented a case study. For the area investigated has been proposed a mathematical method to estimate the volume of LNAPL by a free CAD software (ScketchUp) and compare it with the partition method for grid area. Were also performed 3D graphics designs of feathers contamination. Research results showed that passive benzene contamination in groundwater was 2791.77 ?g/L, when the maximum allowed by CONAMA Resolution 420 is 5 ?g/L which is the potability standards. The individual and cumulative risks were calculated from 4.4 x10-3, both above the limits of 1.0 x10-5 or by RBCA 1.0 x10-6 by the Public Ministry/RN. Corrective action points that remediation of dissolved phase benzene is expected to reach a concentration of 25 ?g/L, based on carcinogenic risk for ingestion of groundwater by residents residential, diverging legislation. According to the proposed model, the volume of LNAPL using the ScketchUp was 17.59 m3, while by the grid partitioning method was 14.02 m3. Because of the low recovery, the expected removal of LNAPL is 11 years, if the multiphase extraction system installed in the enterprise is not optimized / Atividades que possuem sistema de armazenamento subterr?neo de combust?veis s?o consideradas potencialmente poluidoras pela Resolu??o CONAMA 273/2000, devido ? possibilidade de vazamento, derramamento e transbordamento de combust?veis para o solo. Sendo ainda mais preocupante quando contaminam ?guas subterr?neas destinadas ao abastecimento p?blico, como o caso de Natal. Por este motivo, o Minist?rio P?blico/RN, em parceria com a UFRN, desenvolveu o projeto de adequa??o ambiental dos postos revendedores de combust?veis em Natal, dos quais 36% apresentaram ind?cios de contamina??o. Este trabalho descreve as quatro etapas do gerenciamento de ?reas contaminadas: avalia??o preliminar do passivo ambiental, investiga??o confirmat?ria detalhada da contamina??o, an?lise de risco a sa?de humana (RBCA), bem como o plano de remedia??o das ?reas degradadas. E apresenta um estudo de caso. Para a ?rea investigada ? proposto um m?todo matem?tico para estimar o volume de fase livre auxiliado por um software CAD livre (ScketchUp), este foi comparado com o m?todo de parti??o da ?rea por grid. Tamb?m s?o realizados os designs gr?ficos 3D das plumas de contamina??o. Os resultados da investiga??o de passivo mostraram que a contamina??o por benzeno na ?gua subterr?nea foi 2791,77 ?g/L, quando o m?ximo permitido pela Resolu??o CONAMA 420/2009 ? de 5 ?g/L que ? o padr?o de potabilidade. Os riscos individual e cumulativo calculados foram de 4,4x10-3, ambos acima dos limites aceit?veis pelo RBCA de 1,0x10-5 ou pelo Minist?rio P?blico/RN de 1,0x10-6. A a??o corretiva aponta que a remedia??o da fase dissolvida de benzeno dever? atingir uma concentra??o de 25 ?g/L, com base no risco carcinog?nico, para ingest?o de ?gua subterr?nea para moradores residenciais, divergindo da legisla??o. De acordo com o modelo proposto, o volume de fase livre utilizando o ScketchUp foi de ? de 17,59 m3, enquanto o m?todo de parti??o por grid foi de 14,02 m3. Devido ? baixa recupera??o, a previs?o de remo??o da fase livre ? de 11 anos, caso o sistema de extra??o multif?sica instalado no empreendimento n?o seja otimizado / 2020-01-01