abstract: Characterization of petroleum spill site source zones directly influences the selection of corrective action plans and frequently affects the success of remediation efforts. For example, simply knowing whether or not nonaqueous phase liquid (NAPL) is present, or if there is chemical storage in less hydraulically accessible regions, will influence corrective action planning. The overarching objective of this study was to assess if macroscopic source zone features can be inferred from dissolved concentration vs. time data. Laboratory-scale physical model studies were conducted for idealized sources; defined as Type-1) NAPL-impacted high permeability zones, Type-2) NAPL-impacted lower permeability zones, and Type-3) dissolved chemical matrix storage in lower permeability zones. Aquifer source release studies were conducted using two-dimensional stainless steel flow-through tanks outfitted with sampling ports for the monitoring of effluent concentrations and flow rates. An idealized NAPL mixture of key gasoline components was used to create the NAPL source zones, and dissolved sources were created using aqueous solutions having concentrations similar to water in equilibrium with the NAPL sources. The average linear velocity was controlled by pumping to be about 2 ft/d, and dissolved effluent concentrations were monitored daily. The Type-1 experiment resulted in a source signature similar to that expected for a relatively well-mixed NAPL source, with dissolved concentrations dependent on chemical solubility and initial mass fraction. The Type-2 and Type-3 experiments were conducted for 320 d and 190 d respectively. Unlike the Type-1 experiment, the concentration vs. time behavior was similar for all chemicals, for both source types. The magnitudes of the effluent concentrations varied between the Type-2 and Type-3 experiments, and were related to the hydrocarbon source mass. A fourth physical model experiment was performed to identify differences between ideal equilibrium behavior and the source concentration vs. time behavior observed in the tank experiments. Screening-level mathematical models predicted the general behavior observed in the experiments. The results of these studies suggest that dissolved concentration vs. time data can be used to distinguish between Type-1 sources in transmissive zones and Type-2 and Type-3 sources in lower permeability zones, provided that many years to decades of data are available. The results also suggest that concentration vs. time data alone will be insufficient to distinguish between NAPL and dissolved-phase storage sources in lower permeability regions. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2014

Doctor of Philosophy / Department of Civil Engineering / Yacoub M. Najjar / This study explored the potential use of ANNs for profiling and characterization of various environmental sites. A static ANN with back-propagation algorithm was used to model the environmental containment at a hypothetical data-rich contaminated site. The performance of the ANN profiling model was then compared with eight known profiling methods. The comparison showed that the ANN-based models proved to yield the lowest error values in the 2-D and 3-D comparison cases. The ANN-based profiling models also produced the best contaminant distribution contour maps when compared to the actual maps. Along with the fact that ANN is the only profiling methodology that allows for efficient 3-D profiling, this study clearly demonstrates that ANN-based methodology, when properly used, has the potential to provide the most accurate predictions and site profiling contour maps for a contaminated site. ANN with a back-propagation learning algorithm was utilized in the site characterization of contaminants at the Kansas City landfill. The use of ANN profiling models made it possible to obtain reliable predictions about the location and concentration of lead and copper contamination at the associated Kansas City landfill site. The resulting profiles can be used to determine additional sampling locations, if needed, for both groundwater and soil in any contaminated zones. Back-propagation networks were also used to characterize the MMR Demo 1 site. The purpose of the developed ANN models was to predict the concentrations of perchlorate at the MMR from appropriate input parameters. To determine the most-appropriate input parameters for this model, three different cases were investigated using nine potential input parameters. The ANN modeling used in this case demonstrates the neural network’s ability to accurately predict perchlorate contamination using multiple variables. When comparing the trends observed using the ANN-generated data and the actual trends identified in the MMR 2006 System Performance Monitoring Report, both agree that perchlorate levels are decreasing due to the use of the Extraction, Treatment, and Recharge (ETR) systems. This research demonstrates the advantages of ANN site characterization modeling in contrast with traditional modeling schemes. Accordingly, characterization task-related uncertainties of site contaminations were curtailed by the use of ANN-based models.

The National Science Foundation has announced a plan to establish a Deep Underground Science and Engineering Laboratory (DUSEL) for interdisciplinary research in physics, geosciences, biosciences and engineering. The proposed laboratory will extend to a depth of about 2200 meters and will consist of research facilities for long term study. To date, eight sites in North America have been proposed to host DUSEL. One of these sites, known as Kimballton, is located near Butt Mountain in Giles County in southwestern Virginia. Two seismic lines were acquired along the top of Butt Mountain in June of 2004 to support the ongoing integrated site characterization effort by the Kimballton Science Team. Both lines, approximately 3 km in length, are standard multifold seismic reflection data aimed at imaging faults, thrust sheets, and repeated sections of Paleozoic rocks in the vicinity of the proposed Kimballton site. Crooked line geometry, irregular geophone spacing, ground roll, and poor impedance contrasts between juxtapositioned rock units were challenges in processing the data. Non-standard processing techniques included the use of travel time tomography to accurately constrain near surface velocities, the use of 2D median filters to remove ground roll, and stacking only offsets exceeding 500 m. Interpretation of seismic data supports a triplicated stratigraphic section caused by the stacking of the the St. Clair and Narrows thrust sheets. The St. Clair and Narrows faults are interpreted as shear zones within ductile units of the Martinsburg Formation. 3D travel time tomography was used to build a near surface velocity model of Lines 1 and 2 for the purposes of imaging near surface structure and constraining the extent of topographic lineaments, which are interpreted as bedrock joint systems. Interpretation of the velocity models suggests that the broadly folded strata of the Butt Mountain synclinorium dip gently to the east along the hinge surface. The surface extrapolation of the Lookout Rock fault and the intersection of topographic lineaments with the seismic lines are expressed as low velocity zones that extend to depths of 150 m. This may be related to accelerated weathering along jointed rock surfaces. Results of this study have already been incorporated into the NSF proposal submitted by the Kimballton Science Team (http://www.phys.vt.edu/~kimballton/s2p/b2.pdf). / Master of Science

Thesis advisor: John E. Ebel / Thesis advisor: Alan L. Kafka / As the best seismic indicator of shear modulus, shear-wave velocity is an important property in engineering problems in near-surface site characterization. Several surface-wave methods have been developed to obtain the subsurface shear-wave velocity structure. This thesis compared three surface-wave methods, Spectral Analysis of Surface Waves (SASW) (Nazarian et al., 1983), Multichannel Analysis of Surface Waves (MASW) (Park et al., 1999), and Refraction Microtremor (ReMi) (Louie, 2001), to determine which method gives the best estimation of the 1-D shear-wave velocity profile of near-surface soils. We collected seismic data at three sites in the greater Boston area where there are direct measurements of shear-wave velocities for comparison. The three methods were compared in terms of accuracy and precision. Overall, the MASW and the ReMi methods have comparable quality of accuracy, whereas the SASW method is the least accurate method with the highest percentage differences with direct measurements. The MASW method is the most precise method among the three methods with the smallest standard deviations. In general, the MASW method is concluded to be the best surface-wave method in determining the shear-wave velocities of the subsurface structure in the greater Boston area.

The effective and efficient remediation of contaminated groundwater sites requires site specific information regarding the physical, chemical and biological properties of the aquifer. Building on the dipole flow test (DFT) and the dipole flow and tracer test (DFTT), the dipole flow and reactive tracer test (DFRTT) has been proposed as an alternative to current aquifer parameter estimation methods. A steady-state dipole flow field is created by circulating groundwater between chambers isolated by the dipole tool. A tracer is released into the injection chamber and the breakthrough curve at the extraction chamber is interpreted with the DFRTT specific model. The overall goal of this thesis was to demonstrate the ability of a prototype dipole system to produce tracer BTCs in conventional wells installed in an unconfined sandy aquifer. The Waterloo dipole probe was constructed and field tested at CFB Borden. DFTs conducted along the length of the screen of non-filter packed monitoring wells provided similar estimates of radial hydraulic conductivity (Kr) to slug tests and literature values. The geometric mean Kr estimated in the filter packed wells was approximately an order of magnitude greater than the mean Kr estimate for the non-filter packed wells due to short-circuiting through the filter pack. A total of 46 DFTTs were completed in the monitoring wells at CFB Borden to investigate the properties of the BTCs. The shape of the BTC for a conservative tracer is affected by test set up parameters, well construction, and aquifer formation properties. The BTCs from the DFTTs completed in the non-filter pack monitoring wells were categorized into four “type curves” based on the BTC properties. The differences between the type curves were largely defined by the ratio of K between the skin zone and the aquifer (Ks/Kr). Now that a series of DFTT BTCs have been generated, the DFRTT model will be used to estimate the aquifer parameters. To continue the work outlined in this thesis, DFRTTs are planned for well-documented contaminated sites.

The purpose of this study was to evaluate the effectiveness of traditional hydrogeologic characterization approaches in a highly heterogeneous glaciofluvial aquifer at the North Campus Research Site (NCRS), situated on the University of Waterloo campus. Continuous soil cores to a depth of approximately 18 m were collected during the installation of the CMT monitoring wells and the multi-screen pumping well. K estimates were obtained for the core by obtaining 471 samples and testing them with a falling head permeameter, as well as by utilizing empirical equations developed to estimate K. A geostatistical analysis performed on the K datasets yielded strongly heterogeneous kriged K fields for the site. K and Ss were also estimated via type curve analysis of slug and pumping test data collected at the site. The various K and Ss estimates were then evaluated by simulating the transient drawdown data using a 3D forward numerical model constructed using Hydrogeosphere (Therrien et al., 2005). Results showed that, while drawdown predictions generally improved as more complexity was introduced into the model, the ability to make accurate drawdown predictions at all of the CMT ports was inconsistent. These results suggest that new techniques may be required to accurately capture subsurface heterogeneity for improved predictions of flow in similar systems.

The effective and efficient remediation of contaminated groundwater sites requires site specific information regarding the physical, chemical and biological properties of the aquifer. Building on the dipole flow test (DFT) and the dipole flow and tracer test (DFTT), the dipole flow and reactive tracer test (DFRTT) has been proposed as an alternative to current aquifer parameter estimation methods. A steady-state dipole flow field is created by circulating groundwater between chambers isolated by the dipole tool. A tracer is released into the injection chamber and the breakthrough curve at the extraction chamber is interpreted with the DFRTT specific model. The overall goal of this thesis was to demonstrate the ability of a prototype dipole system to produce tracer BTCs in conventional wells installed in an unconfined sandy aquifer. The Waterloo dipole probe was constructed and field tested at CFB Borden. DFTs conducted along the length of the screen of non-filter packed monitoring wells provided similar estimates of radial hydraulic conductivity (Kr) to slug tests and literature values. The geometric mean Kr estimated in the filter packed wells was approximately an order of magnitude greater than the mean Kr estimate for the non-filter packed wells due to short-circuiting through the filter pack. A total of 46 DFTTs were completed in the monitoring wells at CFB Borden to investigate the properties of the BTCs. The shape of the BTC for a conservative tracer is affected by test set up parameters, well construction, and aquifer formation properties. The BTCs from the DFTTs completed in the non-filter pack monitoring wells were categorized into four “type curves” based on the BTC properties. The differences between the type curves were largely defined by the ratio of K between the skin zone and the aquifer (Ks/Kr). Now that a series of DFTT BTCs have been generated, the DFRTT model will be used to estimate the aquifer parameters. To continue the work outlined in this thesis, DFRTTs are planned for well-documented contaminated sites.

The purpose of this study was to evaluate the effectiveness of traditional hydrogeologic characterization approaches in a highly heterogeneous glaciofluvial aquifer at the North Campus Research Site (NCRS), situated on the University of Waterloo campus. Continuous soil cores to a depth of approximately 18 m were collected during the installation of the CMT monitoring wells and the multi-screen pumping well. K estimates were obtained for the core by obtaining 471 samples and testing them with a falling head permeameter, as well as by utilizing empirical equations developed to estimate K. A geostatistical analysis performed on the K datasets yielded strongly heterogeneous kriged K fields for the site. K and Ss were also estimated via type curve analysis of slug and pumping test data collected at the site. The various K and Ss estimates were then evaluated by simulating the transient drawdown data using a 3D forward numerical model constructed using Hydrogeosphere (Therrien et al., 2005). Results showed that, while drawdown predictions generally improved as more complexity was introduced into the model, the ability to make accurate drawdown predictions at all of the CMT ports was inconsistent. These results suggest that new techniques may be required to accurately capture subsurface heterogeneity for improved predictions of flow in similar systems.

Submitted by LEANDRO GOMES DE FREITAS (legfreitas_br@yahoo.com.br) on 2017-05-16T03:49:19Z No. of bitstreams: 1 FREITAS,L.G._MESTRADO_HRSC_CH4.pdf: 28183033 bytes, checksum: 7752fe6e8f1336ebae2d7abc6db48c10 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-16T14:56:51Z (GMT) No. of bitstreams: 1 freitas_lg_me_rcla.pdf: 28183033 bytes, checksum: 7752fe6e8f1336ebae2d7abc6db48c10 (MD5) / Made available in DSpace on 2017-05-16T14:56:51Z (GMT). No. of bitstreams: 1 freitas_lg_me_rcla.pdf: 28183033 bytes, checksum: 7752fe6e8f1336ebae2d7abc6db48c10 (MD5) Previous issue date: 2017-03-24 / Os riscos associados à intrusão de gases e vapores do solo em edificações estão ganhando crescente interesse da sociedade, principalmente pelos possíveis danos à saúde humana ou até mesmo por explosões. Na região metropolitana de São Paulo, estudos ambientais vêm relatando com frequência a ocorrência de gás metano (CH4) no subsolo, gerando preocupações sociais, políticas e econômicas. Uma forma inovadora de otimizar o diagnóstico dessas áreas e gerar Modelos Conceituais mais consistentes, se dá com a utilização de técnicas de investigação de alta resolução, como o Membrane Interface Probe (MIP). Nesse contexto, foi conduzido um estudo para avaliar o potencial do MIP, associado a outras técnicas de investigação, para o diagnóstico geoambiental de uma área com a ocorrência de gás metano no subsolo. A área de estudo foi o campus da USP Leste, no município de São Paulo. O estudo foi realizado em três etapas. Na primeira, foram realizados testes de bancada para a obtenção de curvas de resposta do detector de ionização por chama (FID) do sistema MIP para diferentes misturas gasosas, com diferentes temperaturas de aquecimento da sonda. Na segunda etapa foram realizados os ensaios de campo com o MIP e com as seguintes técnicas auxiliares: Soil Color Optical Screening Tool (SCOST); amostragem de gases do solo com o sistema Post Run Tubbing (PRT); e, amostragem de solo por sondagens direct push. Na terceira etapa foram realizadas as análises laboratoriais das amostras de solo coletadas. Os resultados obtidos foram apresentados por meio de perfis e seções representativas da área de estudo. Nos ensaios de bancada, todas as curvas de resposta mostraram alta correlação entre as respostas do FID e as concentrações de CH4 das amostras. Os perfis obtidos em campo pelo sensor de condutividade elétrica do MIP, bem como os perfis de cores obtidos pelo SCOST, apresentaram boa correlação qualitativa com as descrições litológicas e com os perfis granulométricos, auxiliando na caracterização litoestratigráfica. Os ensaios MIP confirmaram a alta sensibilidade da ferramenta para a detecção de CH4, principalmente com a sonda aquecida, possibilitando o mapeamento de acumulações de biogás no subsolo. A amostragem com o PRT confirmou a existência de concentrações de até 77% v/v de CH4 nas camadas de depósitos tecnogênicos. Já as análises de teor de matéria orgânica e fração de carbono orgânico mostraram a presença de camadas com elevado teor orgânico e alto potencial metanogênico, principalmente nas camadas de argila orgânica em meio aos sedimentos quaternários. Conclui-se que o MIP demonstra um grande potencial para a caracterização em alta resolução de áreas com ocorrência de gás metano no subsolo e que as técnicas auxiliares forneceram informações importantes para apoiar a interpretação e a validação dos resultados obtidos. / The risks associated with soil gases and vapor intrusion in buildings are gaining increasing attention in our society, mainly because of possible harm to human health or even explosions. In São Paulo Metropolitan Area, environmental studies have frequently reported methane (CH4) in the subsoil, causing social, political and economic concerns. An innovative approach to optimize site assessment for these cases and generate more consistent conceptual site models (CSM), is through the application of high resolution site characterization (HRSC) tools, as the Membrane Interface Probe (MIP). In this context, a study was carried out to evaluate the potential of the MIP, associated with other subsurface investigation techniques, for the geoenvironmental diagnosis of an area with methane gas occurrence in the subsoil. The study area was the university campus of USP Leste, at São Paulo city. The study was performed in three stages, including laboratory and field procedures. On the first one, bench tests were performed to obtain response curves of the MIP’s Flame Ionization Detector (MIP/FID) for different gas mixtures, with variable probe heating temperatures. On the second stage, MIP tests were performed in the field, with the following auxiliary techniques: Soil Color Optical Screening Tool (SCOST); soil gas sampling with the Post Run Tubbing (PRT) system; and the direct push whole core soil sampling. The third and last stage consisted of laboratory analysis of the soil samples. The results of the bench tests showed very strong correlations between the FID’s response and the CH4 concentration of the samples. The profiles obtained on the field by the MIP’s electrical conductivity sensor and by the SCOST showed good qualitative correlation with the lithological descriptions and with the granulometric profiles, supporting the lithostratigraphic characterization. The MIP/FID results confirmed its high sensitivity to CH4 detection, especially with the heated probe, enabling the mapping of biogas accumulations in the subsurface. The PRT gas sampling confirmed methane’s concentrations as high as 77% v/v in the landfill layers. The organic matter analysis showed high organic content layers with great methanogenic potential, especially in the organic clay layers of the quaternary sediments. It was concluded that MIP has a great potential for the high resolution characterization of sites with methane gas occurrence and the auxiliary techniques also provided valuable information to support the interpretation and validation of the results.

The McCurtain Creek watershed was proposed for a large reservoir project resulting in the commissioning of this study to assess the site?s geology, hydrogeology, and surface hydrology to find whether or not the site was suitable. Data was collected from 57 geophysical logs from coal exploration boreholes to produce geologic and aquifer cross sections. A program to assess discharge identified surface hydrology characteristics of the stream at five locations. Twenty-seven geotechnical boreholes, 23 standpipe piezometers, and the data from the coal exploration were used to map the water table using ArcGIS 8.3 software. Eighteen piezometers at stream sites, used to measure discharge, assessed groundwater/surface water interactions of the basin. After careful analysis, the results of this study concluded that the geology and hydrology of the basin is sufficient to support the large reservoir although engineering design will be required to mitigate some highly permeable sands for the proposed levee.