Browsing by Author "Sale, Thomas, advisor"
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Item Open Access Biotic control of LNAPL longevity - laboratory and field- scale studies(Colorado State University. Libraries, 2017) Emerson, Eric Douglas, author; De Long, Susan K., advisor; Sale, Thomas, advisor; Butters, Gregory, committee memberNatural source zone depletion (NSZD) is an emerging strategy for managing light nonaqueous phase liquids (LNAPLs). Unfortunately, little is known about NSZD rates over extended periods of time, where heterogeneous redox conditions and changing LNAPL saturations may influence processes governing losses. Understanding long-term rates is central to anticipating LNAPL longevity under both natural and engineered conditions. Herein, laboratory and field-scale modeling studies were conducted to evaluate LNAPL longevity. Laboratory studies evaluated loss rates as a function of total contaminant concentration under sulfate-reducing (SR) and methanogenic (MG) conditions. Biotic and abiotic loss rates were determined via tracking biodegradation products and hydrocarbons in column effluents and produced gasses over time. Furthermore, compositional weathering of LNAPL was evaluated. Loss rates with elevated sulfate averaged 39.8 mmole carbon/day/m3 (±9.1 mmole carbon/day/m3). Once sulfate in the soil was depleted to influent water sulfate concentrations of 20 mg/L, subsequent average loss rates were 39.7 mmole carbon/day/m3 (±19.6 mmole carbon/day/m3). Overall, loss rates with and without elevated sulfate were similar. Furthermore, results suggested that loss rates are independent of LNAPL concentration over the range of 9,000 to 37,000 mg/kg and redox conditions observed. Loss rates independent of LNAPL concentrations indicated that biologically mediated NSZD follows zero-order kinetics over the range of conditions evaluated. Column loss rates were compared to field-measured loss rates assuming an LNAPL thickness of three meters. Given this assumption, mean observed early- and late-loss rates are 1.38 and 1.41 μmole carbon/m2/sec, respectively. Assuming decane as a representative LNAPL, observed loss rates are equivalent to 7890 and 8060 L/hectare/year. A column was sacrificed at the completion of the study. Predicted mass losses of the study equate to approximately 1% total initial LNAPL mass lost. Total petroleum hydrocarbons (TPH) soil analysis of initial and final grab samples of column soil did not detect significant mass losses. Moreover, no significant shifts in the LNAPL composition were seen during the course of the study. Mass losses in this range are difficult to accurately quantify via soil-phase hydrocarbon analyses, thus highlighting the utility of the approach used herein. An LNAPL longevity model (The Glide Path Model) was applied at a field site using a zero-order rate model for biological NSZD. LNAPL Longevity ranged from 35 to 105 years using a mean NSZD rate, plus or minus factors of 2 and ½, respectively. Active recovery was shown to have little effect on the longevity of LNAPL.Item Open Access Coupled analytical modeling of water level dynamics and energy use for operational well fields in the Denver Basin aquifers(Colorado State University. Libraries, 2013) Davis, Jennifer Anne, author; Ronayne, Michael, advisor; Sale, Thomas, advisor; Sanford, William, committee member; Bau, Domenico, committee memberThe South Metro Denver area in Colorado has been experiencing rapid growth in recent years and many municipalities in this region rely on the groundwater resources available in the Denver Basin as their chief water supply. As the population continues to increase, municipal water demands must be met with a sustainable approach. The Denver Basin aquifer system consists of four major aquifers that are composed of interbedded layers of sandstones, siltstones, and shales. The aquifers receive limited annual recharge and consequently the groundwater within them has the potential to be depleted. Declining water levels associated with groundwater depletion, interference between pumping wells, and fouling of wells is leading to losses in well productivity. Furthermore, declining water levels translates to higher electrical energy costs associated with water production. Regional-scale numerical models developed for the Denver Basin aquifer system do not capture the local-scale drawdown about pumping wells, which is needed to effectively manage existing groundwater well fields. This research project utilizes production well data from the town of Castle Rock, Colorado to test the merits of using a Theis based approach to model water levels about production wells in the Denver and Arapahoe aquifers in Castle Rock. The model applies superposition of the Theis solution throughout both space and time to resolve the combined effects of pumping from multiple wells. This research demonstrated that the analytical method can be successfully applied as a predictor of continuous water levels at pumping wells. In addition, the analytical model provided a novel method for estimating aquifer properties using data from an operational well field, and it contributed a better understanding of the cross-well interferences that increase well drawdown. The model results were used to evaluate alternative pumping scenarios intended to reduce electrical energy costs associated with water production and increase sustainable yields from these aquifers. The alternative pumping scenarios achieved a net reduction in energy consumption ranging from 1.62% to 13.0% and led to a stronger conceptual understanding of how each aquifer responds to varying pumping conditions. This research demonstrates that the analytical solution modeling approach may be beneficial for application to many other projects involving groundwater supply management and optimization.Item Embargo Development and characterization of solid-state, internet of things-based pH sensors for in-situ monitoring of soil and groundwater(Colorado State University. Libraries, 2022) VanTilburg, Charles Henry, IV, author; Scalia, Joseph, advisor; Sale, Thomas, advisor; Ham, Jay, committee memberHerein I test and examine a new solid state pH sensor design for use in soils and groundwater monitoring. The concept presented here is intended to expand the capabilities for monitoring geochemical parameters in the subsurface by combining a durable, solid-state pH sensor for subsurface deployment with an automated 'internet of things' (IoT) based pH meter that allows the collection of near-real-time continuous data streams for monitoring biogeochemical processes in hydrologic systems. Tests performed in this work were intended to provide a benchmark for further refinement of the design and yielded promising results, including hydrogeologically useful response times (on the order of hours), durability (stresses >1,000 kPa), and reproducible behaviors with multiple sensors. These results support that this technology is promising for future work. The pH sensor design combines a titanium mixed-metal-oxide electrode (TiMMO), solid epoxy body, and a proton-selective Nafion™ ionomer coating to yield a durable solid-state sensor that is sensitive to aqueous proton activities. As the sensor is exposed to water, the diffusion of aqueous protons through the selective Nafion™ coating causes an increase in voltage on the electrode as compared to a reference electrode. The Nafion™ coating reduces the influence of other ions in the system, creating a proton selective sensor. Because of the durable solid-state construction, the sensor can likely be deployed in-situ in challenging environments such as in soils where common glass pH sensors are too fragile for use. This unique advantage allows the pursuit of new biogeochemical monitoring strategies that leverage a high volume of discrete in-situ measurements for near-real-time continuous datastreams. This new strategy, powered by IoT systems, can integrate with smart networks of multiple components and generate large amounts of data for use in artificial intelligence and machine learning systems while also providing insight into processes that occur at smaller spatial and temporal scales than those understood with current subsurface monitoring strategies. pH is a master variable in aqueous and soil chemistry, both an indicator and controller of most chemical reactions and many physical processes that take place in soil and groundwater. pH is important for understanding chemical speciation, mobility, and stability in the soil, while also influencing soil physical properties like soil structure. pH is a parameter of interest to many industries and fields of study including, but not limited to, agriculture, mining, water resources, and engineering. As this work was intended to be a first approximation for studying this technology, multiple promising results and points of improvement were discovered. This work identifies a clear voltage response by the sensor to pH changes (-29 mV/pH) while also demonstrating the change behavior during stepwise pH changes to be approximately logarithmic (Δvolt=3.85ln[t], where Δvolt is the change in millivolts and t is time in minutes). Furthermore, this work demonstrated that these sensors can be used with an IoT monitoring system in the intended application. However, more work is needed to remove variability in the data, explore further designs and processes for coating and treating the sensors, analyze the long-term use, drift, and standardization of the sensors, and employ the data in analytics. Future work should include further lab testing to compare alternative design features and to evaluate stressors such as non-target ions and dehydration. After refinement in the lab, the sensors should be installed in pilot scale studies and in the field to evaluate their performance in real world conditions.Item Open Access Direct measurement of LNAPL flow in porous media using tracer dilution techniques(Colorado State University. Libraries, 2004) Taylor, Geoffrey Ryan, author; Sale, Thomas, advisor; McWhorter, David, committee member; Warner, James, committee memberPetroleum liquids, commonly referred to as LNAPL's, have become a basic building block of modem society. Used as fuels, lubricants, solvents and chemical feed stocks, petroleum liquids have brought many conveniences to our lives. However, a small fraction of these liquids have been inadvertently released into the subsurface forming contiguous bodies of separate phase liquids. Resolving how to manage these releases hinges largely on the rate at which these bodies are moving. To that end, a number of techniques have been developed in an effort to measure the migration, or flow rate, of LNAPL in the subsurface. Many of the current methods require challenging and costly indirect measurements to estimate this migration. The purpose of this thesis is to explore a promising new method that directly measures the flow rate of LNAPL's, a method that builds on the tracer dilution technique used to measure the flow of groundwater. Traditional tracer dilution techniques measures the dilution of a tracer, placed into a well, to determine the flow rate of water through the well. The flow rate through the well is then used to calculate the flow rate of groundwater. The same theory applies to LNAPL's flowing through a well. Determining the potential of the tracer dilution technique to measure LNAPL flow through a well requires investigating the mathematics governing the tracer dilution technique. A first order dilution equation was adapted for LNAPL. A method to analyze the results in a dimensionless format was also developed because it provides a technique to determine when the data conforms to the assumptions of the dilution equation. The mathematics necessary to convert the flow rate of LNAPL through a well into common measures is also derived. Laboratory studies were conducted to verify the mathematics and to determine the applicability of the tracer dilution technique to measure LNAPL flow. At first, small scale experiments were used to visualize the dilution process and develop the technology necessary to conduct tracer dilution tests in LNAPL. A fluorescent dye, BSL 715, was selected as a tracer. A spectrometer and computer were used to measure and log the fluorescent intensity, which is a measure of the tracer concentration. A device to mix the tracer in the well without causing adverse dilution was also developed. A large tank study explored the tracer dilution technique using a typical range of LNAPL thicknesses and flow rates. The flow rates varied from 7.2 m3/m/yr to 0.035 m3/m/yr and the LNAPL thicknesses varied from 9cm to 24cm. The results of the large tank study demonstrated that the tracer dilution technique is an accurate and reliable method to measure the migration of petroleum liquids in the subsurface. The measured error tends to increase at lower flow rates but is insensitive to the LNAPL thickness. The results of the large tank study led to a field test at the former ChevronTexaco Refinery in Casper, WY. The tracer dilution method was deployed in two locations. The first location was near an active recovery well where the flow rate was expected to be high. The second test was conducted in a quiescent area where the flow rate was low. The first test, near the recovery well, measured a flow rate of 0.1 m3/m/yr to 0.3 m3/m/yr. The second test, in a quiescent area, indicated a flow rate of less then 0.005 m3/m/yr. In addition, opportunities for improving sensitivity and increasing the usefulness of the method were discovered. In all, the experiments have shown the tracer dilution technique to be an effective method to directly measure the in situ migration of petroleum liquids in the subsurface.Item Open Access Internet of things monitoring of the oxidation reduction potential in an oleophilic bio-barrier(Colorado State University. Libraries, 2020) Hogan, Wesley W., author; Scalia, Joseph, advisor; Sale, Thomas, advisor; Ham, Jay, committee memberPetroleum hydrocarbons discharged to surface water at a groundwater-surface water interface (GSI) resulting in violations of the Clean Water Act often spark costly cleanup efforts. The oleophilic bio-barrier (OBB) has been shown to be effective in catching and retaining oils via an oleophilic (oil-loving) geocomposite and facilitating biodegradation through cyclic delivery of oxygen and nutrients via tidally driven water level fluctuations. Conventional resistive (e.g., geomembrane) or absorptive-only (e.g., organoclay) barriers for oil at GSIs limit oxygen diffusion into underlying sediments and are susceptible to overloading and bypass. Conversely, OBBs are designed to function as sustainable oil-degrading bioreactors. For an OBB to be effective, the barrier must maintain aerobic conditions created by tidally driven oxygen delivery. Oxidation reduction potential (ORP) sensors were installed within an OBB in the northeastern US with an internet of things (IoT) monitoring system to either confirm the sustained oxidizing conditions within the OBB, or to detect a problem within the OBB and trigger additional remedial action. Real-time ORP data revealed consistently aerobic oxidation-reduction (redox) conditions within the OBB with periods of slightly less oxidized redox conditions in response to precipitation. By interpreting ORP data in real time, we were able to verify that the OBB maintained the oxidizing conditions critical to the barrier functioning as an effective aerobic bioreactor to degrade potentially-sheen generating oils at GSIs. In addition, alternative oleophilic materials were tested to increase the range of candidate materials that may function as the oleophilic component of an OBB. Materials tested included thin black (232 g/m2), thin white (244 g/m2), medium black (380 g/m2), and thick black (1055 g/m2) geotextiles, as well as a coconut fiber coir mat. Finally, a model was developed to estimate the required sorptive capacity of the oleophilic component of an OBB based on site-specific conditions, which can be used to inform OBB design.Item Open Access Particle tracking using dynamic water level data(Colorado State University. Libraries, 2017) Gao, Yuan, author; Sale, Thomas, advisor; Ronayne, Michael, committee member; Blotevogel, Jens, committee memberMovement of fluid particles about historic subsurface releases and through well fields is often governed by dynamic subsurface water levels. Factors influencing temporal changes in water levels include changes in river stage, tidal fluctuation, seasonal transpiration from trees and pumping of wells. Motivations for tracking the movement of fluid particles include tracking the fate of subsurface contaminants and resolving the fate of water stored in subsurface aquifers. This research provides novel methods for predicting the movement of subsurface particles relying on dynamic water level data derived from continuously recording pressure transducers or an analytic solution based on a Theis superposition model that predicts water levels about dynamically operated wells in well fields. For particle tracking at field sites without pumping conditions, firstly, the dynamic water level data obtained from sites in Kansas City, Missouri; Pueblo, Colorado; and Honolulu, Hawaii are employed. The basic idea is to use water-level data from at least three wells to solve for the plane of the water table and obtain the hydraulic gradient in the x and y directions. Secondly, based on the Darcy's equation, the position of a particle is moved in the x and y directions at each time step. Finally, by connecting all the positions of particle together, the path line of particle flowed in the subsurface can be obtained. Homogeneous, isotropic and homogeneous, anisotropic conditions with retardation were considered for particle tracking at the three sites in this research. Also, consideration is given to natural degradation of contaminants in the subsurface. By assuming the degradation of contaminants at each site follows first order kinetics, the distance the contaminants can flow within the minimum concentration requirement and the time when the concentration of contaminants arrived at the minimum concentration requirement can be obtained. Based on the results from this research, river stage, seasonal transpiration and precipitation, and tidal fluctuation at three sites all have great influences on local groundwater flow. The great changes of water-level in short periods caused by seasonal recharge and discharge and seasonal transpiration and precipitation make the hydraulic gradient changed greatly, subsequently make the direction of groundwater flow altered. For the site near a harbor, tidal fluctuations make the groundwater level changed, which correspondingly have the hydraulic gradient and direction of groundwater flow changed. Initial review of water-level in rose chart indicates a range of groundwater flow direction and gradient with time. This indicates a wide range of temporally changing flow directions and gradients. Surprisingly, despite temporal variation in flow directions, the net groundwater flow at all field sites is largely constant in one direction. From the results of particle tracking and rose charts, groundwater flow mainly follows the direction of the hydraulic gradients with large magnitudes in rose charts, but does not follow every direction of hydraulic gradient in the rose chart. The explanation for this phenomena is the main direction of groundwater flow is driven by hydraulic gradient with large magnitude, because the time interval for each groundwater flow driven by each hydraulic gradient is the same, according to the Darcy's equation, hydraulic gradient in the direction with small magnitude cannot drive particles flow long enough to make particles flow away from the main direction. Moreover, this research uses dynamic pumping well data to test how particles move under dynamic pumping conditions in well fields. Based on superposition of the Theis solution in both space and time, this research uses an analytical solution to resolve how fluid particles move about wells under dynamic pumping conditions. The results from particle tracking under dynamic pumping conditions in this research provide: firstly, a relatively uniform capture zone in the well field. Secondly, even under continuous pumping and injection conditions, groundwater will not flow far away from the well. Thirdly, particle tracking provides groundwater positions and delineates the position of storage water under dynamic pumping and injection condition.Item Open Access Real-time visualization of advective groundwater flow(Colorado State University. Libraries, 2020) Ferrie, Zach, author; Sale, Thomas, advisor; Blotevogel, Jens, advisor; Ham, Jay, committee memberAs the portfolio of sites with subsurface contamination matures, long-term monitoring is becoming the primary factor governing costs for managing historical releases of contaminants to soil and groundwater. Hydraulic gradients are the primary factor driving the velocity and direction in which subsurface contaminants move, making them an important parameter to resolve. Current best practices for tracking groundwater flow include either collecting head data by hand or deploying pressure transducers and periodically returning to manually download the data. Unfortunately, cost restraints and infrequent data collection and processing are not conducive to timely responses to adverse conditions. In this study, two low-cost cellular connected data acquisition systems are developed which allow for collection and analysis of head data in real-time. Using planar regressions of three head values, automated algorithms are used to estimate the direction and rate of groundwater flow on an hourly basis. Another novel addition is the integration of real-time alerts. By automating various alerts, site managers can be notified when conditions reach a pre-determined threshold. Automated alerts allow for swift action to be taken to adverse conditions and can lead to greater safety for the public while saving sites from costly mistakes. Following Devlin and McElwee (2007), uncertainty in groundwater flow direction is a function of measurement error, spacing between wells, and local hydraulic gradients. By using these sources of uncertainty to create synthetic datasets, algorithms are used to estimate the likely range of a groundwater flow path. The effects of pressure transducer drift (i.e. increasing measurement error over time) and their effect on uncertainty are also explored. Results from this study show that as long as the drift is similar in magnitude and direction for all pressure transducers, the effect on the uncertainty in the model is negligible. Additionally, the effects of uncertainty in anisotropy on deviation from the estimated flow path are considered by way of synthetic datasets, which is novel to this research. The results of this research reveal that the effects of anisotropy uncertainty on groundwater flow direction and seepage velocity are also tied to well spacing. Comparisons of the effects of measurement error vs anisotropy uncertainty are compared for four field sites. Results show that the magnitudes of each source of error are site specific and that the effects of measurement error are not always greater than the effects of anisotropy uncertainty and vice versa. Lastly, the seepage velocities are expressed by way of a color scheme common across sites. This novel addition allows for easy visualization of seepage velocities across time and space. Overall, the vision from this research is that real-time, continuous collection and analysis of head data can proceed as outlined in this Thesis. In the future manually collected and interpreted head data need to be compared to the automated analyses described in this Thesis to further support the validity of the methods proposed herein. Another future test is to investigate alternative technologies to pressure transducers for gaining head measurements that are more accurate and reliable.Item Open Access Thermal monitoring of natural source zone depletion(Colorado State University. Libraries, 2019) Karimi Askarani, Kayvan, author; Sale, Thomas, advisor; Ham, Jay, committee member; Scalia, Joseph, committee member; Bailey, Ryan, committee memberNatural Source Zone Depletion (NSZD) has emerged as a viable remedial approach for mature releases of petroleum liquids in soils and groundwater. Herein, petroleum liquids in soils and groundwater are referred to as LNAPL. In recent years, gradient, dynamic chamber, and carbon trap methods have been developed to quantify NSZD rates based on measuring the consumption of O2 or the generation of CO2 associated with biodegradation of LNAPL. A promising alternative approach to resolving LNAPL NSZD rates is real-time monitoring of subsurface temperatures. Transformation of temperature data to NSZD rates involves use of background-corrected temperature data, energy balances to resolve NSZD energy, and an estimate of heat produced through NSZD. All current computational methods for quantifying NSZD rates using temperature data have the drawbacks of: 1) incomplete energy balances 2) ignoring the effect of water table fluctuation, and 3) using linear extrapolations of temperature profiles to calculate thermal gradients. A regression algorithm is advanced to overcome the primary drawbacks of current computational methods that convert subsurface temperature data to NSZD rates using background correction. The regression algorithm is demonstrated using 42 million temperature measurements from a fuel terminal. An 8% difference between NSZD rates from the CO2 Trap method and the regression algorithm supported the validity of regression algorithm for estimation of NSZD rates using subsurface temperatures. In addition, seasonal behavior of NSZD rates is captured and correlated water content in shallow soils and depth to the water table. It is concluded that as the water table rises, the apparent NSZD rates increase, while larger water content in shallow soil causes a reduction in the apparent NSZD rates. Imperfection with background-correction approaches can be attributed to many factors, including differing infiltration of precipitation, vegetative cover, soil properties, and net solar radiation, at background versus impacted locations. Differences between the background location and the impacted area cause anomalous background-corrected temperatures leading to over/under estimation of NSZD rates. A new computational model is developed to eliminate the need for background correction of temperature data in calculating NSZD rates. Since the new model uses only the temperature data collected from the temperature sensors attached to a single solid stick, the model is referred to as the "single stick" method. The validity of the single stick model is evaluated using a numerical model and field temperature data. Agreement between the results from a numerical model with imposed heat fluxes, and estimated heat fluxes using temperature data derived from the numerical model, supports the validity of single stick model. In addition, a close match between single stick simulated temperatures using estimated heat fluxes and actual measure temperatures supports the validity of the single stick model. Furthermore, comparison of NSZD rates from the single stick model with the rates from background correction methods at background locations shows that the single stick model is the only algorithm that consistently provides near zero NSZD rates in clean areas. Lastly, per thermodynamic calculations and preliminary lab studies, it is observed that negative NSZD rates may be due to endothermic methanogenic process. Thermal conductivity is one of the key input parameters for all computational methods converting temperature data to NSZD rates. An integrated Internet of Things (IoT) instrument and computational model is developed to measure real-time in-situ thermal conductivity of soils. Favorable agreement between measure ex-situ and in-situ thermal conductivities values supports the validity of the demonstrated in-situ techniques for estimating thermal conductivities. Favorable attributes of the new in-situ methods include lower cost, automated data acquisition and an ability to acquire in-situ estimates of thermal conductivities through time. Overall, this work demonstrated that monitoring subsurface temperature is a viable technique to resolve NSZD rates for LNAPLs. A promising next step for evaluating the validity of thermal NSZD rates is to periodically collect and analyze cryogenic cores from field sites to independently validate NSZD rates. Also, further work is needed to better resolve NSZD thermodynamics.Item Open Access Thermally enhanced bioremediation of LNAPL(Colorado State University. Libraries, 2013) Zeman, Natalie Rae, author; De Long, Susan K., advisor; Sale, Thomas, advisor; Stromberger, Mary, committee memberInadvertent releases of petroleum liquids into the environment have led to widespread soil and groundwater contamination. Petroleum liquids, referred to as Light Non-Aqueous Phase Liquid (LNAPL), pose a threat to the environment and human health. The purpose of the research described herein was to evaluate thermally enhanced bioremediation as a sustainable remediation technology for rapid cleanup of LNAPL zones. Thermally enhanced LNAPL attenuation was investigated via a thermal microcosm study that considered six different temperatures: 4¡ÆC, 9¡ÆC, 22¡ÆC, 30¡ÆC, 35¡ÆC, and 40¡ÆC. Microcosms were run for a period of 188 days using soil, water and LNAPL from a decommissioned refinery in Evansville, WY. The soil microcosms simulated anaerobic subsurface conditions where sulfate reduction and methanogenesis were the pathways for biodegradation. To determine the optimal temperature range for thermal stimulation and provide guidance for design of field-scale application, both contaminant degradation and soil microbiology were monitored. CH4 and CO2 generation occurred in microcosms at 22¡ÆC, 30¡ÆC, 35¡ÆC and 40¡ÆC but was not observed at 4¡ÆC and 9¡ÆC. The total volume of biogas generated after 188 days of incubation was 19 times higher in microcosms at 22¡ÆC and 30¡ÆC compared to the microcosms at 35¡ÆC. When compared to microcosms at 40¡ÆC, the total biogas generated was 3 times higher at both 22¡ÆC and 30¡ÆC. The onset of CH4 and CO2 production occurred first within the microcosms held at 30¡ÆC beginning after 28 days of incubation, and second within microcosms at 22¡ÆC beginning after 58 days of incubation. A delay in CH4 and CO2 production was observed within microcosms held at 35¡ÆC and 40¡ÆC (beginning after 173 and 138 days after incubation) contributing to lower cumulative biogas generation at these temperatures relative to 22¨¬C and 30¨¬C. Microcosms incubated at 4¨¬C, 22¡ÆC, 30¨¬C, 35 ¨¬C and 40 ¨¬C showed statistically significant biological removal of gasoline range organics (GRO) at the ¥á=0.05 level over the course of the 188-day incubation period. Biotic removal of GRO was significantly higher at 22¨¬C and 30¨¬C when compared to 4¨¬C and 9¨¬C. The observed removals at 22 ¨¬C, 30 ¨¬C, 35 ¨¬C and 40¨¬C were not statistically different from each other. The biological removal of DRO compounds was found to be statistically significant at 22¨¬C, 30 ¨¬C, 35 ¨¬C and 40 ¨¬C and was significantly higher at 22¨¬C when compared to 4¨¬C and 9¨¬C. The percent biological removal of DRO compounds at these temperatures was not statistically different from each other and ranged from 18-22%. Statistically significant biological degradation of all the BTEX compounds only occurred in microcosms at 22¡ÆC and 30¡ÆC. Benzene, toluene, and xylene biodegradation was observed to be statistically significant in microcosms at 35¡ÆC. Phylogenetic analysis of the microbial communities present at 22¡ÆC via a 16S rRNA gene archaeal clone library and pyrosequencing revealed the presence of both hydrogenotrophic and acetoclastic methanogens. Pyrosequencing data from microcosms at 4¡ÆC, 22¡ÆC and 35¡ÆC revealed that temperature impacted both archaeal and bacterial community structure. A potential requirement for changes in microbial community structure at the higher temperatures (35¡ÆC and 40¡ÆC) could explain the observed delay in biogas production. The results of the thermal microcosm study led to the development of a pilot study to investigate the efficacy of Sustainable Thermally Enhanced LNAPL Attenuation STELA at the site in Evansville, WY. The thermal pilot study approach and preliminary data is included in this thesis. The outcome and results of the pilot study will be presented in the masters theses of other students.Item Open Access Third-generation site characterization: cryogenic core collection, nuclear magnetic resonance, and electrical resistivity(Colorado State University. Libraries, 2016) Kiaalhosseini, Saeed, author; Sale, Thomas, advisor; Blotevogel, Jens, advisor; Johnson, Richard, committee member; Butters, Gregory, committee memberTo view the abstract, please see the full text of the document.