• Evaluation of the modes of transporting GTL products through the Trans-Alaska Pipeline System (TAPS)

      Akwukwaegbu, Chinedu Franklyn (2001-05)
      Gas-to-liquids (GTL) conversion technology, where natural gas is chemically converted to transportable hydrocarbon liquid products, is an emerging technology that will undoubtedly reach commercialization within the next decade. Two GTL transportation modes, that could be used to exploit vast Alaska Natural Gas resources in the form of stable liquid through the Trans-Alaska Pipeline System (TAPS), are evaluated either as single slugs (batches) or commingled (mixed) with Crude Oil. In this study, thee pertinent energy equations are solved for both batch and commingled flow modes. The solutions of these equations are analytically presented for determining among other parameters, the pressure gradient and pertinent slug length required for batching. The application of the determined hydraulic parameters will aid in the analysis and economic evaluation of the GTL transportation modes through the Trans-Alaska Pipeline System (TAPS).
    • Evaluation of the Overheight Detection System Effectiveness at Eklutna Bridge

      Lee, Ming; Moose, Dan (Alaska University Transportation Center, 2013-03)
      The Eklutna River/Glenn Highway bridge has sustained repeated impacts from overheight trucks. In 2006, ADOT&PF installed an overheight vehicle warning system. The system includes laser detectors, alarms, and message boards. Since installation, personnel have seen no new damage, and no sign that the alarm system has been triggered. Although this is good news, the particulars are a mystery: Is the system working? Is the presence of the equipment enough to deter drivers from gambling with a vehicle that might be over the height limit? Is it worth installing similar systems at other overpasses? This project is examining the bridge for any evidence of damage, and is fitting the system with a datalogger to record and video any events that trigger the warning system. Finally, just to be sure, researchers will test the system with (officially) overheight vehicles. Project results will help ADOT&PF determine if this system is functioning, and if a similar system installed at other bridges would be cost-effective.
    • Evaluation of the trophic types of several Alaskan lakes by assessment of the benthic fauna

      LaPerriere, Jacqueline D. (University of Alaska, Institute of Water Resources, 1975-03)
      Public Law 92-500 (1972) which amends the Federal Water Pollution Control Act contains Section No. 314 entitled Clean Lakes which gives each state a mandate to "... prepare or establish ... an identification and classification according to eutrophic condition of all publicly owned fresh water lakes in such state . . . ." This mandate presents an awesome task to the State of Alaska which contains millions of lakes which must be evaluated according to the interpretation of this law. It was the intent of this project to examine the application of a biological index of eutrophy to several Alaskan lakes by comparing benthic macroinvertebrate faunal distribution to selected chemical and physical indices of trophic state. The investigator chose to consider "indicator organisms" as the focus of the study and found this concept to be interestingly difficult to apply.
    • An evaluation of the use of moderate resolution imaging spectroradiometer (MODIS)-derived aerosol optical depth to estimate ground level PM2.5 in Alaska

      Mathers, Alyson Marie McPhetres; Aggarwal, Srijan; Belz, Nathan; Perkins, Robert (2018-12)
      The air quality monitoring (AQM) network in Alaska is limited to major urban areas and national parks thus leaving a large proportion of the state unmonitored. To evaluate the use of Moderate Resolution Imaging Spectroradiometer (MODIS)-derived aerosol optical depth (AOD) to predict ground-level PM2.5 concentrations and thereby increase the spatial coverage of the AQM network in Alaska, MODIS AOD was first validated against ground-based measurements of AOD in Utqiagvik and Bonanza Creek Alaska. MODIS AOD from 2000 to 2014 was obtained from MODIS collection 6 using the dark target land and ocean algorithms between the months of April and October. Based on validation results, individual Aqua and Terra products are valid for both locations at 10-kilometer and 3-kilometer resolution. In addition, combined Aqua and Terra MODIS AOD products are valid for both locations at 3-kilometer resolution and 10-kilometer resolution for Utqiagvik. The available PM2.5 data was then compared for satellite retrieval and all retrieval days to determine if there was sufficient data and the amount of bias introduced by possible low retrieval rates. Overall, Juneau had the lowest retrieval rates while Fairbanks and North Pole had the highest retrieval rates. In addition, Juneau appeared to have relatively high bias while stations located in Anchorage, Palmer, Fairbanks and North Pole had relatively low bias. Based on these findings, no models were developed for Juneau (southeast Alaska). Multilinear regression models were then developed for southcentral (Anchorage and Palmer) and interior (Fairbanks and North Pole) Alaska where the log-transform of PM2.5 was the response and meteorological data and the log-transform of MODIS AOD were the predictors. MODIS AOD appeared to be most highly correlated with PM2.5 in interior Alaska, while there was little to no correlation between MODIS AOD and PM2.5 in southcentral Alaska. All models underestimate surface PM2.5 concentrations which may be due to the high percentage of low PM2.5 values used to develop the models and the limited retrieval rates. Alternative modeling methods such as mixed-effects modeling may be necessary to develop adequate models for predicting surface PM2.5 concentrations. The MLR models did not perform well and should not be used to predict ground-based PM2.5 concentrations. Further research using alternative modeling methods should be performed. Model performance may also be improved by only using higher concentrations of PM2.5 to develop models. Overall, the limited spatial coverage of Alaska's air quality monitoring network and the low temporal resolution of MODIS-derived AOD make modeling the relationship between MODIS AOD and PM2.5 difficult in Alaska.
    • Evaluation of Warm Mix Asphalt for Alaska Conditions

      Liu, Juanyu (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2010)
    • Evaluation of Warm Mix Asphalt for Alaska Conditions

      Liu, Juanyu (Alaska University Transportation Center, 2010-04)
      In line with a field demonstration project of WMA using Sasobit conducted in Southeast Alaska, this study focused on experimentally assessing the engineering properties of Sasobit modified WMA binders and mixes. Performance tests of binders were conducted according to Superpave specification to assess the correlation between the content of additives, and Superpave performance grade (PG) and stiffness of modified binders. Tests conducted to assess the performance of WMA included 1) permanent deformation (rutting) susceptibility, 2) low temperature cracking performance including tensile strength and tensile creep compliance properties, 3) moisture susceptibility, and 4) dynamic modulus |E*|. Laboratory investigation of Sasobit-modified binders and WMAs in this study identified a lot of engineering benefits of WMAs using Sasobit over traditional HMA. WMAs using Sasobit with reduced mixing and compaction temperatures, improved workability and rutting resistance, and insignificant effect on moisture susceptibility favorably indicated the suitability of this WMA technology for Alaska conditions. The indirect tension test (IDT) results showed degraded resistance to low temperature cracking of WMA using Sasobit in this study. However, additional tests at lower temperatures, along with a more complete thermal cracking analysis for specific environments of interest should be performed to get a more definitive answer regarding the effects of Sasobit on low temperature cracking.
    • Evaluation of Water Research Needs in Alaska : Project Completion Report

      Behlke, Charles E. (University of Alaska, Institute of Water Resources, 1968)
      The water resource research requirements for Alaska revolve around the needs of a rapidly expanding population and industrial growth in an unpopulated country. It appears that many of the problems which have been researched elsewhere must be restudied in Alaska because of the extremes of climate which Alaska exhibits . Most of the southern coastal areas of the State exhibit from 70 to 350 inches of runoff per year and in much of the northern part of the State permafrost to great depths and seasonal frost lock virtually all of the water in the solid state for a major part of the year. Alaska Is proving to be an area with vast petroleum reserves. These reserves are being brought into production and are resulting in the development of previously unpopulated areas. The proper management of previously untouched waters requires knowledge of the nature of the existing resources and then an evaluation of the probable effects of alternative water uses in order to optimize the desirable use of Alaskan water resources. This evaluation of present conditions and the analysis of future possible uses provide vast amounts of required research.
    • Event based modeling studying three sub-basins in the Kenai River watershed

      Wells, Brett M.; Toniolo, Horacio; Stuefer, Svetlana; Barnes, David (2016-12)
      Streams in the Kenai River watershed are characterized by a fish-rich environment, with competing interests between commercial industry and recreational users. Resource managers strive to balance the needs of both these user groups while maintaining the sustainability of the resource. The ability to estimate future river conditions could help maintain the resource, and a strong, sustainable economy on the Kenai Peninsula. This research used the U.S. Army Corps of Engineers Hydrological Modeling System (HMS), which transforms rainfall to river discharge. The main goal was to define a set of parameters that were calibrated using an event based strategy, and concurrent rainfall and discharge data. The model was calibrated and validated in three sub-basins located in different environmental settings (i.e. lowlands, mid, and high elevation). In addition, the Kenai River watershed, as a whole, was modeled. Due to limited concurrent datasets, a combination of current and historic rainfall and discharge data was used in the calibration. Over the period of time between the historic data and the current data, no major changes in the watershed were detected. Model results at the sub-basin and watershed scale provided reasonable results over the modeling period. Each sub-basin maintained errors below 10% for the calibration and only slight increase in the error for the verification trials. It was found that during an extreme precipitation event, the model did not perform within reasonable bounds.
    • Examination of the Variability in Grout Test Results

      Ahn, Il-Sang; Friend, Trenton (2019-08-31)
      Keyway grouting is an operation that connects decked bulb-tee girders into one system. The quality of grout should be well maintained through reliable material test procedures. Due to the issues of discrepancy and variability, there have been several cases in which grout materials did not satisfy the compressive strength standard specified in the DOT&PF Standard Specifications for Highway Construction. This research examined the causes of such issues. Six factors – grout material, mix consistency, workmanship, initial curing/storing, curing method, and test equipment – were identified as the causes of strength variation. Their effects on strength variation were investigated by testing compressive strength of cube and cylinder specimens made from 5 grout materials that were used or considered to be used in DOT&PF projects. Grout material characteristics such as grout material and mix consistency have significant effect on strength variation. Workability and consolidation can be different from one material to another. Consequently, they affect compressive strength and its variation. Workmanship and test equipment were evaluated in this research to have moderate effect on strength variation. Especially, strength variation can increase when the workmanship factor combines with the grout material characteristics factor.
    • Exhaust thimble for arctic environments

      Evans, Mark P.; Peterson, Rorik; Kim, Sun woo; Lin, Chuen-Sen (2016-05)
    • Experimental and computational studies of nanofluids

      Vajjha, Ravikanth S.; Das, Debendra K.; Lin, Chuen-Sen; Chukwu, Godwin A.; Shur, Yuri (2014-12)
      The goals of this dissertation were (i) to experimentally investigate the fluid dynamic and heat transfer performance of nanofluids in a circular tube, (ii) to study the influence of temperature and particle volumetric concentration of nanofluids on thermophysical properties, heat transfer and pumping power, (iii) to measure the rheological properties of various nanofluids and (iv) to investigate using a computational fluid dynamic (CFD) technique the performance of nanofluids in the flat tube of a radiator. Nanofluids are a new class of fluids prepared by dispersing nanoparticles with average sizes of less than 100 nm in traditional heat transfer fluids such as water, oil, ethylene glycol and propylene glycol. In cold regions of the world, the choice of base fluid for heat transfer applications is an ethylene glycol or propylene glycol mixed with water in different proportions. In the present research, a 60% ethylene glycol (EG) or propylene glycol (PG) and 40% water (W) by mass fluid mixture (60:40 EG/W or 60:40 PG/W) was used as a base fluid, which provides freeze protection to a very low level of temperature. Experiments were conducted to measure the convective heat transfer coefficient and pressure loss of nanofluids flowing in a circular tube in the fully developed turbulent regime. The experimental measurements were carried out for aluminum oxide (Al₂O₃), copper oxide (CuO) and silicon dioxide (SiO₂) nanoparticles dispersed in 60:40 EG/W base fluid. Experiments revealed that the heat transfer coefficient of nanofluids showed an increase with the particle volumetric concentration. Pressure loss was also observed to increase with the nanoparticle volumetric concentration. New correlations for the Nusselt number and the friction factor were developed. The effects of temperature and particle volumetric concentration on different thermophysical properties (e.g. viscosity, thermal conductivity, specific heat and density) and subsequently on the Prandtl number, Reynolds number and Nusselt number of three nanofluids were investigated. The three nanofluids studied were Al₂O₃, CuO and SiO₂ nanoparticles dispersed in a base fluid of 60:40 EG/W. Results showed that the Prandtl number of nanofluids increased with increasing particle volumetric concentration and decreased with an increase in the temperature. The Reynolds number of nanofluids for a specified geometry and velocity increased with an increase in temperature and decreased with an increase in particle volumetric concentration. The Mouromtseff numbers of nanofluids were higher than those of the conventional fluids under both laminar and turbulent flow conditions, proving the superiority of nanofluids in electronic cooling applications. Experiments were performed to investigate the rheological properties of various nanoparticles dispersed in a 60:40 PG/W base fluid. The nanoparticles studied were; Al₂O₃, CuO, SiO₂, zinc oxide (ZnO), titanium oxide (TiO₂) with particle diameters ranging from 15 to 75 nm and particle volumetric concentrations of up to 6%. All the nanofluids exhibited a non-Newtonian Bingham plastic behavior at the lower temperature range of 243 K to 273 K and a Newtonian behavior in the temperature range of 273 K to 363 K. A new correlation was developed for the viscosity of nanofluids as a function of temperature, particle volumetric concentration, particle diameter, the properties of nanoparticles and those of the base fluid. Measurements were also conducted for single wall, bamboo-like structured and hollow structured multi-wall carbon nanotubes dispersed in a base fluid of 20:80 PG/W. A low-volume concentration (0.229%) of these carbon nanotubes (CNT) nanofluids revealed a non-Newtonian behavior over a measured temperature range of 273 K to 363 K. From the experimental data, a new correlation was developed which related viscosity to temperature and the Péclet number for CNT nanofluids. A three-dimensional CFD study was performed to analyze the heat transfer and fluid dynamic performance of nanofluids flowing in the turbulent regime in a flat tube of an automotive radiator. Computations were carried out for the Al₂O₃ and CuO nanoparticles of 0 to 6% particle volumetric concentrations dispersed in a base fluid of 60:40 EG/W. The numerical study revealed that under equal pumping power basis, the Al₂O₃ and CuO nanofluids up to 3% and 2% particle volumetric concentrations respectively, provided higher heat transfer coefficients than those provided by the base fluid. From this study, several new correlations to determine the Nusselt number and friction factor for the nanofluids flowing in the flat tubes of a radiator were developed for the entrance as well as the fully developed regions.
    • Experimental and economic evaluation of GTL fluid flow properties and effect on TAPS

      Ramakrishnan, Hariharan (2000-12)
      In this study, procedures are outlined to recondition and sample crude oil from high-pressure Welker cylinders. Standard laboratory procedures are developed to determine viscosity and density properties of crude oil, GTL and their mixtures. The steps needed to ensure Quality Assurance and Project Plan (QAPjp) is given in detail. A calibration macro is written to automate viscometer calibration calculations. A preliminary economic model is developed to evaluate GTL transportation options. Viscosity and density are measured for various samples at different temperatures. The reproducibility of the results is found to be within 5%. Batching is more preferable then blending for the parameter values considered in the economic model. In brief, GTL option appears to be a feasible way of utilizing Alaskan North Slope (ANS) gas resources and increasing the lifetime of TAPS, if suitable advancement in GTL conversion technology results in a substantial reduction in capital investment.
    • Experimental and numerical fluid flow analysis of an intersecting channel flow-field for proton exchange membrane fuel cell applications

      Gudimetla, Venkata A.; Witmer, Dennis E.; Misra, Debasmita; Lin, Chuen-Sen (2006-12)
      The present work aims to analyze the geometry of a new flow-field plate called the intersecting channel flow-field, developed at the University of Alaska Fairbanks (UAF). Four different two-dimensional models have been investigated and analyzed for the uniform spatial mass flow distribution of air in the channels. Based on the outcome of the two-dimensional models, a three-dimensional model of the flow-field was analyzed using CFD and the results were compared with those from an experiment which was conducted at UAF. The results from the three-dimensional numerical analysis showed a minor deviation from the experimental results.
    • Experimental and numerical simulation of hydraulic fracturing

      Hoveidafar, Mohammad; Chen, Gang; Metz, Paul; Ahn, Il Sang; Zhang, Yin (2017-12)
      Hydraulic Fracturing (HF) has many applications in different fields such as stimulation of oil and gas reservoirs, in situ stress measurements, stress relief for tunneling projects as well as in underground mining applications such as block caving mining. In the HF process, high pressure fluid is injected into a well to generate fractures in tight rock formations. This technique is particularly suitable for developing hydrocarbon energy resources in tight rock formations such as shale with very low permeability. An experimental setup was designed and developed to simulate the HF process in the laboratory. Cubic plaster specimens were molded and HF experiments were conducted with simulated plaster models. Five laboratory tests were performed on cubic specimens under different stress conditions. Because the uniaxial compressive strength of the plaster was about 1600 psi, in all experiments the applied vertical stress was 1000 psi to avoid breaking the specimens before injection of fluid. The differential horizontal stress varied from 100 to 500 psi. These stress levels are related to shallow formations in a real environment. It was observed that increasing the differential horizontal stress by 100 psi, the minimum pressure required to initiate HF decreases about 100 psi. These results were in agreement by 2D failure criterion of HF. All in all, the small scale HF experiments were conducted successfully in the rock mechanics lab. It was observed that vertical hydraulic fractures would propagate along maximum horizontal stress, which is in agreement with propagation of HF theory. Three-dimensional (3D) numerical models were developed and computer simulations were conducted with ABAQUS, a commercially available finite element analysis (FEA) software. The numerical simulation results compared favorably with those from the laboratory experiments, and verification and analysis were carried out. Since the results obtained from the numerical model were in agreement with the results of experiments and verified the correctness of the model, further investigation was carried out with developed computer models. Several scenarios with different vertical stresses and different levels of horizontal stress were simulated. A statistical software, R, was used to generate a 3D failure criterion for the HF in shallow formations.... It can be stated that in shallow formations, vertical stress has the least effect among stress components on the minimum pressure required to initiate HF.
    • Experimental And Numerical Study Of Sonic Wave Propagation In Freezing Sand And Silt

      Li, Hui (2009)
      A numerical model for delineating the temperature-velocity relationship of freezing porous media and soil is developed in Matlab based on Leclaire's Biot-type three-phase theory. Leclaire's theory gives lower sonic velocities than the experimental results because it does not take into consideration the effect of the solid-ice frame when water is freezing. To take the solid-ice effective frame into account, the average bulk and shear moduli estimation are modified with a proposed procedure. The modification gives higher P-wave and S-wave velocities that fit experimental data well. A comprehensive suite of physical and acoustic laboratory experiments are conducted on artificial sands, sand-clay mixtures and Fairbanks silts to investigate the temperature-velocity relationship during the freezing process and the effects of grain size and fine clay content. A Multi-channel ultrasonic scanning system (MUSS) is designed, installed and programmed for the experimental computerized ultrasonic tomography (CUST) study. The inward and outward freezing process and freezing front development in Fairbanks silt samples are observed using computerized ultrasonic tomography (CUST) in the laboratory. The experiments generate sonic wave velocity and temperature distribution during the freezing process. The freezing front is clearly identified in the CUST as a function of time and temperature. Comprehensive numerical finite element method (FEM) simulations, which account for the conduction in porous media, the latent heat effect and the nonlinear thermal properties of soil, are performed on the inward and outward freezing process of Fairbanks silt based on the experimental conditions. In conjunction with the temperature-velocity model developed in the study, sonic wave velocity tomograms are generated. The results are comparable with those obtained by CUST. The study indicates that CUST is an effective method for studying freezing processes and has potential for indirect measurement of unfrozen water content variations in the soil without interfering with the freezing process.
    • Experimental investigation of fiber-reininforced polymer composite bridge deck panel in cold regions

      Choppali, Usha (2005-08)
      To build highway bridges in cold regions like Alaska, cast-in-place concrete has been found to be difficult and expensive, especially in winter seasons. Decked Bulb-Tee bridge members can be heavy and the deck cannot be replaced. On the other hand, fiber-reinforced plastic (FRP) composite materials offer a great opportunity in this area. The primary technical barrier to the use of composite materials in infrastructure applications is lack of data on environmental durability. The present study presents experimental load and strain results of a FRP composite panel that was subjected to cold temperatures. The FRP panel consists of an upper and a bottom laminate tied by a honeycomb core, which was produced by sequentially bonding a flat sheet to a corrugated sheet. Specifically, the objective of this research was to understand the effects of low temperature and low-temperature thermal cycling on the performance of FRP composite bridge deck panels in cold regions. This was achieved by analyzing static tests and results for a FRP deck panel. The research results reported herein showed an increase in stiffness as temperature was lowered up to a certain point, and a reverse trend at a further lower temperature.
    • Experimental investigation of low salinity enhanced oil recovery potential and wettability characterization of Alaska North Slope cores

      Patil, Shivkumar B. (2007-12)
      Rock wettability and the chemical properties of the injection water influence fluid distribution and multiphase fluid flow behavior in petroleum reservoirs and hence it consequently affects the final residual oil saturation. Many researchers have proven that oil recovery is increased by decreasing the salinity of water used for waterflooding process. Three sets of experiments were conducted on representative Alaska North Slope (ANS) core samples to experimentally ascertain the influence of injected brine/fluid composition on wettability and hence on oil recovery in secondary oil recovery mode. All the sets of experiments examined the effect of brine salinity variation on wettability and residual oil saturation of representative core samples. The core samples used in the first and third set were new (clean) while in the second set core samples were oil aged. For first and second sets laboratory reconstituted 22,000 TDS, 11,000 TDS and 5,500 IDS (total dissolved solids) brines were used while for the third set ANS lake water was used. Oil aging of core decreased the water wetting state of cores slightly. This observation could be attributed to adsorption of polar compounds of crude oil. The general trend observed in all the coreflood experiment was reduction in Sor (up to 20%) and slight increase in the Amott-Harvey Wettability Index with decrease in salinity of the injected brine at reservoir temperature.
    • Experimental investigation of low salinity water flooding to improve viscous oil recovery from the Schrader Bluff Reservoir on Alaska North Slope

      Cheng, Yaoze; Zhang, Yin; Dandekar, Abhijit; Awoleke, Obadare; Chen, Gang (2018-05)
      Alaska's North Slope (ANS) contains vast resources of viscous oil that have not been developed efficiently using conventional water flooding. Although thermal methods are most commonly applied to recover viscous oil, they are impractical on ANS because of the concern of thawing the permafrost, which could cause disastrous environmental damage. Recently, low salinity water flooding (LSWF) has been considered to enhance oil recovery by reducing residual oil saturation in the Schrader Bluff viscous oil reservoir. In this study, lab experiments have been conducted to investigate the potential of LSWF to improve heavy oil recovery from the Schrader Bluff sand. Fresh-state core plugs cut from preserved core samples with original oil saturations have been flooded sequentially with high salinity water, low salinity water, and softened low salinity water. The cumulative oil production and pressure drops have been recorded, and the oil recovery factors and residual oil saturation after each flooding have been determined based on material balance. In addition, restored-state core plugs saturated with viscous oil have been employed to conduct unsteady-state displacement experiments to measure the oil-water relative permeabilities using high salinity water and low salinity water, respectively. The emulsification of provided viscous oil and low salinity water has also been investigated. Furthermore, the contact angles between the crude oil and reservoir rock have been measured. It has been found that the core plugs are very unconsolidated, with porosity and absolute permeability in the range of 33% to 36% and 155 mD to 330 mD, respectively. A produced crude oil sample having a viscosity of 63 cP at ambient conditions was used in the experiments. The total dissolved solids (TDS) of the high salinity water and the low salinity water are 28,000 mg/L and 2,940 mg/L, respectively. Softening had little effect on the TDS of the low salinity water, but the concentration of Ca²⁺ was reduced significantly. The residual oil saturations were reduced gradually by applying LSWF and softened LSWF successively after high salinity water flooding. On average, LSWF can improve viscous oil recovery by 6.3% OOIP over high salinity water flooding, while the softened LSWF further enhances the oil recovery by 1.3% OOIP. The pressure drops observed in the LSWF and softened LSWF demonstrate more fluctuation than that in the high salinity water flooding, which indicates potential clay migration in LSWF and softened LSWF. Furthermore, it was found that, regardless of the salinities, the calculated water relative permeabilities are much lower than the typical values in conventional systems, implying more complex reactions between the reservoir rock, viscous oil, and injected water. Mixing the provided viscous oil and low salinity water generates stable water-in-oil (W/O) emulsions. The viscosities of the W/O emulsions made from water-oil ratios of 20:80 and 50:50 are higher than that of the provided viscous oil. Moreover, the contact angle between the crude oil and reservoir rock in the presence of low salinity water is larger than that in the presence of high salinity water, which may result from the wettability change of the reservoir rock by contact with the low salinity water.
    • An experimental investigation of natural freezing and biopolymers for permeability modification to reduce the volume of dense non-aqueous phase liquids in groundwater

      D'Cunha, Neil John (2004-12)
      Dense Non-Aqueous Phase Liquid (DNAPL) contamination is one of the major environmental concerns today. DNAPL can remain in significant quantities as residual contaminants in the low permeability zones even after the bulk phase has been removed. As the drive fluid sweeps through the aquifer it follows the path of least resistance, which is the high permeability zone. Thus the contaminants trapped in the low permeability zones remain as residuals and serve as a source for prolonged contamination. Conventional remediation techniques are ill-equipped to deal with the heterogeneities of the aquifers. Various techniques to enhance the efficiency of the conventional methods are tried without significant success. Reducing the temperature of soil formations can modify aquifer flow paths. The natural freezing of soils in winter may be used effectively to modify the flow paths. In summer, permeability modification can be accomplished by emplacement of microbial polymer gels. In this thesis, we have investigated using a laboratory scale one dimensional column experiment, a novel technique to reduce the volume of residual DNAPL using a combination of natural freezing in winter and biopolymer in summer.