Fly Ash Soil Stabilization for Non-Uniform Subgrade Soils, Volume I: Engineering Properties and Construction Guidelines, TR-461, 2005

Soil treated with self-cementing fly ash is increasingly being used in Iowa to stabilize fine-grained pavement subgrades, but without a complete understanding of the short- and long-term behavior. To develop a broader understanding of fly ash engineering properties, mixtures of five different soil types, ranging from ML to CH, and several different fly ash sources (including hydrated and conditioned fly ashes) were evaluated. Results show that soil compaction characteristics, compressive strength, wet/dry durability, freeze/thaw durability, hydration characteristics, rate of strength gain, and plasticity characteristics are all affected by the addition of fly ash. Specifically, Iowa selfcementing fly ashes are effective at stabilizing fine-grained Iowa soils for earthwork and paving operations; fly ash increases compacted dry density and reduces the optimum moisture content; strength gain in soil-fly ash mixtures depends on cure time and temperature, compaction energy, and compaction delay; sulfur contents can form expansive minerals in soil–fly ash mixtures, which severely reduces the long-term strength and durability; fly ash increases the California bearing ratio of fine-grained soil–fly ash effectively dries wet soils and provides an initial rapid strength gain; fly ash decreases swell potential of expansive soils; soil-fly ash mixtures cured below freezing temperatures and then soaked in water are highly susceptible to slaking and strength loss; soil stabilized with fly ash exhibits increased freeze-thaw durability; soil strength can be increased with the addition of hydrated fly ash and conditioned fly ash, but at higher rates and not as effectively as self-cementing fly ash. Based on the results of this study, three proposed specifications were developed for the use of self-cementing fly ash, hydrated fly ash, and conditioned fly ash. The specifications describe laboratory evaluation, field placement, moisture conditioning, compaction, quality control testing procedures, and basis of payment.

Covalent cell surface functionalization of human fetal osteoblasts for tissue engineering.

The chemical functionalization of cell-surface proteins of human primary fetal bone cells with hydrophilic bioorthogonal intermediates was investigated. Toward this goal, chemical pathways were developed for click reaction-mediated coupling of alkyne derivatives with cellular azido-expressing proteins. The incorporation via a tetraethylene glycol linker of a dipeptide and a reporter biotin allowed the proof of concept for the introduction of cell-specific peptide ligands and to follow the reaction in living cells. Tuning the conditions of the click reaction resulted in chemical functionalization of living human fetal osteoblasts with excellent cell survival.

Estimating traveltimes and groundwater flow patterns using 3D time-lapse crosshole ERT imaging of electrical resistivity fluctuations induced by infiltrating river water

The infiltration of river water into aquifers is of high relevance to drinking-water production and is a key driver of biogeochemical processes in the hyporheic and riparian zone, but the distribution and quantification of the infiltrating water are difficult to determine using conventional hydrological methods (e.g., borehole logging and tracer tests). By time-lapse inverting crosshole ERT (electrical resistivity tomography) monitoring data, we imaged groundwater flow patterns driven by river water infiltrating a perialpine gravel aquifer in northeastern Switzerland. This was possible because the electrical resistivity of the infiltrating water changed during rainfall-runoff events. Our time-lapse resistivity models indicated rather complex flow patterns as a result of spatially heterogeneous bank filtration and aquifer heterogeneity. The upper part of the aquifer was most affected by the river infiltrate, and the highest groundwater velocities and possible preferential flow occurred at shallow to intermediate depths. Time series of the reconstructed resistivity models matched groundwater electrical resistivity data recorded on borehole loggers in the upper and middle parts of the aquifer, whereas the resistivity models displayed smaller variations and delayed responses with respect to the logging data. in the lower part. This study demonstrated that crosshole ERT monitoring of natural electrical resistivity variations of river infiltrate could be used to image and quantify 3D bank filtration and aquifer dynamics at a high spatial resolution.

Pore-scale modeling of two-phase flow instabilities in porous media

Les problèmes d'écoulements multiphasiques en média poreux sont d'un grand intérêt pour de nombreuses applications scientifiques et techniques ; comme la séquestration de C02, l'extraction de pétrole et la dépollution des aquifères. La complexité intrinsèque des systèmes multiphasiques et l'hétérogénéité des formations géologiques sur des échelles multiples représentent un challenge majeur pour comprendre et modéliser les déplacements immiscibles dans les milieux poreux. Les descriptions à l'échelle supérieure basées sur la généralisation de l'équation de Darcy sont largement utilisées, mais ces méthodes sont sujettes à limitations pour les écoulements présentant de l'hystérèse. Les avancées récentes en terme de performances computationnelles et le développement de méthodes précises pour caractériser l'espace interstitiel ainsi que la distribution des phases ont favorisé l'utilisation de modèles qui permettent une résolution fine à l'échelle du pore. Ces modèles offrent un aperçu des caractéristiques de l'écoulement qui ne peuvent pas être facilement observées en laboratoire et peuvent être utilisé pour expliquer la différence entre les processus physiques et les modèles à l'échelle macroscopique existants. L'objet premier de la thèse se porte sur la simulation numérique directe : les équations de Navier-Stokes sont résolues dans l'espace interstitiel et la méthode du volume de fluide (VOF) est employée pour suivre l'évolution de l'interface. Dans VOF, la distribution des phases est décrite par une fonction fluide pour l'ensemble du domaine et des conditions aux bords particulières permettent la prise en compte des propriétés de mouillage du milieu poreux. Dans la première partie de la thèse, nous simulons le drainage dans une cellule Hele-Shaw 2D avec des obstacles cylindriques. Nous montrons que l'approche proposée est applicable même pour des ratios de densité et de viscosité très importants et permet de modéliser la transition entre déplacement stable et digitation visqueuse. Nous intéressons ensuite à l'interprétation de la pression capillaire à l'échelle macroscopique. Nous montrons que les techniques basées sur la moyenne spatiale de la pression présentent plusieurs limitations et sont imprécises en présence d'effets visqueux et de piégeage. Au contraire, une définition basée sur l'énergie permet de séparer les contributions capillaires des effets visqueux. La seconde partie de la thèse est consacrée à l'investigation des effets d'inertie associés aux reconfigurations irréversibles du ménisque causé par l'interface des instabilités. Comme prototype pour ces phénomènes, nous étudions d'abord la dynamique d'un ménisque dans un pore angulaire. Nous montrons que, dans un réseau de pores cubiques, les sauts et reconfigurations sont si fréquents que les effets d'inertie mènent à différentes configurations des fluides. A cause de la non-linéarité du problème, la distribution des fluides influence le travail des forces de pression, qui, à son tour, provoque une chute de pression dans la loi de Darcy. Cela suggère que ces phénomènes devraient être pris en compte lorsque que l'on décrit l'écoulement multiphasique en média poreux à l'échelle macroscopique. La dernière partie de la thèse s'attache à démontrer la validité de notre approche par une comparaison avec des expériences en laboratoire : un drainage instable dans un milieu poreux quasi 2D (une cellule Hele-Shaw avec des obstacles cylindriques). Plusieurs simulations sont tournées sous différentes conditions aux bords et en utilisant différents modèles (modèle intégré 2D et modèle 3D) afin de comparer certaines quantités macroscopiques avec les observations au laboratoire correspondantes. Malgré le challenge de modéliser des déplacements instables, où, par définition, de petites perturbations peuvent grandir sans fin, notre approche numérique apporte de résultats satisfaisants pour tous les cas étudiés. - Problems involving multiphase flow in porous media are of great interest in many scientific and engineering applications including Carbon Capture and Storage, oil recovery and groundwater remediation. The intrinsic complexity of multiphase systems and the multi scale heterogeneity of geological formations represent the major challenges to understand and model immiscible displacement in porous media. Upscaled descriptions based on generalization of Darcy's law are widely used, but they are subject to several limitations for flow that exhibit hysteric and history- dependent behaviors. Recent advances in high performance computing and the development of accurate methods to characterize pore space and phase distribution have fostered the use of models that allow sub-pore resolution. These models provide an insight on flow characteristics that cannot be easily achieved by laboratory experiments and can be used to explain the gap between physical processes and existing macro-scale models. We focus on direct numerical simulations: we solve the Navier-Stokes equations for mass and momentum conservation in the pore space and employ the Volume Of Fluid (VOF) method to track the evolution of the interface. In the VOF the distribution of the phases is described by a fluid function (whole-domain formulation) and special boundary conditions account for the wetting properties of the porous medium. In the first part of this thesis we simulate drainage in a 2-D Hele-Shaw cell filled with cylindrical obstacles. We show that the proposed approach can handle very large density and viscosity ratios and it is able to model the transition from stable displacement to viscous fingering. We then focus on the interpretation of the macroscopic capillary pressure showing that pressure average techniques are subject to several limitations and they are not accurate in presence of viscous effects and trapping. On the contrary an energy-based definition allows separating viscous and capillary contributions. In the second part of the thesis we investigate inertia effects associated with abrupt and irreversible reconfigurations of the menisci caused by interface instabilities. As a prototype of these phenomena we first consider the dynamics of a meniscus in an angular pore. We show that in a network of cubic pores, jumps and reconfigurations are so frequent that inertia effects lead to different fluid configurations. Due to the non-linearity of the problem, the distribution of the fluids influences the work done by pressure forces, which is in turn related to the pressure drop in Darcy's law. This suggests that these phenomena should be taken into account when upscaling multiphase flow in porous media. The last part of the thesis is devoted to proving the accuracy of the numerical approach by validation with experiments of unstable primary drainage in a quasi-2D porous medium (i.e., Hele-Shaw cell filled with cylindrical obstacles). We perform simulations under different boundary conditions and using different models (2-D integrated and full 3-D) and we compare several macroscopic quantities with the corresponding experiment. Despite the intrinsic challenges of modeling unstable displacement, where by definition small perturbations can grow without bounds, the numerical method gives satisfactory results for all the cases studied.

Re-Engineering CTE in Iowa: Aligning Career and Technical Education Reform, Workforce Development and Economic Development, August 2007

Iowa is a relatively small state and is on the rebound economically. It has an overall population that is stable, but which is shifting within the state from more rural areas to suburban and urban centers. There is a very tight labor market with high levels of employment. Iowa now has a time-sensitive opportunity to exert global leadership in renewable energy, while maintaining its leadership in other key industries like finance and agriculture.

Health consultation : Hills, Iowa Perchlorate Groundwater Contamination Site 2012 Update Hills, Johnson County, Iowa CERCLIS No. IAN000704368 (2012)

The Iowa Department of Natural Resources (IDNR) has requested that the Iowa Department of Public Health (IDPH) complete an update of the health consultation for the Hills, Iowa Perchlorate Groundwater Contamination Site that was originally completed in June 2004. In this updated health consultation, the IDPH will: 1) summarize background information on this site, 2) summarize the progress of work that has been completed regarding the site, 3) summarize the environmental data that has been collected, 4) summarize toxicological information and regulatory information regarding perchlorate, and 5) provide an update to any conclusions and recommendations from the Iowa Department of Public Health. The Iowa Department of Public Health’s priority is to ensure the Hills community has the best information possible to safeguard its health and the IDNR has the best information to guide its activities. That information is included in the following paragraphs.

Cross-validation of methods used for analysis of MTBE and other gasoline components in groundwater.

Head space gas chromatography with flame-ionization detection (HS-GC-FID), ancl purge and trap gas chromatography-mass spectrometry (P&T-GC-MS) have been used to determine methyl-tert-butyl ether (MTBE) and benzene, toluene, and the ylenes (BTEX) in groundwater. In the work discussed in this paper measures of quality, e.g. recovery (94-111%), precision (4.6 - 12.2%), limits of detection (0.3 - 5.7 I~g L 1 for HS and 0.001 I~g L 1 for PT), and robust-ness, for both methods were compared. In addition, for purposes of comparison, groundwater samples from areas suffering from odor problems because of fuel spillage and tank leakage were analyzed by use of both techniques. For high concentration levels there was good correlation between results from both methods.

Geologic and Engineering Properties of Pleistocene Materials in Iowa, Iowa Highway Research Board Bulletin No. 20, 1960

This bulletin is a compilation of the reports on completed research done for the Iowa State Highway Research Board Project HR-1, "The Loess and Glacial Till Materials of Iowa; an Investigation of Their Physical and Chemical Properties and Techniques for Processing Them to Increase Their All-Weather Stability for Road Construction.” The research, started in 1950, was done by the Iowa Engineering Experiment Station under its project 283-S. The project was supported by funds from the Iowa State Highway Commission.

Public health assessment : Railroad Avenue groundwater contamination, West Des Moines, Polk County, Iowa EPA facility ID: IA0001610963 (2004)

The Railroad Avenue groundwater contamination site (the site) is in West Des Moines, Polk County, Iowa. Located on approximately 120 acres. The site comprises mixed residential, industrial and commercial properties. Underneath the site, chlorinated volatile organic compounds (VOCs) have contaminatcd the shallow (i.e., 30-50 feet deep) groundwater. These compounds have compromised several shallow wells within the West Des Moines water works system. A contamination source, however, has not yet been identified. In 1993, routine water analysis by the City of West Des Moines identified 1, 2 cis-dichlorocthylcne (1, 2 cis-DCE) at a concentration of 1.2 μg/L (micrograms) per liter of water) in the water supply. Subsequently. several shallow municipal wells were found to be contaminated by VOCs, including 1. 2 cis-DCE, trichloroethylene (TCE), tetrachloroethylene (PCE) and benzene. Five of these wells have been taken out of service. Because of the impact on the West Des Moines water supply, the U.S. Environmental Protection Agency (USEPA) has assigned the site to the National Priorities List. Surface water und sediment at the site have not been impacted by the VOCs. Testing for VOCs in surface soils has not revealed any significant VOC contamination. Subsurface soils -- generally 8 feet or greater in depth -- are contaminated with VOCs, but at levels which should not present a health hazard. The past, present, and future health hazard category chosen for this site is no apparent public health hazard. This category is used when exposure to toxins might be occurring or might have occurrcd in the past, but at levels below any known health hazard. Analysis of available environmental data has not revealed that residental or commercial water customers are or have been exposed to VOCs at concentrations that might cause any adverse health effects.

Health consultation : Climbing Hill groundwater contaminiation site, Climbing Hill, Woodbury County, Iowa (2004)

The Iowa Department of Natural Resources (IDNR) asked the Iowa Department of Public Health (IDPH) Hazardous Waste Site Health Assessment Program to perform a health consultation for the Climbing Hill, Iowa, groundwater contamination site. IDNR wants to know if the site poses a public health hazard. The information in this health consultation was current at the time of writing. Data that emerges later could alter this document’s conclusions and recommendations. Climbing Hill is an unincorporated town in Woodbury County, Iowa, approximately 15 miles southeast of Sioux City. The town has approximately 120 residents. All of the residents and most businesses within the town use private wells to supply their drinking water. The local restaurant has an individual well that is classified as a public water supply system because it has the potential to serve more than 25 people in a day. Several wells in the town have become contaminated with gasoline and diesel fuel leaking from two underground storage tanks. All of the wells are roughly 75–80 feet deep (R. Cardinale, IDNR, Underground Storage Tank Section, personal communication, January 30, 2004).

Health consultation : Hills, Iowa perchlorate groundwater contamination site, Hills, Johnson County, EPA facility ID: IAN 000704368 (2004)

The U. S. Environmental Protection Agency (EPA) Region 7, as well as concerned citizens, asked the Iowa Department of Public Health (IDPH) Hazardous Waste Site Health Assessment Program to perform a health consultation for the Hills, Iowa Perchlorate Groundwater Contamination Site. Specifically, IDPH was asked to determine if EPA’s action of providing bottled water to residents whose private wells had concentrations of greater than 18 μg/L (micrograms per liter) or 18 parts per billion (ppb) perchlorate is protective of public health, and to address some community health concerns. The information included in this health consultation was current at the time of writing. Data that emerges later could alter this document’s conclusions and recommendations.