Civil and Environmental Engineering, 2000-2025

This senior thesis explores how 3D printing-induced buckling can enhance both the mechanical Strength and carbonation potential of calcium silicate-based cement. I did so by using a wollastonite-based binder and a cement printing setup. I designed and printed six different architectural sample types: Cast, Laminar, Cellular, Coiling, Alternating Loop, and Meander.

The goal was to test how the formation of different samples using different instability ratios changed and affected the internal geometry and from this its impact on structural performance and CO2 absorption. After letting the samples cure in a controlled carbonation chamber, samples were evaluated through three-point bending and phenolphthalein tests to assess both flexural Strength and carbonation. Results showed that printed samples carbonated fully within 72 hours, while cast samples were still uncarbonated in the center. Mechanically, Cellular samples performed best in both Modulus of Rupture (MOR) and energy absorption, while the Coiling and Meander samples showed promising ductility and stress redistribution after failure.

These results highlight the potential of architected geometries to make cementitious structures both stronger and more sustainable. By changing printing patterns and leveraging instabilities like coiling, we can design structures that naturally sequester more CO2 while outperforming conventional forms in strength and toughness.

The Feammox (iron reduction coupled to ammonium oxidation) reaction facilitated by Acidimicrobium sp. A6 can be used to defluorinate per- and polyfluoroalkyl substances (PFAS). The reaction is limited in part by the availability of the oxidizing agent, Fe(III), which is reduced to Fe(II) as the reaction proceeds. A theorized pathway of recycling the produced Fe(II) into Fe(III) through the addition of elemental sulfur (S0 ) was tested in Feammox incubations by varying S0 concentrations in incubations with and without PFOA. While the presence of S0 appeared to correlate with an increase in NH4

• removal and PFOA defluorination, differences between 400% Sulfur, 100%, and No sulfur generally lacked statistical significance due to varying bacterial activity. Furthermore, the apparent production of sulfate points to S0 oxidation rather than the expected reduction, making it seem unlikely that iron recycling was achieved in this case.

Concrete use produces carbon emissions excessively. For safety reasons, cost reasons, and convenience in construction, concrete is a nonnegotiable introducer of carbon emissions; it will not stop. It is nonetheless, more so even, as a result, increasingly important as climate change continues and global anthropogenic carbon dioxide in the atmosphere proliferates to introduce mitigation into the concrete production and use that is increasing. This research aims to reduce the carbon emissions of reinforced concrete foundations by motivating material producers, optimizing structural design, alongside integrating sustainability into code for convenient design tools that maintain safety concerns upfront. Interestingly, existing research does not provide any conclusive evidence as to ways to outweigh concrete’s impact on climate change with sustainability concerns. It is important to continuously monitor data and to optimize based on that data without interrupting construction for safety reasons.

As global warming intensifies and climate change causes sea levels to rise in coastal communities, storm surge barriers are essential to protecting lives and property. Ideally, these structures would serve not only as emergency barriers but also have a secondary function, such as a pedestrian bridge for everyday use. This proposed dual-purpose concept is referred to as the Sustainable Hybrid Bridge-Barrier (SHBB) in this thesis. The objective of this thesis is to evaluate the aerodynamic wind coefficients and structural feasibility of a hybrid tube bridge-barrier structure. To do this, a design prototype was developed using Newtown Creek in NYC as the site, based on the NY-NJ HATS study. The minimum dimensions of the SHBB were determined by analyzing both site constraints and design code requirements. Inspired by existing tube bridges, several CAD models were created and 3D printed to test different design features in a wind tunnel. Three tube bridges were tested: one with no holes, and two with 25% porosity, one using smaller holes and the other using larger holes. A metal deck and printed arch were also tested in various combinations with the tubes. Wind tunnel results confirmed that adding porosity reduces the drag coefficient, with larger holes producing lower drag than smaller holes. The deck had little effect on drag and lift, while the arch had a significant impact. Without the arch, the lift coefficients were approximately zero. Drag coefficients ranged from approximately 1.2 to 1.5. As a result, the recommended tube bridge design should feature large perforations for reduced drag, a minimum diameter of 13 feet, and a conservative wall thickness of approximately 4 inches (assuming a steel material), though thinner sections may also be feasible.

Highways pose several environmental, health, and social concerns. The air and noise pollution from vehicles pose a health risk to those living near highways, often disproportionately affecting marginalized communities. One solution to mitigate these negative externalities is highway capping—constructing lids above highways for conversion into deck parks. A highway capping project was recently proposed for the Cross-Bronx Expressway, but little research has been done on its environmental impact, as it is still in the ideation phase. Thus, this thesis uses a differential analysis to assess how the proposed Cross-Bronx Expressway cap would impact air quality in the surrounding area. Using a Gaussian equation model and verifying results through AERMOD, the Environmental Protection Agency’s regulatory atmospheric dispersion model, pollutant concentrations were calculated in areas adjacent to the proposed cap for the no-build and build scenarios. The study found that air quality marginally improves in areas directly adjacent to the cap, but worsens in areas close to the cap exits, particularly the east exit. While the cap keeps PM2.5 and CO concentrations within the National Ambient Air Quality Standards (NAAQS), it exacerbates existing high NOx concentrations near the cap exits. These findings reveal that there is high variation in how community members will be impacted, depending on their proximity to the cap exits.

This thesis investigated the ability of field-based and remote sensing variables from an unmanned aerial vehicle (UAV) to predict plant species diversity in an alpine ecosystem on Snodgrass Hillslope, located adjacent to Mount Crested Butte, Colorado. Using multiple linear regression models across 88 field plots, soil moisture and slope aspect were the most consistent predictors of species diversity. Other variables in models included slope angle, soil texture, soil temperature, and infrared temperature. Field-based models explained between 37% and 77% of the variance in plant species diversity, with the strongest performance in the upper forested grid. The incorporation of remote sensing variables, including Normalized Difference Vegetation Index (NDVI) and estimated percent vegetation coverage, improved model performance in most cases and most significantly improved performance when modeling the combined lower and upper plots. Remote-only models using NDVI minimum and slope aspect provided a visualization for species diversity across the entire grids but explained less site-level variance with R2 values of 0.6663 (Adj. R2 = 0.555) for the upper grid and an R2 of 0.4123 (Adj. R2 = 0.2227) for the lower grid. These results highlight both the advantages and limitations of solely UAV-based modelling in mountainous terrain. Future projections using SnowClim v1.0 climate projections demonstrated that areas such as Snodgrass Hillslope will become warmer and more stressed for late-season moisture as snowpack decreases, snowmelt timing advances, and summer temperatures rise. These climate shifts may reduce species diversity in water-limited habitats and alter plant community composition in alpine landscapes. Keywords: alpine plant species diversity, multiple linear models, volumetric water content (VWC), slope aspect, soil texture, remote sensing, unmanned aerial vehicles (UAVs), SnowClim v1.0

This thesis investigates the effect of in-situ hydrogel deposition on water absorption in additively manufactured cement paste samples. Hydrogels can absorb many times their weight in water and are commonly used in traditional concrete to assist hydration, but become relatively useless after curing. In this project, hydrogel powders were deposited directly onto 3D printed cement paste samples, with the intention of water diffusing through the sample, thus allowing the hydrogels to absorb water after curing is complete. Samples were printed by depositing hydrogels on varying layers, then submerging the cured samples in water. Absorption is measured by changes in mass over time. Results demonstrated that hydrogels consistently increased water uptake, especially within the first hour of submersion, though absorption plateaued after two hours. Samples with higher hydrogel content experienced layer delamination, as well as gels seeping out the sides. While this gave the gels much more room to expand and dramatically increased water uptake, it destroyed the samples. A proposed solution involves modifying print geometry to include internal cavities for hydrogel containment and expansion. These findings support the potential for additively manufactured cement with embedded hydrogels to serve as a passive flood mitigation strategy in urban areas.

Inequity reveals itself in the five senses. The fumes of fresh pesticides burning nose hairs, red blistering skin from not wearing enough PPE at work, the sound of constant trucks rolling by, the feeling of worry settling in, while you see the clouds of dust skipping in your direction. Is it normal or have you just gotten used to it? There is comfort in familiarity and for areas such as the San Joaquin Valley, there are consistent exploitations of labor, resources, and goods. Cities in the Central Valley hold the top ranking for cities with the worst air quality in the U.S. yet contribute 25 percent of the nations food supply. Through examining five different concentrations of chemicals gathered from the California Department of Pesticide Regulation: Air Monitoring Network, the goal is to understand how (or if) the trends of pesticide exposure in the past fifteen years reflect a pattern of slow violence. The main trade off analyzed is the transition from Methyl Bromide- a highly toxic that has the potential to cause neurological damage- to the carcinogen, 1,3-Dichloropropepe. Seasonal and temporal trends are examined using a variety of plots to compare possible health effects and potentials of cumulative impacts. This data was chosen to be gathered from the Shafter monitoring site because Kern County has already been identified as a disadvantaged community by the state of California. Ultimately, results show that there are consistent trends of overexposure that has dated back multiple years. While this is a result of structural inequities, implementations of environment justice frameworks have the potential to be transformative for pesticide reform.

A geothermal heat pump (GHP) is a heating and cooling system that uses the Earth as a heat source and sink. GHPs possess the environmental benefits associated with all forms of renewable energy, and further have the benefit of meeting a significant demand—building heating and cooling—by tapping an energy source located on site. Moreover, GHPs are efficient and require minimal maintenance. The main drawback of this technology is its high capital cost, which is largely attributed to borehole drilling and pipe installation. Geothermal energy piles (GEPs) provide a way to decrease that cost. On projects that require foundation piles for structural support, geothermal heat exchange tubing can be installed within the piles without any detrimental effect to the foundation's structural integrity. Geothermal energy piles thus increase the viability of GHPs.

This thesis assesses the feasibility of a geothermal energy pile system on the proposed Newark Liberty International Airport AirTrain stations, which will rest on pile foundations. The analysis addresses both the capacity and cost effectiveness of this system. First, calculations demonstrate that geothermal energy piles can provide sufficient heating and cooling capacity given the energy demand, soil conditions, and proposed pile layout. Second, a cost assessment indicates that this system will save money over time despite a higher installation cost. The installation of GEPs on this project could increase awareness of this beneficial technology, which remains relatively uncommon and unknown.

As the risks for coastal hazards increase, traditional countermeasures such as flood walls and storm surge barriers pose a problem, as they hinder access to the beach and diminish coastal beauty. A kinetic hypar umbrella has been proposed as an alternative solution that can provide hybrid benefits of coastal protection and structural art. While hydrostatic and hydrodynamic loads have been tested for the hypar geometry, wind loads have not yet been tested. This thesis seeks to understand the aerodynamic performance of the kinetic umbrellas under varying conditions of inclination and incidence angles. To do so, $CRUE20OWT$ (a wind tunnel at the Forrestal Campus of Princeton University) was validated by comparison with data sets collected at a vetted wind tunnel located at the University of Oviedo. Secondly, a velocity profile was measured for $CRUE20OWT$ to understand the variance in wind across the face of the nozzle. Both tests concluded that the difference between the data sets and the variance in the velocity profile was within the realm of testing errors to vet the wind tunnel, especially to study the behavior trends of the aerodynamic coefficients.

The impacts of changing inclination angles on drag and lift coefficients were observed to match the general behavior of airplane wings and its angle of attack. The drag and moment coefficient curves showed a U-shaped curvature with respect to inclination angles, which increased in value as the inclination decreased or increased away from 0 degrees. The lift coefficient showed a more sine-like curvature with a point symmetry about the 0 degrees point. With respect to the angle of incidence, the drag and moment coefficient curves also displayed a U-shaped curvature, increasing in value as the inclination decreased or increased away from 90 degrees. The lift coefficient exhibited a cosine-like curvature where the value decreases as the incidence angle increases from 0 and continues to decrease as the incidence angle increases to 180 degrees. The shape of the curvatures with respect to angle of incidence matches the expected behavior; changing the incidence angle rotation is essentially changing the angle of attack in another axis.

Rocking isolation is a form of base isolation that relies on a structure’s ability to uplift and rock during ground excitations, dissipating energy via impact with the ground. In 2D, the planar rocking motion is easily understood and modeled. But in the 3D scheme, the system becomes more complex, requiring more intensive calculations and parameters to consider. This thesis will use Distinct Element Modeling to simulate the 3D rocking behavior of free-standing columns and their framed systems. A parametric approach is taken to examine how a column’s geometry and a frame’s orientation can impact its rocking behavior and overall stability under various ground accelerations modeled using a Single-Pulse Sine wave and time history velocities of recorded earthquakes. The analyses reveal that a column’s capacity to endure intense ground excitations can be predicted based on its column’s size and shape. Additionally, this thesis finds that when an array (2D) or matrix (3D) of solitary columns are capped by a freely supported, rigid beam or slab, its capacity to endure intense ground movements is enhanced. The rocking behavior will be ascertained through the numerical analysis of the vertical displacements and velocities of the column’s centroid, in tandem to the qualitative observations of the system’s overall displacements from its original position. Small-scale, physical experimentations are performed to provide qualitative observations of how the 3D rocking model behaves under real-time loading conditions and constraints. Discussion of results will be done in context of performance-based design criteria in hopes of informing applications to modern designs.

As temperatures have increased with a changing climate, streamflow in the Upper Colorado River Basin (UCRB) has declined, posing a severe threat to public well-being. Much of this downstream surface water originates as groundwater in mountainous catchments. As conditions warm, plants’ demand for water increases, potentially reducing groundwater's contributions to surface water downstream. Yet this response to warming is complicated by transpiration’s dependence on energy and water limitation, which varies spatially and temporally in topographically complex catchments of the UCRB.

This study quantifies the effect of warming on summer transpiration in the East-Taylor Watershed (ETW), a representative catchment of the UCRB, under conditions of varying energy and water limitation. ParFlow-CLM is used to model hydrologic and land surface processes with meteorological forcing input from a wet year (WY2017) and dry year (WY2018). Baseline temperature forcings are then uniformly increased by 1.5oC to explore the effects of projected warming alongside different precipitation inputs, resulting in four total simulations. Analysis focuses on transpiration and recharge, studying the spatial variation of these fluxes with land cover type and elevation. Results indicate that warming has a more substantial effect on plant groundwater use in the ETW during an energy limited water year. Analysis of daily soil moisture change across each root zone layer further reveals an increased reliance on deeper root zone moisture with warming, which is strongest under hot and dry conditions.

This thesis presents an investigation into the structural behavior of a concrete beam with welded connections in an operational parking garage. Long-gauge fiber Bragg grating (FBG) sensors were installed at strategic locations to measure strain under various loading configurations. The research explores the discrepancies between numerical calculations and measured beam response to understand how the complex geometry and boundary conditions influence structural behavior. Finite element analysis (FEA) simulations were conducted using Abaqus software to establish boundary conditions representing two extreme cases: a simply supported beam and a beam with constrained points. These models served as limit states for interpreting the influence of welded connections on beam strain. Measured strain data was compared with FEA predictions, and the effect of welded connections was quantified using a percent effectiveness metric. Results demonstrate that welded connections exert diverse influences on beam deflection depending on both measurement location and load configuration. The connections' behavior generally falls between that of a simply supported beam and one with fixed constraint points, with the proximity to either extreme end condition varying throughout the beam. FEA models showed particular difficulty in accurately predicting lateral bending behavior. The study was constrained by limitations in sensor placement, load magnitude restrictions, and simplifications in the FEA models. Despite these constraints, the methodology demonstrates an effective approach for analyzing structures with complex geometries and boundary conditions. This research contributes to understanding CarbonCure concrete performance in operational structures and supports the ongoing development of structural health monitoring techniques that can enhance the safety and maintenance of built infrastructure.

This thesis develops and tests a process based model of streamflow and nitrogen concentration in the urban stream network of the Bassett Creek watershed. The model treats the watershed as a control volume. This allows for a simplified but physically grounded representation of nitrogen inputs, transformations, and losses. Streamflow is used as the primary control variable. Hydrologic variability is modeled as a key factor shaping nitrogen export over time. This model uses a forward Euler method for two differential equations of streamflow and nitrogen dynamics. These equations are implemented manually in MATLAB to emphasize clarity and sensitivity to parameter changes. The model is calibrated using long term data on rainfall, streamflow, and nitrogen concentrations. Sensitivity analyses are used to identify which parameters most strongly influence outcomes. Results show that the streamflow model captures general runoff behavior with moderate accuracy. The nitrogen model reveals useful qualitative trends but struggles with predictive power due to limited data and the complexity of underlying processes. By grounding the model in first principles and real world observations, this thesis offers an accessible alternative to black box models. It is particularly well suited for environments with limited data and exploratory research in urban watershed systems.

The origin of the oil industry is in the Appalachian Basin, which has resulted in thousands of abandoned wells over the years. Improperly sealed wells may leak contaminants into the groundwater, which introduces public health risks to a resource that millions of Americans rely on for drinking water. While methane emissions from abandoned wells are well-studied, aqueous contamination risks remain understudied, especially with regard to human exposure through domestic groundwater wells. This project quantifies the vulnerability of groundwater and its population due to contamination coming from abandoned wells. The total number of people relying on private drinking wells is determined and then used to analyze its spatial distribution by applying a hotspot analysis. The project employs a source-pathway-receptor framework. In this framework, the source consists of a dataset of abandoned wells, while the pathway includes USGS-developed programs ModFlow-6 and ModPath-7, which are used to track particles through the groundwater. The receptors in this system are private drinking wells. In total, an area of 8,815.3 km2 is determined to show vulnerability coming from abandoned wells, potentially exposing a population of 402,948 people that rely on private drinking wells. Particles were tracked often shorter than 2 km, but notable outliers reached almost 17 km. These results emphasize the risk to public health due to the legacy impacts of the oil industry, and thus should be considered in future environmental policy and energy planning.

This thesis works through the design process for a flood protection barrier falling within a special sub-category that the research team has defined: Sustainable Hybrid Bridge Barriers (SHBB). The design starts with what is known as a visor gate, which has some limited precedent around the world. But this project offers a unique new approach to that basic structure, which not only performs as a barrier in large storms, but also incorporates a pedestrian bridge, functions in a relatively more sustainable fashion, and has aesthetic appeal. The design process for each element of the barrier, including its unique ballast system, are worked through in the paper. Future work to be done to implement such a design in reality is also described systematically. The design on this iteration was unfortunately unsuccessful, but the groundwork has still been laid for next steps.

The aim of this project is to create a queueing framework to be implemented in Walt Disney World that maximizes guest enjoyment and efficiency of movement, while also taking into consideration sensory needs of guests with intellectual and developmental disabilities (IDDs). To achieve these goals, this project explores the idea of a “second story” being added to Disney World in the form of queueing spaces to both maximize perceived efficiency and utilize verticality that is currently being wasted. The results from this research include observations from spatial ethnography conducted in Disney World, survey data regarding queueing systems in general and in Disney World, and a framework for a queueing system that meets all of the requirements for efficiency, enjoyment, and accessibility as defined by the survey and spatial ethnography. Drawings of two queueing systems that implement this framework are included to better conceptualize how these queues fit into the space, as well as a representative structural analysis of the typical building an attraction queue adhering to this frame- work would be housed in. This new queueing framework, if implemented and found successful, could be replicated in other facets of life to improve queueing experience for all people, regardless of ability.