Digital Commons Network^™

Understanding The 2024 Legacy Rule Risk Assessments, Ishita Shrivastava, Ari Lewis, John Kondziolka, Andrew Bittner

World of Coal Ash Proceedings

The United States Environmental Protection Agency's (US EPA's) May 2024 Legacy Coal Combustion Residuals (CCR) Rule aims to address potential releases and associated risks from legacy surface impoundments and CCR management units (CCRMUs) that were not regulated under the 2015 CCR Rule. As part of the 2024 rule, US EPA conducted several risk analyses to quantify risks from historical disposal units and CCRMU fills. For historical units, US EPA relied on modeling results for “previously excluded” units from the 2014 CCR Risk Assessment. For CCRMU fills, however, US EPA performed new modeling that incorporated several different assumptions relative to the …

Establishing Groundwater Monitoring Systems Under The Legacy Rule: A Systematic Approach For Utilities, Chris Hoglund

World of Coal Ash Proceedings

The USEPA’s Legacy CCR Rule introduces new requirements for establishing groundwater monitoring systems at Legacy Surface Impoundments (LSIs) and Coal Combustion Residual Management Units (CCRMUs). These requirements present unique challenges for electric utilities, particularly at inactive or historically operated facilities where subsurface data are limited and CCR units may have nontraditional configurations such as linear roadways, elongated embankments, or distributed disposal areas. Utilities must also determine how best to apply single-unit or multi-unit monitoring approaches, integrate newly regulated units into existing monitoring networks, and align monitoring system design with planned closure strategies. This presentation outlines a systematic, defensible framework to …

Risk Evaluation Of Linear Coal Combustion Residual Management Unit (Ccrmu) Fills, Qian Zhang, Andrew Bittner, John Kondziolka, Masoud Arshadi

World of Coal Ash Proceedings

In 2024, the US Environmental Protection Agency (US EPA) established new regulations for coal combustion residual management units (CCRMUs), defined as coal combustion residual (CCR) deposits placed on power plant properties outside of landfills or surface impoundments. US EPA supported the rulemaking with modeling-based risk analyses and established regulatory requirements based on fill size. Linear CCRMU, such as backfill along pipelines or haul roads, have individual segments that may be composed of a small amount of mass below the threshold for regulation, but the cumulative mass over the full linear feature extent may exceed regulatory thresholds. This study applies US …

Application Of Mine Tailings Flow Failure Assessment On Ccr, Zachary Fallert

World of Coal Ash Proceedings

A new geotechnical stability analysis method has been implemented for a CCR surface impoundment to aid in design for temporary cut slopes and final closure grades. Conditions have come to light after significant tailings dam failures occurred across the globe, specifically those exhibiting flow failures (i.e. failures in which tailings behave a liquid and flow out of the facility). These failures have come under intense scrutiny as the failures pose significant risk to public safety and the environment and have been observed in CCR. Additionally, static liquefaction has arisen as another potential but less well understood causative mechanism. As the …

Message To Judy, Lloyd C. Clark

Lloyd Clark Papers

Copy of news clipping, from Arizona State University's publishing on commencement, with a note from Lloyd C. Clark to Ms. Judy Smith, from the Office of the President, of The University of Texas at Arlington.

Letter To Robert, Lloyd C. Clark

Lloyd Clark Papers

Letter to Robert E. Witt, President of The University of Texas at Arlington, from Lloyd C. Clark, regarding a student interested in enrollment.

Letter To Lloyd, Carol Ireland

Lloyd Clark Papers

Letter to Lloyd C. Clark from Carol Ireland, regarding her sons interest in attending The University of Texas at Arlington, with her sons attached resume and awards.

Lessons Learned: Commissioning An Fgd Wastewater Treatment System, Bella Triolet, Mckale Grant, Louis Manigault

World of Coal Ash Proceedings

Stantec recently supported commissioning a flue gas desulfurization (FGD) Wastewater Treatment System in accordance with the 2020 Environmental Protection Agency (EPA) Effluent Limitations Guidelines (ELG) Rule, which requires that coal fired power plants meet their more stringent requirements by December 31, 2025. With the addition of the 2024 EPA ELG Rule, coal fired power plants will now be expected to move to zero liquid discharge (ZLD) systems or permanently cease coal combustion by 2034. Due to this change, it is likely that coal fired power plants will be looking to design and install ZLD systems within the next decade. While …

Risk Evaluation Of Linear Coal Combustion Residual Management Unit (Ccrmu) Fills, Qian Zhang, Andrew Bittner, John Kondziolka, Masoud Arshadi

World of Coal Ash Proceedings

In 2024, the US Environmental Protection Agency (US EPA) established new regulations for coal combustion residual management units (CCRMUs), defined as coal combustion residual (CCR) deposits placed on power plant properties outside of landfills or surface impoundments. US EPA supported the rulemaking with modeling-based risk analyses and established regulatory requirements based on fill size. Linear CCRMU, such as backfill along pipelines or haul roads, have individual segments that may be composed of a small amount of mass below the threshold for regulation, but the cumulative mass over the full linear feature extent may exceed regulatory thresholds. This study applies US …

Site Characterization, Design, Permitting, And Construction For Clean Closure Of A Small But Challenging Legacy Ccr Disposal Impoundment, John Garten, Bob Baker, Lee Lenhart

World of Coal Ash Proceedings

The Lay of Land Area (LOLA) is a 10-acre (40,468 square meters) legacy disposal impoundment containing approximately 55,000 cubic yards (42,000 cubic meters) of sluiced coal combustion residuals (CCRs) produced during startup operations of a former fossil plant. Most of its perimeter is bounded by water, with a river to the north and a cooling water lake to the south. The entire area lies within a 100-year floodplain, is heavily forested, and groundwater is typically encountered within a few feet of the existing ground surface. As part of an overall CCR closure-by-removal and ash beneficiation program, planning, design, permitting, and …

Trimble County Pond Closures, Steven Turner, Shanti Montgomery

World of Coal Ash Proceedings

The Trimble County Closure Project is a 5-year project to close the 40-acre (161,900 square meters) Gypsum Storage Pond (GSP) through closure-by-removal and the 100-acre (404,700 square meters) Bottom Ash Pond (BAP) through closure-in-place in accordance with coal combustion residual (CCR) Rule. The excavated gypsum from the GSP was “Beneficially Reused” to fill the BAP to the prescribed grade for drainage through a monitored outfall to the adjacent creek. The daily plant produced CCRs of fly ash, bottom ash, and gypsum were also used for four years to supplement the filling of the BAP as well as several onsite soil/rock …

Green Infrastructure As A Strategy For Revitalizing Old Residential Neighborhoods: Evaluation Of Carbon Footprint And Energy Performance - Case Study Of Heliopolis, Cairo, Ahmad Abouisaadat, Eman Gameel, Shoroq Adel

Mansoura Engineering Journal

This study aims to address the challenge of reducing energy consumption and greenhouse gas (GHG) emissions in urban areas, particularly in aging residential neighborhoods. Despite the benefits of Urban Green Infrastructure (UGI) and residential retrofitting, current research often examines these strategies separately, leaving a gap in understanding their combined impact at the district scale. The research proposes a methodology that integrates GIS-based spatial analysis, Urban Building Energy Modeling (UBEM), and Life Cycle Assessment (LCA) to evaluate the effects of UGI (e.g., green roofs, urban trees) and retrofitting strategies on energy use, CO2 reduction, and urban microclimates. The study will provide …

Uta Student Newsletter

Lloyd Clark Papers

Newsletter published by the Student Foundation at The University of Texas at Arlington consisting of student and faculty news and campus events.

Letter And Brochure, Pam Bagby

Lloyd Clark Papers

Letter to Lloyd and Jean Clark from Pam Bagby, President of Friends of The University of Texas at Arlington Libraries. Brochure for Friends of The University of Texas at Arlington Libraries, featuring a description of the organization and member benefits.

Building Better Partnerships: Design-Build Lessons From The Ash Pond Closure Front Lines, Brian Egan, Nicholas Golden, Mark Edlebeck

World of Coal Ash Proceedings

This presentation shares lessons learned on an ash pond dig-and-haul project delivered by a design-build team with CTI providing engineering and Fisher Contracting delivering construction services. CTI and Fisher Contracting will discuss how they formed their partnership, what makes a good teaming arrangement work, and the challenges that come with working closely together. This team has worked side by side from early design through construction, which has helped cut costs and keep the project on schedule. The talk will show how the partners divide tasks, then adjust roles as needed instead of locking into a fixed plan. In some cases, …

Dewatering System Operations And Modeling Of A Bottom Ash Ccr Surface Impoundment, Craig Schuettpelz, Todd Stong, Ben Sieren

World of Coal Ash Proceedings

Dewatering of coal combustion residual (CCR) surface impoundments is a technically challenging item for sites with CCR units at closure. Generation has ceased at this site where fly ash was mostly sold for beneficial use and bottom ash was sluiced to composite-lined CCR surface impoundments to passively drain prior to landfilling. During site closure and restoration, bottom ash and relatively minor amounts of other permitted waste materials were consolidated into the site’s landfill and bottom ash impoundment. The bottom ash impoundment entered closure 5 years ago with installation of a final cover system and construction of a sump to allow …

A Doubly Stochastic Model Of Government Interventions To Preserve Ecosystems Services In The Context Of Large-Scale Industrial Agriculture, Karma Brame, Wendy Calderon, Kaylee Clark, Josh Hiller, Natalia Negrete

Spora: A Journal of Biomathematics

Deforestation, driven by industrial agriculture and cattle farming, has significantly impacted communities and ecosystems across the globe. In this paper, we develop a discrete-time Markov model to evaluate the effectiveness of market-based interventions, such as payments for ecosystem services (PES) and taxes, in addressing forest loss within the context of large-scale agriculture. Specifically, we focus on how commodity price variability influences deforestation decisions. To model these price fluctuations, we represent agricultural prices as geometric Brownian motion (GBM). By linking commodity price dynamics to land use transitions, our model aims to provide insight into how financial mechanisms can slow or stop …

Illinois Coal Ash Impoundment Assessment, Randy Locke

World of Coal Ash Proceedings

Coal combustion residuals (CCR) present one of the most significant waste management challenges in the United States. Illinois hosts 72 coal ash impoundments at 23 facilities across 22 counties. In 2019, the state enacted Public Act 101 0171 (Coal Ash Pollution Prevention Act), followed by Illinois Administrative Code Title 35, Part 845, establishing CCR surface impoundment standards. Even with federal and state requirements, significant gaps remain in identifying management options and site-specific risks. Key limitations include: (1) incomplete understanding of ash composition and variability within and among impoundments; and (2) fragmented information on impoundment physical properties, operational status, and geological …

Upset Letters

Lloyd Clark Papers

Letters from William Pinney, John R. Tillinghast, Shirley Rhea, and Lloyd Clark upset over Bob Ray Sander's comments about the University of Texas at Arlington.

University Event, Dawn Prejean, Lloyd C. Clark

Lloyd Clark Papers

Letter to Lloyd C. Clark from Dawn Prejean inviting him to the 1994 Distinguished Alumni Gala and also asking him to sponsor the event. Lloyd responds with form stating he will not attend and a check for $25, September 4, 1994.

Response Surface Modelling And Multi-Objective Optimisation Of Asphalt Binder And Mixture Properties Modified With Reclaimed Automotive Lubricants And Waste Glass Bottle Powder, Nura Shehu Aliyu Yaro, Jacob Adedayo Adedeji, Luvuno Nkosinathi Jele, Nasir Khan, Aliyu Usman, Jacob Olumuyiwa Ikotun

Journal of Sustainable Construction Materials and Technologies

Large volumes of reclaimed automotive lubricant (RAL) and waste glass bottle powder (WGBP) are disposed of inappropriately, causing serious environmental concerns. Furthermore, the paradigm shift towards sustainability in the pavement industry has prompted academics to investigate alternatives to conventional materials. As a result, one possible approach is to use these waste products as alternative materials in the asphalt pavement sector. This study investigated the combined use of RAL and WGBP as complementary modifiers, extending beyond the conventional single-modifier approaches reported in previous studies. Thus, in this study, response surface methodology (RSM) was utilised to optimise and predict the synergistic effects …

The Nexus Between Sustainable Banking, Customer Trust, And Bank Loyalty In The Bangladeshi Banking Industry: A Structural Equation Modelling Approach, Rashed Mahmud Shakil, Md. Ashfikul Islam, Md Raihatul Islam Hridoy

Business Review

The increasing customer demand for environmentally-friendly practices makes adoption of sustainable banking (SB) strategies a great opportunity for banks wanting to ensure greater loyalty among their customers. However, the impact of SB on bank loyalty (BL) of customers in the Bangladeshi banking sector is limited in the scholarly literature. Thus, the present research investigates the association between SB and BL and the intervening influence of customer trust (CT) in this association. The proposed research model was developed based on the Social Exchange Theory. The research utilized a purposive sampling technique and employed data obtained through 230 questionnaires distributed amongst customers …

Privacy-Preserving Local Authorization For Regulated, Safety-Critical, And Financial Systems, Jonathan Stephen Baker

Defensive Publications Series

This disclosure describes systems and methods for controlling access to regulated, age-restricted, safety-critical, high-liability, and financial devices using privacy-preserving local authorization. In disclosed embodiments, a user device, terminal, embedded controller, or local authorization module verifies that a requesting user satisfies one or more access conditions before enabling operation of a protected physical or digital system. The authorization process may be performed locally or at the edge, without requiring persistent storage of raw biometric data, identity templates, or reusable personal credentials by a relying party. The system outputs a limited authorization result, proof, token, permission state, or access decision indicating that …

Gci Hydrocarbon Normalization & Mechanical Fuel Conditioning Platform (V1.5), Michael Victor Caldwell Mr.

Defensive Publications Series

A modular, low-temperature mechanical processing system designed to normalize variable hydrocarbon waste streams (used motor oil, vegetable oil, or pre-processed pyrolysis liquids). This platform does not perform traditional refining. Instead, it uses hydrodynamic shearing, controlled cavitation, centrifugal phase grading, contaminant removal, and adaptive recirculation to transform inconsistent waste fluids into stable, standardized, combustion-compatible fuel blends suitable for industrial engines, burners, and off-grid power systems.

This system emphasizes selective energy application, multi-pass conditioning, and real-time feedback control to maximize efficiency, reduce waste, and improve fuel usability without relying on high-temperature or catalytic refining processes.

Knowledge Tokens For Multi-Dimensional Epistemic Representation In Ai Systems, Johny Manuel-Devadoss, Deepthi Prasad

Defensive Publications Series

We propose a framework that replaces scalar confidence estimates in AI outputs with structured, multi-dimensional representations termed knowledge tokens. Each token encodes orthogonal epistemic attributes including provenance weight, empirical grounding, consensus density, and temporal freshness. Unlike conventional probabilistic confidence scores, knowledge tokens provide composable, inspectable, and tradeable representations of informational quality. This enables downstream systems to reason not only about likelihood but about the structure and reliability of knowledge itself. We formalize the representation, integration into model architectures, training objectives, and evaluation methodologies, and outline how such tokens enable new forms of reasoning, aggregation, and economic exchange over knowledge.

An Adversarial Self-Invalidation Framework For Robust Reasoning, Johny Manuel-Devadoss, Deepthi Prasad

Defensive Publications Series

We propose a novel inference-time and training-time paradigm for improving the epistemic reliability of large language models (LLMs) and tool-augmented AI systems, termed Forced Epistemic Reset (FER). Unlike conventional self-consistency or critique-based methods, FER introduces a structured adversarial self-invalidation cycle in which a model is periodically required to challenge, falsify, and independently re-derive its own outputs using heterogeneous reasoning paths. The system explicitly treats intermediate conclusions as provisional hypotheses subject to internal falsification pressure. We formalize the architecture, training objectives, reset triggering mechanisms, and multi-path recomputation strategy. Empirical evaluation protocols are also outlined, focusing on contradiction recovery, robustness under reasoning …

Natural-Language Multi-Tenant Product Configurator Using Llm Tool-Calling Against A Curated Relational Database, Without A Constraint Solver, Christian Hinterdorfer

Defensive Publications Series

This disclosure describes a multi-tenant Configure-Price-Quote (CPQ) software architecture in which a Large Language Model (LLM) configures complex technical products through natural-language conversation while guaranteeing that every selected option is valid for the relevant product line. Validity is enforced not by translating the conversation into a formal constraint language and running a constraint solver (SAT/CSP/MIP/MiniZinc), but by restricting the LLM's action space: the LLM can only invoke a small, fixed set of tools that operate against a curated relational database, and it can only pass option identifiers that the database itself has previously returned. Hallucinated or invalid identifiers are structurally …

Biology Major Awarded Goldwater Scholarship For Stem Research Leaders, Dave Larsen

College of Arts and Sciences Newsroom

Ashley Williams is UD’s seventh Goldwater Scholar and the fourth in biology.

A Multi-Layer Graph-Theoretic Framework For Understanding Electric Vehicle Adoption Across U.S. Counties, Fahad Alrasheedi

Computer Science Theses, Dissertations, and Student Creative Activity

This dissertation develops a multi-layer analytical framework to understand electric vehicle (EV) adoption across U.S. counties by integrating (1) temporal correlation networks, (2) predictive modeling, and (3) similarity networks. Existing research often focuses on coarse geographic units, embeds charging infrastructure (CI) within broad multivariable models, or overlooks structural differences among counties. These limitations leave open key questions regarding the directionality of EV–CI relationships, the determinants of county-level adoption, and whether similar counties exhibit similar adoption patterns. The first component examines temporal correlations between counties for EV adoption and CI expansion, as well as Granger-causality relationships under two scenarios: Early Adoption …

“Gc Flight, Lock The Doors” How Communication Resilience Shapes Crisis Response In Human Space Flight, Jessica Hilt

Communications Theses, Dissertations, and Student Creative Activity

A precursor to the National Aeronautics and Space Administration (NASA), the National Advisory Committee for Aeronautics (NACA) has been pushing the boundaries of space flight since 1915 (“NASA History – The NACA,” 2024c). Space flight as we know it today began in 1962, with an address given by President John F. Kennedy at Rice University. “We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard…” (Kennedy, 1962, p. 3). Words of which have inspired generations of children, men, and women who were courageous enough to …