KC Carroll's Research Projects:

Link to list of publications.

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Development of Geochemical and Solute Transport Attenuation and Mass Flux Quantification Approaches for Subsurface Contaminant Mixtures Relevant to the Hanford Site

Funded By: DOE Environmental Management and supported by PNNL

https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-22322.pdf

Objective

The goal of the proposed work is to quantify geochemical, fluid flow, and mass transport of contaminant mixtures impacting the deep vadose zone (DVZ) at the Hanford Site.

Technical Approach

Objectives include: (Obj. 1) quantification of mass flux processes of contaminant mixtures; (Obj. 2) quantification of natural attenuation processes of contaminant mixtures; (Obj. 3) develop prediction capability for modeling flux and attenuation of contaminant mixtures; and (Obj. 4) translate research/knowledge to communities and students within minority or underrepresented groups. Determination of contaminant reactivity in mixtures of organic and inorganic species and with dissolved/solid reactive phases and improving our prediction of reactive transport processes is required for contaminant natural attenuation evaluation. We can then leverage that natural attenuation mechanism quantification in developing contaminant attenuation enhancement approaches for in situ remediation feasibility.

Benefits

This project will advance our ability to characterize contaminant attenuation. These research results will enhance our ability to quantify and predict feasibility of remediation approaches, and assessment of natural attenuation processes will support extension of naturally occurring contaminant attenuation processes to actively enhanced attenuation for contaminant remediation.



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Coupling Direct and Indirect Characterization Methods for Mercury Transport and Surface Water-Hyporheic Zone Exchange

Funded By: DOE Environmental Management and supported by ORNL

http://www.esd.ornl.gov/romic_afrc/expertise.shtml

Objective

The overall goal of the proposed work is to quantify water and Hg secondary sources and fluxes from contaminated creek hyporheic zone (HZ) sediments to the overlying surface water in a stream impacted by historical Hg contamination.

Technical Approach

Specific objectives and approach includes: (Obj 1) directly measure water and solute exchange between surface water and interstitial pore water in the HZ of the creek; (Obj 2) use of geophysical monitoring techniques to indirectly and non-destructively measure the spatial distribution of the groundwater, surface water, and HZ; (Obj 3) determine location and spatial variability of water and Hg source areas within the creek-bed sediments of the HZ; and (Obj 4) translate research/knowledge to communities and students within minority or underrepresented groups.

Benefits

This project will advance our ability to characterize and our mechanistic understanding of flow, transport, and geochemical reactions occuring within hyporheic zones, which will advance Hg contamination cleanup efficiency.



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Isotopic and geochemical characterization of deep and shallow groundwater residence time, connectivity, and mixing in the Mesilla Basin, New Mexico

Funded By: Transboundary Aquifer Assessment Act (with USGS and NM WRRI), the Bureau of Reclamation, and Statewide Water Assessment (NM WRRI)

https://nmwrri.nmsu.edu/?page_id=5275/#DSWB

Research Problems

We need additional methods to assess how much flow, mixing, and salinity transfer occurs between the shallow and deep aquifers. We do not know how sustainable our water resources are, because we have not characterized the storage, flow dynamics, and resiliency of the groundwater system, especially for the deeper aquifers. Also, use of nontraditional (e.g., saline) water sources requires evaluation of how sustainable these sources are and if there will be impacts to traditional sources.

Objective

The objectives of the study are to characterize the deep groundwater system in the Mesilla Basin and to determine the contribution of deep groundwater to flow and salinity in the shallow groundwater of the Mesilla Basin. Geochemical and isotopic tracers will be used to pursue these objectives, as well as to evaluate the potential for cross-basin recharge from the adjacent basins. This study will identify the sources and determine the rates of recharge of the Mesilla Basin Aquifer groundwater by employing environmental isotopes in a multi-tracer approach to characterize groundwater movement.

Benefits

This project will use multiple geochemical and isotopic signatures to characterize the age (and residence time) and sources (and mixing) of groundwater at various depths within the Mesilla Aquifer system. This will include the development and use isotopes of noble gases for the first time in this region of the world, which will fill a critical time gap in methods commonly used for groundwater age dating. This project will provide the stakeholders in the region with quantified estimates of the deep groundwater contributions to the shallow groundwater and surface-water systems of the Mesilla Basin. The study provides water resource managers with information on groundwater movement and salinity to aid in effectively managing the water resources of the Mesilla Basin, by protecting the sources of recharge and fresh groundwater reserves and managing use to reduce salt loading. Age dating and residence time evaluation versus depth within the groundwater system will support evaluation of recharge, upwelling flow sources, flow dynamics, and resiliency of the groundwater system, which is critical for sustainable management of our groundwater as a water supply resource.



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Evaluation of Source Water, Extraction Potential, and Potential Impacts of Using Brackish Water for Desalination in New Mexico

Funded By: the USDA Southwest Hub for Risk Adaptation and Mitigation to Climate Change and the Bureau of Reclamation

http://www.climatehubs.oce.usda.gov/southwest

Research Problems

Desalinization is being considered in NM to provide a longer-term source of water to support irrigated agriculture and domestic development. However, we do not know if the brackish water formations are permeable enough to produce the water and what impacts this will have on the hydrologic system (e.g., drawing fresh water into saline formations, land subsidence, induced seismicity). There is an urgent need to characterize source water for desalination and to evaluate the feasibility and potential impacts of brackish water production.

Objective

The objectives of this study are to 1) develop a groundwater database using all existing information into a Geographic Information System (GIS) to map out the spatial distribution of groundwater for visual and spatial analysis, 2) calculate the volume of fresh and brackish water within the Mesilla Aquifer at various depths, and 3) evaluate the hydraulic connectivity between the brackish and fresh water aquifers 4) quantify the extractability of the brackish water 5) quantify the potential for land subsidence.

Benefits

Desalinization is the future of water supply in New Mexico and the Southwest, and this State urgently needs to assess the amount, locations, and depths of brackish water available as feed water for desalinization. This analysis will provide essential data and analyses required for a feasibility analysis for developing desalinization at various locations across the southern part of the State. NM is in a critical and fragile time with respect to water resources, and this project evaluates an alternative source of water to sustain the NM population and industry, which will provide stakeholders a powerful tool for planning.



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KC Carroll's Selected Completed Research Projects:

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Facilitated Transport Enabled In Situ Chemical Oxidation of 1,4-Dioxane-Contaminated Groundwater

Funded By: SERDP (DoD) Project ER-2302

http://www.serdp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-2302

http://web.nmsu.edu/~kccarr/SERDP-ER-2302.html

Objective

1,4-dioxane occurrence in large groundwater contamination plumes represents a significant liability because of potential adverse health risks and remediation costs. Properties of 1,4-dioxane, including infinite water solubility, negligible adsorption, and low volatilization, have resulted in extensive groundwater contaminant plumes. The objectives of this project were to: (1) develop the ability to cost-effectively remediate 1,4-dioxane using facilitated-transport enabled in situ oxidation; (2) investigate the ability of delivery agents to enhance the effectiveness of commonly used advanced oxidation process (AOP) reagents, such as O3 combined with H2O2, through complexation; (3) investigate the ability of delivery agents to increase the specificity of oxidant reactivity for 1,4-dioxane and to enhance the stability and longevity of the oxidant; (4) investigate the effectiveness of facilitated transport of oxidants complexed with delivery agents within sediments collected from a Department of Defense (DoD) site; and (5) investigate the biodegradation of delivery agents as a method for creating timed-release of oxidants from complexation. This oxidant-facilitated transport technology has the potential to increase treatment effectiveness and decrease costs for both source zones and low-concentration plumes.

Technical Approach

This project developed in situ chemical oxidation as a viable technology for 1,4-dioxane groundwater plume remediation by enhancing the solubility, stability, and transportability of strong oxidants (e.g., O3), which facilitates the in situ treatment of groundwater plumes. This was achieved through the co-injection of oxidants with chemical agents that facilitate the transport of the oxidant. Several delivery enhancement alternatives were considered. We found that aqueous ozone forms an inclusion complex with cyclodextrin by partitioning into that delivery agent molecule cavity, which in return, increased the amount of oxidant that can be delivered to the plume. Also, changes in reactivity during facilitated transport actually increased specificity of oxidation for compounds of concern including 1,4-dioxane and co-contaminant chlorinated solvents that also partitioned into the delivery agent. Two parallel technologies were developed, including iron activated persulfate and peroxone activated persulfate, to also enhance reagent delivery at the plume scale.

Benefits

This project has developed three novel, cost-effective, in situ treatment alternative for 1,4-dioxane-contaminated source zones and groundwater plumes, and it has advance the understanding of processes controlling the complexation of strong oxidants and the impact of complexation, or other transport-related processes, on advanced oxidation process reactions. Co-injecting oxidants with a complexing agent was used to facilitate the transport of oxidants into groundwater plumes to increase the longevity and transportability of oxidants, enhance the treatable volume of 1,4-dioxane groundwater plume, and decrease the cost and time required to remediate such contaminated sites. This method for in situ advanced oxidation of 1,4-dioxane has the potential to significantly decrease remediation costs and support the effective management of DoD sites contaminated with 1,4-dioxane.



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Interactive, Online, Labs to Support Discovery of the Scientific Process

Funded By: DOE Environmental Management and supported by ORNL

and by NMSU Allocation of President’s Performance Fund

Check out the labs. See virtuallabs.nmsu.edu and scienceofsoil.com

Background

Science students require more than methods practice in lab activities; they must gain an understanding of the application of the scientific process through lab work. Large classes, time constraints, and funding may limit student access to science labs, denying students access to the types of experiential learning needed to motivate and develop new scientists.

Objective

Interactive, discovery-based computer simulations and virtual labs provide an alternative, low-risk opportunity for learners to engage in lab processes and activities. Students can conduct experiments, collect data, draw conclusions, and even abort a session. We have developed an online virtual lab, through which students can interactively develop as scientists as they learn about scientific concepts, lab equipment, and proper lab techniques.

Benefits

In addition to learning the specific procedures involved in each lab, the online activities will prompt exploration and practice in key scientific and mathematical concepts, such as unit conversion, significant digits, assessing risks, evaluating bias, and assessing quantity and quality of data. These labs are not designed to replace traditional lab instruction, but to supplement instruction on challenging or particularly time-consuming concepts. To complement classroom instruction, students can engage in a lab experience outside the lab and over a shorter time period than often required with real-world adsorption studies. More importantly, students can reflect, discuss, review, and even fail at their lab experience as part of the process to see why natural processes and scientific approaches work the way they do.



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Assessment of Spatiotemporal Groundwater Level Changes Throughout New Mexico

Funded By: NM State through the NM Water Resources Research Institute (NM WRRI)

http://wrri.nmsu.edu/ https://nmwrri.nmsu.edu/?page_id=5275/#DSWB

Statement of Critical Water Resource Problem

New Mexico is in a long-term drought that threatens the sustainability of the agricultural industry as well as drinking water supply. Surface water is continuing to decrease despite being over allocated, and groundwater is being used without replenishment to buffer declines in surface water. We currently do not have a way to evaluate the decline in groundwater levels spatially or over time.

Benefits

This project has developed a map of groundwater level changes over time. A groundwater map supports the spatial examination of groundwater as a resource throughout the State, and a map of the change in groundwater levels over time provides a quantification of the impact of groundwater withdrawals over time on the sustainability of the groundwater system as a water supply resource. This type of spatiotemporal groundwater level assessment has been valuable for evaluating the impact of increased groundwater extraction and utilization on the groundwater supply as a resource.



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Waste Processing with Pyrolysis to Recover Water and Nutrients

Funded By: NASA Kennedy Space Center Technology Advancing Partnership (PI was Catie Brewer NMSU Chemical Engineering: cbrewer@nmsu.edu)

https://wordpress.nmsu.edu/cbrewer/projects/

Background and Research Problem

Manned spaceflight outside of low-Earth orbit will require significant advances in closing loops within life support systems, especially the recycling of solid and liquid wastes to produce oxygen, food, and fresh water. Long-term (2011-2029) technology development goals for these functions include recovering more water from more waste streams, transitioning from waste stabilization and reduction to material recovery, and enabling food production.

Objective and Approach

Pyrolysis, or heating in a limited oxygen environment, is one waste conversion method that has received considerable attention due to its potential to enable improvements in all three functions. In this project, we developed a moderate-temperature slow pyrolysis reaction system that can transform solid waste and brine from the water treatment system into a nutrient-rich crop growth medium, while recovering water and carbon dioxide.



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Quantifying Water Quality Spatiotemporal Variability within Wastewater Produced in Oil & Gas Operations

Funded By: The New Mexico Environment Division (through NM WRRI) and the NMSU Office of the Vice President for Research

Objective

This project quantified water quality variability associated with wastewater produced during oil and gas production in the Permian Basin (southeast NM and west Texas). We have been evaluating environmentally sound strategies and beneficial use of produced waters. We developed produced water quality maps that supports the spatial examination of this unconventional water as a resource throughout NM State, which will be a valuable management tool for water managers, regulators, municipalities, growers, and irrigation districts.

Technical Approach

This project utilized various chemical analysis techniques to characterize the composition of produced water. Additionally, all available water quality data was mapped using Geographic Information System (GIS) tools, and statistical analyses were used to quantify the variability.



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Use Of Mass-Flux Measurement and Vapor-Phase Tomography to Quantify Vadose-Zone Source Strength and Distribution

Funded By: ESTCP (DoD) Project ER-201125

http://www.serdp.org/Program-Areas/Environmental-Restoration/Contaminated-Groundwater/Emerging-Issues/ER-2302

Objective

The overall objective of this project was to demonstrate that the vapor-phase mass discharge test and vapor-phase tomography can effectively characterize persistent contaminant sources in the vadose zone and measure their associated mass discharge. This technology can improve evaluation of vadose-zone source impacts on groundwater and vapor intrusion. The specific technical objectives for this demonstration were as follows: (1) demonstrate the vapor-phase mass discharge test as an effective means to quantitatively measure contaminant mass discharge in the vadose zone; (2) demonstrate vapor-phase tomography as a means of characterizing the 3D distribution of persistent contaminant sources in the vadose zone; (3) integrate the mass-discharge and vapor-phase tomography measurements with existing pneumatic and tracer tomography methods to provide a comprehensive technology to evaluate the impact of persistent vadose-zone sources on groundwater and vapor intrusion; (4) determine cost-performance factors for applying the technology as a function of site conditions, and compare them to costs associated with standard practices; and (5) develop decision-support tools to assist users in selection and application of the technology.

Technical Approach

The vadose-zone characterization technology that was demonstrated was a combination of two recently developed methods (vapor-phase mass discharge test and vapor-phase tomography) and two existing methods (pneumatic tomography and tracer tomography). The technology improved upon existing vadose-zone characterization methods by providing three key sets of information for vadose-zone contaminant sources: 1. Accurate measurements of vapor-phase contaminant mass discharge 2. Characterization of mass-transfer conditions (e.g., whether or not mass transfer is rate limited, and to what degree) 3. Higher resolution characterization of source distribution and source-zone architecture. The technology was designed to be used in a tiered approach that is sensitive to associated cost-benefits and responsive to specific requirements of the site.

Benefits

It was anticipated that the vadose-zone characterization technology would produce information that will greatly improve the assessment of vadose-zone source impacts on groundwater and vapor intrusion. Specific applications for this information include decisions regarding implementation of vadose-zone remediation efforts, setting of remediation goals, optimization of remediation systems, and assessment of remediation system transition or closure. The technology can be especially useful for enhancing the performance of soil vapor extraction (SVE) systems and for supporting closure assessment for SVE systems.



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Reservoir-Stimulation Optimization with Operational Monitoring for Creation of Enhanced Geothermal Systems

Funded By: DOE-EERE Geothermal Technologies Program

http://energy.gov/sites/prod/files/2014/02/f7/reservoir_optimization_geo_sys_peer2013.pdf

Objective

The overall objective of this project was to develop novel rock fracturing techniques and monitoring capabilities to allow reservoir stimulation for renewable energy production using enhanced geothermal systems (EGS).

Benefits

Much of the western U.S. has significant quantities of geothermal energy within the upper 3-10 km depth range. However, EGS requires increased permeability to transmit fluids into the subsurface for heat extraction. If we can fracture rocks to develop reservoirs under geothermal temperatures and pressures, we can develop the feasibility of EGS energy production within the western U.S.

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