![[logo] US EPA](https://webarchive.library.unt.edu/eot2008/20081105184449im_/http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
2000 Progress Report: Influence of Cyclic Interfacial Redox Conditions on the Structure and Integrity of Clay Liners for Landfills Subject to Variable High Groundwater Conditions in the Gulf Coast Region
EPA Grant Number: R827933C020Subproject: this is subproject number 020 , established and managed by the Center Director under grant R825427
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Urban Waste Management and Research Center (University New Orleans)
Center Director: McManis, Kenneth
Title: Influence of Cyclic Interfacial Redox Conditions on the Structure and Integrity of Clay Liners for Landfills Subject to Variable High Groundwater Conditions in the Gulf Coast Region
Investigators: Sansalone, John , Cartledge, Frank K. , Tittlebaum, Marty
Current Investigators: Sansalone, John , Cartledge, Frank K. , Tittlbaum, Marty
Institution: University of New Orleans , Louisiana State University - Baton Rouge
Current Institution: Louisiana State University - Baton Rouge , University of New Orleans
EPA Project Officer: Krishnan, Bala S.
Project Period: July 1, 2000 through June 30, 2003
Project Period Covered by this Report: July 1, 2000 through June 30, 2001
RFA: Urban Waste Management & Research Center (1998)
Research Category: Targeted Research
Description:
Objective:This research is a bench-scale experimental study on the influence of cyclic interfacial redox conditions and resulting pH changes that result from variably high groundwater conditions typical of the Gulf Coast region. Therefore, an experimental model will be designed, fabricated, and instrumented to conduct in situ model measurements such as redox potential, pH, temperature, and conductivity. An experimental matrix will be developed as a function of water table conditions, soil type, time (number and duration of redox cycles simulating long-term seasonal geoenvironment), and position in and around the clay liner periphery. This bench-scale system also will be designed to permit sampling of leachate, clay liner, surrounding soil, and soil porewater. Three separate clay liner materials will be investigated: (1) bentonite, (2) kaolinite, and (3) native Louisiana clay. The surrounding soil will be typical of common soils with the variable high groundwater conditions of south Louisiana. The bench-scale experimental system also will be designed, fabricated, and instrumented for the purposes of quantifying changes in clay structure, mineralogy, and hydraulic properties to experimentally simulated conditions.
The second objective is to evaluate changes to mineralogy, structure, porosity, and fabric of the clay liner under different redox conditions and coupled pH changes. This will be experimentally conducted for a number of cases: Case I: This case will experimentally simulate moist yet unsaturated conditions, replicating drained aerobic conditions that can occur for landfill liners either (1) above the natural phreatic surface; or (2) above the lowered water table (and phreatic surface) as a result of engineered subsurface drainage; Case II: This case will experimentally simulate constant saturated anaerobic conditions typical of high water table conditions. Case I and II serve as controls and limiting aerobic and anaerobic conditions for a given set of experimental and soil parameters; and Case III: This case will experimentally simulate cyclic redox conditions with variable frequency and duration of the redox cycles. Based on both the scientific background and engineering requirements for a clay liner under cyclic redox conditions, clay liner analysis will include x-ray and x-ray absorption spectroscopy (EXAFS, XANES, x-ray microprobe) to provide data on chemical valence state and bonding influence on environmental behavior in a nondestructive manner. A particular advantage of the nondestructive character is that changes over time can be monitored as dynamic processes occur.
The final objective of the research is to assess the impact of cyclic redox conditions (Case III as compared with Case I and II) and commensurate pH changes on the mobilization and transport of heavy metal leachate through the clay liner. Lower redox conditions (anaerobic conditions) and decrease in pH lead to speciation changes, increased dissolution of immobilized or partitioned heavy metals, and therefore increased mobility of heavy metals. Redox (typically represented as Eh and measured in volts) and pH reactions are coupled reactions in the subsurface environment and as such, represent master variables for heavy metal speciation. The ability to identify equilibrium speciation in Eh-pH space from in situ Eh (redox) and pH measurements provides a valuable tool to assess fate and transport. As an example of a leachate heavy metal in geochemical environment influenced by redox changes and coupled pH changes, consider Cd speciation as a function of Eh and pH. Figure 1 demonstrates the importance of redox changes and associated pH changes. Liquid (pore water and leachate) and digested soil sample analyses taken as part of an experimental matrix will be analyzed for heavy metals with ICP-MS. Heavy metals of interest are amenable to XAS spectroscopy, and studies of surface interaction between metals and clay will be conducted.
Progress Summary:A number of tasks have been completed in the first year of the research. As part of Task I, a thorough literature review has been completed with more than 100 references obtained and reviewed. Standard testing and experimentation protocols have been reviewed, and protocols have been developed for the experimentation. Equipment and supplies have been procured for the initial experimental setup. As part of Task II, the bench-scale landfills have been designed. A schedule of materials and supplies was developed. As part of Task III, three candidate soils/clay liners were identified, selected, and obtained. Three separate clay liner materials will be investigated: (1) Na-bentonite, (2) kaolinite, and (3) native Louisiana clay. As part of Task IV, fabrication of three landfill experimental systems has been completed by the Mechanical Engineering Shop at Louisiana State University. Instrumentation on these systems is complete. A second set of three experimental systems and instrumentation is being completed by Louisiana State University for the University of New Orleans.
One thousand pounds of Na-bentonite and 1,000 lbs of kaolinite have been obtained. Characterization of the clay liner material has progressed. Particle gradation analyses, specific gravity, surface charge, and specific surface area have been completed. Batch isotherm data for Na-bentonite and kaolinite have been completed for Pb, Zn, Cu, and Cd. Experimentation regarding the construction and compaction of cylindrical landfill liners has progressed. Results of batch isotherms under noncompetitive and competitive conditions are illustrated below for Cu and Cu under competitive conditions with Zn, Cd, and Pb. Results for Cu and the other experimental combinations not shown were successfully fit to a Freundlich-type isotherm model.
Figure 1. Cu Adsorptions Isotherm at Various Experimental Conditions.
During the next year, batch isotherms will be completed. SEM analyses of clay before and after heavy metal loadings will be obtained and examined. From the characterization and isotherm work, a peer-reviewed manuscript (ASCE Journal of Environmental Engineering or similar) and conference proceedings (WEFTEC 2002) will be submitted. A major activity in the next year will be the landfill experimental simulations. For these simulations, the role of cyclic redox conditions on the adsorption/desorption of heavy metals by the clay material will be examined. This work is intended to provide insight into the complex nature of redox, pH, clay, and heavy metal interaction under cyclic redox conditions.
Supplemental Keywords:clay, heavy metals, speciation, oxidation-reduction, freundlich, isotherm, sorption partitioning. , INTERNATIONAL COOPERATION, Scientific Discipline, Waste, Civil/Environmental Engineering, Ecological Risk Assessment, Environmental Engineering, Municipal, Civil Engineering, Urban and Regional Planning, Engineering, evaluation of leaching, landfill design, solid waste, clay liners, landfill operation, municipal solid waste landfills, redox conditions, metals, municipal waste
Relevant Websites:
Progress and Final Reports:
Original Abstract
Final Report
Main Center Abstract and Reports:
R825427 Urban Waste Management and Research Center (University New Orleans)
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825427C001 Comprehensive Evaluation of The Dual Trickling Filter Solids Contact Process
R825427C002 Issues Involving the Vertical Expansion of Landfills
R825427C003 Deep Foundations on Brownfields Sites
R825427C004 Ambient Particulate Concentration Model for Traffic Intersections
R825427C005 Effectiveness of Rehabilitation Approaches for I/I Reduction
R825427C006 Urban Solid Waste Management Videos
R825427C007 UWMRC Community Outreach Multimedia Exhibit
R825427C008 Including New Technology into the Investigation of Inappropriate Pollutant Entries into Storm Drainage Systems - A User's Guide
R825427C009 Investigation of Hydraulic Characteristics and Alternative Model Development of Subsurface Flow Constructed Wetlands
R825427C010 Beneficial Use Of Urban Runoff For Wetland Enhancement
R825427C011 Urban Storm and Waste Water Outfall Modeling
R827933C001 Development of a Model Sediment Control Ordinance for Louisisana
R827933C002 Inappropriate Discharge to Stormwater Drainage (Demonstration Project)
R827933C003 Alternate Liner Evaluation Model
R827933C004 LA DNR - DEQ - Regional Waste Management
R827933C005 Landfill Design Specifications
R827933C006 Geosynthetic Clay Liners as Alternative Barrier Systems
R827933C007 Used Tire Monofill
R827933C008 A Comparison of Upflow Anaerobic Sludge Bed (USAB) and the Anaerobic Biofilm Fluidized Bed Reactor (ABFBR) for the Treatment of Municipal Wastewater
R827933C009 Integrated Environmental Management Plan for Shipbuilding Facilities
R827933C010 Nicaragua
R827933C011 Louisiana Environmental Education and Resource Program
R827933C012 Costa Rica - Costa Rican Initiative
R827933C013 Evaluation of Cr(VI) Exposure Assessment in the Shipbuilding Industry
R827933C014 LaTAP, Louisiana Technical Assistance Program: Pollution Prevention for Small Businesses
R827933C015 Louisiana Environmental Leadership Pollution Prevention Program
R827933C016 Inexpensive Non-Toxic Pigment Substitute for Chromium in Primer for Aluminum Sibstrate
R827933C017 China - Innovative Waste Composting Plan for the City of Benxi, People's Rupublic of China
R827933C018 Institutional Control in Brownfields Redevelopment: A Methodology for Community Participation and Sustainability
R827933C019 Physico-Chemical Assessment for Treatment of Storm Water From Impervious Urban Watersheds Typical of the Gulf Coast
R827933C020 Influence of Cyclic Interfacial Redox Conditions on the Structure and Integrity of Clay Liners for Landfills Subject to Variable High Groundwater Conditions in the Gulf Coast Region
R827933C021 Characterizing Moisture Content Within Landfills
R827933C022 Bioreactor Landfill Moisture Management
R827933C023 Urban Water Issues: A Video Series
R827933C024 Water Quality Modeling in Urban Storm Water Systems
R827933C025 The Development of a Web Based Instruction (WBI) Program for the UWMRC User's Guide (Investigation of Inappropriate Pollutant Entries Into Storm Drainage Systems)
R827933C027 Legal Issues of SSO's: Private Property Sources and Non-NPDES Entities
R827933C028 Brownfields Issues: A Video Series
R827933C029 Facultative Landfill Bioreactors (FLB): A Pilot-Scale Study of Waste Stabilization, Landfill Gas Emissions, Leachate Treatment, and Landfill Geotechnical Properties
R827933C030 Advances in Municipal Wastewater Treatment
R827933C031 Design Criteria for Sanitary Sewer System Rehabilitation
R827933C032 Deep Foundations in Brownfield Areas: Continuing Investigation
R827933C033 Gradation-Based Transport, Kinetics, Coagulation, and Flocculation of Urban Watershed Rainfall-Runoff Particulate Matter
R827933C034 Leaching and Stabilization of Solid-Phase Residuals Separated by Storm Water BMPs Capturing Urban Runoff Impacted by Transportation Activities and Infrastructure
R827933C035 Fate of Pathogens in Storm Water Runoff
R87933C020 Influence of Cyclic Interfacial Redox Conditions on the Structure and Integrity of Clay Liners for Landfills Subject to Variable High Groundwater Conditions in the Gulf Coast Region