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Final Report: Issues Involving the Vertical Expansion of Landfills
EPA Grant Number: R825427C002Subproject: this is subproject number 002 , 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: Issues Involving the Vertical Expansion of Landfills
Investigators: McManis, Kenneth , Boutwell, G. , Debnath, D. , Nataraj, Mysore
Institution: University of New Orleans
EPA Project Officer: Krishnan, Bala S.
Project Period: August 17, 1998 through April 30, 2002
RFA: Urban Waste Management & Research Center (1998)
Research Category: Targeted Research
Description:
Objective:The proposal for the vertical expansion of landfills has raised serious concerns by many state and federal regulators regarding the stability of a high refuse fill under static and dynamic loading conditions, the contamination of ground water by liner/leachate collection system (L/LCS) damage and the increased potential for leachate generation. To address these issues, basic design parameters are necessary for the rational design of a vertical expansion. These include the parameters for: settlement, development of the load-leachate generation relationship, deformation strain, hydraulic conductivity, etc. Many of these parameters are not readily available nor routinely determined and have received only limited attention in the literature. To determine these parameters, this study included a field sampling and testing program, and a laboratory investigation.
The material tested included MSW that had been buried in-place and excavated, and that which was being delivered. The field investigation of the study included the in-place unit weight and moisture character of the waste material according to ASTM D5030. Bulk samples used for the tests were collected from the Tangipahoa Regional Solid Waste Facility near Amite, Louisiana, U.S.A. Two types of samples were collected from the landfill; one was compacted (excavated) MSW. This is old in-place MSW was mixed with daily soil cover. The second was a fresh (recently received) MSW. This MSW had been recently collected, delivered, and was ready to be placed in the landfill. The excavated MSW was collected from a depth of 0.9 to 1.2 m (4 to 4 ft) beneath the surface and consisted primarily of plastic bags and bottles, dirt, paper, wood, cloth etc. The gravimetric moisture content of the waste ranged from 15 to 19 percent. The field unit weight of the compacted waste was 12 kN/m3 determined as per ASTM D5030. The fresh MSW was collected immediately after dumping at the landfill. It was similar to the compacted waste but with less dirt. The gravimetric moisture content of the waste ranged from 19 to 23 percent. The laboratory tests utilized these two sample types, i.e., 1) compacted in-place (excavated) municipal solid waste (MSW) and 2) fresh (recently received) municipal solid waste.
The settlement behavior, leachate release, and hydraulic conductivity that an existing landfill would be subjected to due to vertical expansion were simulated in a laboratory, large-scale testing program. The testing program was divided into three parts: 1) Liquid Release Tests (LRT), 2) Hydraulic Conductivity Tests (HCT) and a 3) settlement test on a saturated sample. The liquid release tests were conducted on both the excavated samples of MSW and the fresh MSW. Four of the leachate release tests were conducted on the excavated (older) MSW and three were conducted on the fresh (recent) MSW at various initial density levels. The settlement behavior of the unsaturated excavated MSW and fresh MSW were observed in the leachate release tests. Three hydraulic conductivity tests were performed on the excavated older MSW and the hydraulic conductivity values were measured at four different density levels for the same test. One settlement test was performed on the excavated MSW at 100 percent saturation. Two different types of PVC (Schedule 80) test chambers were fabricated for the tests.
The liquid release test (LRT) determines whether or not liquids will be released when the MSW is subjected to additional overburden pressures in a landfill. This test was performed according to EPA Method 9096. The MSW was hand compacted into a 22.5-inch diameter, 38-inch high Schedule 80 PVC test chamber. The total height of the sample varied from 2 ft to 2.5 ft. A 2-inch sand and geotextile layers were placed on top and bottom of the waste specimen to distribute the load and to collect the flow. Various initial water contents and densities of the waste based on reported field values were used. The waste sample was compressed by axial loading (using a load frame and hydraulic jack system) under increments of load. The amount of compression (measured at three different points) and the liquid released were measured at each increment of load. The load increased typically from 14.5kN/m2 to 1440 kN/m2.
The amount of settlement was greater with the fresh MSW than the excavated, compacted MSW. Leachate started to release at about 192 kN/m2 in the fresh (initial wet density, 4.7kN/m3) and 480 kN/m2 in the compacted (initial wet density, 7.85 kN/m3) MSW, respectively. From this point of view, the total vertical height of the existing landfill that could be placed on an existing landfill without leachate release is approximately 24 m (80 ft) for the fresh MSW and 43 m (140 ft) for the compacted MSW. Here, 7.85 kN/m3 and 11 kN/m3 are the average wet densities for the fresh and the compacted MSW respectively. The amount of settlement (as vertical strain) at maximum pressure depended on the degree of initial compaction of the sample.
The values of the coefficient of compression (Cc) were calculated from the slope of the strain vs log pressure curves. The compression plots were sensitive to the compaction preparation of the test specimens. The pressure required to overcome the quasi-preconsolidation pressure was a function of the initial density. The Cc values determined in these tests ranged from 0.292 to 0.344. The values were similar, but a little higher than values previously reported by others. The ratio of leachate release volume to the waste volume reduction was observed to increase exponentially with the degree of saturation.
The hydraulic conductivity tests were conducted as per EPA 9100. The waste samples were placed in a test chamber similar to the one used for the liquid release test. However, this test chamber was covered with a PVC plate which allowed for use of a pressurized fluid. Perforated steel and PVC plates were used to allow the water to pass through the chamber. The tests were conducted at four different waste density levels, which were achieved by axial loading. The permeating water was under air pressure to induce flow. This test involved compression under saturated conditions. The results could thus be compared with those from the unsaturated LRT's.
The hydraulic conductivity values vary from 5 x 10-5 to 4 x 10-3 cm/sec for dry densities that ranged from 42 to 94 pcf. The hydraulic conductivities decrease with increasing dry density as expected, and this decrease follows an exponential function of density. The hydraulic conductivity values from this study match and confirm those reported in previous studies.
A saturated specimen of the excavated MSW was tested under incremental loading and extended load times to compare the settlement parameters with the values obtained from the liquid release tests, in which the values were unsaturated. The same test chamber and loading technique as used in the liquid release test was used in this test. The sample was saturated prior to loading with two way drainage existing. However, the incremental loading was applied over an extended period of time in order to establish the time-deformation character. Values for the compression index (Cc), and the coefficient of consolidation (Cv) were determined. The log-time plots were relatively flat and could not be used for calculating the coefficient of consolidation (Cv). The square root of time, Taylor's technique, was used to estimate the consolidation coefficient. The range of values for Cv in this study were comparable to other reported values found in the literature.
Supplemental Keywords:landfills, vertical expansion, leachate release, landfill hydraulic conductivity, landfill settlement. , Geographic Area, Scientific Discipline, Waste, Ecology, Ecological Risk Assessment, Atmospheric Sciences, Municipal, Environmental Chemistry, Ecology and Ecosystems, State, waste minimization, landfill operation, urban waste, groundwater quality, New Orleans (NO), urban runoff, technology transfer, waste management, municipal waste, outreach
Relevant Websites:
Progress and Final Reports:
Original Abstract
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