- CLOGGING OF DRAINAGE MATERIAL IN LEACHATE COLLECTION SYSTEMS 9' 9' A Thesis Presented to The Faculty of the College of Engineering and Technology Ohio University Athens, Ohio In Partial Fulfillment of the Requirements for the Degree Master of Science in Civil Engineering BY V.K. Reddy Nandela) - .- June, 1992 This thesis has been approved for the Department of Civil Engineering and the College of Engineering and Technology Dean of the College of Engineering and Technology ABSTRACT Clogging of leachate collection systems could be a real possibility if one assumes that mechanisms such as those responsible for clogging of agricultural drainage tiles would be applicable in the landfill environment. An extensive laboratory testing program was undertaken to investigate the clogging mechanism of three types of drainage media typically utilized in the leachate collection system in the U.S. Two permeameters, 5 inches in diameter by 12 inches long, were fabricated, and flow of actual landfill leachate was maintained gravitationally without recirculation at 1 and 2% hydraulic gradients in a constant head permeability test environment to simulate landfill bottom drainage conditions. Flow rates were monitored, and influent and effluent leachate samples were collected for various physical and chemical characterizations. The study results indicated that the permeability of gravel, poorly graded sand and well-graded sand was reduced from lo0, lo-*, cm/sec, to approximately 10-~, crn/sec, respectively. ACKNOWLEDGMENT I greatly appreciate the assistance and encouragement given to me by my advisor, Dr. Gayle F. Mitchell. I would like to express my gratitude to Dr. William B. Greer, for his guidance and numerous hours spent with me to initiate this project. I would like also to express my appreciation to Dr. Shad Sargand for his valuable comments and suggestions. Special thanks to Dr. James Shirey for serving as a member of my thesis committee. I would like to express my special gratitude for the help rendered by Mr. Teruhisa Masada. I appreciate Waste Management of North America, Inc. for providing partial support of my graduate research work. TABLE OF CONTENTS Abstract ............................................... iii Acknowledgements ....................................... iv Table of Contents ...................................... v List of Tables .................................. viii List of Figures ........................................ ix Chapter 1 INTRODUCTION 1.1. GENERAL ......................................... 1 1.2. OBJECTIVES ...................................... 6 1.3. RESEARCH OUTLINE ................................ 6 Chapter 2 LITERATURE REVIEW 2.1. LEACHATE COLLECTION SYSTEMS ..................... 8 2.1.1. DESIGN .......................................... 10 2.1.1.1. DRAINAGE LAYER .................................. 12 2.1.1.2. FILTER LAYER ................................... 15 2.1.1.3. COLLECTION PIPES ................................ 18 2.2. CLOGGING AND FAILURE OF LCS ..................... 19 2.2.1. PHYSICAL MECHANISMS ............................. 19 2.2.2. CHEMICAL MECHANISMS ............................. 22 2.2.3. BIOCHEMICAL MECHANISMS .......................... 24 2.2.4. BIOLOGICAL MECHANISMS ........................... 27 Chapter 3 EXPERIMENTAL STUDY 3.1. CHARACTERIZATION AND PREPARATION OF MEDIA ....... 28 3.2. DESCRIPTION OF APPARATUS ........................ 32 3.2.1. PERMEAMETER ..................................... 32 3.2.2. CYLINDERS ....................................... 37 3.3. LABORATORY EXPERIMENTAL SETUP ................... 37 3.4. DETERMINING BASELINE PERMEABILITY ............... 40 3.5. LEACHATE CHARACTERIZATION ....................... 42 Chapter 4 DISCUSSION OF RESULTS 4.1. BASELINE PERMEABILITY TESTS .................... 45 4.1.1. GENERAL ................................. 45 4.1.2. AASHTO #8 GRAVEL ............................... 47 4.1.3. POORLY GRADED SAND ............................. 47 4.1.4. WELL-GRADED SAND ............................... 50 4.2. LEACHATE FLOW TEST RESULTS ..................... 53 4.2.1. AASHTO #8 GRAVEL ............................... 53 4.2.2. POORLY GRADED SAND ............................. 54 4.2.3. WELL-GRADED SAND ............................... 64 4.3. CHARACTERIZATION OF INFLUENT AND EFFLUENT LEACHATE ....................................... 64 4.3.1. SOLIDS ANALYSIS ................................ 69 4.3.2. CHEMICAL ANALYSIS .............................. 74 4.3.3. METAL ANALYSIS ................................. 78 4.3.4. pH ANALYSIS ................................ 97 4.3.5. ANALYSIS OF LEACHATE, AND RESIDUE DEPOSITED ON MEDIA AT THE CONCLUSION OF EXPERIMENTS .......... 97 Chapter 5 CONCLUSIONS AND RECOMMENDATIONS 5.1. CONCLUSIONS .................................... 101 5.2. RECOMMENDATIONS ......................... 104 References ............................................. 105 Appendix A ......................................... 118 LIST OF TABLES Chapter 2 Table 2.1. Particle size requirements for filters ........... 16 Chapter 4 Table 4.1. Baseline permeability test results ............... 46 Table 4.2. Metal analysis results for gravel (Test la) ...... 83 Table 4.3a. Suspended solids and metal analysis of contents of permeameter and cells at the completion of Tests la and lb (Gravel) ......................... 98 Table 4.3b. Suspended solids and metal analysis of contents of permeameter and cells at the completion of Tests 4a and 4b (Poorly graded sand) ............. 99 Table 4.3~.Suspended solids and metal analysis of contents of permeameter and cells at the completion of Tests 5a and 5b (Well-graded sand) ............... 100 LIST OF FIGURES Chapter 2 Figure 2.1. Leachate collection system layout Chapter 3 Figure 3.la. Sieve arrangements for AASHTO #8 gravel Figure 3.lb. Sieve arrangements for poorly graded sand Figure 3.1~.Sieve arrangements for well-graded sand Figure 3.2a. Grain size distribution curve for AASHTO #8 gravel Figure 3.2b. Grain size distribution curve for poorly graded sand Figure 3.2~.Grain size distribution curve for well-graded sand Figure 3.3. Overall experimental set-up of large scale constant head permeability and clogging test system Figure 3.4. Schematic of construction and dimensions of permeameter Figure 3.5. Schematic of construction and dimensions of Biological cell unit. Chapter 4 Figure Baseline permeability for gravel in the upper, the lower, and the overall sections of the media for Test lb. Figure Baseline permeability for poorly graded sand in the upper, the lower, and the overall sections of the media for Test 4a. Figure Baseline permeability for well-graded sand in the upper, the lower, and the overall sections of the media for Test 5b. Figure Permeability in the overall section of the media for 2.3% hydraulic gradient system in Test lb. Figure Permeability in the upper and the lower sections of the media for 2.3% hydraulic gradient system in Test lb. Figure Rate of flow curve for 2.3% hydraulic gradient system in Test lb. Figure Permeability in the overall section of the media for 1% hydraulic gradient system in Test 4a. Figure Permeability in the overall section of the media for 2.17% hydraulic gradient system in Test 4b. Figure Permeability in the upper and the lower sections of the media for 1% hydraulic gradient system in Test 4a. Figure Permeability in the upper and the lower sections of the media for 2.17% hydraulic gradient system in Test 4b. Figure Permeability in the overall section of the media for 1% hydraulic gradient system in Test 5a. Figure Permeability in the overall section of the media for 2% hydraulic gradient system in Test 5b. Figure Permeability in the upper and the lower sections of the media for 1%hydraulic gradient system in Test 5a. Figure Permeability in the upper and the lower sections of the media for 2% hydraulic gradient system in Test 5b. Figure Total suspended solids for the influent and effluent leachate samples of 0.75% hydraulic gradient system in Test la. Figure Total suspended solids for the influent and effluent leachate samples of 2.3% hydraulic gradient system in Test lb. Figure Total suspended solids for the influent and effluent leachate samples of 1%hydraulic gradient system in Test 4a. Figure Total suspended solids for the influent and effluent leachate samples of 2.17% hydraulic gradient system in Test 4b. Figure Total suspended solids for the influent and effluent leachate samples of 1%hydraulic gradient system in Test 5a. Figure COD and alkalinity test results for the influent and effluent leachate samples of 0.75% hydraulic gradient system in Test la. Figure 4.21. COD and alkalinity test results for the influent and effluent leachate samples of 2.3% hydraulic gradient system in Test la. Figure 4.22. TOC test results for the influent and effluent leachate samples of 1%hydraulic gradient system in Test 4a. Figure 4.23. TOC test results for the influent and effluent leachate samples of 2.17% hydraulic gradient system in Test 4b. Figure 4.24. TOC test results for the influent and effluent leachate samples of 1%hydraulic gradient system in Test 5a. Figure 4.25. TOC test results for the influent and effluent leachate samples of 2% hydraulic gradient system in Test 5b. Figure 4.26. Iron concentration in the influent and effluent leachate samples of 1.77% hydraulic gradient system in Test 3a. Figure 4.27. Iron concentration in the influent and effluent leachate samples of 2.32% hydraulic gradient system in Test 3b. Figure 4.28. Iron concentration in the influent and