New Challenges, Solutions, and Opportunities in Leachate Collection Systems By Matthew Poore, Progressive Environmental Services
Protecting What's Been Built, Restoring What's Been Broken. Descaling, Disinfection, Preservation, Rebuilding Healthier Water. A cleaner and safer Environment. Minimal disruption to life & the economy. Protecting What's Been Built, Restoring What's Been Broken Copyright 2013, Progressive Environmental Services, LLC
Manhole & Wet Well Structural Rehab Protecting What's Been Built, Restoring What's Been Broken.
Chemical Cleaning and Restoration Protecting What's Been Built, Restoring What's Been Broken. System Inspection (e.g. pre video) / Other Tests Cleaning: Recirculation or Surging, Verification Neutralization, Disposal Return to Service Determination of steps is critical to achieve desired end results.
Outline Introduction Clogging Mechanisms Characteristics of Leachate and Precipitate Chemical Cleaning Results Conclusions Questions?
Introduction
Clogging Mechanisms Sedimentation Thermodynamically Favored Precipitation Biologically Induced Precipitation
Clogging Mechanisms Sedimentation Straining Interception Geotextile Gravel Pack Perforated Collection line
Clogging Mechanisms Thermodynamically Favored Precipitation Saturation Index = Q (Activity Product) K (Equilibrium Constant) If SI = 1 => Saturation If SI < 1 => Unsaturated If SI > 1 => Supersaturated (e.g. Langlier Index)
Characteristics of Leachate and Precipitate Leachate Analysis Precipitate X-Ray Diffraction Biological Activity Reaction Tests (BART)
Leachate Analysis MSW/Ash 1 MSW/Ash 2 MSW/Ash 3 MSW/Ash 4 Ash Mono 1 Ash Mono 2 Parameters Units Inorganics Chloride mg/l 18,000 14,000 760 12,000 41,000 44,000 Sulfate mg/l 630 570 560 990 280 240 Total Alkalinity mg/l 6,100 780 2,700 9,900 330 330 Total Organic Carbon mg/l 4,200 390 2,100 12,000 7.0 7.9 Metals Calcium mg/l 920 1,300 34 1,400 6,000 7,600 Iron mg/l 75 13 3.0 270 0.05 0.6 Magnesium mg/l 150 110 29 230 30 23 Sodium mg/l 5,600 4,500 500 5,400 12,000 13,000 Metals, Dissolved Iron mg/l 65 6.0 3.2 21 0.02 0.06 Silica (SiO2) mg/l 93 38 70 170 141 15 Volatile Fatty Acids Acetic Acid mg/l 2,700 1.8 3,500 8,700 Propionic Acid mg/l 940-810 3,000 Butyic Acid mg/l 1,200 0 1,400 4,000
Geochemical Modeling Possible Precipitates 2.5 Quartz Calcite Mineral Saturation State 2 1.5 1.5 0.5 Mineral Log Q/K Hydroxyapatite 6.9 Calcite 1.34 Quartz 0.80 1 Hydroxyapatite 1.5 0 10 20 30 40 50 60 70 80 90 Time (days) Possible Precipitates Calcite 2.5 2 1.5 1 Quartz Mineral Log Q/K Hydroxyapatite 10.57 Calcite 1.19 Quartz 0.38.5 0.5 Hydroxyapatite 0 10 20 30 40 50 60 70 80 90 Time (days)
Precipitate Analysis - XRD Calcium Carbonate
Precipitate Analysis XRD Brushite Calcium Carbonate Gypsum
Biological Activity Reaction Tests (BART) MSW/Ash leachate showed high IRB/SRB Populations => Biologically induced CaCO 3 and FeS precipitation
Leachate & Precipitate Characteristics Leachate analysis and geochemical modeling showed thermodynamically favored precipitation of hydroxyapatite and calcite. BART showed high populations of SRB and IRB. XRD of precipitate showed presence of calcium carbonate, brushite, and gypsum. Sludge of Biomass and Mineral Precipitant
Cleaning Methods & Trials
Cleaning Methods & Trials Mechanical Methods Cutters and Milling Machines Water pressure driven Designed to align within pipe Potential for damage to pipe Transitions Changes in pipe material Welds within HDPE piping. Explosion potential Landfill Gas
Cleaning Methods & Trials Mechanical Methods High-Pressure Water Jetting (4,000 and 10,000 psi) Equally Distributed Point-Focus Rotating Flushing
Cleaning Methods & Trials High-pressure water jetting Successful at removing large, intact pieces of precipitate Difficulty flushing large pieces Does not clean outside of leachate piping Slow, staged cleaning approach required Increased time and cost Requires access for removal of debris
Cleaning Methods & Trials High-pressure water jetting Up to 1,500 feet per week, depending on: Amount of precipitate and Access/removal $10 to $60 per foot Flow remained relatively the same.
Cleaning Methods & Trials Chemical Cleaning Recirculation and/or Surging of chemical solution Certified biodegradable acid solution Hydrochloric acid, carboxylic acid, alkanolamine, and sodium alkylsufonate Catalysts Penetrants Dispersants Inhibitors for base materials protection
Cleaning Methods & Trials Chemical Cleaning Successful in cleaning: Non-perforated LCS piping Perforated LCS pipe with multiple access points 100-150 feet of single access perforated LCS piping Cleans gravel pack, geotextile and pipe. Requires large chemical volumes
Cleaning Methods & Trials Chemical cleaning Over 2,000 feet per week $20 to $40 per foot Flow increases up to 6X Chemical cleaning determined to be the best technology for removing heavy precipitate buildup CDM Smith
Full Scale Chemical Cleaning 40,000 Gallons per month 35,000 Successful in removing precipitate from 30,000 25,000 20,000 Over 10,000 feet of perforated laterals 4,000 feet of perforated headers 4,000 feet of gravity mains 15,000 Restored flow in areas that appeared stagnant Reduced leachate head and liner leakage 10,000 Leak Detection Flow Rates 5,000 0 01-Oct-10 01-Nov-10 01-Dec-10 01-Jan-11 01-Feb-11 01-Mar-11 01-Apr-11 01-May-11 01-Jun-11 01-Jul-11 01-Aug-11 01-Sep-11 01-Oct-11 01-Nov-11 01-Dec-11 01-Jan-12 01-Feb-12 01-Mar-12 01-Apr-12 01-May-12 01-Jun-12 Completed Chemical Cleaning
Design & Operational Considerations Correlation between precipitate formation and leachate flow Minimal flow / stagnant conditions create saturated zones, allowing formation and growth of precipitate Keep leachate levels as low as possible Minimize outflow response time Maintaining continuous flow reduces both sediment buildup and the formation of precipitate Keep system clear of precipitate and sludge
Polk County North Central Landfill
Polk County North Central Landfill
Foam
Unique Challenges in this Business
Protecting What's Been Built, Restoring What's Been Broken. Questions & Answers Descaling, Disinfection, Preservation, Rebuilding Healthier Water. A cleaner and safer Environment. Minimal disruption to life & the economy. Protecting What's Been Built, Restoring What's Been Broken Copyright 2013, Progressive Environmental Services, LLC