Sustainable Landfills: The Future of Land Disposal of Municipal Solid Waste (MSW) Patrick Hettiaratchi Associate Professor, Department of Civil Engineering & CEERE ( Center for Environmental Engineering Research & Education) Faculty of Engineering, University of Calgary Chair, Environmental Engineering Division (EED), Canadian Society for Civil Engineering (CSCE) April 17, 2003 Presentation to CSCE – Calgary Section

Sustainable Landfills Landfills that are designed and constructed to achieve Sustainable Development (SD), or … … designed and constructed using SD principles Sustainable Development is “development that meets the needs of the present without compromising the ability of future generations to meet their own needs (1987 UN Commission on SD; Bruntland Report)” Sustainable Development is “Common-Sense”

Sustainable Development & Engineering SD is Common-Sense ……. Engineers have no choice, but to apply SD principles in their practice  Sustainable Infrastructure  Sustainable Transportation  Sustainable Landfills Engineering is “common-sense application of technology to meet human needs (current and future)”

Sustainable Landfills Landfills…… … … designed and constructed using SD principles SD Principles…. Current Landfilling Practice….  Is this Sustainable?  Are we applying SD principles in Landfill development now? (you be the judge…..) ReduceReuse Recycle (or recovery of Recyclables) Recovery (of Energy and Compost)

Open Dumps, Sanitary Landfills and Sustainable Landfills: a Natural Progression?? Past: Past: We started with Open Dumps…….. (until someone showed that it is not a good practice) But But, still common practice in most developing countries!!!!!

Today: We have converted Open Dumps to Sanitary Landfills ….. Conventional “dry-tomb type” Sanitary Landfills are designed and constructed to eliminate problems associated with “Open Dumps”

Prevention of GW contamination with bottom liner systems  Prevention of GW contamination with bottom liner systems  Leachate is “garbage juice” or an aqueous liquid produced within the landfill X-section along the length of the landfill Stream Area A Area C Area B Working Face (Area D)  Leachate can contaminate Groundwater (unseen) or Surface Water (obvious) “Dry Tomb” landfill Problem: Landfill Leachate

Landfill Construction Final cover Daily cover Intermediate cover

Leave it Alone !!!!! R I P

Problems with the Dry-tomb Sanitary Landfillling Approach  Un-sustainable??? Loss of Space…. Need to find new space every few years (Toronto, Edmonton)  Long-term liability: Need to monitor potential impact for a long- time (until waste stability is achieved)  Liability associated with landfill gas:  Landfill gas contains CH 4 and CO 2 (both are GHGs) 1/3 of anthropogenic CH 4 in USA come from Landfills  If gas is extracted (for energy recovery)…. Possible to minimize concerns  In most cases, gas production is low; not economical to extract methane gas for energy recovery  Gas can be a major hazard (Ecuador example)

Zambisa Landfill (Quito, Ecuador) X-section along the transverse direction

Zambisa Landfill (Quito, Ecuador) X-section along the transverse direction

Sustainable Landfill The Concept:  Holistic approach (not “piece-meal”)  Stabilize the waste quickly (Anaerobic and Aerobic)  “Mine” the cell, and extract recyclables & compost  Reuse space  Increase biological activity in landfill cell; possible to extract large quantities of gas in a short period of time

Sustainable Landfill Anaerobic Reactor

Sustainable Landfill Aerobic Reactor

Aerobic Year 5 Aerobic Year 4 Anaerobic Year 3 Anaerobic Year 2 Anaerobic Year 1 Mining/ Space Recovery Year 6 Sustainable Landfill Operation (Calgary Biocell Concept)

Problems to Resolve Moisture Distribution Within the Cell What We Want….. What We Get

Leachate Pools: Created by “over-zealous” Leachate Recirculation

Problems to Resolve Surface Gas Emissions  Could occur during construction of the biocell (may take 1 or 2 years to completely fill a cell)  Significant quantities can escape from surface even with a gas capture system example: Loma Los Colorados Landfill, Chile

Loma Los Colorados Landfill, Chile

Gas Wells Loma Los Colorados (contd…)

Landfill Gas Incinerator CH 4 burned= 85 tonnes/year (or 330 m 3 /d)

Total CH 4 emitted/burned = 17,040 tonnes/year (exclude “leachate pool” emissions) Loma Los Colorados Bioreactor Landfill More than 75% of the “produced methane gas” escapes across the cover soil (worth about $3 million/year in the “open Carbon market”) Landfill Methane Budget:

Calgary Sustainable Biocell  Pilot Project (1 hectare: 50,000 tonnes of waste)  Partners/Participants: City of Calgary, University of Calgary and Stantech Consultants  Mitigation Measures:  Biocap, or Methane Oxidation Layer (MOL), to control methane gas emissions during construction and operation

Landfill Bio-Caps or MOLs  A new concept  Use a naturally occurring bacteria to convert methane CH 4 & CO 2 Generation CO 2 Emissions CH 4 & CO 2 Emissions Commercial Recovery CH 4 & CO 2 Lateral Migration Oxidation In landfill cover (Methanotrophs)

Biofiltration of CH 4 Microbially mediated oxidation of CH 4 is carried out by methanotrophic bacteria (Methylomonas methanica)

CH 4 Oxidation in Landfill Caps

Conclusions  Waste disposal has progressed from “open dumps” (in the past) to “sanitary landfills” (in the present). Sustainable Landfills could be the future.  Sustainable landfilling follows a holistic approach. It is consistent with the “current thinking” (in terms of SD).  Technical challenges need to be overcome, before Sustainable Landfill concept could be universally applied.  Civil Engineers should take a lead to role to ensure SD principles are adopted in the practice of land disposal. Thank You!