Understanding Landfills: How Our Trash is Managed and Processed

1. Where Does our Trash Go? Nationally: 27% Recycled 16% Burned 57% Landfilled 31% Recycled 69% Landfilled 4.5 Pounds of Trash are produced Per Person Per Day

2. What is in our Waste? (After Recycling) Total 151.9 million tons of trash per year

3. What is a Landfill? • Dump – a hole where trash is dumped • Landfill – a structured place where trash is deposited

4. Burying Solid Waste • Most of the world’s MSW is buried in landfills that eventually are expected to leak toxic liquids into the soil and underlying aquifers. • Open dumps: are fields or holes in the ground where garbage is deposited and sometimes covered with soil. Mostly used in developing countries. • Sanitary landfills: solid wastes are spread out in thin layers, compacted and covered daily with a fresh layer of clay or plastic foam.

5. When landfill is full, layers of soil and clay seal in trash Topsoil Electricity generator building Sand Clay Methane storage and compressor building Leachate treatment system Garbage Probes to detect methane leaks Pipes collect explosive methane as used as fuel to generate electricity Methane gas recovery well Leachate storage tank Compacted solid waste Groundwater monitoring well Garbage Leachate pipes Leachate pumped up to storage tank for safe disposal Sand Synthetic liner Leachate monitoring well Sand Groundwater Clay and plastic lining to prevent leaks; pipes collect leachate from bottom of landfill Clay Subsoil

6. Trade-Offs Sanitary Landfills Advantages Disadvantages Noise and traffic No open burning Dust Little odor Air pollution from toxic gases and volatile organic compounds Low groundwater pollution if sited properly Releases greenhouse gases (methane and CO2) unless they are collected Can be built quickly Low operating costs Groundwater contamination Can handle large amounts of waste Slow decomposition of wastes Filled land can be used for other purposes Discourages recycling, reuse, and waste reduction Eventually leaks and can contaminate groundwater No shortage of landfill space in many areas

7. History of a Landfill Before 1960’s Most waste was burned in open dumps. • produced clouds of smoke • produced a bad oder • created a breeding ground for flies and rats Before and early 1960’s Waste burned in incinerators and combustion facilities (high temperatures burn waste more completely than in open burns) • prime sources of air pollution 1960’s and 1970’s Laws passed regulating air pollution 1970’s Dumps converted to full operating landfills. 1988-2001 Number of landfills decline from 8,000 to 1,858 – because landfill size and recycling have increased and regulations are tighter.

8. Landfill: Design = Function Challenges of a Landfill groundwater contamination from liquids produced in landfill methane production from anerobic decomposition of trash incomplete decomposition (newspapers in a landfill have been found to be up to 100 years old!) as trash decomposes it compacts and settles caustin landfills to sink most neighborhoods oppose having a landfill built in their vicinity

9. Simple Anatomy of a Landfill Soil Trash Gravel Drainage Foam Mat Plastic Liner Clay bottom

10. Anatomy of a Working Landfill Daily Cover At the end of each day, waste is covered with 6-12 inches of soil. • reduces odors • keeps litter from blowing away • deters scavengers/animals/rodents Waste Waste is compacted in layers to reduce its volume. Sand/Gravel Layer Collects leachate (liquid produced from waste) and funnels it to leachate pip system below. Leachate Pipe System Pipes collect leachate and pump it out of the landfill and to a water treatment plant, retention pond, or another proper method of disposal. Geomembrane – Plastic Layer A thick plastic layer lines the landfills and prevents leachate from entering the ground. The plastic is made from high-density polyethylene which is tough and impermeable. Clay Layer Compacted Clay is first laid in the landfill space to form a barrier to prevent leachate leaks to protect the soil and hold the trash in place. Clay is used due to its moldable and impermeability qualities.

11. Anatomy of a Closed Landfill Protective Cover Cover Vegetation – when landfills are full they are covered with native grasses and shrubs and used as recreation areas. Top Soil & Cover Soil – supports and maintains the growth of vegetation and protects the landfill cap. Protective Cover Geomembrane and Clay – Compacted clay and a thick plastic layer forms a ‘cap’ that prevents excess precipitation from entering landfill and prevent the escape of landfill gas. Soil and Trash Layers of Working Landfill

12. A Landfill Cell The goal of a landfill is to cover it, isolate it, and keep it from contaminating our air and groundwater. Tractors Compact Waste to Create Layers in a Landfill Cell

13. Landfill – Soil Top Layer At the end of every day, the waste is compacted and a layer of soil called “daily cover” is spread over it to minimize odor, prevent windblown litter, and deter insects and vermin.

14. Leachate Collection System Collects and removes liquids from the landfill. Leachate Pond Contaminants are removed and taken to: • retention pond • waste water treatment plant • another proper treatment facility

15. Gas Contaminants in a Landfill Aneorobic decomposition of waste produces Methane gas. The gas must be removed from the landfill or the landfill cell may become explosive Methane Flare Methane storage tank Pipes in the landfill remove the gases which are then… burned on a Methane Flare Stored and treated until no longer noxious Burned and used as energy.