Typical Anatomy of a Protective Cover

1 COVER VEGETATION As portions of the landfill are completed, native grasses and shrubs are planted and the areas are maintained as open spaces. The vegetation is visually pleasing and prevents erosion of the underlying 1 .

2 Top Helps to support and maintain the growth of vegetation by retaining moisture and 2 providing nutrients. Collection System Leachate is a liquid that has filtered 3 PROTECTIVE COVER SOIL through the landfill. It consists primarily of Protects the landfill cap system and precipitation with a small amount coming provides additional moisture retention to from the natural of the help support the cover vegetation. . The leachate collection system col- 3 lects the leachate so that it can be removed from the landfill and properly treated or dis- 4 posed of. The leachate collection system has Composite Cap System the following components:

4 Drainage Layer 9 A layer of sand or gravel or a thick 5 Leachate Collection Layer mesh called a geonet drains excess precipi- A layer of sand or gravel or a thick plastic tation from the protective cover soil to mesh called a geonet collects leachate and enhance stability and help prevent infiltra- 6 allows it to drain by gravity to the leachate tion of water through the landfill cap collection pipe system. system. A geotextile fabric, similar in appearance to felt, may be located on top 10 Filter Geotextile of the drainage layer to provide separation A geotextile fabric, similar in appearance of solid particles from liquid. This prevents to felt, may be located on top of the clogging of the drainage layer. 7 leachate collection pipe system to provide separation of solid particles from liquid. This 5 Geomembrane prevents clogging of the pipe system. A thick plastic layer forms a cap that prevents excess precipitation from entering 11 Leachate Collection the landfill and forming leachate. This Pipe System 8 layer also helps to prevent the escape of Perforated pipes, surrounded by a bed of landfill , thereby reducing odors. gravel, collected leachate to specially designed low points called sumps. Pumps, located within the sumps, automati- cally remove the leachate from the landfill 6 Compacted and transport it to the leachate management Is placed over the waste to form a cap 7 facilities for treatment or another proper when the landfill reaches the permitted method of disposal. height. This layer prevents excess precipi- tation from entering the landfill and forming leachate and helps to prevent the escape of , thereby 8 reducing odors. Composite Liner System

12 Geomembrane A thick plastic layer forms a liner that pre- Working Landfill vents leachate from leaving the landfill and entering the environment. This geomem- 9 7 brane is typically constructed of a special At the end of each working period, waste type of plastic called high-density polyeth- ylene or HDPE. HDPE is tough, impermeable is covered with six to twelve inches 10 of soil or other approved material. Daily and extremely resistant to attack by the cover reduces odors, keeps from compounds that might be in the leachate. scattering and helps deter scavengers. This layer also helps to prevent the escape of landfill gas. 8 Waste As waste arrives, it is compacted in layers 13 Compacted Clay within a small area to reduce the volume Is located directly below the geomembrane consumed within the landfill. This practice and forms an additional barrier to prevent also helps to reduce odors, keeps litter leachate from leaving the landfill and enter- from scattering and deters scavengers. 11 ing the environment. This layer also helps to prevent the escape of landfill gas.

14 Prepared Subgrade 12 Please Note: This illustration The native soils beneath the landfill are depicts a cross section of the standard prepared as needed prior to beginning landfill technologies construction. of modern . While the tech- nologies used in most landfills are similar, the exact sequence and type 13 of materials may differ from site to site depending on design, location, climate and underlying geology. 14

(Not to scale)

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