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Typical Anatomy of a Landfill
Please Note: This illustrationdepicts a cross section of the standardenvironmental protection technologiesof modern landfills. While the tech-nologies used in most landfills aresimilar, the exact sequence and typeof materials may differ from site to sitedepending on design, location, climateand underlying geology.
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COVER VEGETATIONAs portions of the landfill are completed,native grasses and shrubs are plantedand the areas are maintained as openspaces. The vegetation is visually pleasingand prevents erosion of the underlyingsoils.
TOP SOILHelps to support and maintain the growthof vegetation by retaining moisture andproviding nutrients.
3 PROTECTIVE COVER SOILProtects the landfill cap system andprovides additional moisture retention tohelp support the cover vegetation.
DRAINAGE LAYERA layer of sand or gravel or a thick plasticmesh called a geonet drains excess precipi-tation from the protective cover soil toenhance stability and help prevent infiltra-tion of water through the landfill capsystem. A geotextile fabric, similar inappearance to felt, may be located on topof the drainage layer to provide separationof solid particles from liquid. This preventsclogging of the drainage layer.
5 GEOMEMBRANEA thick plastic layer forms a cap thatprevents excess precipitation from enteringthe landfill and forming leachate. Thislayer also helps to prevent the escape oflandfill gas, thereby reducing odors.
6 COMPACTED CLAYIs placed over the waste to form a capwhen the landfill reaches the permittedheight. This layer prevents excess precipi-tation from entering the landfill andforming leachate and helps to preventthe escape of landfill gas, therebyreducing odors.
7 DAILY COVERAt the end of each working period, wasteis covered with six to twelve inchesof soil or other approved material. Dailycover reduces odors, keeps litter fromscattering and helps deter scavengers.
8 WASTEAs waste arrives, it is compacted in layerswithin a small area to reduce the volumeconsumed within the landfill. This practicealso helps to reduce odors, keeps litterfrom scattering and deters scavengers.
LEACHATECOLLECTION SYSTEMLeachate is a liquid that has filteredthrough the landfill. It consists primarily ofprecipitation with a small amount comingfrom the natural decomposition of thewaste. The leachate collection system col-lects the leachate so that it can be removedfrom the landfill and properly treated or dis-posed of. The leachate collection system hasthe following components:
9 LEACHATE COLLECTION LAYERA layer of sand or gravel or a thick plasticmesh called a geonet collects leachate andallows it to drain by gravity to the leachatecollection pipe system.
10 FILTER GEOTEXTILEA geotextile fabric, similar in appearanceto felt, may be located on top of theleachate collection pipe system to provideseparation of solid particles from liquid. Thisprevents clogging of the pipe system.
11 LEACHATE COLLECTIONPIPE SYSTEMPerforated pipes, surrounded by a bed ofgravel, transport collected leachate tospecially designed low points called sumps.Pumps, located within the sumps, automati-cally remove the leachate from the landfilland transport it to the leachate managementfacilities for treatment or another propermethod of disposal.
12 GEOMEMBRANEA thick plastic layer forms a liner that pre-vents leachate from leaving the landfill andentering the environment. This geomem-brane is typically constructed of a specialtype of plastic called high-density polyeth-ylene or HDPE. HDPE is tough, impermeableand extremely resistant to attack by thecompounds that might be in the leachate.This layer also helps to prevent the escapeof landfill gas.
13 COMPACTED CLAYIs located directly below the geomembraneand forms an additional barrier to preventleachate from leaving the landfill and enter-ing the environment. This layer also helps toprevent the escape of landfill gas.
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PROTECTIVE COVER
COMPOSITE CAP SYSTEM
WORKING LANDFILL
COMPOSITE LINER SYSTEM
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14 PREPARED SUBGRADEThe native soils beneath the landfill areprepared as needed prior to beginning landfillconstruction.
©2002, Waste Management www.wm.com
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