Encyclopedia of Global Resources part 74 provides a wide variety of perspectives on both traditional and more recent views of Earth's resources. It serves as a bridge connecting the domains of resource exploitation, environmentalism, geology, and biology, and it explains their interrelationships in terms that students and other nonspecialists can understand. The articles in this set are extremely diverse, with articles covering soil, fisheries, forests, aluminum, the Industrial Revolution, the . Department of the Interior, the hydrologic cycle, glass, and placer mineral deposits. . | 678 Landfills Global Resources Schematic of a Municipal Landfill Gas flare or collection Leachate Down-gradient collection water If present these features could provide avenues for the downward or lateral migration of mineralized fluids generated in the landfill. The site should also not be near an airport because of the possibility of birds attracted to the site encountering aircraft in flight. Design and Procedure Most landfills employ a multiple-barrier approach to contain the materials placed at the site The base and sides of the excavation are generally covered by an impervious synthetic plastic sheet and or a compacted clay liner. The landfill is topped by a clay cap that is more than a meter thick. A clay dike is sometimes constructed within the Earthen cavity to separate the main trash collection area from a leachate collection basin. Dry wells surrounding the landfill monitor the vadose zone. This zone is a band above the water table where some water droplets suspended within the layer migrate downward toward the water table or move laterally to a discharge point. Deep wells on the fringe of the site penetrate the water table and monitor the quality of water stored there. Potential Hazards and Problems There are numerous potential health-related problems associated with the storage of municipal waste. Joel B. Goldsteen in Danger All Around Waste Storage Crisis on the Texas and Louisiana Gulf Coast 1993 points out some of the major concerns about waste storage on the Texas and Louisiana Gulf Coast. Among the possible hazards are fluid leachate generation gas generation air and noise pollution flooding land subsidence and fire. Leachate is an undesirable fluid produced in most landfills as solid waste comes in contact with downward-percolating water within the vadose zone or migrating groundwater. Generally the fluid is acidic with a high iron concentration up to 5 000 parts per million . In rare cases the leachate produces a bathtub effect and overflows the
