Botkin Environmental Science Earth as Living Planet 8th txtbk

23.8 Municipal Solid-Waste Management 535
1
8
Sanitary landfill
5
2
4
7
6
Groundwater table
Leachate
3
Compacted cells of waste
Leachate
Groundwater
1
2
3
Atmosphere
Retention in soil
Groundwater
5
6
7
Removal in crops
Plant residue
Stream flow
Hazardous-waste pollutant
4
Surface runoff from land
8
Wind
FIGURE 23.13 Idealized diagram showing eight paths that pollutants from a sanitary landfill site may follow to enter the
environment.
Modern sanitary landfills are engineered to include
multiple barriers: clay and plastic liners to limit the
movement of leachate; surface and subsurface drainage
to collect leachate; systems to collect methane gas from
decomposing waste; and groundwater monitoring to detect
leaks of leachate below and adjacent to the landfill. A
thorough monitoring program considers all eight possible
paths by which pollutants enter the environment. In practice,
however, monitoring seldom includes all pathways.
It is particularly important to monitor the zone above the
water table to identify potential pollution before it reaches
and contaminates groundwater, where correction would
be very expensive. Figure 23.14 shows (a) an idealized diagram
of a landfill that uses the multiple-barrier approach
and (b) a photograph of a landfill site under construction.
Federal Legislation for Sanitary Landfills
New landfills that opened in the United States after
1993 must comply with stricter requirements under the
Resource Conservation and Recovery Act of 1980. The
legislation, as its title states, is intended to strengthen
and standardize the design, operation, and monitoring
of sanitary landfills. Landfills that cannot comply with
regulations face closure. However, states may choose between
two options: (1) comply with federal standards or
(2) seek EPA approval of solid-waste management plans.
The federal standards include the following:
Landfills may not be sited on floodplains, wetlands,
earthquake zones, unstable land, or near airports (birds
drawn to landfill sites are a hazard to aircraft).