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42 Waste Management Practices: Municipal, Hazardous, and Industrial
other products of incomplete combustion were released in abundance via the flue (stack). A recent
study of sediments in Central Park Lake, New York City, correlates the accumulation of lead, tin, and
zinc with the use of incinerators (Chillrud et al., 1999). By the late 1960s to the early 1970s, public
concerns with regard to management of both domestic and toxic chemical wastes increased. The Air
Quality Act of 1967 introduced new emissions standards that required the retrofitting of air pollution
control devices, such as scrubbers and precipitators (see Chapter 9) to older incinerators. Since incin-
erators were already more expensive and technology-intensive than landfills, the Act essentially
priced incineration out of the market. Within five years of the Act, 100 large-scale incinerators had
been shut down (Tammemagi, 1999).
The energy crises of the 1970s created a resurgent interest in the possibility of obtaining inex-
pensive energy from the thermal decomposition of MSW. The so-called “waste-to-energy” plants
and “refuse-derived fuel” systems were designed and developed. Given the continued closing of
sanitary landfills across the United States, incineration with the possible production of energy began
to appear as an attractive alternative. In the early to mid-1980s, approximately 100 new plants were
committed and another 200 planned in the United States (Tammemagi, 1999).

2.9 LAND DISPOSAL AND THE SANITARY LANDFILL
Until the 1900s, “land disposal” of solid wastes involved nothing more than direct dumping on to
the land surface followed by abandonment. On the outskirts of many cities, wetlands, often consid-
ered “nuisance areas,” were filled using layers of household refuse and ash. Early in the century,
however, disposal methods prescient of sanitary landfills began to evolve. Simple burying was
employed in the United States in 1904 (Public Administration Service, 1970; McBean et al., 1995).
The first excavated site that was periodically covered with soil, a precursor of today’s modern
sanitary landfill, opened in 1935 in California (Figure 2.14). In addition to MSW, the landfill
accepted industrial wastes. As a result, the site has secured a ranking on the U.S. EPA Superfund
list due to its content of hazardous materials (Gerlat, 1999; Vesilind et al., 2002).
Up to the 1950s, however, open-pit dumping of wastes remained a standard procedure
(California State Water Pollution Control Board, 1954; McBean et al., 1995). Due to the incompat-
ibility of wastes (e.g., disposal of hot ashes with paper products), fires were a frequent hazard. In
many municipalities, controlled burning was allowed for the purpose of volume reduction. There
were considerable problems with odor, smoke, insects, noise, and seagulls. Up to this point, most
disposal sites were obviously not designed or constructed with much engineering input. Planning to
address environmental protection remained inadequate. Siting of the landfill was based on conven-
ience and efficiency, rather than practical technical concerns such as proximity to surface water and
groundwater, and soil and geologic considerations. When such landfills were completed, they were
often covered with a thin cap of soil, and the growth of surface vegetation was encouraged. Land
subsidence was common and many sites leaked for decades after closure. Subsurface liners were
rarely used and the layers of waste were usually only a few meters thick. As landfills expanded,
growth occurred laterally and covered large tracts of land. Many were situated near expanding
urban areas and their water supplies. As a result, public opposition to these landfills became increas-
ingly contentious.
Alternative waste disposal techniques were attempted in the United States; however, landfills
remained the most common method due to the appealing costs of land and labor, and the simple,
inexpensive technology involved. To address the growing criticism, the concept of the “sanitary
landfill” was introduced in the 1950s. Also known as a “cut and cover” or controlled tipping sys-
tem, the sanitary landfill was touted as an engineered system for disposing solid wastes on land
by spreading them into thin layers, compacting to the smallest practical volume, and covering
with a layer of soil at the end of each working day (Stone, 1977). The concept of controlled tip-
ping, in which solid wastes are sealed in “cells” formed from soil or other cover material at reg-
ular intervals, was devised in order to keep wastes relatively free from odor, less attractive to