Environmental Engineering Reference
In-Depth Information
FIGURE 10.5
Approximate extent of coal fields of the Pennsylvanian formations in the eastern United States. (From Averitt,
P.,
USGS Bull, 1275,
U.S. Govt., Printing Office, Washington, DC, 1967.)
Salt Mines
In the United States, salt is mined from the subsurface in New York, Kansas, Michigan,
Utah, Texas, Louisiana, and California.
Kansas
In Kansas, natural sinkholes, such as Lake Inman in McPherson County, are common on
the solution front along the eastern edge of the Hutchinson Salt Member. Solution mining
has resulted in subsidence in and around the city of Hutchinson. In 1974, a sinkhole 300 ft
in diameter occurred at the Cargill Plant, southeast of the city.
In Russell County, I-70 crosses two active sinkholes that have been causing the highway
to subside since its construction in the mid-1960s. In the area, sandstone and shale overlie
a 270-ft-thick salt bed 1300 ft below the surface. It is believed that old, improperly plugged,
abandoned oil wells allowed fresh water to pass through the salt bed resulting in dissolu-
tion of the salt and the creation of a large void. Subsidence has been of the order of 4 to 5
in./year, and in recent years a nearby bridge has subsided over another sinkhole. Over the
years, the roadway grade has been raised and repaved. In 1978, a sinkhole 75 ft across and
100 ft deep, centered about an abandoned oil well, opened up about 20 mi from the I-70
sinks. Plugging old wells and performing cement injections have failed to stop the subsi-
dence (Croxton, 2002).
New York
On March 12, 1994, a 650
650 ft panel 1180 ft under the Genesse Valley in Retsof,
New York, failed catastrophically generating a magnitude 3.6 seismic event. A similar
size panel failed a month later, and groundwater immediately entered the mine. Two
sinkholes, 700 ft across and up to 75 ft deep, opened over the failed mine panels
(William, 1995). Surface subsidence over a large area in the valley due to (1) dissolution
of pillars and (2) dewatering of valley-fill sediments was occurring at rates measured in
