Wednesday, June 23, 2010
The thousands of mine shafts that pockmark the Sierra Nevada and testify
to California's Gold Rush riches have also left a legacy of toxic
contamination in some of the state's popular recreation areas, according
to a new study.
Soil tests on a handful of trails near mine mouths in the foothills have
revealed extremely high levels of lead, arsenic and asbestos, said
researchers at the Sierra Fund, a small environmental advocacy group.
The naturally occurring minerals were pounded to dust generations ago
and carted to the surface, where they are now stirred up and inhaled by
hikers, off-roaders, bikers and horseback riders.
The Gold Rush "not only brought wealth and hundreds of thousands of
people to California, it also brought mining machines that ripped down
sides of mountains and tunneled thousands of feet into rock, leaving
behind arsenic and lead," said Elizabeth Martin, chief executive of the
nonprofit group. "This is the longest neglected environmental problem in
California."
While their analysis was limited to 80 samples from 11 trails and
recreation spots in the Foresthill, Downieville and Nevada City areas,
the group says California's 47,000 abandoned mines pose significant
threats to public safety, particularly in the dry summer months when
families flock to the foothills.
"A lot of people are aware that their kids can fall into a hole at an
old mine. But they don't know that asbestos fibers can lodge into their
lungs or lead can be absorbed into their skin," Martin said in an
interview Tuesday.
For that reason, the group said additional testing must be done in
select areas where historic mine waste intersects with well-trafficked
trails. The fund is also pushing for warning signs and, in some cases,
restricting access to public trails with high levels of hazardous minerals.
Federal attention
So many mines are scattered across different landscapes and under
various ownership that it is unclear who would coordinate such an effort
and how - not just in California but across the country.
With development and recreational activity encroaching on remote areas,
the problem has gained the attention of federal authorities.
A federal audit in 2008 charged the Bureau of Land Management, which
controls a number of abandoned mining sites in California, Nevada,
Arizona and other states, with endangering public health by failing to
clean up arsenic, lead and mercury near the shafts or to erect barriers
around them. In the Rand Mining District outside Los Angeles, the
inspector general of the Interior Department found piles of toxic mine
waste in residential areas as well as biking trails awash in arsenic
particles.
That same year, the agency closed about half of the Clear Creek
Management Area, a 31,000-acre off-road vehicle paradise in the hills
outside of Hollister, after a U.S. Environmental Protection Agency
report said waste from the defunct asbestos mining in the area posed a
serious risk to those who work, camp, hunt and ride on the property.
Above safe levels
In the Sierra Fund's study, researchers reported levels of arsenic,
asbestos and lead well above levels deemed safe for human exposure. At
the Foresthill Off-Highway Vehicle area near the Marall Chrome Mine pit,
science director Carrie Monohan said lead levels were nearly 18 times
the state and federal standards, and 40 percent of the soil samples
showed asbestos contamination.
Asbestos, a mineral that shows up in nature as bundles of tiny, twisty
fibers, is of significant concern because it can embed in throat and
lung tissue, causing cancer and other respiratory diseases.
Difficult to clean up
Because of the diffuse nature of the hazardous minerals in surface
soils, they are almost impossible to clean up, according to David
Christy, spokesman with the Bureau of Land Management's Central
California division.
"The technology is a challenge," he said. "The approach to cleaning up
mines is steam cleaning them and cementing over them, and that costs a
lot of money."
Under President Obama's federal stimulus plan, California received about
$20 million of the $73 million set aside for cleaning and maintaining
abandoned mines nationwide. Some estimates peg the number of abandoned
mines in the United States at 500,000 and the amount needed to detoxify
them in the billions.