explosives also
physical hazard.
Nevada County Community
Development Agency
present
a
significant
Abandoned Mine Lands
Abandoned Mine Land in Nevada County
—Information for Developers, Property
Owners and Prospective Property Owners
1849—The Gold Rush
Nevada City and Grass Valley owe much of
their charm to the Gold Rush years. Mining
relics can be found in museums and parks
throughout the Gold Country. The mineral
wealth of the Sierra Nevada contributed
immensely to the State’s economy, and
many Sierra foothill communities originally
grew from those colorful days. Many folks
are fascinated by the local history, the feats
of engineering, and the tales of the lives of
men and women who lived the Gold Rush.
It is easy to romanticize the days when a
person could stake a claim and test muscle
and will for visions of quick wealth.
The 21st Century
Fast forward to today.
Times have
changed, and most of the tens of thousands
of mines dug in California have been long
abandoned. Some of those little mining
towns that swelled and shrunk with the
success of the mines are now growing
communities. As they grow, the many
abandoned mines are becoming areas
sought for homes, schools and businesses.
These old mining areas are termed
“Abandoned Mine Land”, or AML. While
they may hold some romance and nostalgia,
they can also hold both physical and
chemical hazards. These hazards are the
subject of a report prepared by the
California Department of Conservation,
Office of Mine Reclamation in June 2000
entitled California’s Abandoned Mines1.
The report estimates that there are
approximately 39,000 historic and inactive
mine sites in the state. It also estimates
that a high percentage of these sites
present physical hazards, and a lesser
percentage present environmental hazards.
Historic mining information lists several
thousand abandoned claims and mines
throughout Nevada County. As properties
develop in the historic mine country,
consideration of these issues becomes
important in maintaining the health and
safety of our growing community.
AML Hazards
The physical hazards that can be
encountered are such things as open shafts
and adits (tunnels). Some old shafts were
closed off with timbers and covered with
earth rendering them nearly invisible today.
As the timbers slowly rot away, the “plug”
can suddenly collapse under the weight of a
vehicle or person.
Although rare, old
1
The report may be viewed online at
http://www.consrv.ca.gov/OMR/abandoned_min
e_lands/california_abandoned_mines/overview.
htm
Environmental hazards are primarily
hazardous
minerals
and
chemicals.
Examples of these hazards include
mercury, arsenic, and acid mine drainage.
Some hazardous materials are process
wastes; others result from the disturbance
of naturally occurring minerals that have
been released into the environment at
hazardous levels.
Issues with Hazardous Materials
Elevated levels of minerals such as arsenic
can present a hazard to human health either
through inhalation or ingestion of dust. For
example, arsenic that is “bound up” in rock
is not “bio-available”, and generally does not
present a hazard to health. However, some
mining processes employed crushing the
rock, and the result can be bio-available
arsenic at hazardous levels. This is only
one example of mineral hazards associated
with historic mining activities.
State Laws pertaining to Hazardous
Wastes
Because of concerns over elevated health
risk from human exposure to significant
quantities of hazardous waste, the State of
California has enacted laws that require
appropriate mitigation and/or removal of
hazardous wastes. These laws place the
evaluation and “cleanup” responsibilities
upon the property owner. (See California
Health & Safety Code, Section 25221, et
seq.2 at the end of this brochure.) One of
several State agencies may be involved in
the review, approval and final disposition of
the cleanup activities. These include the
Department of Toxic Substances Control
(DTSC) and the Regional Water Quality
Control Board (RWQCB). For human health
concerns, DTSC is generally the agency
with which a cleanup is coordinated; for
water quality concerns, the agency
concerned is usually the RWQCB.
Determining if Hazards Exist
Further Information
There are several different sources of
additional information. These include:
California Department of Conservation,
Office of Mine Reclamation
(916) 323-9198
http://www.consrv.ca.gov/OMR/abandoned_
mine_lands/index.htm
A qualified professional is needed to
evaluate both physical and environmental
hazards relating to old mining activities.
There are local and regional consulting
firms who provide this service. These firms
can also work with you and the State if a
cleanup of hazardous materials is required.
California Department of Toxic Substances
Control
For physical hazards, a Professional
Engineer is usually required to design a
safe method of eliminating the hazard. In
some instances, a County permit may be
required to do the work.
(916) 464-3291
For hazardous waste concerns, the first
step is for a qualified consultant to complete
a Site Assessment. If the Site Assessment
suggests or reveals significant hazardous
waste, further investigation is required in the
form of a Preliminary Endangerment
Assessment (PEA). From the PEA will be
established a plan describing how the
hazardous waste will be mitigated and/or
removed. Once the PEA and plan are
approved by the appropriate State agency,
the property owner then enters into an
agreement with the State as to how the site
will be cleaned up. Persons trained and
licensed to remove hazardous materials
must be employed to complete the cleanup
activities.
(800) 728-6942
http://www.dtsc.ca.gov/SiteCleanup/index.ht
ml
Central Valley Regional Water Quality
Control Board
http://www.waterboards.ca.gov/centralvalley
Nevada County Department of
Environmental Health
(530) 265-1222
www.mynevadacounty.com/eh
2
25221. (a) Any person as owner, lessor, or
lessee who (1) knows, or has probable cause to
believe, that a significant disposal of hazardous
waste has occurred on, under, or into the land
which he or she owns or leases or that the land
is within 2,000 feet of a significant disposal of
hazardous waste, and (2) intends to construct or
allow the construction on that land of a building
or structure to be used for a purpose which is
described in subdivision (b) of Section 25232
within one year, shall apply to the department*
prior to construction for a determination as to
whether the land should be designated a
hazardous waste property or a border zone
property pursuant to Section 25229.
25232. (b) (1) Construction or placement of a
building or structure on the land which is
intended for use as any of the following, or the
new use of an existing structure for the purpose
of serving as any of the following:
(A) A residence, including any mobile home or
factory built housing constructed or installed
for use as permanently occupied human
habitation, except that the addition of rooms
or living space to an existing single-family
dwelling or other minor repairs or
improvements to residential property which
do not change the use of the property or
increase the population density does not
constitute construction or placement of a
building or structure for the purposes of this
paragraph.
(B) A hospital for humans.
(C) A school for persons under 21 years of age.
(D) A day care center for children.
(E) Any permanently occupied human habitation
other than those used for industrial
purposes.
*”Department” refers to the State Department of
Toxic Substances Control