About Abandoned Mine Land Hazards

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The purpose of BLM’s California Desert District’s AML program is to assist partners in fulfilling broad missions of improving water quality and enhancing public safety.  Our vision is to mitigate hazards to protect public health and safety, and restore watersheds for resources, recreation, and wildlife by remediating significant hardrock AML sites on or affecting the pubic lands.  Key program objectives are to:

• Identify sites within a quarter (.25) of a mile of populated or high use visitor areas.
• Prioritize sites based on risks.
• Remediate sites with available resources over specified time periods.
• Report program accomplishments.
• Conduct education and outreach activities to warn people about the potential dangers of AML sites.

In so doing, BLM aims to:

• Maintain a working inventory of known AML sites, with accurate and complete information needed by the public and decision-makers.
• Select from the inventory sites to be remediated based on priority criteria.
• Complete ongoing remediation and mitigation projects before engaging in new projects, except for emergency related situations.
• Conduct further inventory and field validation work in accordance with land use planning efforts.
• Report, manage and reduce contingent environmental cleanup liabilities.
• Leverage funds and achieve cost savings through partnerships, use of volunteers, and cost avoidance/cost recovery authorities.
• Provide needed policy, direction, and program management tools to Field Offices.

BLM addresses physical safety and environmental hazards using a risk-based approach. The type of remediation activities performed at an abandoned mine site determines which regulations guide site activities. In general, BLM follows National Environmental Policy Act (NEPA) procedures (BLM Handbook H-1790-1) when conducting activities to address physical safety issues and for those sites where activities have historic, cultural, or wildlife impacts.  BLM implements the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process for sites with a release or the threat of a release of a hazardous substance.

Types of AML sites include:

Ø  Physical Safety Hazard Emergency Sites include accidents and deaths or the immediate potential for such tragedies on BLM-administered lands.  Once BLM is notified of a physical safety hazard emergency the local authorities are contacted and appropriate emergency procedures are initiated.

Ø  Physical Safety Hazard Sites may contain one or more of the following: 

o   Shafts are vertical mine openings that can extend hundreds of feet to the lower level of a mine. Open shafts can be concealed by mine debris, dirt, rock, and even water. 

o   Adits are horizontal mine opening that can extend hundreds of feet.  Both shafts and adits tend to follow the original ore veins.  Within a short distance of the entrance there is no light, and these openings can be the cause of becoming lost and disoriented inside a mine. 

o   Unstable Rock and Decayed Support includes once solid beams and frameworks that have been decaying for more than a hundred years.  In many cases, there may be no support beams at all and the fractured roof or walls of the mine tunnel eventually collapse in response to vibrations and/or the force of gravity.

o   Deadly Gases and Lack of Oxygen can be present in abandoned mines that are not ventilated.  Pockets of methane, carbon dioxide, and other deadly gases can form or simply displace oxygen with no visible sign.  When these gases enter the body, muscles stop responding normally, thinking becomes clouded, and unconsciousness and death can occur.

o   Explosives and Toxic Chemicals were often left behind when an active mining operation was abandoned. Explosives such as dynamite and blasting caps become very unstable over time, and can explode if disturbed. Storage containers, boxes, barrels, and drums deteriorate allowing toxic chemicals to leak or combine into highly dangerous mixtures.

o   Highwalls and Open Pits are located where large areas of the surface have been disturbed to get at minerals near the surface. Open pits can be filled with water that can be highly acidic or laden with harmful chemicals.  Highwalls can be unstable at the top and the bottom and are prone to collapse. When approached from the top, the vertical edge of a highwall may not be seen in time or may crumble, leading to a fatal fall.

o   More subtle hazards associated with AML’s include encounters with wild animals (e.g., rattlesnakes, bears, mountain lions); exposure to bat droppings, hantavirus, radon and radiation; and toxic soil, water, and air contaminated with cyanide, lead, arsenic, mercury, and other toxins which may be inhaled through dust and particles or through contact with impounded acidic water.

Ø  Water Quality Sites are those sites where a hazardous substance release has occurred, is suspected, or the threat of release exists.  BLM generally uses CERCLA authority to address these sites, and can address physical safety hazards concurrently with the environmental remediation under CERCLA.

Physical Safety and Remediation Measures

BLM may take temporary measures to mitigate against physical safety hazards, such as by posting warning signs and fencing.  Additional remedial measures include closure of adits and shafts, backfilling of highwalls, drainage of impoundments, removal of leftover equipment and debris, and reclaiming to help offset erosion and improve stability.

 If during the site characterization BLM determines that remedial activities may have historical, cultural, or wildlife impacts they must address these impacts in conjunction with the remedial activities. To mitigate impacts to bats, bat grates and cupolas are often installed using standard designs established by Bat Conservation International.

Water Quality and Remediation Measures

Typical remedies for water quality sites include removing the source of the contamination, treating the contaminated water, and/or rerouting the flow of water. The cleanup activities performed at water quality sites are conducted under CERCLA authority and follow the CERCLA process.

Site Closure and Monitoring

When the remediation goals have been met the abandoned mine site is considered closed and BLM prepares a Closure Report. All sites will need to be monitored to ensure that the remedy remains in place as long as necessary and continues to achieve the desired result. Water quality sites will likely require at least periodic sample collection to determine if previously established water quality criteria have been and continue to be met.

What can you do?

The State of California Abandoned Mine Land Unit has a toll free number, 877-OLD-MINE, where members of the public may call to report abandoned mines.  Or you can contact your local BLM Field Office.  While staff tries to perform field visits to reported sites as soon as possible, resource constraints and other obligations may limit their availability.  It is most helpful if you have GPS coordinate and a picture in order to find the site during a field visit.

Remember, Stay Out, Stay Alive!