AML PROJECT: INVENTORY AND CHARACTERIZATION OF INACTIVE/ABANDONED MINE
(AML) FEATURES IN NEW MEXICO
Virginia T. McLemoreNew Mexico Bureau of Geology and Mineral Resources, New Mexico Tech, Socorro, NM
ACKNOWLEDGEMENTS Funding
• New Mexico Bureau of Geology and Mineral Resources (NMBGMR)• Energy Minerals and Natural Resources Department and the U.S.
Department of the Interior, Office of Surface Mining and Reclamation(OSMRE)
• Mineral Engineering Department of NMIMT• New Mexico Geological Society• New Mexico EPSCoR (funded by the National Science Foundation
award #IIA-1301346))
Numerous M.S. theses Professional staff and many students who worked on these
projects (Nelia Dunbar, Lynn Heizler, John Asafo-Akowuah, William Zutah, Marcus Silva, John Durica, Bonnie Durica, Joseph Shackleford, Navid Mojtabai, Bonnie Frey)
Is there a potential Gold King disaster in New Mexico?
What is the state of AML/inactive/legacy mines in New Mexico?
AML=Abandoned Mine Lands
Lands that were mined and left unreclaimed where no individual or company has reclamation responsibility. These may consist of excavations, either caved in or sealed, that have been deserted and where further mining is not intended. Also called inactive, legacy and orphaned mines.
What are AML?
Waste rock pile
Most AML projects focused on physical hazards
Gold King spill is a game changer in how government agencies handle remediation of AML
Many state and federal agencies and mining companies have mitigated many of the physical safety hazards of AML, but very few of these reclamation efforts have examined the long-term environmental effects, unless the NMED identified them as a source of contamination of water sources
There is still potential for environmental effects long after remediation of the physical hazards Terrero (Pecos), Jackpile and Questa mines
The NMBGMR in cooperation with the Mineral Engineering Department at New Mexico Tech and the NM AML program is conducting research on legacy mine features in New Mexico
WHAT IS BEING DONE?
Superfund established in 1980 Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA) Designed to clean up sites contaminated with
hazardous substances and pollutants OSM (Office of Surface Mining) was established
with the passage of the Surface Mining Control and Reclamation Act (SMCRA) of 1977 (mostly coal) Collection of reclamation fees from current coal
mining operators and awarding reclamation grants to states and tribes that have current coal production to cleanup all mine sites
Mining companies today have major reclamation projects
Tyrone, tailings NM
SUPERFUND SITES
There are 19 active superfund sites in NM 6 are mining sites
Chevron, Inc. (formerly Molycorp) Questa mine, Red River (molybdenum mine and mill)
Cimarron Mining Corp. (Carrizozo, gold mills that used cyanide, completed in 1992, but monitoring is ongoing)
Cleveland mill (Silver City, gold, silver, copper mine and mill, completed in 2001)
Homestake Mining Co. mill, Grants uranium districtJackpile-Paquate mine, Grants uranium districtUnited Nuclear Corp., Grants uranium district
Homestake mill, Grants
OUTLINE• Potential
problems• Purpose of
NMBGMR AML program
• Methods• Lessons learned• Summary Lordsburg mining district,
Hidalgo County
POSTER IN THE LOBBY
WHAT ARE POTENTIAL IMPACTS ASSOCIATED WITH AML?
Most mines, waste rock piles, tailings, and heap leach facilities are safe and have remained stable with little or no environmental impacts.
But physical hazards are common in many districts.
There has been a major tailings dam or rock pile failure or unintended water release every year somewhere in the world over the last few decades and a few in NM.
Acid rock drainage and contamination by metals and other constituents is a problem at some sites in NM.
CHURCH ROCK TAILINGS SPILL, NM
1,100 tons of radioactive tailings and 94 million gallons of acidic wastewater were released to the Puerco River in the spill
Spill fluids traveled at least 80 miles downstream in the Puerco River
The 20-foot breach in the tailings dam formed around 5:30 am on the
morning of July 16, 1979.
GOLD QUARRY, NEVADA
In February 2005, one of Newmont's 10-million ton waste rock dumps at the Gold Quarry mine, collapsed and slid across Nevada Highway 766. Possible cause by placing clay on top of other rock material, then weaken by excessive rain water.
Hillsboro
Jicarilla
Pinos Altos
Hillsboro
EROSION AND SEDIMENTATION
More than $68 billion worth of minerals have been produced from New Mexico since 1804
245 mining districts 28 coal fields
BUT WE DO NOT KNOW HOW MANY TOTAL INACTIVE OR AML MINE SITES
ARE IN NM (best guess >30,000 mine features)
Mines in New Mexico (from the New Mexico Mines Database and BLM data, includes aggregate pits)
NM AML PROGRAM (NM MINING AND MINERALS DIVISION)
Started in 1981 Safeguarded over 2,300 mine openings In about 250 separate construction
projects Including coal gob (waste material)
reclamation Funded by coal mine tax
OSMRE Office of Surface Mining and Reclamation
Swastika coal mine, Raton (AML photo)
https://amlis.osmre.gov/Map.aspx
NM AML sites
OTHER CLOSURE EFFORTS
Mining companies USFS and USBLM
PURPOSE OF NMBGMR AML PROGRAM
Develop a better procedure to inventory and characterize legacy, inactive or abandoned mine features in New Mexico that addresses potential environmental issues and potential impacts to water and human health
Sampling at Lucky Don U mine and waste rock pile in Rosedale district
PURPOSE OF NMBGMR AML PROGRAM
Summit mine, Steeple Rock district, Grant
County
Provide data on districts, mines, and mills in New Mexico
– Help plan and assess reclamation procedures
– Determine background concentrations
– Understand geologic processes– Compare trace-element
concentrations in mined versus undisturbed areas
– Provide background data that can assist with the planning of future mining operations
Purpose—continuedTo make informed decisions about
– Economic impacts– Resource development and
management (mineral resource potential)
– Impacts on water supplies – Impacts on land use – Environmental impacts (including
potential sources of AD [acid drainage] or other MIW [mine influenced waters])
– Physical hazard assessment and remediation
Adit, Jicarilla Mountains,
Lincoln County
METHODS Inventory the mines
History of the site (production, commodities, mine methods, processing facilities)
Characterization Paste pH, mineralogy, chemistry, etc.
Prioritize mine features Detailed characterization of high priority
sites Detailed mineralogy and chemistry ABA/NAG tests Particle size analyses Shear tests
SOIL PETROGRAPHY–FIRST STEP IN DETERMINING MINERALOGY
2 mm
Pyrite characterization Evaluate the
distribution, form, size, amount, surface area of pyrite in the rock piles
1
2
3
4
5
6
7
8
9
0.01 0.1 1 10 100 1000
NAG
pH
NPR
ARD Classification Plot
UNCERTAIN
NON-ACID FORMING
POTENTIAL ACID
FORMINGUNCERTAIN
Little Davie and Lucky Don Rosedale
Jeter Jicarilla
Acid Rock Drainage (ARD) classification plot of composite waste rock pile samplesfrom various districts. Little Davie, Lucky Don (Socorro district), Jeter (LadronMountains district), and Rosedale district samples are in Socorro County. Jicarilladistrict is in Lincoln County.
SELECTED PAST AND ONGOING PROJECTS
New Mexico Mines Database Questa weathering study—examine the effects
of weathering on the stability of the Questa mine waste rock piles
Geochemistry of legacy mines in Socorro and Sierra Counties
Pecos River project—examine stream sediments and water above and below a volcanic massive sulfide mine and mill
EPSCoR project—examine the mobility of uranium in the Grants district
LESSONS LEARNED
CAUSES OF UNDESIRABLE IMPACTS
Too much water Results in weathering of the rock and soil Can creates unstable features and acid drainage
Need to control water into the mine workings, rock pile, tailings, heap leach, and foundation materials
Poor foundation conditions Weak materials like clay, altered, fractured rock
Poor understanding of effects of weathering on the degradation of materials
Every site is different and must be specifically characterized
HOW CAN THESE IMPACTS BE PREVENTED OR MANAGED?
Every site should be characterized
In some areas, develop monitoring programs to examine changes in the future
Have plans in place for the worse case scenario
Continue research on processes and improved technologies
HYDROLOGY
GEOLOGY/MINERALOGY/CHEMISTRY/BIOLOGY
GEOTECH
SUMMARY Geologic processes affect the chemistry,
mineralogy, acid potential and stability of mine sites in New Mexico
Characterization (geology, hydrology, geotechnical) is important to prevent loss of life, prevent contamination of adjacent areas, and construct a stable facility
Every site requires specific characterization of the mine features, overburden, waste rock piles, tailings, foundation, and cover materials• Must control water• Must understand the effects of weathering on the
materials Continue research on processes and improved
technologies
