Wednesday, May 18, 2011

New Mexico Uranium Mining Contamination is a Complex Story

One quarter of the Superfund sites in New Mexico are related to mining and near Grants, New Mexico, there are 97 old uranium mining sites that make up two Superfund sites. Together these mines produced more uranium than any other place on the globe between 1951 and 1980.

Superfund Site in New Mexico

Homestake Mining Company Superfund Site
One is the Homestake Mining Company Site and the other is called the Grants Mining District with its 96 abandoned uranium mines that offer, besides potential groundwater contamination, open adits and shafts. Adits are the horizontal access ways to mines. No doubt many amateur explorers and spelunkers have ventured into these openings to see what they could see, only to leave with an invisible glow lasting the rest of their lifetimes. The New Mexico Environment Department and the Environmental Protection Agency are watching the impact on the region’s groundwater.

While the Homestake site has its own Superfund designation, it is still grouped in with the Grants Mining District. Notable old uranium mills in the area include Phillips Mill, Ambrosia Lake Mill, Bluewater Mill, L-Bar Mill and the Borkum Mill. The Jackpile Mine, near the Laguna Pueblo, was at one time the world’s largest open pit uranium mine and investigations are underway to determine ground water to surface water migration at that site.

Ground water contamination by radioactive materials in this area is complex. The earth’s stratified materials intrude across layers creating pathways that allow surface water, ground water and even the deeper aquifer water to commingle easily. Then there’s the problem of what is called “elevated background radiation.” That’s the normal amount of radioactivity in the area and in the local waters. Because of the high amount of uranium in the ground there is naturally higher levels of radioactive substances in the water.

But mining activities such as storing water that was used for milling processes in large ponds above ground have tended to concentrate the radioactivity before releasing it back to the ground. One example of that comes from the Bluewater Mill where a 30 to 40 acre pond temporarily held mill waste water until it seeped back into the ground. This caused water in a nearby well to rise by 10 feet over its previous 10-year high. Once the ground water effect was noticed, the mill went to Plan B which was to inject the waste water into an injection well, placing it far below ground water at depths between 900 and 1,400 feet. That well operated for 13 years from 1960 to 1973 and handled approximately 500 million gallons of waste water. The result was extensive seepage of waste water and tailings into the potable water aquifers.

Of the total 97 sites in the Grants Mining District, federal and state environmental agencies have screened 58. The remaining 39 sites are planned to be screened by September 2011. As far as the Homestake Site goes, “It is unlikely that the ground water in the alluvial and Chinle aquifers will ever meet the drinking water standards of State of New Mexico or EPA without adequate water filtration. All residences in the subdivisions near the Homestake Mining Company (HMC) site have been provided a clean safe adequate water supply through hook-up to public water service.”

Sometimes, having a lot of unoccupied space can be a problem since it can encourage nonchalant attitudes about handling toxic substances. That is demonstrated in Alaska where throughout the 1940s and 1950s the Army used about eight acres under its control for dumping scrap metal, and apparently some materials that created PCB contamination. Read recent news about Homestake, here.

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