Sunday, September 06, 2015

Misleading counts of inactive mines in the U.S.

It's not surprising that in the wake of the Gold King mine waste water spill there would be numerous efforts to uncover other potential mine problems elsewhere.  But some of the efforts are misinformed or misleading and appear to be overstating the scale of the problem.

On August 31 an organization called Skytruth put on
line an interactive map of "inactive metal mines" in the U.S.:

This map was created by accessing the USGS Mineral Resources Data System (MRDS) database and selecting mines listed as ‘past producer’ and then “excluding sites that exclusively produced non-metallic commodities.”  This was done to avoid ‘cluttering’ the map with gravel pits and the like.  

However, there are problems with the claims made about this map.

The map claims to show inactive metal mines but a quick scan of Arizona sites turned up many sites as being primarily silica, perlite,  or unidentified products.

The Skytruth group reports they were using 2012 data. It doesn’t change things much, but most of the US Bureau of Mines  MILS (Mineral Industry Location System) compilations in the USGS MRDS dataset today are records that were made in the late 1970s. The status field has not been updated since then for the majority of the records.  In Arizona we think many of the mines labeled as "active" would be considered past producers today. 

update 9-6-15 8pm:  It was also pointed out to me that one of the biggest problems in using the MRDS/MILS data base from the USGS is there are many duplicate entries for the same mine (one from the MRDS data set and one for MILS data set.). For example, in Arizona's Helvetia Rosemont mining distrct, their map shows two Broadtop mines, two East Helvetia mines, two Leader mines and two Copper World mines.  One of the entries is from the MRDS data and the other is from the MILS data.

Our colleagues in Maine reviewed all the Maine sites on the interactive map and found that more than 70 of them were gemstone or feldspar mines, mostly active in the late 1800s through mid-1900s.  They made Skytruth’s cut because some metallic minerals are listed in MRDS commodities fields, thus failing the exclusively non-metallic test.  From their direct knowledge of these sites, they know that any metallic minerals mined were by-products of the chief commodity – gemstones or feldspar.

They noted that several years ago they compiled a comprehensive list of mineral localities, including undeveloped deposits and ‘past producer’ sites, augmenting and improving the MRDS.  They found about 180 sites that had some level of past production from underground workings.  Most were small adits or shafts of less than 50 feet length with miniscule environmental footprints.  All but two of these sites have no chance of a catastrophic release of waste into the environment.  The two large inactive mine sites are well known and undergoing environmental remediation.

So, before panicking that there are 64,883 mines capable of producing the kind of problem that occurred at Colorado's Gold King mine, realize that many of those "mines" were not much more than initial scrapings in the ground, did not produce metals, do not have potential for backing up waste waters, or are not in acid-water conditions.  Are there acid mine drainage problems in some old or abandoned mines?   Yes, of course, but let's focus our efforts on the real problems and not run around claiming the sky is falling.

[Thanks to David Briggs for spotting the duplicate entries from the MRDS and MILS data bases]

1 comment:

  1. Anonymous9:04 AM

    Great points, I've been to some of the local sites here and may are no bigger than an army fox hole...