I THINK MINING

In the last week of May, folk will gather at this conference:  Remediation of Uranium Mining and Processing Sites – Sustainability and Long Term Aspects.   This is the part of the story that I know:

Chemnitz was, before the Second World War, a thriving textile center.  Rich Jewish merchants built beautiful homes from the profits of cloth and clothes.  Then came the war.  The Nazis moved into the houses and took the riches unto themselves. 

   The Russians came from the east and displaced the Nazis.  The Russians needed the uranium in the local strata.  They fenced off an area big enough to surround the uranium deposits and they began to mine.  The area was a total Russian enclave:  its own cars, phone system, medical services, and mining operations.  They mined with no regard for the environment: underground workings beneath houses and huge tailings impoundments right above villages.  I have stood on the crest of one of these impoundments and looked down into the kitchen of a cute, old house. 

With time, this empire too crumbled and the east joined with the west.  To stimulate the economy of the east, reclamation programs were put in place.  The Canadian government paid for Canadian consultants to go join the new search for the riches of mine restoration.  I went with an American company to market our services—but we were no match for those with Canadian grants.  Later I went with my Spanish clients to see what they were doing as a possible way to close a uranium mill tailings pile in Andujar, Southern Spain.

To put covers on the many tailings impoundments and their soft surfaces, this is what they did: Carefully advance geotextiles and geogrids out over the soft tailings.  Then they placed sheets of plywood and other planks and out along these they advanced a small rig to install wick drains.  The wick drains caused some dewatering of the upper layer of tailings and hence a gain of strength.  As the strengths of the upper tailings increased, they were able to advance a thin layer of sand out over the geosynthetics.  Then more wick drains, more dewatering, more strength gain, and another lift of sand.  This process continued until the tailings were strong enough and the sand layer thick enough to support the passage of big trucks and other equipment used to sculpt and revegetated the final cover. 

   What was done at Wismut was the basis of what was done at the Suncor Energy oil sand tailings impoundment Pond 5.  Except there we were able to let the upper zone of the tailings freeze and advance strong geotextile and geogrids out over the frozen surface.  Then we placed a layer of light-weight coke, which has so low a density that it in effect floats on the tailings.  Thus we had no need to install wick drains to promote consolidation and strength gain of the tailings to support the heavy construction equipment we used. 

Meanwhile remediation continues under Wismut.  Ponds are still being covered, mines backfilled, groundwater dealt with.  The work will never end. 

Here is what the conference announcement has to say on this story:

With the environmental restoration project conducted by the national WISMUT GmbH being implemented for 20 years now, remediation of the legacies of uranium mining in Saxony and Thuringia is, for the most part, drawing to a successful conclusion. Remedial results achieved so far receive favourable recognition and appreciation at the national and international levels.  The specifics, complexity and the sheer size of the WISMUT project are unique features which  make the operations emerge as an important international reference project for state-of-the-art  technologies for the remediation of radioactive historic wastes. Conducting remediation work in an intelligent and sustainable way also implies to address economic and social aspects as well as consider ecological decision criteria. Experience gained and acquired technical know how are also applied in conjunction with international missions. Based on a condensed summary and scientific reflection of the remedial performances, the purpose of the symposium is to discuss and appreciate the importance of sustainability and long-term aspects of the remediation of uranium mining and processing sites. The symposium will also have to address the issues of potentialities and constraints with regard to the reuse of formerly radioactively contaminated mining areas.  The selected venues of Ronneburg and Gera as well as the proposed excursions provide excellent  opportunities for seeing with your own eyes the evidence of   remediation achievements and their impacts on regional development and revitalisation of the former mining sites.