independent concept for the flooding of the Königstein
mine was developed back in 1991. Ten years later the stage was set to
initiate controlled flooding of that mine.
The flood water is treated in a treatment plant. Following removal of
the dissolved uranium, the mine water is fed to a water treatment plant
prior to discharge into the Elbe river. It will probably take longer
than 2012 to complete flooding of the mine complex.
Treatment of the flood water will be required beyond that point in time. Pumped via two newly drilled pumping boreholes reaching ca. 300 m down into the mine, the flood water contaminated with radionuclides and heavy metals will be delivered to the water treatment plant. This process will have to continue until such time as no more significant impact to aquifers and the Elbe River is to be anticipated.
Treatment of mine
water, however, will have to continue beyond that timeframe. Wismut
has put in place a comprehensive system of measurement points to monitor
the flooding process and to document flood level and water quality.
Flooding of the Dresden-Gittersee mine site
Flooding of the mine which comprises the two mine fields of Dresden-Gittersee /
Bannewitz and Heidenschanze was initiated in May, 1995. The flooding
is aimed at restoring the natural ground water level in the Freital
mining district. Sequence of the flooding is characterised either by
the step-wise increase of the flood level or by its freeze made possible
by two production wells installed in the mine fields. This measure is
designed to prevent mine subsidence and other damage that might be caused
by the abandoned mine.
When the flood level reached approx. 180 m a.s.l. in July, 2003, there
was locally emergence of mine water in Freital-Potschappel. Thereupon,
the flooding was suspended, and the flood level was lowered to some
156 m a.s.l. by the resumption of mine water pumping. Wismut, regulators,
and advisers took months to determine the reasons of this emergence.
It is assumed that some unknown water routing from century-old coal
mining operations had played a major part. To achieve consolidated findings,
an application was filed for the resumption of filling up to a level
of 165 m a.s.l. At level rise > 156 m a.s.l. there was confirmation of the hydraulic connection existing between the Gittersee/Bannewitz and Heidenschanze mine fields. With a view to avoiding any further mine damage from such flood water levels, a connecting gallery (WISMUT-Stolln) is being driven at the geotechnically uncritical level of 120 a.s.l. starting from the Dresden/Gittersee/Bannewitz mine field to the Elbstolln to ensure the sustained safe discharge of flood water from the mine fields located on the right bank of the Weißeritz creek. This gallery will divert flood waters from the abandoned uranium mine fields to the Tiefer Elbstolln that ensures controlled discharge into the Elbe River. This will keep the flood water at a constant level of 120 m a.s.l.
|
