Technogenic Water in Closed Oil Shale Mines

Reinsalu, Enno; Valgma, Ingo; Lind, Helena; Sokman, K.

doi:10.3176/oil.2006.1.03

Cited by 7 publications

(4 citation statements)

References 2 publications

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“…Quality studies of mine water have shown that in about five years after the closure of a mine the content of sulfates and iron decreases below the maximum permitted level in drinking water. The highest permitted content of iron in first-class drinking water is 0.2 mg/l and that of sulfates 250 mg/l [10].…”

Section: Summary Of the Discussionmentioning

confidence: 98%

Water Problems Connected With Oil Shale Mining in North-East Estonia

Perens¹,

Punning²,

Reinsalu³

2006

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This paper presents a short overview about the discussion about the hydrogeological problems connected with oil shale exploration in NE Estonia. On the basis of the results of the solution to the hydrogeological model developed at Geological Survey of Estonia it was found that the proportion of unconfined groundwater in different open-cast mine fields accounts for 6-34% and precipitation water makes up 66-84% in the depleted area. Presently a unified groundwater model of Estonian-Russian border region comprising a 200×200-km area north from Lake Peipsi is being compiled under the initiative of French Geological Survey (BRGM).

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Section: Summary Of the Discussionmentioning

confidence: 98%

Water Problems Connected With Oil Shale Mining in North-East Estonia

Perens¹,

Punning²,

Reinsalu³

2006

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“…In active circulation belts the temperature of water depends mostly on air temperature, while the temperature of groundwater depends on geological conditions and rock bedding depth [17]. The quality of water in closed mines improves with time as the content of sulphates and iron in the mine water decreases, gradually dropping below the maximum level permitted for drinking water within five years after mine closure [18].…”

Section: Mine Water As a Heat Sourcementioning

confidence: 99%

“…This depends on the physical properties of the porous medium, such as grain size and shape, and their arrangement and interconnection between its pores. Water permeability is largely affected by the geological disturbance of the earth's crust, which makes the aquifer highly anisotropic [18]. The permeability of rock is determined by the size of pores and cracks between its particles [19,20].…”

Section: Mine Water As a Heat Sourcementioning

confidence: 99%

“…The quantity of pumped-out water from mines depends highly on the amount of precipitation and to a lesser extent on the amount of groundwater or water infiltrating from closed mines. According to performed measurements and calculations, precipitation accounts for up to 70% of the amount of water pumped out of mines [18,24]. If the hydraulic conductivity of the streambed is high, the cone of the depression may extend only partway across the stream.…”

Section: Mine Water As a Heat Sourcementioning

confidence: 99%

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Mine Water as a Potential Source of Energy From Underground Mined Areas in Estonian Oil Shale Deposit

Karu¹,

Valgma²,

Kolats³

2013

Oil Shale

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Underground oil shale mining has been applied for ninety years inEstonian deposit in the middle-north part of Baltic oil shale deposit. The underground mining method of oil shale creates underground free space and the mine workings are filled with water after closure, which makes issues of land stability topical.Underground water pools or technogenic water bodies with all-the-yearround stable temperature are formed in the filled underground of oil shale mines. These water bodies have a potential for use as a source of heat for heat pumps and reduction of wintertime heating costs. The aim of this research is to calculate the amount of mine water in closed or abandoned oil shale mines in the central part of Estonian oil shale deposit and offer solutions for usage of undermined areas.Using mine water as a source of heat for heat pump stations means the possibility of using geothermal energy. The first pilot pump in Estonia was launched in Kiikla settlement in 2011. The best solution for such systems is a heat pump complex near Ahtme thermal power plant. The optimal size for the heat pump at Ahtme is 10 MW heat production. Different methods of heat collection for heat pump plants can be applied when other mines will be closed in the future.A 3D-model of the mined underground area has been created using geometric data of mine plans, acts of closed mines, as well as borehole and land survey data. The main tools chosen for spatial modelling were spreadsheets and Microsoft Access databases for systemising and querying data, MapInfo Professional for georeferencing, Vertical Mapper for interpolating and grid calculations and MODFLOW for pumping simulation. Each step of model creation involved analysis and decision on which values should be used to obtain modelling results. Layer thicknesses and required properties of water body were calculated using interpolated grids and surface elevations.

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Impact of Oil Shale Mining on Flow Regimes in Northeast Estonia

2011

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In addition to the well-documented effects of aquatic pollution, mining operations can have major impacts on hydrological pathways and flow regime in downstream catchments. This paper documents long term changes in surface drainage areas and runoff characteristics in two small to medium (100-1,000 km 2 ) rivers draining part of the Ordovician oil shale field of north east Estonia. Through coupling analysis of flow regime with mining records (discharge rates and workings locations) the impact of expansion in oil shale mining through the mid to late twentieth century on downstream flow is assessed. During phases of intense mining, winter and summer baseflow is between 53 and 72% higher than long term average baseflow in the Purtse catchment and between 66 and 92% higher in the smaller Pühajõgi catchment where the volumetric significance of mine discharges is greater. The contribution of pumped deeper groundwater to surface run-off is shown to control the largest increases in mean annual run-off. While flow augmentation is the most common hydrological impact of the mining operations, phases of dehydration are also recognised in streams where crosswatershed transfers reduce the effective catchment area.Implications of the changed flow regime on river quality and management options are considered.

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Technogenic Water in Closed Oil Shale Mines

Cited by 7 publications

References 2 publications

Water Problems Connected With Oil Shale Mining in North-East Estonia

Water Problems Connected With Oil Shale Mining in North-East Estonia

Mine Water as a Potential Source of Energy From Underground Mined Areas in Estonian Oil Shale Deposit

Impact of Oil Shale Mining on Flow Regimes in Northeast Estonia

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