4 th MIN-GUIDE Policy Laboratory Workshop, Athens, September 2017 GKB-Bergbau GmbH

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2 Activities in relation to abandoned coal mines in the responsibility of GKB-Bergbau GmbH 4 th MIN-GUIDE Policy Laboratory Workshop September 21-22, 2017 Athens, Greece

3 Content Introduction and responsibility of GKB-Bergbau GmbH (Austria) Overview of Austrian mining law concerning mine closure (extract) Concept of monitoring and active safekeeping of abandoned lignite mines in Austria Innovative aspects concerning mine closure activities 4 th MIN-GUIDE Policy Laboratory Workshop, Athens, September GKB-Bergbau GmbH

4 About GKB-Bergbau GmbH (GKB) 100% state owned Responsible for the organised withdrawal of former stated owned companies from mining industry Carries out securing and closing measures required by law, including re-cultivation GKB is responsible for following sites: Voitsberg-Köflach lignite field Former Wies-Eibiswald anthracite field Ratten, Weiz, Wiesenau, Thallern fields (lignite) Field of former Lavanttaler Kohlenbergbau GmbH (lignite) Former Fohnsdorf field (lignite) Closed mines of Bleiberger Bergwerksunion (BBU) in Bleiberg and other locations (zinc, lead, antimony, etc.) 2

5 Responsibility of GKB (lignite) Overview Austrian lignite districts: Pointsize represents the mined amount of coal Responsibility GKB Other 4 th MIN-GUIDE Policy Laboratory Workshop, Athens, September GKB-Bergbau GmbH

6 Austrian Mining Law concerning mine closure (extract) Owner of mining authorisations is responsible for the safety of surface level after termination of mining activities ( 109 MinroG (1) ) Return to use of surface after termination of mining activities ( 159 MinroG) Responsibility for the remediation of surface damages comprises present and former mining licences ( 161(1), 161(2)) GKB owns ha present mining licences and is responsible for ha former mining licences for lignite (1) MinroG: Mineralrohstoffgesetz 1999, Austrian Mining Law 4

7 Theory of active safekeeping - risk management for abandoned coal mines Mining situation kind of mine, conditions of coal deposit, depth maps, results of surveys geology conditions of mining law Kind of surface-usage (public areas, infrastructure, living areas, forests etc ) Basic principle: Intersection between mining situation and surface-usage results in a potential risk Is it necessary to do anything? Which areas should be secured first? Validation of potential risk Determination of intensity of activity 5

8 Subsidence [cm] Mining situation, consequences of deep mining on surface Subsidence above excavated seams (based on surveys on surface during mining) Consequences temporally limited Time of measurement [mm.yyyy] Example from Wies-Eibiswald fields: thickness of seam 1.4 m, working depth about 220 m 6

9 Amount of incidents Amount of incidents Mining situation, consequences of mining to near surface Determination of critical depths based on recognised incidents, using an empirical maximum-value-method Consequences temporally NOT limited surface caving subsidence surface caving subsidence Depth [m] Depth [m] Lignite district Mittleres Lavanttal Lignite district Wies-Eibiswald 7

10 Mining situation, consequences of mining on surface (III) Examples of incidents (sink-holes) 8

11 Mining situation, mining situations with potential risk to surface Drift entrance, shafts Mining in shallow depths (drifts, stopes, shallow longwall-mining) 9

12 Kind of surface usage Based on Austrian digital land register (DKM) Includes the information about the kind of surface usage (NFL) 10

13 Tasks to localise potential risk areas and active safekeeping (I) Task Surface and subsoil Abandonend mine Background Information Topographic maps Mine layout, operating maps, other maps concerning the mine Files of mine damages, information about consequences of mine on surface Derivation of regional relations Detect and keep records Kind of usage of surface Determination of problematic areas Define problematic areas in maps or GIS If necessary, additional investigations Evaluation Evaluation with respect to mine damages Determination of areas of suspicion Validation of potential risk 11

14 Tasks to localise potential risk areas and active safekeeping (II) Task Surface and subsoil Abandonend mine Validation of potential risk Validation Already secured Consequences with advanced indications Consequences without advanced indications Monitoring General review based on state of the art Observation, Catalogue of possible counter measures If necessary, additional investigations Prevention of hazards Need for action, if irregularity Need for action in case of specific risk Immediate measures for prevention of hazards Secure secured Expand safety safety Review Frequent processing Anual security reports Concentrated reviews every 5 years 12

15 Validation of potential risk Determined areas of suspicion can not be processed at the same time, an priority criteria has to be developed Priority depends on kind of surface usage and condition of the shallow mine excavations (intersection between them) - results finally in intensity of activity 13

16 Result: Intensity of activity Calculation of intensity of activity based on geographic-information-system (GIS) The darker the zone, the higher the intensity of activity 14

17 Active savekeeping as riskmanagement 179 MinroG 1999: If the life or the health of human beings or foreign objects are threatened/could be threatened through incidents and conditions after closing mining activities, the mining authority has to order the necessary security measures HOWEVER, GKB DOES IT IN ADVANCE. Final goal: Intention to stabilize, i.e. to fill verified, free of settling, resistant against erosion and stable in its position, all abandoned mine areas with a potential risk for the surface to minimize safekeeping expenditure in the future. 15

18 Filling material Stollen-SSM (I) Since more than 15 years, GKB made base investigations and participated in development projects to provable stabilization of backfilled shafts in stagnant water to limit erosion of backfill in stagnant water to environmental compatibility of filling material As result of those investigations, together with Schotter- und Betonwerk Karl Schwarzl Betriebsgesellschaft m.b.h. and the civil engineer Erich Pintaritsch, a filling material called Stollen-SSM was developed and used for active safekeeping activities. The requirements to the filling material were: free of settling resistant against erosion and stable in position compression strength 2 N/mm² quality control chemical stability provable backfilling 16

19 Filling material Stollen-SSM (II) Characteristic Stollen-SSM F38 (stiff) Stollen-SSM F66 Max. grain [mm] 8 4 or 8 Bulk density [kg/m³] Expansion according to ON B3303 [cm] 38 (+/- 3) 66 (+/- 3) Angle of slope under water [ ] >35 <3 ph-value Sedimentation [%] <1 <2 Uniaxial Compression Strength, tested on cylinder (d=100 mm, h=100 mm) after 90 days [N/mm²]

20 Filling material Stollen-SSM (III) 18

21 Innovations concerning the safety of abandoned mines Approach of active safekeeping Risk management of abandoned lignite mines in Austria Development of an appropriate filling material Using GIS technology for identification of areas of suspicion 19

22 Thank you for your attention!