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Abandoned sites – Assessment and risk management Lars-Åke Lindahl Workshop on the safety of tailings management facilities Yerevan, 12-13 November 2007
Outline • Background • National approaches • Other EU initiatives • UNECE Guideline
Definition - “Abandoned sites” • A site with no active monitoring or management and no responsible party, or no party accepting responsibility (as opposed to closed sites where a responsible party still has some level of control)
EU “Mine Waste Directive” Article 20 ”Inventory of closed waste facilities” • MS shall ensure that an inventory of closed waste facilities, including abandoned waste facilities, located on their territory which cause serious negative environmental impacts or have the potential of becoming in the medium or short term a serious threat to human health or the environment is drawn up and periodically updated. Such an inventory, to be made available to the public, shall be carried out by 1 May 2012, taking into account the methodologies as referred to in Article 21, if available.
Article 21 ”Exchange of information” 1. The Commission , … , shall ensure that there is an appropriate exchange of technical and scientific information between MS, with a view to developing methodologies relating to: (a) the implementation of Article 20; (b) the rehabilitation of those closed waste facilities identified under Article 20 in order to satisfy the requirements of Article 4. Such methodologies shall allow for the development of the most appropriate risk assessment procedures and remedial actions having regard to the variation of geological, hydrogeological and climatological characteristics across Europe.
Abandoned sites – The Problem • Chemical risk/impact - Ongoing or potential detrimental release of contaminants • Physical failure - Risks of dam failures, heaps collapsing etc • Land use, safety aspects, …. • Lack of information • Financial - Usually no funds available for measures
Slovakia >17000 sites • Hungary 5000-6000 sites
Sites very different in scale and potential impacts • Main concern, operations from 20th century • Tailings facilities
National approaches • Example - Swedish EPA • MIFO – Methodology for Inventories of Contaminated Sites • Phase 1 - Archive drilling, background information - Potential contaminants - Possible routes of transport/exposure - Sensitivity of receiving environment
- Preliminary classification in 4 Risk Classes, (Very high, High, Medium and Low risk) - Prioritisation of sites for further studies • Phase 2 - Field visit - Basic sampling and field investigations - Geology and hydrology - Refined risk assessment • Phase 3 - Detailed sampling - Planning of remedial action
BRGM Study • Contract by the Commission, 2001 • Desk study • Inventory of mine waste and mine waste facilities in the EU • General Risk identification • Recommendations
BRGM recommended methodology – abandoned sites - Inventory (location, type of facility, type of waste) - Prioritisation in terms of general environmental impacts and risks - Evaluation of the risks (incl dam safety) and measures to be taken - Remediation plans to address the most problematic sites http://www.brgm.fr/
PECOMINES • Inventory • Development of ranking system • Based on current impacts • http://viso.jrc.it/pecomines_ext/main.html
SAFEMANMIN • Safe Management of Mining Waste and Waste Facilities • Jan 2007 – June 2008 • WP2 - Collect Relevant Information for the Risk Assessment of Mining Waste Facilities including Old/Abandoned Mining Waste Facilities • http://www.biutec.at/safemanmin
UNECE Draft Guideline II.A Recommendations to UNECE member countries 23. UNECE member countries should designate competent authorities … necessary competences for the tasks foreseen in these recommendations. 24. UNECE member countries should initiate a national inventory of closed, abandoned or orphaned Tailings Management Facilities that may constitute a risk to human health or the environment. 25. National inventories of closed, abandoned or orphaned Tailings Management Facilities should consider both current impacts and risks for future acute (accidents and spills) or long term (leaching) negative effects.
II.B Recommendations to competent authorities 31. Competent authorities should apply methodologies for risk assessment and identification of the closed, abandoned or orphaned TMF using a step by step approach, starting with a basic screening of sites, whereby resources are gradually directed towards sites with the highest risks. 32. Based on the risks identified, competent authorities should make plans for risk reduction measures and/or monitoring (early warning) for the closed, abandoned or orphaned TMF
Technical Annex Management of abandoned sites • The management system for closed, abandoned or orphaned sites should include the organizational structure, responsibilities, procedures and resources for determining and implementing the accident prevention policy: • Organizational structure: competent authorities should be nominated to carry out the assessment, monitoring of closed, abandoned or orphaned sites. They should be allocated adequate staff, technical means and budget to accomplish its mandate.
Identification and evaluation of hazards: closed, abandoned or orphaned sites should be known and catalogued in a inventory containing their location and key characteristic and they should be labelled accordingly. • Monitoring and maintenance: the sites should be monitored and maintained and remediation should be undertaken in the first place at these sites, where failures are likely or very likely to happen. • Removing or reengineering of sites will in most cases mean very high costs and should only be undertaken where risk capping fails.
Inspections of abandoned sites • The closed, abandoned or orphaned sites should be inspected depending on the risk posed by the site assessed in the initial screening. • The initial screening/STEP 1/ should include a walkover survey concentrating on TMF features such as containment dam, beach, water management system and hydrographic catchment area.
The components, structures and parameters specifically inspected and screened in case of any signs of unusual behaviour /STEP 2/ should be the following: (a) morphological situation and catchment area (inflowing streams, size and topography of TMF catchment area, expected frequency and magnitude of flood events) (b) dam crest (materials used, irregularities, depressions, signs of erosion) (c) slope geometry (height, angle, berms) (d) containment dam slope condition (materials, vegetation, signs of erosion, seepages, slumping, active mass movements such as slumping, sliding or rotational failures)
(e) lagoon condition (size relative to TMF, depth, geometry, vegetation, alien deposits such as litter) (f) water management system (existence and condition of drainages, bypasses, decantation plant, contingency/emergency spillways, pumps) (g) monitoring equipment (inter alia trigonometric points, survey targets, piezometers / standpipes) (h) historic incidents and accidents. • Depending on the result of the screening the sites should be labelled from “very low risk”, “low risk”, through “intermediate risk”, big risk” to “very high risk”
Sites labelled as posing “intermediate” and “higher risk” should undergo a detailed assessment process /STEP 3/ in order to separate those sites where monitoring of hazard factors would be sufficient as risk mitigation approach from those where failures are likely or very likely to happen in short term. The detailed assessment should include: (a) research on existing documentation, (b) detailed site surveys (c) potential spot investigations (d) calculations “back of the envelope” on probabilities of identified specific failure modes
The high risk sites should undergo appropriate investigation and data generation measures (e.g. topographical surveys). For each of them specific remediation programmes should be designed, tendered and contracted. /STEP 4/
Emergency planning for abandoned sites • The competent authorities should develop emergency plans for abandoned sites. Before developing the plans it should be verified which capabilities and responsibilities already exist (a) existing regional emergency response frameworks, such as civil protection, fire brigades, flood response (b) emergency response plans in place for a coordinated regional/transboundary response (c) clear command structure and management of interfaces between concerned authorities (d) existing models of scenarios for mining accidents and their integration into the emergency plans
Abandoned sites - Closing remarks • Impacts, risks and technical solutions not significantly different compared to operating or closed sites. • Main challenges – lack of information, organisation/management, costs/funding • Stepwise, risk based prioritisation needed • Concentrate on what’s important, don’t spend time on low priorities
Thank you for your attention! Questions or comments?