INTRODUCTION INTRODUCTION

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1 INTRODUCTION INTRODUCTION 1.1. Background The exploitation of mining deposits in Namibia has been going on for more several thousand years. At first this productive activity was undertaken by Late Stone Age and Iron Age communities using very simple methods to extract ore from rich veins of gold, silver, iron and copper. These processes gradually gave way to more technical ones until reaching the sophisticated procedures that are applied today. During this time many mines were abandoned without a suitable decommissioning process, and so many of these abandoned mines remain dotted across the country today. These operations mainly mined gold, copper, silver, tin, pyrite, lead, zinc, fluorspar, tungsten, lithium and semi-precious stones, and their ore extraction and treatment processes left sites that could pose major risks to human and environmental health and safety. Safety risks are related to the presence of unprotected shafts, open pits, waste rock dumps, tailings dams, old machinery and buildings, while health risks may be associated with polluted water, windblown dust and contaminated soil. Of the 157 Shut Down or Abandoned Mine Sites (SD/AMS) on the GSN data base, only some are believed to present a significant risk to human and/or environmental health and safety. The mine sites that possess these kinds of risks are called Mining Environmental Liabilities (MEL). This Manual has been prepared to (1) determine which SD/AMS pose a significant risk to human and/or environmental health and safety; (2) enable current MELs to be organised according to their risk level, which in turn will support decision-making on remediation by the authorities legally responsible for this task; and (3) enable other sites not classified as MELs to be organised into lower risk categories, thereby allowing for their regular re-assessment in future based on relative priority. This Manual was originally developed as part of the MEL Remediation Framework project being implemented by Chile s National Geological and Mining Service and Germany s Federal Institute for Geosciences and Natural Resources (BGR), under the Chile-Germany Cooperation Agreement. The original Handbook was written in Spanish for use in the Chilean mining context. BGR has had the document translated into English and customised for the Namibian mining environment, so that the risk assessment methodology can be used in Namibia. The Manual seeks to create a technical framework to address the impacts caused by historical mining by remediating abandoned mines that pose a significant risk to humans, the environment or economic activities. The inventory of shut down and abandoned mine sites was prepared by staff of the Geological Survey of Namibia (GSN) in the Ministry of Mines and Energy (MME) and is included in this Handbook as Annex G. In July-August 2011, staff from the Ministry of Mines and Energy, tertiary institutions and other government ministries were given a two-day programme of theoretical training on risk assessment,

2 INTRODUCTION 1-2 followed by four days of practical training in the field at abandoned mine sites, where the programme was pilot tested for applicability in Namibia. The Manual was revised on the basis of feedback received during the pilot testing process Objectives of this Handbook The main objective of this Handbook is to make available systematic procedures for identifying which Shut Down or Abandoned Mine Sites (SD/AMS) are Mining Environmental Liabilities (MELs) and to classify these sites by risk level for prioritizing future action. The specific objectives of this Handbook are: Provide a methodology so users can identify the information required for a Simplified Risk Assessment (SRA) and Detailed Risk Assessment (DRA) of a SD/AMS. Provide a methodology for preliminary safety analyses of tailings dams, waste rock dumps, heap leach pads, open shafts and pits and similar structures that could pose a risk to human safety. Provide a methodology for preliminary analyses of chemical contamination risks present in a given SD/AMS that could affect human and/or environmental health and/or impact economic activities. This methodology includes simple parameters that can be used in the field. Set the criteria for classifying a risk as significant, in terms of both site safety and contamination. Establish a methodology for prioritizing MELs. Provide guidelines for scoping, preparing, reviewing and approving DRAs conducted by third parties (consultants) Scope of this Handbook Type of Mining and Associated Processes This Handbook has been prepared for SD/AMS associated with precious and semi-precious stones, base and precious metals, rare earth minerals, industrial minerals and nuclear fuels. It takes into account the most common production processes that may have been used in each of these mining operations to date. Some SD/AMSs date back many decades and the ore processing methods are unknown at these sites. In those that are known, the method of extraction ranges from being very basic, e.g. shaking tables, gravity separation and hand sorting, to more modern methods of ore processing such as cyanidation, flotation, magnetic concentration and smelting (Annex G).

3 INTRODUCTION Mining Site Status This Handbook applies to those Abandoned and Shut Down Mine Sites as listed on the GSN inventory (Annex G) and should not be applied to operating mines. The locations of the AD/AMSs in Namibia are shown in Figure 1-1 and detailed maps of areas of high concentrations of sites (the Otavi Mountainland and Erongo Region) are provided in Figures 1-2 and 1-3. Note that the numbers on these maps correspond to the inventory (Annex G).

4 INTRODUCTION 1-4 Figure 1-1: Abandoned/Dormant Mines in Namibia

5 INTRODUCTION 1-5 Figure 1-2: Abandoned/Dormant Mines in the Tsumeb-Otavi-Grootfontein Area

6 INTRODUCTION 1-6 Figure 1-3: Abandoned/Dormant Mines in the Erongo Region

7 INTRODUCTION Components of a Shut Down or Abandoned Mine Site SD/AMS include all installations and workplaces used for the mining industry such as mines, treatment plants, smelters, refineries, metal shops, workshops, explosives magazines, camps, warehouses, waste deposits, and in general all works, installations, support services and infrastructure necessary for the operation (Table 1-2). For the purpose of this Handbook, SD/AMS components have been divided into the following groups: mine, processing plant, large scale mining waste, small scale and industrial mining waste, and associated infrastructure. Mines can be underground or open pit mines. Plants include all facilities used in ore extraction and processing that are left abandoned or shut down when operations come to a close. With regards to waste, there are two classes: large scale mining waste such as waste rock and tailings, and industrial and small scale mining waste (e.g. scrap metal, drums, pipes etc). Finally, associated infrastructure includes support services such as explosives magazines, offices, workshops, storehouses, camps, water and electrical systems, and mine access roads and tracks. These facilities are considered apart from the plant when they are physically separated from it, i.e. when they do not constitute part of the plant itself or of any other component. However, they are not considered separate components when they are located on the same property as the plant. Table 1-1: Components of a SD/AMS Component Mine Plants Large Scale Mining Waste Small scale and industrial mining waste Underground Operations Surface Operations (open pit) Installations / Deposits / Operations Crushing plant Processing (concentrator) plant Refinery/smelter/roasting plant Tailings dam/storage facility Tailings dry stacked or deposited otherwise Heap leach waste dump Dumps for waste rock and low grade ore Slag heap Small scale mining waste (concentrate, smelting and roasting dust, potentially hazardous waste, discarded solutions, lab waste). Industrial waste ( scrap yards, garbage dumps).

8 INTRODUCTION 1-8 Component Associated infrastructure Explosives magazine Offices, camps, workshops, storehouses Water systems and tanks Tracks, roads and bridges Power lines and substations Wells, water reservoirs, pipelines Installations / Deposits / Operations 1.4. Basic Risk Concepts In order to use this Handbook effectively, the Assessor should have some basic knowledge of risk assessment. However, some basic risk assessment concepts are explained below to guide the Assessor in the correct application of the Handbook. The risk assessment of a given SD/AMS will involve reviewing situations that affect physical safety and chemical (contamination) safety, as both situations can have a negative impact on people, the environment and/or economic activities. The concepts used are generally accepted and agreed upon in each case, enabling parties involved to understand the problem at hand. It is therefore worth defining the conceptual risk assessment framework for each case, for risks to physical safety and those related to contamination Risk of Contamination For a contamination risk, three components must be present: There has to be a source of contamination present in concentrations that will generate undesired effects on the receptor; There has to be at least one Receptor (humans and/or animals); There has to be an exposure pathway 1 that will bring the receptor into direct contact with the source. Source Receptor RISK Exposure pathway 1 Exposure pathway: The way in which a chemical substance comes into contact with the organism exposed to it (ingestion, skin contact, inhalation).

9 INTRODUCTION 1-9 Where any one of these three components is absent, there is no risk; when all three are present, however, the risk should be assessed. The description of the origin, causes and effects of the events that generate a risk is called the Hazard Scenario (HS), and the risk assessment process begins by identifying the HS. This process then continues with estimations of the Likelihood of Occurrence and Severity of the Consequences, according to the criteria and methods contained in this Handbook (section 4.2 and Chapter 6). By way of example, a dry tailings dam (source of contamination) could cause the inhalation of particles (exposure pathway) by a population (receptors), making it advisable to conduct a contamination risk assessment when these three elements are present together. Risk assessment of safety hazards uses quite similar concepts that have been arrived at through the general consensus of experts in this field Risk to Safety To constitute a risk to human and animal safety, the environment or economic activities, the following two elements must be present: There must be a Hazard Scenario - a situation that involves a threat to safety (open mineshaft, open pit, tailings dam, unstable structures, etc.); and There must be a potential Receptor who could be affected by the Hazard Scenario. Hazard Scenario Receptor RISK Assessing the level of risk of a SD/AMS with regard to safety therefore involves estimating the Likelihood of Occurrence and Severity of Consequences for the Hazard Scenarios identified, based on the criteria established in this Handbook (section 4.1 and Chapter 5).