Jack Caldwell - Mining Engineer - Robertson GeoConsultants


Integral to any new mine or expansion of a mine is the preparation of an Environmental Impact Assessment (EIA).  If you seek to significantly expand the mine’s tailings, waste rock, or heap leach facilities, you may have to prepare a new or supplemental EIA.   Here are references to and extacts from some documents that we recently collected from the web.  I do not provide links—you can easiy find them via a Google search if you are inteested.

First note that at this link you can get the complete EIS for the proposed Rosemont Copper Mine south of Tucson, Arizona.  A fine example of an EIS—that is still not fully approved. 

From the document EIA For Developing Countries (1997) this simple reasons for compiling an EIA: 

The past failure of development planning processes to take adequate account of the detrimental impacts of economic development activities led to the advent of environmental impact assessment (EIA) processes. EIA was first employed by industrialized countries in the early 1970s. Since that time, most countries have adopted EIA processes to examine the social and environmental consequences of projects prior to their execution. The purpose of these processes is to provide information to decision makers and the public about the environmental implications of proposed actions before decisions are made.

Before writing the EIA, it is prudent to scope out the EIA and seek concurrence from the regulators and the affected public on the nature and scope of the proposed document.  Here is an example from one EIA scoping document as relates to the mine’s waste disposal facilities:

From the Coal Valley Mining Expansion, Mercoal West and Yellowhead Tower Mine Project EIA Proposed Terms of Reference (2006) It says: The document shall:

·         Identify anticipated hazardous and non-hazardous wastes and recyclables and dangerous goods generated or used in the mining operation.

·         Identify how each waste stream will be managed; and

·         Demonstrate that the selected management options are consistent with the current regulatory requirements and industry practice.

Here is what one EIA says about the proposed mine’s waste rock dump and tailings facility.  It is brief and to the point.  We do not know if the mine went ahead.  From the Equinox Copper Ventures Limited, Lumwana Copper Project, EIA. (2005) 

Construction of the Lumwana East River diversion to make way for the Malundwe main and east pits and waste rock dump and tailings storage facility will have a permanent environmental impact. However, the loss of aquatic flora and fauna and riverine forest will be limited and the aquatic ecosystem of the upstream and downstream sections of the Lumwana East River will not be adversely impacted. ECV will ensure adequate flow rates are maintained through the construction and operational phases of the project.

Here from the EIA Review Checklist from mining and the environment.com (2008)are some questions an EIA reviewer may ask in considering and evaluating a mine’s waste facilities: 

·         Are the types and quantities of mine waste (in particular overburden and tailings) and other residual materials such as waste oil and scrap metals, and the rate at which these will be produced estimated? Note that by the very nature subsurface conditions vary locally and as a consequence mine waste characteristics will change over time.

·         Is mine waste management over time documented together with the routes by which they will eventually be disposed of to the environment? This commonly includes the preparation of overburden and tailings management plans to support the findings of the environmental assessment.

·         How are the quantities of residuals and wastes estimated and what is the decree of uncertainty? Mines often operate over one or more decades and even the best exploration efforts cannot cover all subsurface conditions that one will encounter during mine operation. Mine plans and mine wastes will change over time.

·         Is the behavior of the ecosystem receiving mine wastes fully understood? Tailings disposal of the Ok Tedi mine in PNG and the Freeport mine in Papua are most likely the two most prominent points in case of this particular aspect of a mine EIA review. For both mines, ecological risk assessment studies span over many years, and environmental impacts continue to be in dispute.

From the EIA Technical Review Guideline: Non-Metal and Metal Mining U.S. EPA  (2011), we copy three checklists of issues related to a mine’s waste facilities and how  they should be addressed in an EIA.  They first provide this list of the design details that should be included in the EIA:

·         Location of all stockpiles, dumps, and tailings structures

·         Clearing and grubbing, including disposal of debris

·         Engineering design of structures, including dump foundations and drainage structures,

·         and justification for the design

·         Transport ramps onto structures

·         Stability analysis of each structure

·         Construction and design details of structure (dimensions, volume, slopes) by year

·         Chemical and physical characterization of materials in tailings, dumps and piles

·         Potential for pollutants and contaminants

·         Design to prevent pollution and contamination (water, air, and direct contact)

·         Equipment roster specifying type and quantity by: size, motor size, and fuel requirements

·         for each type of equipment

·         Water and air quality monitoring programs

·         Location and design of monitoring wells and air monitors

Then they list the following environmental concerns that they recommend should be addressed regarding a mine’s waste facilities in an EIA:

·         Erosion and sedimentation

·         Spills/overflows from ponds during storm events or electricity failures

·         Containment failures (e.g. dam breaches)

·         Acid rock drainage potential (metal and coal mining)

·         Cyanide contamination of groundwater and surface water

·         Increased potential for trace metals/other contaminants

·         Deforestation and loss of habitat

·         Poisoning of birds and other wildlife

·         Disruption of migration routes/nesting/breeding activities

·         Areas made unproductive for nonmine uses

·         Disturbance or destruction of cultural and heritage sites

·         Traditional uses disrupted

·         Tailings dams and rock waste disposal sites are unsightly

·         Health and safety of workers transported to the site, using equipment and working in inhospitable environments

According to the International Finance Corporation (IFC) (2007), management of mine tailings and waste dumps include the following actions, and these are recommendations for what should appear in an EIA on the topics::

·         Design, operation, and maintenance of structures according to internationally recognized standards based on a risk assessment strategy. Appropriate independent review should be undertaken at design and construction stages with ongoing monitoring of both the physical structure and water quality, during operation and decommissioning.

·         Where structures are located in areas with a risk of high seismic loadings, the independent review should include a check on the maximum design earthquake assumptions and the stability of the structure to ensure that during seismic events there will be no uncontrolled release of tailings.

·         Design of tailings storage and waste rock facilities should take into account the specific risks and hazards associated with geotechnical stability or hydraulic failure and the associated risks to downstream economic assets, ecosystems and human health and safety. Environmental considerations should thus also consider emergency preparedness and response planning and containment/mitigation measures in case of catastrophic release of tailings or supernatant waters.

·         Any diversion drains, ditches and stream channels to divert water from surrounding catchment areas away from the tailings and waste rock structures should be built to the flood event recurrence interval standards. Usually, these diversions are designed for 100year runoff event but could vary by country.

·         Design specifications should take into consideration the probable maximum flood event and the required freeboard to safely contain it (depending on site specific risks) across the planned life of the tailings dam, including its decommissioned phase.

·         Where potential liquefaction risks exist, including risks associated with seismic behavior, the design specification should take into consideration the maximum design earthquake.

·         Onland disposal should be in a system that can isolate acidgenerating material from oxidation or percolating water, such as a tailings impoundment with dam and subsequent dewatering and capping. Onland disposal alternatives should be designed, constructed and operated according to internationally recognized geotechnical safety standards.

·         In addition, tailings impoundments and waste rock dumps should be constructed in a manner that minimizes the release of contaminants by including liners if seepage would result in groundwater or surface water contamination.

·         Waste facilities should have adequate monitoring and seepage collection systems to detect and collect any contaminants released in the immediate vicinity.  This should include:

o    Consideration of seepage management and related stability analysis in design and operation of tailings storage facilities. This is likely to require a piezometer based monitoring system for seepage water levels within the structure wall and downstream of it, which should be maintained throughout its life cycle.

o    Consideration of zero discharge tailings facilities and completion of a full water balance and risk assessment for the mine process circuit including storage reservoirs and tailings dams.

o    Consideration of use of natural or synthetic liners to minimize risks.

o    Consideration of thickening or formation of paste to be backfilled into pits or underground workings during mine progression.

o    Utilization at decommissioned leach pads of a combination of surface management systems, seepage collection and active or passive treatment systems to ensure that post-closure water quality is maintained.

Not everybody is so optimistic.  Here is one critique from Documenting Accountability: EIA in Peruvian Mining Project by Fabiana Li.  

Over the past two decades, practices of accountability have acquired a new presence in neoliberal governance and resource extraction in Peru. In the context of mining activity, accountability generally refers to public mechanisms of evaluation and record-keeping through which citizens can make corporations and governments answerable to them. However, I argue that these practices often prioritize mining interests by enabling corporations to define and ultimately enforce standards of performance. This article focuses on a key process in the making of social and environmental accountability in mining projects: Environmental Impact Assessment (EIA). I show that the form of the documents produced for the EIA (i.e., their required components, as established in legal frameworks) and the process of making them public (participatory meetings and public forums) can take precedence over their content. I examine two aspects of the EIA that make this possible. First, the risks that are identified in the EIA are those that a company deems to be technically manageable based on the solutions and interventions that it has to offer. Second, the participatory process of the EIA creates collaborative relationships among state agents, corporations, NGOs, and communities that strengthen the EIA’s claims of accountability while circumscribing the spaces for opposition to a proposed project.

For completeness, here is a repea of a previus blog posting on the topic.  The Environmental Law Alliance Worldwide has a publication all prospective miners and mine investors should read.  The publication is free to download.  I have, and recommend you do so too.  The document is Guidebook for Evaluating Mining Project EIAs.  It is available in English, Spanish, and French.  Here is how they describe it:

Most countries require an environmental impact assessment (EIA) before giving the green light to a mining project. EIA processes provide a valuable opportunity for citizens to participate in decisions about mines. The problem is, project proponents often submit long, complex EIA documents that are incomprehensible to lay people.   We hope this Guidebook for Evaluating Mining Project EIAs will help grassroots advocates and communities understand mining EIAs, identify flaws in mining project plans, convince decision-makers to reject ill-conceived mining projects, and explore ways that proposed mining projects could be made socially and environmentally acceptable.   The Guidebook was produced in 2010 by a team of experts at the Environmental Law Alliance Worldwide (ELAW), including ELAW Board Chair Dr. Glenn Miller, Director of the Graduate Program in Environmental Sciences and Health at the University of Nevada at Reno.   ELAW has helped partners around the world evaluate dozens of EIAs for proposed mining projects. The Guidebook consolidates what we have learned and points to many critical resources for communities seeking to make their voices heard about proposed mining projects.