reviewing typical eia for mining projects

7/25/2019 Reviewing Typical EIA for Mining Projects

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Reviewing EIA documents can be daunting. Project proponents submit reports that include complexand obscure technical terms. Sometimes only the Executive Summary is made available to thepublic. The purpose of an EIA is to provide clear and impartial information about a projects potential

environmental and social impacts. Questions to consider when reviewing an EIA include:

Does the EIA fulfill requirements for theproposed activity, as set out in the relevantEIA guidelines or Terms of Reference?

Does the EIA focus on the issues thatmost concern the community?

Does the description of the existingenvironment reflect actual conditions? Isthe information sufficient?

Has the EIA defined the area of directand indirect influence of the project?

Is the impact analysis clear about theextent and significance of the impacts? Isthe analysis rigorous enough?

What sources support the conclusions?Can they be verified?

Is there enough information aboutalternatives to the project?

Is the EIA clear and easy tounderstand? Does it acknowledgelimitations and difficulties?

Does the EIA describe how the projectwould implement proposed mitigation andmanagement measures (including pollutioncontrol measures and closure)?

3.1 EVALUATING THE EXECUTIVE SUMMARY

The Executive Summary of an EIA providesdecision-makers and the public with a concisepresentation of the most significant issuescontained in the body of an EIA. The ExecutiveSummary is critical because an EIA may be severalhundred pages long and decision-makers mayread the Executive Summary, and nothing else.

Since project proponents understand thatdecision-makers may only read the Executive

Summary, material from the body of the EIAthat describes serious environmental and socialimpacts may be softened or omitted entirelyfrom the Executive Summary. Statements in theExecutive Summary that are favorable to theproject proponent must be carefully comparedwith related material in the body of the EIA.

3. Reviewing a Typical EIAfor a Mining Project


2/606 Guidebook for Evaluating Mining Project EIAs

3.2 EVALUATING THE PROJECT DESCRIPTION

The Project Description is one of the mostimportant sections of the EIA. The crucial issueis whether this section describes each and everyaspect of the proposed mining project in sufficient

detail to enable citizens to understand the projectstrue environmental and social impacts.

For example, the Project Description in a poor EIAmight state: A wet tailings impoundment shall beconstructed for disposal of tailings from the miningproject. This statement is missing details that areessential to predicting what the environmental andsocial impacts of the tailings impoundment mighttruly be.

In this case, a good Project Description wouldanswer questions like: Where would the tailingsimpoundment be located and what surfacewaters would it connect with? What would be thedimensions of the tailings impoundment? Whatmaterials would be used to construct the tailingsdam? Would the mining company treat effluentfrom the tailings impoundment before releasing itto surface water? If so, how? Would the tailingsimpoundment include an impermeable liner to

protect groundwater?

Each of these questions should be answered indetail, accompanied by large-scale technicaldrawings, in the Project Description.

3.2.1 Project alternatives

The Project Description should analyze alternativeways to undertake the project and identify the leastenvironmentally-damaging practical alternative.

The following are a few examples of alternativesthat a good EIA would consider.

3.2.1.1 Alternative siting of mine facilities

Alternative locations for the mine itself are usuallynot up for discussion, because the ore depositexists where it is. However, a mining companymay be able to change from an open-pit

extraction method to an underground extractionmethod, to preserve surface resources. Anunderground mine might displace fewer humaninhabitants and better protect surface waters,

groundwater, or ecologically important wildlifehabitat.

The alternatives section of an EIA should answerthe question: Is the preferred alternative the leastenvironmentally-damaging practical alternative?

The location of key mine facilities can also bediscussed. These include the location of oreprocessing facilities (e.g., beneficiation plants)and the location of waste disposal facilities,

including facilities for the disposal of overburdenand tailings. The location of these facilities shouldbe chosen to protect public safety and minimizeimpact on critical resources, such as surfacewaters, groundwater, or ecologically importantwildlife habitat.

For example, if a wet tailings impoundmentfacility is the least environmentally-damagingpractical alternative for tailings disposal, then its

location should be carefully considered. A tailingsimpoundment should not be located near criticalwater resources and should be located at a safedistance (called a setback or buffer zone) fromresidences and public buildings.

The alternatives section of an EIA should answerthe question: Are mine facilities located in theleast environmentally-damaging locations?

3.2.1.2 Alternative ore beneficiation

methods

Mining companies often have a choice ofbeneficiation methods to concentrate thedesired metals in the metallic ore they havemined. Some ore beneficiation methods have lessserious impacts than others. For example, gravityconcentration of gold ore has less potential tocontaminate the environment and threaten public


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If you answered yes to ALL of these questions, then the projectalternatives section of the EIA may be adequate.

Does the EIA include an analysis ofproject alternatives?

Does the EIA include an analysis ofthe no project alternative?

Does the EIA include an analysis ofwhether the proposed

extent of mineral ore extraction isthe least environmentally-damaging

practical alternative?

Does the EIA include an analysis ofthe least environmentally-damaging

locations for the siting of criticalmine facilities, including waste

rock piles, tailings disposalfacilities, and leach facilities?

Does the EIA include an analysis ofwhether the proposed

ore beneficiation method is theleast environmentally-damaging

practical alternative?

Does the EIA propose todewater tailings and dispose of thiswaste as backfill for mined areas?

If you answered no to ANY of these questions,then the project alternatives section of the EIAis likely inadequate.

NO TOANY

YES TO ALL

FLOWCHART 3.1- Project Alternatives



health than cyanide leaching. However, few typesof gold ore are amenable to gravity concentration.

The U.S. EPA cites the following as the mostcommon beneficiation methods for specific oretypes.

The most common beneficiation processes

include gravity concentration (used only withplacer gold deposits); milling and floating(used for base metal ores); leaching (usedfor tank and heap leaching); dump leaching(used for low-grade copper); and magnetic

separation. Typical beneficiation steps includeone or more of the following: milling; washing;filtration; sorting; sizing; magnetic separation;pressure oxidation; flotation; leaching; gravityconcentration; and agglomeration (pelletizing,

sintering, briquetting, or nodulizing).

Milling extracted ore produces uniform-sized particles, using crushing and grindingprocesses. As many as three crushing stepsmay be required to reduce the ore to thedesired particle size. Milled ore in the form of a

slurry is then pumped to the next beneficiationstage.

Flotation uses a chemical reagent to make

one or a group of minerals adhere to airbubbles for collection. Chemical reagentsinclude collectors, frothers, antifoams,activators, and depressants; the type ofreagent used depends on the characteristicsof a given ore. These flotation agents maycontain sulfur dioxide, sulfuric acid, cyanidecompounds, cresols, petroleum hydrocarbons,hydrochloric acids, copper compounds, and

zinc fume or dust.

Gravity concentration separates mineralsbased on differences in their gravity. The sizeof the particles being separated is important,thus sizes are kept uniform with classifiers (suchas screens and hydrocyclones).

Thickening/filtering removes most of theliquid from both slurried concentrates and milltailings. Thickened tailings are discharged to

a tailings impoundment; the liquid is usuallyrecycled to a holding pond for reuse at themill. Chemical flocculants, such as aluminum

sulfate, lime, iron, calcium salts, and starches,may be added to increase the efficiency of thethickening process.

Leaching is the process of extracting a

soluble metallic compound from an ore byselectively dissolving it in a solvent suchas water, sulfuric or hydrochloric acid, orcyanide solution. The desired metal is thenremoved from the pregnant leach solutionby chemical precipitation or another chemicalor electrochemical process. Leachingmethods include dump, heap, and tankoperations. Heap leaching is widely used in thegold industry, and dump leaching in the copper

industry.

Beneficiation of copper consists of crushingand grinding; washing; filtration; sorting and

sizing; gravity concentration; flotation; roasting;autoclaving; chlorination; dump and in situleaching; ion exchange; solvent extraction;electrowinning; and precipitation. The methods

selected vary according to ore characteristicsand economic factors; approximately half ofcopper beneficiation occurs through dump

leaching, while a combination of solventextraction/froth flotation/electrowinning isgenerally used for the other half. Often, morethan one metal is the target of beneficiationactivities (silver, for example, is often recoveredwith copper).

Copper is increasingly recovered by solutionmethods, including dump and in situ leaching.Because most copper ores are insoluble inwater, chemical reactions are required toconvert copper into a water-soluble form;copper is recovered from a leaching solutionthrough precipitation or by solvent extraction/electrowinning (SX/EW). Solution beneficiationmethods account for approximately 30 percentof domestic copper production; two-thirds ofall domestic copper mines use some form of

solution operations. Typical leaching agentsused in solution beneficiation are hydrochloric


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and sulfuric acids. Microbial (or bacterial)leaching is used for low-grade sulfide ores,however this type of leaching is much slowerthan standard acid leaching and its use is stillbeing piloted. ...

Beneficiation of lead and zinc ores includescrushing and grinding; filtration; sizing;

flotation; and sintering of concentrates.Flotation is the most common method forconcentrating lead-zinc minerals.

Three principal techniques are used toprocess gold and silver ore: cyanide leaching,flotation of base metal ores followed by

smelting, and gravity concentration. ... Gravityconcentration is used primarily by gold and

silver placer operations.

Cyanide leaching is a relatively inexpensivemethod of treating gold ores and is the chiefmethod in use. In this technique, sodium orpotassium cyanide solution is either applieddirectly to ore on open heaps or is mixed witha fine ore slurry in tanks; heap leaching isgenerally used to recover gold from low-gradeore, while tank leaching is used for highergrade ore.15

The EIA should demonstrate that the beneficiationmethod preferred by the mining company isthe least environmentally-damaging practicalalternative.

3.2.1.3 Alternative methods oftailings disposal

Mine tailings are a high-volume waste that oftencontain toxic substances in high concentrations.There are three main alternatives for the disposalof tailings: (1) use of a wet tailings impoundmentfacility or tailings pond; (2) dewatering anddisposal of dry tailings as paste backfill or drytailings disposal; and (3) the release of tailings

15 United States Environmental Protection Agency (1995)Office of Compliance Sector Notebook Project: Profile of theMetal Mining Industry. http://www.epa.gov/compliance/re-sources/publications/assistance/sectors/notebooks/metminsn.pdf

into the deep sea via a long pipeline or sub-marine tailings disposal.

Of these alternatives, the clear choice for theenvironment is dry tailings disposal. Evenmining industry representatives understand theadvantages of dry tailings disposal. It may costmore in the short-term, but it has long-term cost

advantages.

The following is an explanation of the environ-mental and cost-advantages of dry tailingsdisposal, by Rens B.M. Verburg, a scientistwith a U.S. mining industry consultant, Golder

Associates:

In recent years, use of paste fill has evolvedfrom an experimental backfill method withlimited application to a technically viableand economically attractive alternative.This is primarily due to the development ofdewatering and transportation systems thatallow for controlled and consistent productionand delivery of paste in a cost-effectivemanner. In addition, it has been recognizedthat underground backfill provides for amechanism to safely dispose of mine wastes

such as tailings, which results in cost savingsand reduced immediate and long-term liability.Minimizing this liability through a reduction in

surface disposal will have a beneficial effect onthe feasibility of any mining venture.

In addition to the use of paste forunderground backfill, the improvements in

Dry tailings disposal method, La Coipa mine, ChilePHOTO: Tailings.info



dewatering and transport technology havegenerated industry interest in so-called drydisposal of tailings as a paste. This interestis further stimulated by increased regulatorypressure on hydraulic structures (dams)and other aspects (e.g., liners) of the moretraditional subaerial tailings managementmethods. The public perception of tailings

impoundments as being generally unsafestructures is another driving force behindthe current revival of alternative tailingsmanagement concepts.

Of all potential advantages associatedwith disposal of tailings in paste form, theenvironmental benefits are among the mostpromising. In particular as regulatory and

societal demands on the mining industry

continue to increase, use of paste technologymay provide an avenue for minimizing or eveneliminating various environmental issues.

The environmental benefits of surfacedisposal of paste can be divided into two maincategories; those that stem from the physicaland chemical characteristics of paste itself, andthose that are more operational in nature.

. First, very little free water is available

for generation of a leachate, therebyreducing potential impacts on receivingwaters and biological receptors. In addition,the permeability of a poorly sorted, run-of-mill paste is significantly lower than that ofclassified, well-sorted tailings. In a surface

scenario, this limits infiltration of rainfall andsnowmelt, which also results in a reductionof the seepage volume. When placedunderground, the paste may represent ahydraulic barrier to groundwater flow, therebylimiting generation of a potentially onerousleachate. Furthermore, the saturated conditionswithin the paste minimize the ingress ofoxygen, thereby reducing the potential forgeneration of acid rock drainage. Second,the paste production technology allows forproduction of an engineered material bymodifying the paste geochemistry in such amanner that environmental benefits result. For

instance, addition of Portland cement has beenshown to be very effective in reducing metalsmobility. In addition, acid generation in thetailings can be markedly curtailed by mixingwith alkaline materials. Third, co-disposalof other waste materials with paste is madefeasible by the paste production technology.In particular, encapsulation of acid generating

waste rock in appropriately designed pastemay provide significant benefits in terms ofenvironmental control and waste management.

There are additional, operational aspects ofsurface disposal of paste that benefit the mineowner and the environment. The placementof pastes on the surface allows for increasedflexibility in both facility siting and disposal

strategy. The absence of a pond affords the

use of management strategies that are muchless restrictive, thereby opening the way forsiting and disposal options that are leastdetrimental to the environment. In addition,the footprint of a paste facility will generallybe smaller than that of an impoundmentdesigned for an equivalent amount of tailings.

A second operational benefit results fromthe improved recovery of water. In particularin arid regions, the reduced water use mayrepresent an important economic incentive.

A third benefit stems from the potential forconcurrent reclamation and creation of a truewalk-away facility at closure. As reclamation

strategies can be incorporated into theplacement options, land disturbance can beminimized during operation. This results in areduction of visual impacts and operationalhazards (e.g., dust generation). In addition,unnecessary loss of pre-mining land uses(agriculture, timber, wildlife habitat, etc.) canbe prevented.16

If the EIA does not propose dry tailings disposal,which is almost always the environmentally-preferable alternative, then the EIA must clearlydemonstrate that dry tailings disposal is not

16 Verburg, R.B.M (2001) Use of Paste Technology for Tail-ings Disposal: Potential Environmental Benefits and Requirementsfor Geochemical Characterization. IMWA Symposium 2001.http://www.imwa.info/docs/BeloHorizonte/UseofPaste.pdf
http://www.imwa.info/docs/BeloHorizonte/UseofPaste.pdfhttp://www.imwa.info/docs/BeloHorizonte/UseofPaste.pdf


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feasible in the specific instance and, if feasible,that a wet tailings impoundment has clear, site-specific environmental advantages over drytailings disposal.

The third alternative for disposal of mine tailingsis sub-marine tailings disposal. This is onlypossible when mines are located near deep sea

environments. Sub-marine tailings disposal isillegal in several jurisdictions and has a poorenvironmental record. The IFC/World BankGroup explains:

Deep sea tailings placement (DSTP) maybe considered as an alternative only in theabsence of an environmentally and socially

sound land-based alternative and based onan independent scientific impact assessment.

If and when DSTP is considered, suchconsideration should be based on detailedfeasibility and environmental and socialimpact assessment of all tailings managementalternatives, and only if the impact assessmentdemonstrates that the discharge is not likely tohave significant adverse effects on marine andcoastal resources, or on local communities.17

If an EIA proposes sub-marine tailings disposal,then the EIA must explain why this alternative

should be considered when it has been prohibited17 IFC/World Bank (December 2007) Environmental,Health and Safety Guidelines for Mining. http://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuide-lines2007_Mining/$FILE/Final+-+Mining.pdf

in many jurisdictions and caused significantenvironmental damage in places where it hasbeen practiced.

3.2.1.4 The no-action alternative

An EIA is not complete without a comparativeanalysis of the environmental and social impacts

of the no-action alternative (a future in whichthe proposed project does not take place). Thelaws and regulations of many countries explicitlyrequire that an EIA contain a separate assessmentof the no-action alternative.

An assessment of the environmental and socialimpacts of a future, in which the proposed miningproject does not take place, is important tounderstanding what benefits might be lost if the

project does not move foreward.

For example, if a proposed mining projectwould be located in a tropical forest with high-biodiversity, and the project does not take place,then tourism to the area may greatly expand,providing employment and income to localcommunities. These benefits may only come tolight if the EIA assesses the environmental andsocial impacts of the no-action alternative.
http://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdf



3.3 EVALUATING THE ENVIRONMENTAL BASELINE

The section of an EIA that details existingconditions (often called the environmentalbaseline) demonstrates whether the projectproponent truly understands the environmental

and social conditions that the proposed miningproject may disturb. For example, if the EIAdoes not include details about existing surfacewater quality, air quality, and the abundanceand distribution of threatened and endangeredspecies, then it simply is not possible for theproject proponent to formulate accuratepredictions about how the project would impactwater quality, air quality, and threatened andendangered species.

The section of an EIA that describes theenvironmental baseline may often containmisleading information. For example, it is in theinterest of the project proponents to describeenvironmental conditions as already degraded orimpaired, or to minimize the extent to which localcommunities inhabit and make use of the projectarea.

If the environmental baseline contains claims that

the environment is degraded or uninhabited, thenthose claims should be questioned and evidenceto the contrary provided.

The following is a more detailed discussion ofthe specific kinds of environmental baseline datathat an EIA for a proposed mining project needsto contain, and how to evaluate whether theinformation provided adequately characterizesbaseline conditions.

3.3.1 Characterization of minedmaterials

The environmental baseline should begin witha detailed characterization of the geologicalenvironment, including the metallic mineral orereserve and materials comprising the overburden.These materials must be managed properlybecause they give rise to the high-volume waste

that a mining project generates. Mined materialsmust be carefully characterized for concentrationsof toxic substances and the potential to becomeacidic at any future time (creating the potential for

acid mine drainage).

3.3.1.1 Mineralogy and wholerock analysis

Maest et al. (2005) provide the followingguidance about the kind of geochemical analysisa mining project proponent must include topredict possible water quality impacts, includingthe release of contaminants and acid drainage:

The first step in characterizing minedmaterials is to determine the geology andmineralogy of the rocks at the mine site.Such analyses include the determination ofrock type, alteration, primary and secondarymineralogy, the availability of acid-producingand - neutralizing and metal-leachingminerals (liberation, e.g., veins, disseminated,encapsulated, etc.), and the locations anddimensions of oxidized and unoxidized zones

for all waste types, pit walls, and undergroundworkings. ...

The next step in the geochemical charac-terization of mined materials is defining thegeochemical test units. Geochemical test unitsare rock types of distinctive [physical andchemical characteristics]...

Depending on the results of the charac-terization, some of the test units may

be grouped together in the mine wastemanagement plan. Alternatively, if an initialunit designation provides a wide range of testoutcomes, it may be necessary to subdivide theunit for waste management purposes...

The third step in characterizing minedmaterials is to estimate the volumes of eachtype of material to be generated and the


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FLOWCHART 3.2- Evaluating the adequacy of the evaluation of acid-generating andcontaminant leaching potential of mined materials

Does the environmental baselinesection of the EIA include a

characterization of the chemicalcomposition of mined materials?

Does the environmental baselinesection of the EIA include

bench-scale tests of representativemined materials, including specificallycreated tailings and leach materials,

that determine the potential

of these materials to generate acidunder static conditions?

If bench-scale tests of representativemined materials show that

these materials will not generateacid under static conditions, doesthe environmental baseline of the

EIA determine the potential of thesematerials to generate acid under

kinetic conditions?

NO TOANY

YES TO ALL

If you answered yes to ALL of these questions, then theenvironmental baseline section of the EIA may be adequatewith respect to characterizing the acid-generating potential ofmined materials.

If you answered no to ANY of thesequestions, then the environmental baselinesection of the EIA is likely inadequatewith respect to characterizing theacid-generating potential of minedmaterials.



distribution of types of material in waste, pit,and underground workings... The informationon geochemical test units should be coordin-ated with the mine waste management plan.

The fourth step in characterization isconducting bench-scale testing of the ore,which involves creating tailings and/or heap

leach materials in a laboratory... The generalcategories of geochemical testing that will beperformed on the geochemical test units arewhole rock analysis, static testing, short-termleach testing, and kinetic testing.18

3.3.1.2 Acid generation potential - staticand kinetic testing of mined materials

To determine the acid generation potential of

mined materials and mine project wastes, an EIAshould include the following test results:

Static testing

Static testing [should be] performed onpotential sources of acid drainage, includingwaste rock, pit wall rock, undergroundworking wall rock, tailings, ore, leachedheap materials, and stockpile materials.The number of samples for each unit will

be defined by the volume of material to begenerated. For acid-generation potential(AGP), the modified Sobek method usingtotal sulfur is recommended. The mineralogyand composition of the sulfides should beconfirmed using mineralogic analysis.

Kinetic testing

The objectives of kinetic testing should beclearly defined. Kinetic testing should beconducted on a representative number of

samples from each geochemical test unit.Special emphasis should be placed on kinetictesting of samples that have an uncertainability to generate acid. Column tests are

18 Maest, A.S., et al. (2005) Predicting Water Quality atHardrock Mines: Methods and Models, Uncertainties, and State-of-the-Art. http://www.swrcb.ca.gov/academy/courses/acid/supporting_material/predictwaterqualityhardrockmines1.pdf

recommended over humidity cell tests for allaerially exposed mined materials, includingnatural on-site construction materials, with theexception of tailings. However, either type ofkinetic test can be useful depending on theobjectives of the testing and if the available

surface areas for reaction are determined inadvance of the testing.19

3.3.1.3 Contaminant leaching potentialshort- and long-term leach tests

Scientists recommend the following analyses todetermine the potential of mined materials andmine project wastes to release toxic substances:

Results from short-term leach tests canbe used to estimate the concentrations of

constituents of concern after a short event(e.g., a storm event) but are not appropriateto use for estimation of long-term leaching.Standard short-term leach tests with a lowerliquid:solid ratio can be conducted on samplesfrom each geochemical test unit. However,using first flush results from longer-term kinetictesting will help coordinate the short-term andlonger-term weathering results and will allowthe determination of weathering on a permass basis. The leachate samples should be

analyzed for constituents of concern (based onwhole rock analysis and known contaminantsof concern) using detection limits that areat least ten times lower than relevant waterquality standards (e.g., for arsenic, which hasa drinking water standard of 10 g/L, thedetection limit should be 1 g/L or lower).Major cations and anions should also bedetermined on the leachate samples, and thecation/anion balance should be checked foreach sample.20

3.3.1.4 Identification of contaminants ofconcern

The section of an EIA that characterizes the minedmaterials should include quantitative predictionsof the concentrations of contaminants of concern

19 Ibid.20 Ibid.
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(e.g., arsenic, lead, cadmium, nickel, chromium,and mercury). These would be found in pollutedwater that a mining project may, at any futurepoint in time, release into the environment. Thesequantitative predictions should then be used toanticipate potential changes in groundwater andsurface water quality.

3.3.2 Characterization of existingclimate

Rainfall is a major concern at mine sites. Infact, rainfall can determine the environmentalacceptability of a proposed mining project. In thetropics, high rainfall generates large quantitiesof runoff. In contrast, mines in arid areas needonly cope with small quantities of runoff. Miningprojects in many tropical areas are fraught with

environmental risk. These projects not onlythreaten pristine ecosystems, but high rainfall andheavy storms overwhelm mining facilities andmitigation measures for preventing environmentaldisasters. An especially rainy climate can, by itself,deem a proposed mining project environmentallyunacceptable.

The following should be included in thedescription of the existing climate at the proposedmine site:

Rainfall patterns including magnitudeand seasonal variability of rainfall must beconsidered. Extremes of climate (droughts,floods, cyclones, etc.) should also be discussedwith particular reference to water managementat the proposal site.21

Climatic conditions (precipitation,evaporation, climate type, seasonal/long-term

climatic variability, dominant wind directions,typical storm events, temperature) for locationsat or close to mine. 22

21 Queensland Environmental Protection Agency (2001)Generic Terms of Reference for Environmental Impact State-ments for Non-Standard Mining Projects. http://www.derm.qld.gov.au/register/p00443aa.pdf22 Maest, A.S., et al. (2005) Predicting Water Quality atHardrock Mines: Methods and Models, Uncertainties, and State-of-the-Art. http://www.swrcb.ca.gov/academy/courses/acid/supporting_material/predictwaterqualityhardrockmines1.pdf

3.3.3 Characterization of existingseismic conditions

If a mining project involves a wet tailingsimpoundment, the EIA must adequatelycharacterize existing seismic conditions, includingthe risk of a major earthquake which coulddamage mine facilities and cause catastrophicconsequences, such as a tailings dam failure. TheU.S. EPA recommends the following analysis:

The design of tailings impoundments usuallyhas to consider potential seismic activity atthe site. This requires the selection of a designearthquake for the site in question. A methodcommonly used to determine the effects ofthe design earthquake on a particular site isto assume that the earthquake occurs on the

closest known possibly active fault. The fault isselected on the basis of the geological studiespreviously conducted in the area. Attenuationtables are then used to estimate the magnitudeof the earthquake forces reaching the site asa result of the design earthquake occurring onthe selected fault.23

The EIA should include a description of thedesign earthquake for the mine site and assess itspotential impact on mine facilities, including the

wet tailings impoundment (if one is proposed).The description of the design earthquake shouldbe based on the most complete and recentseismic data.

The IFC/World Bank Group explains that:

Where structures are located in areaswhere there is a risk of high seismicloadings, the independent review should

include a check on the maximum designearthquake assumptions and the stabilityof the structure to ensure that the design is

such that during seismic events there will beno uncontrolled release of tailings;

23 United States Environmental Protection Agency (1994)Technical Report: Design and Evaluation of Tailings Dams.http://www.epa.gov/epawaste/nonhaz/industrial/special/miningtechdocs/tailings.pdf
http://www.derm.qld.gov.au/register/p00443aa.pdfhttp://www.derm.qld.gov.au/register/p00443aa.pdfhttp://www.derm.qld.gov.au/register/p00443aa.pdfhttp://www.derm.qld.gov.au/register/p00443aa.pdfhttp://www.epa.gov/epawaste/nonhaz/industrial/special/mining/techdocs/tailings.pdfhttp://www.epa.gov/epawaste/nonhaz/industrial/special/mining/techdocs/tailings.pdfhttp://www.derm.qld.gov.au/register/p00443aa.pdfhttp://www.derm.qld.gov.au/register/p00443aa.pdfhttp://www.derm.qld.gov.au/register/p00443aa.pdfhttp://www.derm.qld.gov.au/register/p00443aa.pdf



Design of tailings storage facilities shouldtake into account the specific risks/ hazardsassociated with geotechnical stabilityor hydraulic failure and the associatedrisks to downstream economic assets,ecosystems and human health and safety.Environmental considerations should thusalso consider emergency preparedness

and response planning and containment/mitigation measures in case of catastrophicrelease of tailings or supernatant waters;

Where potential liquefaction risks exist,including risks associated with seismicbehavior, the design specification shouldtake into consideration the maximumdesign earthquake;24

3.3.4 Characterization of existingsurface water quality

Characterizing existing surface water qualityprovides detailed information on the location,distribution, quantity, and quality of all waterresources that could be affected by a projectand its alternatives. The data and analysisshould have a reasonable level of detail, to helpunderstand the conditions of the environmentally-significant geographic areas.

Baseline studies about water quality shouldconsider the local and regional uses of water(domestic, industrial, urban, agricultural,recreational, others) and assess water quality aspart of the ecosystem (in relation to the life ofplant and animal communities). Water qualitystudies should be compared to water standardsand other legal guidelines for each water use.Quantity must reflect several aspects such as

watershed distribution, hydrological processes,and the availability for different water uses at localand regional levels.

24 IFC/World Bank (December 2007) Environmental,Health and Safety Guidelines for Mining. http://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuide-lines2007_Mining/$FILE/Final+-+Mining.pdf

The characterization of existing surface waterquality should address:

Hydrology: Description and locationof the physical, chemical, biological,and hydrological characteristics of allsurface water resources in the project areaand in the area of influence (including

seasonal variations). Maps, location, andcharacterization of river basins, lakes, andstreams. Identification of existing waterpollution sources; location, volume flows,minimum flows.

Identification of wetland areas, floodzones, minimum flow rates, speed,direction.

Applicable water quality standards.

Common water quality parameters:Physical, chemical: pH, turbidity,suspended solids, temperature, DissolvedOxygen (DO), Biochemical OxygenDemand (BOD), Chemical OxygenDemand (COD), Dissolved Solids, salinity,conductivity. Common contaminantsof concern include ammonia, arsenic,cadmium, copper, chromium, cyanide,iron, lead, manganese, mercury,

molybdenum, nickel, nitrate/nitrite, sulfate,thallium, uranium, vanadium, and zinc.When baseline water quality (surface wateror groundwater) samples are collected,they should be analyzed for the full suiteof parameters and contaminants ofconcern listed above, and any others thatare known to be common in the area orspecific to the proposed extraction andbeneficiation methods.

Relevant information of the relationship

between input and output of water in theproject location; environmental scientistsand hydrologists call this water budgetand balance. This allows people to knowwhether or not there are periods whenthere is plenty of water available andwhen there is not enough, and why. Thisinformation is important for water quality
http://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdfhttp://www.ifc.org/ifcext/sustainability.nsf/AttachmentsByTitle/gui_EHSGuidelines2007_Mining/$FILE/Final+-+Mining.pdf


13/60Chapter 3

because it can let people know if there aretimes of the year when the concentration ofwater pollutants would be higher.

Surface water quality data should be supportedby methodological and analytical data. In otherwords, an EIA must include a clear description ofwater sampling methods, and the number and

exact location of sampling points. These should berepresentative of the area of influence of a projectand of all the surface water resources that wouldbe affected by a project. Also, water quality datashould include the results of laboratory analysis.Frequently, this information in an EIA is presentedin tables and figures and the laboratory reports areincluded as annexes.

As mentioned, surface water quality data mustbe compared to existing water quality standards,

according to the uses categorized in national lawsor international guidelines.

3.3.5 Characterization of existingsurface and groundwater quantityGroundwater resources are very complex systems.Depending on the area, groundwater can belocated at low depth with strong interaction withsurface waters, or deep with much less or no

interaction with surface water. Groundwater canalso have different uses, such as agricultural,human consumption, and industrial.

An EIA should include the following basicinformation about groundwater resources:

Depth to groundwater under differentseasonal conditions

Geology and locations of aquifers,

thicknesses, and their hydraulic conductivityranges

Groundwater flow directions

Locations/flows of springs and seeps

Groundwater discharge locations instreams

Groundwater uses

3.3.6 Characterization of existingair quality

Air quality conditions in a project area are criticalto evaluating the potential distribution of airpollutants and their effects in the area of influence.

Air pollutants can travel long distances, so baselineair quality information should be consideredin relation to meteorological conditions, windpatterns, geological formations, and anythingelse that might influence the distribution of airpollutants.

Baseline air quality data should:

Identify air basin

Describe local climate and topography

Identify national and local air qualitystandards

Describe historical air quality trends

Describe air quality of the proposedmining area and/or air basin

Identify sensitive receptors

Describe the exact location of airmonitoring and/or sampling stations

Baseline air quality analyses should includemeasurements of these common parameters:

Particulate matter (PM10 and PM2.5)

Carbon monoxide (CO)

Nitrogen oxides (NOx)

Lead (Pb), cadmium (Cd), arsenic (As),

mercury (Hg)

Total Suspended Solids (TSS)

Sulfur dioxide (SO2)

Baseline air quality information should besupported by methodological and analyticaldata. In other words, the EIA must include a clear



description of the air sampling methods, andnumber and exact location of sampling points.These should be representative of the projectsarea of influence. Frequently, this information isincluded in tables and figures and the laboratoryreports are included as annexes. Results of airwater quality data must be compared to existingair quality standards or international guidelines.

3.3.7 Characterization of existingsoil quality

Soil is defined as the top layer of the land surfaceof the Earth and is composed of small rockparticles, humus (organic matter), water, and air.Soil is a major factor affecting plants, includingagricultural crops and plants that provide the foodand habitats for animals. Avoiding major impacts

on soil can prevent the degradation of a wholeecosystem.

Soil baseline studies are based on three majorsources of information: desk study, fieldwork,and laboratory analysis. Baseline studies shouldinclude soil survey maps, tables documentingthe levels of chemical components, methods ofanalyses, literature review, soil sampling, and theresults of laboratory analysis. Maps should beaccompanied by explanatory information, withinformation on local geology, vegetation, andland use.

Soil sampling information should comprisea reasonable number of sampling pointsrepresentative of the mining concession area.Samples must include each horizon encounteredin soil profiles. The maximum depth to which asoil profile is dug is usually one meter. In general,samples are taken systematically using a sampling

grid, but random sampling or sampling particularareas of interest may be appropriate. The layoutand number of samples required can vary, but thenumber of samples should be representative of theproject area.

Laboratory analysis should provide informationabout soil composition, soil strength (resistanceto crushing), mineral content, and pH. Some

measure of water content, organic content, soiltexture, particle size, and bulk density should alsobe included. Soil chemistry is important in miningprojects because problems with naturally occurringtoxic elements are a real possibility. Baseline soilquality analyses should include measurements ofthese common parameters:

pH

Cation exchange capacity (the totalnumber of cations absorbed on soilcolloids gives some indication of potentialfertility)

Soil nutrient status: potassium, calcium,magnesium, nitrogen, and phosphorus

Heavy metals: lead, copper, zinc,cadmium, mercury, and chromium

3.3.8 Characterization of wildlife

Wildlife comprises all living things that areundomesticated. This includes plants, animals(vertebrates, birds, fish), and other organisms(invertebrates). Baseline information about wildlifemust include a list of wildlife species within theproject area and interactions between species. An

EIA should include a description of the region,species maps, relationships, population densities,and species distribution. All endemic flora andfauna in the project area that have a specialconservation status for example, listed by theInternational Union for Conservation of Nature(IUCN) or by national legislation as a threatenedor endangered species should be surveyed fortheir distribution and abundance in the projectarea.

3.3.8.1 Characterization of terrestrialspecies

Plants are one of the most important indicators ofenvironmental conditions because they reflect theoverall state of life conditions in an area and thestate of all other species in an ecosystem. Plantsare relatively easy to identify and map throughfieldwork and remote sensing. An inventory


15/60Chapter 3

of plant species should include informationabout: composition, density, distribution, status,vegetative cover, and dominant, protected,foreign, threatened, and vulnerable species, aswell as noticeable effects of human presence inthe ecosystem. Some areas have endemic andrare plant species that are of special interest.

Inventories of fauna species are more difficult toobtain, but should include: diversity, distribution,and density, including information about thepresence of endemic, protected, threatened,and endangered species. The EIA shoulddiscuss biomes, indicator species, and relevantinterrelations between communities of species.Depending on the project, other relevant baselineinformation about migration routes, breedinggrounds, nesting sites, wildlife corridors, and

uniqueness of fauna habitat should be discussed.

3.3.8.2 Characterization of aquaticspecies

Aquatic environments include not only fishand amphibians, but also aquatic plants, andinvertebrates (snails, bivalves, crustaceans, insects,worms). Information on aquatic species shouldinclude details on the abundance and distributionof endemic, protected, and endangered species;

detailed data on the abundance and distributionof fisheries of commercial importance or relied onfor sustenance; and impact on migratory aquaticspecies (such as fish) and breeding grounds.

3.3.8.3 Characterization of habitatscritical to ecological processes

At the level of a landscape or region, certainnatural habitats are especially important forecological functioning or species diversity in anecosystem. Unusual climate or edaphic (soilbased) conditions may create local biodiversityhotspots or disproportionately support ecologicalprocesses such as hydrologic patterns, nutrientcycling, and structural complexity. For thesereasons, preservation of specific habitats (usuallythe remaining natural areas within the landscape)should be a priority.

Within a landscape, certain habitats are vital forecosystem functioning. In general, these are theremaining natural areas, especially those thatintegrate the flows of water, nutrients, energy,and biota through the watershed or region. Thisconcept is analogous to that of keystone speciesthat are essential for a community structure.Forests, rangelands, and aquatic ecosystems

all have unique or critical habitats that supportthe provision of ecosystem services within thelandscape.

Around the world, identifying critical orendangered ecosystems has become moreimportant. An EIA for a large-scale metalmining project must consider and be consistentwith national and international classifications ofendangered ecosystems. An EIA should include

consultations with state natural heritage programsfor a more detailed assessment of flora and faunaof special concern.



3.3.9 Local socio-economic baseline

The socio-economic environment is defined as all activities, and social and economic processes,that could be influenced directly or indirectly by the mining project. In most cases, there is a definedsocio-economic environment that will be affected. The community impact assessment is of particularimportance. The range of topics (scope) and level of detail can be highly variable.

The section of an EIA that includes the socio-economic baseline data should explain how the scope ofthe analysis was defined and how the study area was delineated. The section should include informationabout:

Location of the local population in relation to the proposed project area

Population size, age composition, growth

Economic activities, employment, income (inventory of present economic environment withoutthe project)

Quality of life

Housing quality and quantity (this is particularly important if people are to be relocated)

Community organizations, representative institutions, neighborhood cohesion (usuallymeasured with surveys and interviews)

Public safety (police, fire)

Education (average level, access, public and/or private)

Health services

Recreation (public, private)

Existence of local development or well-being plans

Access to public services and sanitation

Maps with location and quantity of farmlands

Maps with existing land-use patterns

Attitudes towards the project


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3.4. EVALUATING POTENTIAL AND PREDICTEDENVIRONMENTAL IMPACTS

3.4.1 How to understand andevaluate environmental impact

matrices

There are several methods for identifyingenvironmental effects and impacts. Some of themost common are:

Checklists

Matrices

Flow diagrams

Batelle environmental evaluationsystems

Checklists

Checklists are based on a list of specialbiophysical, social, and economic factors thatmay be affected by a project. Checklists are easyto use and found in nearly all EIAs. Checklistsdo not usually include direct cause-effect links to

project activities.

Sample checklist for a large-scalemining project:

Sources of Potential Environmental Impacts

Project Phase Activity

Construction Road construction for mineral trans-portation and access to waste sites

Preparation of area for the solid waste

deposit. Storage of the productionplant and leach waste deposit

Construction of deviation channels

Construction of the foundations forthe production plant

Preparation of area for heap leach

Sources of Potential Environmental Impacts

Project Phase Activity

Construction Top soil removal and storage

Preparation of area for domesticwastes disposal

Preparation of area for domesticwaste water treatment facility

Installation of campsites, offices,workshops, storage facilities.

Preparation of open pit area

Operation Exploitation of open pits

Transportation of mineral to the leachpad

Expansion and elevation of the leachpad

Mineral leaching

Transportation and disposal ofmaterials in waste sites

Reception and storage of mineralin the production plant

Management of solutions at theproduction plant

Storage of ground mineral at theproduction plant

Process of mineral recovery at theproduction plant

Waste disposal from the productionplant

Management of industrial anddomestic waste water

Management of hazardous materials

Closure and post-closure

Closure of open pits

Closure of solid waste piles

Closure of heap leach pads

Backfill waste dump sitesClosure of storage sites

Closure of water and electricitysources

Land reclamation

Restoration of internal roads

Revegetation



Matrices

A matrix is a grid-like table for identifying theinteraction between project activities (displayedon one axis) and environmental characteristics(displayed on the other axis). Environment-activityinteractions can be noted in the appropriatecells or intersecting points in the grid. Matrices

organize and quantify the interactions betweenhuman activities and resources of concern. Oncenumerical data is obtained, matrices combinevalues for the magnitude and significance orimportance in individual cells to evaluate multipleactions on individual resources, ecosystems, andhuman communities.

Matrices have values for magnitude andsignificance. Magnitude refers to the extension

or scale while significance is related to theimportance of potential consequences of apreviewed impact. Commonly, matrices representmagnitude and significance on a scale of 1-10,with 10 representing the highest value.

Simple interactive matrix (Leopoldinteraction matrix)

A series of matrices at each stage of a projectcan be an effective way of presenting information.Each matrix can be used to compare options ratedagainst select criteria. The greatest drawback ofmatrices is that they can only effectively illustrate

primary impacts. Sometimes an EIA complementsmatrices with tables, checklists, or networkdiagrams to illustrate higher-order impacts and toindicate how impacts are inter-related.

Sample of a simple interaction matrix:

Pan American Center for Sanitary Engineering and Environmental Sciences [CEPIS] (1981) Environmental impact assessment methodologies descriptionand analysis and first approach to environmental impact assessment methodologies application. http://www.cepis.ops-oms.org/bvsair/e/repindex/repi51/environ/environ.html

Actions that cause an impact

Environm

entalelements

Importance

Land

Water

Air

Activities

Regional Characteristics

Soil

Relief

Surface

Quality

Temperature

Waterfall

Waterflow

Spring

Quality

Quality

Pluviality

Humidity

Temperature

General Alterations

Sea

River

Flora

Faun

a

Drain

age

River

Flows

Land

Parcelling

Joint

Property

Defo

restation

Urba

nization

CivilConstruction

FlyingField

Marine

Hydr

ological

Struc

ture

River

Bed

Cana

ls

Sewe

r

Elect

ricNet

ViaA

ccess

Infrastructures

3/14/3

5/1

8/1

3/1

4/13/1

3/3

2/4

2/4

8/3

8/8

8/32/4

3/1

3/1

3/5

4/5

4/5

4/5

3/1

8/8

Arbo

rization

High

ways


19/60Chapter 3

3.4.2 Impacts on water qualityand quantity

The section of the EIA that assesses the predictedimpacts of a mining project on water qualityshould be quantitative, not just qualitative. Thatmeans the EIA should predict how much the

surface and groundwater baseline levels wouldchange as a result of contaminants from the mine.Numerous computer models and tools exist toprovide these kind of quantitative analyses. Thefollowing are general steps to predicting water-quality:

The prediction of water-quality in a minefacility and in downgradient groundwater and

surface water involves the following generalsteps. Depending on the modeling objectives,not all steps may be required:

1. Develop site-specific conceptual model:Develop a conceptual model for predictionof water quality from the mine unit of

interest. Identify all significant processes andpathways that could influence water quality.Also determine the end point of modeling(e.g., composition of pore fluid in tailingsimpoundment vs. concentrations of constituentsat a receptor). The modeling end point willdetermine which of the following steps need tobe implemented.

Another example of a simple matrix of interactions of activities and environmental effects:

EIA e-Course Module, U.N. University, United Nations Environmental Programme (UNEP)http://eia.unu.edu/wiki/index.php/Assessment_Matrix

Environmental

Effects

Development

Social Environment

Re

creation

La

ndscape/Visual

Pe

rsonal/SocialValues

RisksandAnxieties

Ex

istingLandUses

Se

ttlement

La

ndValue

Em

ployment

Pu

blicParticipation

Historical/Cultural

Physical Environment Biological Environment

Treatment

Sedimentation

Millscreening

Circulation Ponds

Activated Sludge

Trickling Fiber

Nutrient Removal

Chlorination

Further Treatment Offsite

Disposal - Land

Surface Flooding

Rapid Infiltration

Spray Irrigation

Disposal - Inland Water

River

Lake

Disposal - Marine Water

Estuary

Inland Marine

Offshore Marine

Deep Well Injection

La

ndform

Nuisance(noise,dust,smell)

Fo

undationMaterials

Ag

riculturalSoil

GroundWater

Se

dimentation

Su

rfaceWater

Erosion/LandStability

RiverRegime

Climate/Atmosphere

W

etlands

M

arine

Estuaries

Rivers

La

kes

CropLand

UrbanLand

Sand/Shingle/Rock

Herbfield(alpine)

In

tertidal

Grassland

Fo

rest

Shrubland
http://eia.unu.edu/wiki/index.php/Assessment_Matrixhttp://eia.unu.edu/wiki/index.php/Assessment_Matrix



2. Characterize hydrogeologic and chemicalconditions:3. Determine mass fluxes into the facility:Determine water balance for the facility usingbasic meteorological data and numericalor analytical models. Determine chemicalreleases to the unit from mined material

outside of the facility, using short-term and/or long-term leaching data (depending onobjectives) or water quality samples. ...

4. Determine water quality in the facility: Ifwater quality samples are available, and themodeling endpoint is downgradient of thefacility, modeling of water quality in the facilitymay not be required. If water quality in thefacility is a modeling endpoint (e.g., pore water

quality for waste rock, tailings, leach dumps;pit or mine water quality for pit lakes andunderground workings), use inflowing waterchemistry (if relevant), releases from minedmaterial, and water balance information.

A mass-balance geochemical code (e.g.,PHREEQE) can be used to mix waters andcalculate concentrations of constituents, takingprecipitation and adsorption into account.Include an uncertainty analysis in the predictionof water quality. Consider physical, chemical,

and biological processes that can change thewater quality within the facility.

5. Evaluate mass fluxes out of the facility:Evaluate migration of contaminants fromthe mine unit. For waste rock, tailings, ordry pits, this could require estimating waterand chemical mass fluxes discharging fromthe bottom or toes of the dump or tailingsimpoundment, or infiltrating through the floorof the dry pit.

6. Evaluate migration to environmentalreceptors: Environmental receptors includegroundwater and surface water resourceswhere water will be used by humans or wildlife,or where water quality standards are relevant(e.g., points of compliance).

7. Evaluate effects of mitigation: Assessingthe effects of mitigations on the predictedwater quality at downgradient locations mayrequire creating a conceptual model formitigations. Based on the conceptual model,values for releases of water and constituentsfrom or to the facility can be modified. Forexample, if a cover will be added to a tailings

impoundment at Year 10, the infiltrationrates to the impoundment would need tobe decreased after Year 10 in the model.Decreasing infiltration rates will affect theflux of constituents leaving the facility andmigrating to receptors.25

If an EIA does not use a similar approach topredicting water quality, then it lacks essentialinformation for determining whether the mining

project is environmentally acceptable.

25 Maest, A.S., et al. (2005) Predicting Water Quality atHardrock Mines: Methods and Models, Uncertainties, and State-of-the-Art. http://www.swrcb.ca.gov/academy/courses/acid/supporting_material/predictwaterqualityhardrockmines1.pdf
http://www.swrcb.ca.gov/academy/courses/acid/supporting_material/predictwaterqualityhardrockmines1.pdfhttp://www.swrcb.ca.gov/academy/courses/acid/supporting_material/predictwaterqualityhardrockmines1.pdfhttp://www.swrcb.ca.gov/academy/courses/acid/supporting_material/predictwaterqualityhardrockmines1.pdfhttp://www.swrcb.ca.gov/academy/courses/acid/supporting_material/predictwaterqualityhardrockmines1.pdf


21/60Chapter 3

FLOWCHART 3.3- Evaluating the adequacy of predicted impacts on water quality

Does the environmental impacts section of the EIA providequantitative predictions of how the mining project would

change pollutant levels in surface and ground water?

Does the environmental impacts section of the EIA interpretthe environmental and health significance of predicted

pollutant levels in comparison to relevant water qualitystandards for the protection of public health and aquatic life?

YES TO ALL

If you answered yes to ALL of these questions, then theenvironmental impacts section of the EIA may be adequatewith respect to characterizing impacts on water quality.

If you answered no to ANY of thesequestions, then the environmental impactssection of the EIA is likely inadequatewith respect to characterizing impacts onwater quality.

NO TOANY

Do the quantitative predictions of how the mining projectwould change pollutant levels in surface and ground water

rely on careful estimates of pollutant levels in predictedwastewater releases from mine facilities, including theopen pit, waste rock piles, tailings disposal facilities,

and leach facilities?

Do the quantitative predictions of how the mining projectwould change pollutant levels in surface and ground waterrely on representative measurements of existing (baseline)

pollutant levels in surface and ground water?

Do the quantitative predictions of how the mining projectwould change pollutant levels in surface and ground water

rely on use of an appropriate computer model?



3.4.2.1 Water pollutant releases from pitlakes

A mining company should not propose a projectthat allows for the formation of a pit lake.Open pits should be backfilled, recontoured,and revegetated to create a final surface that isconsistent with the original topography of the

area. If a mining company does propose thecreation of a pit lake, then the following additionalconsiderations are necessary to accurately predictwater quality impacts caused by pit lake watercontamination:

For pit lakes, estimate precipitation andevaporation from lake surface, runoff from pithigh walls, groundwater flow rate into and outof the pit (if relevant), discharge rate of any

surface water entering or leaving the pit. Thewater balance can be used to predict rate ofinundation of pit walls with groundwater. .

Determine chemical releases to the unit frommined material outside of the facility, using

short-term and/or long-term leaching data(depending on objectives) or water quality

samples. For pits, these releases may bederived from oxidized wall rock, runoff from pithigh walls, and possibly waste rock backfill.

Oxidation of sulfide minerals in the walls ofunderground workings and dry pits may alsorelease metals and acid to the environment..

For a pit lake or flooded undergroundworkings, the chemical mass flux out ofthe facility would be the amount of waterand quantity of constituents released togroundwater or the vadose zone.

If considering vadose zone transport togroundwater (mass flux from facility initiallyenters vadose zone rather than groundwater),use an unsaturated zone flow and transportanalytical or numerical code. Downgradienttransport of constituents in groundwater can be

evaluated using a groundwater flow and solutetransport code, or a reaction path code.26

3.4.2.2 Water pollutant releases fromtailings impoundments

The environmentally-preferable option for thedisposal of tailings is dewatering and use as

backfill (dry tailings disposal). If an EIA for amining project calls for the creation of a wettailings impoundment, then analysis of waterquality impacts of tailings impoundments shouldinclude the following quantitative predictions:

Tailings pore water quality; Potential forand quality of seepage from impoundments;Downgradient groundwater quality; Surfacewater quality (if tailings seepage impacts

seeps, springs, streams, lakes).27

These quantitative predictions should be based onthe following inputs:

Tailings mineralogy (sulfide content);Contaminant release rates from tailings;Dimensions of tailings impoundment; Tailingsimpoundment water management duringmining and postclosure (presence of pool,degree of saturation); Sulfide mineral oxidation

rates; Liner specifications (release/zero dis-charge); Surface water proximity; Distanceto water table over time; Infiltration ratethrough unsaturated zone; Characteristics ofvadose zone and aquifer that affect hydraulicsand transport; Groundwater transportcharacteristics, if tailings seepage impactsgroundwater; and Surface water characteristics,if tailings seepage discharges to surfacewater.28

26 Ibid.27 Ibid.28 Ibid.


23/60Chapter 3

3.4.2.3 Water pollutant releases fromwaste rock dumps

The analysis of water quality impacts of waste rockdumps should include the following quantitativepredictions:

Potential for and quality of seepage from waste

rock dumps; Downgradient groundwater quality;and Surface water quality (if waste rock seepageimpacts seeps, springs, streams, lakes).29

These quantitative predictions should be based onthe following inputs:

Waste rock mineralogy (sulfide content);Oxidation rate of sulfides in waste rock;Chemical release rates from waste rock;

Quantity and quality of waste rock seepage;Infiltration rates through unsaturated zone;Runoff (amount and chemistry); Dumpdimensions; Physical composition of waste rockdump; Mitigations (cover, liners, etc.);Upgradient groundwater quality; Distanceto water table over time; Distance to surfacewater; Characteristics of vadose zone andaquifer that affect hydraulics and transport;Groundwater transport characteristics, if wasterock seepage impacts groundwater; and

Surface water characteristics, if waste rockseepage discharges to surface water.30

3.4.2.4 Assessing the significance ofwater quality impacts

After an EIA specifies the numerical extent to whichcontaminants the mining project may releasewould elevate the levels of these contaminantsin surface and groundwater (when added tobaseline levels), the next step is to interpret theenvironmental and health significance of thesequantitative predictions. Focus should be placedon toxic substances that are contaminants ofconcern (e.g., arsenic, lead, cadmium, nickel,chromium, and mercury) but should include othersubstances that may have harmful effects (e.g.,salinity, pH, total dissolved solids).

29 Ibid.30 Ibid.

The interpretation of the environmental and healthsignificance of predicted levels of pollutantswill require the comparison of these levels towater quality standards. For predicted levelsof pollutants in groundwater, the relevant waterquality standards for comparison are standards forclean drinking water found in domestic legislationand (especially if domestic clean drinking water

standards are lax or absent) the World HealthOrganizations Guidelines for Drinking WaterQuality.31

For predicted levels of pollutants in surfacewater, the relevant water quality standards forcomparison are standards for clean drinking water(for surface waters used for human consumption)and standards for the protection of fish andaquatic life found in domestic legislation and

(especially if domestic standards are lax or absent)U.S. EPA recommended water quality criteria.32

3.4.2.5 Impacts of surface waterdiversions

Some mining projects propose to alter the courseof rivers, streams, and other surface waters. Forexample, if a river or stream runs above the oredeposit, a mining company may propose divertingthe flow via a pipeline or artificial canal, to gain

access to the ore deposit during open-pit miningoperations.

If a mining project includes a proposal to divertsurface water, then the EIA should include athorough assessment of the impacts. This includeshow the proposed diversion would affect thequality and availability of other surface andgroundwater resources (a diverted stream mightbe a source of groundwater replenishment), andthe aquatic species that might rely on existingconditions in the stream proposed to be diverted.

31 World Health Organization (2006) Guidelines fordrinking-water quality, third edition, incorporating first andsecond addenda. http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/32 United States Environmental Protection Agency (2005)National Recommended Water Quality Criteria. http://www.epa.gov/waterscience/criteria/wqctable/
http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/



3.4.3 Impacts on air quality

Air quality impacts of a mining project are notlimited to the mining concession area. Assessingpotential impacts requires examining a largerregion, including adjacent lands. The followingfactors must be considered:

How are the areas of direct and indirectinfluence of the project defined?

Does the study include documenteddata of the magnitude and direction ofwinds?

What information is included to supportstatements about the dispersion of airpollutants?

The figure below shows an example of theextension of an air basin (compared to awatershed), the location of a proposed project,and areas with different use categories. Theextension of an air basin could be significantlylarger than the proposed project area.

Air quality affects human health, wildlife (plantsand animals), and the water quality in large areas.

An EIA for a project that potentially affects airquality should include:

1. Identification (what kind?) and estimatedamount of air pollutants that would be producedduring all stages of the project.

2. Estimated amount and the effects caused byparticulate matter that will be produced duringexcavations, blasting, transportation, wind erosion(more frequent in open-pit mining), fugitive dustfrom tailings facilities, stockpiles, waste dumps,haul roads, and infrastructure construction.

3. Identification (what kind?) and estimated

amount (how much?) of gases released asemissions from the combustion of fuels instationary sources (ore processing facilities, maincamp, energy generators) and mobile sources(vehicles, equipment, mobile campsites) andblasting.

The following is a list of common potentialemission sources:

Gas exhaust from equipment used inperforation, loading, and transportation ofmaterials

Gases from explosives used in blastingoperations

Dust from excavation, loadingmaterials, and other operations in anopen-pit mine

Dust from grinding and segregation of

materials

Sulfides, hydrocarbons, and othergas emissions from vents in undergroundmining operations

Gas emissions from drying operationsin ore processing (drying of pulp and/orsediment materials during ore processing)

Fugitive emissions during oreprocessing (uncontrolled leaks in

equipment such as valves, pump seals,and others that enter the air without goingthrough a smokestack and is not routed toa pollution control device)

The impacts analysis section of the EIA mustintegrate the baseline data (environmentalconditions before the project) with the assessmentof potential impacts on air quality in all project

California Department of Transportation (2008) Guidance for pre-parers of Cumulative Impact Assessments. http://www.dot.ca.gov/

ser/cumulative_guidance/defining_resource.htm

Water Quality

(watershed)

Air Quality

(air basin) Farmland

Endangered Species Habitat

Proposed

Project


25/60Chapter 3

phases. The assessment must consider theinfluence of industries already existing in theproject area (and area of influence), relevantmeteorological data (trends of wind direction) andthe impacts of particulates and gas emissions onwater, wildlife, soil, and human health.

The EIA should include estimated amounts of air

pollutants, identify the most significant pollutants(particulates, gas emissions from stationary andmobile sources), and include modeling studiesand dispersion analysis of these pollutants.33

Sometimes air pollutants interact with each other,creating what are called secondary pollutants(e.g., ground level ozone and particulate matterformed from gaseous primary pollutants). EIAsusually present rough estimates of the percentage

of air emissions generated by each source.These values must be considered with baselineinformation and meteorological data to assess thedispersion of air pollutants.

3.4.4 Impacts on global climate

Large-scale mining projects have the potentialto alter the global carbon budget in at least thefollowing ways: (1) Lost CO2uptake by forests andvegetation that is cleared in order for mining to

begin; (2) CO2emitted by machines consumingfossil fuels that are involved in extracting andtransporting ore (e.g., diesel-powered heavyvehicles); and (3) CO2emitted by the processingof ore into metal (e.g., by pyro-metallurgicalversus hydro-metallurgical techniques).

The impacts analysis section of the EIA shouldinclude quantitative estimates of each of the abovethree ways a mining project could potentially

affect the global carbon budget. Quantitativeestimates of the second two components shouldbe relatively simple projections, based onexpected rates of fossil fuel consumption.

A quantitative estimate of the first component willrequire a more complicated, site-specific analysis

33 An EIA must include references of the methods used topredict impacts of the project in the air quality such as computermodeling analysis of the dispersion

of the CO2uptake rates by local forests that willbe impacted by the proposed mining project. Thisanalysis is essential because for many proposedmining projects in tropical areas, lost CO2uptakeby forests and vegetation would be the largestfactor determining the projects potential impacton the global climate.

3.4.5 Impacts on ecologicalprocesses

It is useful for analysts to begin their evaluationby investigating discrete ecological processes.There are 10 ecological processes that effectivelycapture ecosystem functioning and should beevaluated for adverse effects:

1. Habitats critical to ecological processes

2. Pattern and connectivity of habitat patches3. Natural disturbance regime4. Structural complexity5. Hydrologic patterns6. Nutrient cycling7. Purification services8. Biotic interactions9. Population dynamics10. Genetic diversity

Loss and degradation of forest habitat is commonto many projects. While forests have beenrecognized as habitat for wildlife species, thevalue associated with different forest types hasonly recently been considered. Specific forestcommunities, particularly old-growth stands,support sensitive species and ecological processesthat cannot be sustained in other forest types.

The degree of impact caused by miningactivities varies both within and among the

phases of mining projects and the differentkinds of activities. The level of impact isdetermined both by the intensity and extent ofthe activity, and by the specific type of impacton the habitat of concern. The impacts tohabitats, and to their values and functions, fallsinto three general categories: (1) Destructionof habitat, (2) Fragmentation of habitat, and(3) Degradation of habitat.



The nature of these impacts depends onthe specific stress created by each activity.In most cases, a single activity will include

several stressor processes that impact habitat.For example, the activity of opening a miningpit includes removal of vegetation, erosionand sedimentation of nearby streams, anddisturbance from noise and human activity.

The major stressor processes affecting habitatsinclude the following: Vegetation removal;Erosion, sedimentation, and soil compaction;

Acidification; Contaminant toxicity; and Noiseand visual disturbance.

These stressor processes can result in thefollowing effects on habitat: Direct mortalityof resident specie; Physiological stress anddecreased reproduction; Disruption of normal

behavior and activities; Segmentation ofinterbreeding population; and Modifiedspecies interactions.

At greatest risk are the following groups ofspecies: large terrestrial mammals, bats, hole-and ground-nesting birds, amphibians, snails,trees, herbs, grasslands, freshwater streamorganisms, river fishes and mollusks, andaquatic vegetation.34

3.4.5.1 Impacts on vegetation and soilquality

Mining projects can contaminate soils over a largearea, potentially affecting nearby agriculturalactivities. Spills and leaks of hazardous materialsand the deposition of contaminated windblowndust can lead to soil contamination. High levelsof arsenic, lead, and radionuclides in windblowndust usually pose the greatest risk.35 Theimpacts analysis section of the EIA should includequantitative estimates of how the deposition ofcontaminated windblown dust could elevate

34 United States Environmental Protection Agency (1993)Habitat Evaluation: Guidance for the Review of EnvironmentalImpact Assessment Documents. http://www.epa.gov/compli-ance/resources/policies/nepa/habitat-evaluation-pg.pdf35 MINEO Consortium (2000) Review of potential envi-ronmental and social impact of mining http://www2.brgm.fr/mineo/UserNeed/IMPACTS.pdf

levels of soil contaminants and impact nearbyagricultural activities.

3.4.6 Impacts on wildlife

The impact analysis section must provide clear,big picture information of the aquatic andterrestrial ecosystems and wildlife species, andhow these would be affected by the miningproject. This section must also contain referencesto the national and/or international legal bodiesprotecting species or providing frameworksregarding their status.

What to look for in the wildlife impactanalysis section

Changes in natural vegetation

Disturbance of aquatic life, river, streams,lake alterations Changes in species population Species relocation Changes in birds, fish, and mammal foodweb nutrient cycling Threatened species evaluation Effects on migratory birds, mammals, fish Impacts on breeding areas and otherconsiderations regarding species reproduction Scope of the areas of analysis (should

consider not only the mining concessionarea but other potential areas of direct andindirect influence)

Key questions in the valuation of impactassessment on wildlife

Has the impact analysis sectionconsidered substantial adverse effects,either directly or through habitat

modifications, on species identified assensitive or special status species in localor regional plans, policies, or regulations?

Does the section provide a rigorousanalysis of the adverse effects onriparian habitat or other sensitive naturalcommunities identified in local or regionalplans, policies, or regulations?
http://www.epa.gov/compliance/resources/policies/nepa/habitat-evaluation-pg.pdfhttp://www.epa.gov/compliance/resources/policies/nepa/habitat-evaluation-pg.pdfhttp://www2.brgm.fr/mineo/UserNeed/IMPACTS.pdfhttp://www2.brgm.fr/mineo/UserNeed/IMPACTS.pdfhttp://www2.brgm.fr/mineo/UserNeed/IMPACTS.pdfhttp://www2.brgm.fr/mineo/UserNeed/IMPACTS.pdfhttp://www.epa.gov/compliance/resources/policies/nepa/habitat-evaluation-pg.pdfhttp://www.epa.gov/compliance/resources/policies/nepa/habitat-evaluation-pg.pdf


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Does the analysis consider long-termand cumulative substantial adverse effectsduring all the mining project cycles?

3.4.7 Social impacts

Large-scale mining projects can cause severeand even permanent social impacts. Changes

in the physical environment, the presence ofhundreds of workers, the building of new accessroads, increased demands on services, changesto land use, access to water, and environmentalcontamination can permanently affect localpeoples lives.

Most EIA guidelines require a social impactanalysis. Social impacts can differ substantially,depending on the duration of the project, thelocation of populated areas in relation to theproject area, and potential mine expansion plans.Factors that should be included in the socialimpact analysis are:

Characteristics of local populations in the projectarea and areas of influence: population location, agedistribution, population growth rate, and ethnic groupcomposition

Relevant information about access to education andhealth services

Sanitation

Development trends (some communities havecommunity life plans and/or local development plans)

Employment and income

Social-economical stratification

Housing (infrastructure, number of houses)

Land use and land property

Presence of indigenous communities, customary landuses, territorial rights

Relevant health data (most prevalent diseases,causes of death)

Access to information and knowledge about theproject, attitudes towards the project

Infrastructure (roads, transportation)

Migration

Rural/urban population distribution

Urban development trends

What to look for in the social impactassessment

The social impact assessment should considerbaseline information related to at least the fourfollowing areas:

1. Changes in access to and power over local

resources (land, water). Increased competitionbetween local people and productive activitiesfor energy, basic services (health, education,sanitation), and access to water resources.

2. Changes in the characteristics of a population(size, composition, traditions, productive activities)

3. Divergent perceptions between decision-makers, the mining company, and local people

about the distribution of economic benefits andsocial/environmental costs of a large miningoperation.

4. Land (property), land use.

Involuntary relocation of a population is a majorsocial problem. In this case, the EIA must includedetailed information about compensation,relocation plans, alternative relocation sites,and information about conditions that would

guarantee people the same quality of life.Another special situation is when areas have littleapparent presence of human activity, but are usedby local people for hunting (not recreational),fishing, and gathering wildlife products necessaryfor their subsistence and livelihood.

Key questions in the valuation of socialimpacts

How is land use and access toenvironmental resources (land, water)valued?

Does the analysis consider changes insubsistence and income? How does thestudy assess short, medium, and long-termeffects on local population income and thelocal economy?



What sources are used to support thesocial impact assessment? Did the studyuse surveys? Who participated in thesurveys? What questions were asked?How were the questions developed?

Has the study included the concerns oflocal people?

If the study mentions surveys andinterviews, were people informed aboutthe use and purpose? What methodswere used? Is the population samplerepresentative?

How are the positive and negativefindings described?

Does the social impact assessmentconsider long-term impacts (including post-

closure)?

3.4.7.1 Cost-benefit analysis

Some laws and/or mining industry guidelinesrequire an EIA to contain a cost-benefit analysis.There are different opinions about what shouldbe included in a cost-benefit analysis. Typically,a cost-benefit analysis means the economiccost-benefit, but the definition has expanded to

include the social cost-benefit and some EIAshave sections dedicated to this. Socio-economiccost-benefit analyses explore the relationshipsbetween socio-economic benefits of mining (jobs,infrastructure, land compensation, royalties, taxrevenue) and the social cost of environmentaldamage to quality of life.

3.4.8 Impacts on public safety

3.4.8.1 Dam break analysis

Some EIA guidelines do not require an analysis ofthe impacts of a failure of a tailings dam (dambreak analysis), despite the major risks and oftenirreversible damage this poses to the environment

and public health.36 In most tailings damfailures, mine tailings liquefy and flow substantialdistances, with the potential for extensive damageto property and life. To assess the potentialfor damage in the case of a dam break, it isnecessary to predict the characteristics of the flowand the possible extent of flood movement.37

According to Danihelka and Cervenanova,38 themost common causes of mine tailings dam breaksare:

Inadequate mine tailings management

Lack of control of hydrological system

Error in site selection and investigation

Unsatisfactory foundation, lack ofstability of downstream slope

Seepage

Overtopping

Earthquake

Does the impact analysis section include a riskanalysis of tailings dams? If the answer is no,local people can request that a tailings dam riskanalysis be included. If the answer is yes, payattention to the following issues:

Dam stability, infrastructure and designconsiderations

Does the analysis consider the influenceof weather conditions (rain, snow, freeze)?

Does the analysis consider earthquakesand induced seismicity factors?

36 United Nations Environmental Programme and Interna-

tional Commission on Large Dams (2001) Tailings Dams, Riskof Dangerous Occurrences, Le