Tailings storage facilities and environmentally sustainable mining.

Erica SchoenbergerDepartment of Geography and Environmental EngineeringThe Johns Hopkins UniversityBaltimore, MD21210

30 May, 201514 July, 2015

Introduction

Tailings dam failures account for about three-fourths of major mining-related environmental disasters

(MMSD, 2002a). Though sometimes referred to as “tailings ponds,” a tailings storage facility (TSF) can

occupy several square kilometers of land with dams that can reach in the tens of meters. Tailings dams are not

like water retention dams. They are built in stages as mining and waste production progresses and they are

built usually of mine wastes rather than, say, concrete. Water management is the critical problem. An

adequate amount of freeboard must be maintained, calibrated on maximum likely storm activity. If water is

adjacent to the dam itself, erosional or seepage processes may lead to breaching. The foundational geology is

also a critical issue bearing on the stability of the embankments. TSFs in seismically active or unusually high

rainfall areas are especially vulnerable (McLeod and Murray, 2003).

The technical challenges of storing mine wastes are significant. Nevertheless, I will argue here that the

principal causes of TSF failures are political rather than technical. Much is known within the mine

engineering community about how to manage tailings in an environmentally sustainable way. These

techniques are costly, however. Some companies may adopt them voluntarily. It seems reasonable to

suppose, however, that until the companies generally are held to higher standards of best practice in managing

tailings, we will continue to see catastrophic TSF failures.

Best practice bears on two issues in particular for the purposes of this paper. The first concerns when

and how environmental considerationns – in particular, the design of TSFs – are built into the development

process. The second concerns the actual techniques involved.

I will show that when mining companies are held to the highest standards, they can and do meet them.

Whether or not they are held to those standards depends in part on the regulatory environment. How exigent

are the regulations, how comprehensive are they, and how well are they enforced? The answers to these

questions, I will suggest, have in part to do with the influence of the industry in particular jurisdictions

compared with other land-intensive uses, especially as this bears on regulatory capacity and competence.

Second, the social composition of the surrounding population also matters. Local populations with political

and financial resources will have a much greater chance of escaping environmental disasters than those

without such resources.

In this paper, I will explore the histories of three mines. Two of them suffered major TSF dam

collapses with widespread and ongoing environmental damage: the Ok Tedi mine in Papua New Guinea

(PNG), and the Mount Polley mine in British Columbia. The third mine – the McLaughlin mine in Northern

California – is a rare success story in which all of the environmental dislocations necessarily associated with

mining were confined on site and, to a significant degree, remediated after active mining ceased. The TSF has

retained its integrity. I have explored the Ok Tedi and McLaughlin mine histories at length elsewhere and will

summarize them briefly here (Schoenberger, 2015). The third case is more recent, dating to August 2014. I

will focus on the construction and maintenance of tailings dams.

What I want to work through in this paper is why the failures failed and why the McLaughlin mine

succeeded at mining in an environmentally sound and responsible way. Because the environmental damages

of mining are closely linked to social harms (through impacts on livelihoods, exposure to environmental toxins

and the like), it is particularly worthwhile getting at the causes of both success and failure in an effort to

determine whether mining can increasingly be done in a way that contains and remediates environmental

harms.

Section two of this paper describes the research method. Subsequent sections (three through five)

describe and analyze the performance of the three mines in question. Section six considers the problems of

TSFs more generally, focusing on what is considered best practice by the engineering community and what

conditions might foster the wider implementation of this knowledge in the design, construction, maintenance

and closure of TSFs. Section seven offers some concluding thoughts.

Research method

This research is qualitative and, in a sense, forensic. It is based on a review of published and

unpublished documents related to the specific cases and to the engineering of TSFs in general. These

documents include technical post mortems of the two failed TSFs. Other information was gathered from

correspondence with and conference presentations of practicing engineers with many decades of experience in

the construction and maintenance of TSFs. Information was also gathered from company websites,

government websites and newspaper accounts.

I have only been able to make one site visit. This was to the McLaughlin mine where I was guided by

the former environmental manager and the current manager of the TSF. One very experienced field engineer

was kind enough to review this manuscript for technical accuracy. Some of my correspondents have preferred

to remain anonymous and I am obliged to respect that request.

Case studies do not allow for statistical validation or generalization. They can, however, shed light on

highly complex situations and possibly provide the grounds for developing testable hypotheses (Schoenberger,

1991).

Ok Tedi

The Ok Tedi is an open pit copper and gold mine in Papua New Guinea (PNG) developed from the

early1980s by a consortium headed by the Australian firm, BHP Billiton. It cost about US$1.4 billion to

develop the mine which sits near the headwaters of the Ok Tedi River in the highlands of Western PNG. Its

waters flow into the Fly River, and thence into the Bay of Papua (see Map 1). The Fly is notable for its

extraordinary biological diversity (Townsend and Townsend, 2004).

Map 1 about here

According to the terms of a 1976 PNG law, the mine developers were required to prepare an

Environmental Impact Statement (EIS). However, the company was only required to spend a maximum of

US$220,000 on this study whose scope was, accordingly, quite limited. A second, government-commissioned

EIS was more thorough, funded at US$1 million (Hyndman, 1988; Townsend and Townsend, 2004).

The critical element here for our purposes is that the second EIS was delivered in 1982, a year after

construction had started. No alternatives to the Consortium’s original design were considered (Townsend and

Townsend, 2004). BHP Billiton had, however, promised the government of PNG that 100% of the tailings

would be contained (MMSD, 2002b). Since the operation generated about 30 million tons of ore and 55

million tons of waste each year, management of the tailings and the waste rock were critical issues (MMSD,

2002b).

A series of disasters hit the mine in 1984, including a large sodium cyanide spill and a smaller

untreated tailings spill. In addition, the still-unfinished tailings containment dam was destroyed by a landslide.

Since then, all the tailings and waste rock have been discharged into the Ok Tedi River and thence into the

Fly, creating a large and still growing dead zone downriver that is likely to reach 2-3,000 square kilometers

(Day, et al., 1993; Hettler, et al,, 1997; Harper and Israel, 1999; MMSD, 2002b; Kirsch, 2003:117-118).

A legal agreement reached in 1996 required BHP Billiton to pay compensation amounting to about

US$500 million and to develop a new tailings containment plan. The company finally concluded, however,

that there was no feasible way to construct a permanent TSF or mitigate the on-going environmental damage,

even if mining were stopped immediately. Indeed, closing the mine would plausibly have increased the

damage. The Ok Tedi and the Fly were naturally alkaline, and the geology around the mine was a mix of

limestone and sulfides. So long as the limestone continued to be discharged with the sulfides, the acid-

generating potential of the sulfides would be mitigated. The potential for mobilizing heavy metals into the

water was, thereby, lessened (Chapman et al., 2000; Kirsch 2002; MMSD, 2002b).

In the end, BHP Billiton transferred majority ownership of the mine to the Papua New Guinea

Sustainable Development Program, Ltd. The government of Papua New Guinea also holds a separate interest

directly (BHP Billiton, 2002).

How did such a disaster happen? The Ok Tedi mine is located in a seismically unstable region in steep

terrain in one of the wettest places on earth – it receives some 10,000 mm of rain a year, often very intense

rain. For this reason, landslides may be expected to occur on almost a daily basis (MMSD, 2002b:H-4). In

that sense, the eventual disaster was not entirely unpredictable.

An analysis by two mining engineers with a combined fifty years experience in PNG, including with

the Ok Tedi mine, is instructive (Murray and Thompson, n.d.). Key elements of this analysis are as follows.

The difficulties of developing on-land disposal facilities in PNG mean that until now riverine or marine

disposal of tailings have been the norm. The steepness of the terrain and the narrowness of valleys severely

limit the available space for TSFs. Rapidly downcutting streams and rivers produce weak and unstable

colluvium deposits; landslides can be set off by high rainfall, earthquakes or with no obvious trigger at all.

PNG is one of the most seismically active zones on earth, with an average of two earthquakes of Richter

magnitude 7.0 or greater each year. The landscape is characterized by extensive development of Karstic

features due to the combination of limestone, high runoff water and the acids produced by abundant rotting

vegetation. Murray and Thompson caution that Karst conditions create exceptional difficulties for ensuring

the integrity of TSF impoundments. Long-term mainenance presents particular problems. They offer a

comparison of the problems of managing tailings in several mining regions including Canada, Australia, Peru

and Chile. PNG ranks the highest in difficulty by a wide margin.

Ok Tedi, it seems reasonable to conclude, could not be mined in an environmentally and socially

acceptable way given the terrain, the geology and the climate. On the other hand, Papua New Guinea is very

poor and it needs the revenues. On the model of carbon offsets or paying American farmers not to grow corn,

one could imagine putting the land in trust once an ore body was identified, indemnifying local groups that

might have gained something from the mining operation (e.g., land rent, employment, social and physical

infrastructure), possibly indemnifying the mine developer, and providing twenty years of virtual royalties to

the government to persuade everyone that they did not actually have to dig in order to benefit. The goal would

be to buy out the whole operation before it starts.

Such an approach could run to billions of dollars so it would not be a trivial effort. Yet the costs of

disasters are also very high. BHP Billiton, after all, walked away from a $1.4 billion investment in the mine

and paid on the order of $500 million in compensation to local residents and other remediation steps as part of

the legal settlement (Kirsch, 2003).

Such an approach is not unheard-of. In post-apartheid South Africa, permission to mine a rich titanium

source in an ecologically fragile area was denied and the area was designated a World Heritage Site (MMSD

2002c). IRMA – the Initiative for Responsible Mining Assurance, a multi-sector body that is developing best

practice standards for all aspects of mining – also recognizes that in some cases the best option will be no

mining and acknowledges that additional steps need to be taken to ensure that less responsible operators do not

step in subsequently.i

McLaughlin

The McLaughlin Mine in California was contemporaneous with Ok Tedi, with active mining running

from 1985 to 2004.ii McLaughlin was developed by the Homestake Mining Company (now owned by

Barrick) headquartered in San Francisco. The mine is located a few hours north of San Francisco, east of the

Coast Ranges, and its operations touch on three counties: Napa, Lake and Yolo (see Map 2).

Map 2 about here

In 1985, Napa County hosted an immensely valuable wine industry. Along with neighboring Sonoma

County, Napa is the center of premium wine production in the US, with output worth some US$5 billion in the

mid-2000s. It was just in 1983 that the industry had persuaded the Federal Bureau of Alcohol, Tobacco and

Firearms to allow geographic denominations of origin following the example of French regional appelations

(Walker, 2009). Land prices in Napa increased from US$1000 per acre in 1960 to US$40,000 per acre in the

mid-1980s and US$120,000 per acre by 2000. This is the most valuable agricultural land in North America

(Walker, 2009: 185).

The profits of the industry and the value of the land are directly related to the fact and the perception of

environmental quality. An accidental release of contaminated tailings – even if they never touched any

grapevines – could be expected to inflict severe damage on the industry. Moreover, the San Francisco Bay

Area has been on the leading edge of the environmental movement in the US. People in the region are acutely

attuned to issues of environmental quality (Walker, 2009). A mine processing roughly 7,500 tpd – a moderate

scale for a gold mine but hardly invisible – would not be an obviously welcome land use. Nevertheless, after

exhuasive review, the mine project was permitted with the support of local environmental groups.

Today, most of the land once deeply scarred by the McLaughlin mine’s operations is part of a nature

reserve and environmental research station managed by the University of California at Davis. The discharge

of toxic substances into local streams is zero and was throughout the life of the mine. The excavated earth was

stockpiled for the life of the mine and has been used to cap and immobilize contaminated tailings and to

resurface and revegetate the surrounding landscape. As described below, the waste dumps were constructed to

isolate and entrap acid producing waste so they are not leaching acids into the adjacent settlement ponds and

creeks. The TSF is fenced off and is still managed by the company.iii

How did the McLaughlin mine succeed in containing and mitigating its environmental presence? The

answer involves a mix of regulatory exigency, management style, and the serendipity of the coming together

of a like-minded group of people from a variety of professional backgrounds – not always mining related –

who rethought what a mine could look like and how it might relate to the land and the community around it.

The geology – highly impermeable – was also helpful (see Schoenberger, 2015 for more detail).

Mining in California is big business, but the state’s economy is enormous (if the state were a separate

country its economy would rank eighth largest in the world) and is dominated by manufacturing, services,

finance and – not at all incidentally – agriculture. Mining companies lack the political clout they can wield in

other places and are less able to influence the terms of regulation and enforcement.

Mines in many jurisdictions must present an environmental management and restoration plan before

they are allowed to go ahead. Several things distinguished the McLaughlin mine in this respect. The first was

that the environmental compliance and reclamation plan was built into the design of the mine from the outset.

The developers did not design the ideal mine from an economic point of view and then add environmental

mitigations to it. It is worth emphasizing the contrast with the Ok Tedi mine where the main environmental

impact study was only produced a year after construction on the mine started.

The company went to unusual lengths to demonstrate its commitment to environmental health to its

prospective neighbors. It financed a 30,000 acre inventory of plants prior to starting up and the original

footprint of the waste dump was shifted to avoid a patch of a rare native plant. A colony of bats that lived in a

cave in the path of the mine was successfully relocated. There was a plan from the outset to segregate and

stockpile the topsoil excavated from the mine and from a reservoir built for water management purposes. This

would be used for capping the TSF and restoring the surrounding landscape. In addition, before mining

commenced, the company cleaned up an old mercury mine nearby.

Second, as the mining progressed, operating plans were continually modified to deal with unexpected

environmental issues. For example, early testing had indicated that a very small proportion of the waste rock

was likely to generate acid drainage and that this would be neutralized by the carbonates in the waste. Once

mining was underway, it became clear they faced a much bigger potential acid drainage problem. To deal

with this, they devised a system in which acid-producing waste was identified at the mine face and mined

separately from non-acid producing waste. The different categories of waste were then arranged in the waste

dumps in such a way that the acid-producing waste was encapsulated on all sides with low-permeability clays

and buffered by non-acid producing materials (Krauss, 2002). Among other things, this suggests that a rigid

regulatory approach that specifies how to develop the mine is not the best option. The regulations arguably

should bear on outcomes, giving the developer the flexibility to adapt as conditions change.

Third, the original plan of the mine in some important ways exceeded the regulatory requirements.

The regulations, for example, required that the TSF be able to withstand a 100-year, 24-hour storm without

breaching. At the same time, other regulations required zero discharge to adjacent land and watercourses.

The environmental manager concluded that these regulations were incompatible: guaranteeing that the TSF

could withstand the 100-year storm would not guarantee zero discharge. The TSF in fact was constructed to

withstand a 1,000 year, 72-hour storm (Krauss, 2002 and personal communication, 2009).

The TSF is the last site with active reclamation still ongoing and remains under the management of the

company. It is surrounded by berms, flanked by diversion channels to redirect runoff water away from the

tailings. The winter rains create seasonal wetlands around the basin’s periphery which have been recolonized

by wind-blown volunteers – cattails and tules – and plantings of willow and cottonwood. In the winter, these

wetlands are crowded with waterfowl. The mine has lived up to its commitment of zero discharge to the

surrounding area.

Mount Polley

Mount Polley is an open-pit copper-gold mine located in South Central British Columbia, near Lake

Quesnel. It was developed, beginning in 1997, by British Columbia-based Imperial Metals Corporation. The

mine processed about 20,000 tons per day (tpd). Run-of-mine ore was crushed on-site and put through a

closed-circuit flotation separation process. After dewatering, the concentrate was shipped overseas – mainly

to Asia – for smelting.

Map 3 about here

The tailings dam at Mount Polley breached on August 4th, 2014, flushing some 25 million cubic meters

of water, tailings solids and construction material into Polley Lake, Hazeltine Creek and thence into Lake

Quesnel.iv This is the largest tailings dam collapse in Canadian history and among the largest in the world

during the last fifty years. Mining has ceased. The company’s market value fell from C$1.26 billion to C$760

million in the immediate aftermath of the breach. It has since recovered to about C$841.v

Map 4 about here

The regulatory environment in British Columbia

Sub-surface mineral rights in British Columbia are owned by the provincial government (Stano and

Lehrer, 2013). The government awards rights to develop mines according to the terms of a law dating to 1859

and largely unchanged since then. Eighty seven percent of the land surface of the province – including

privately owned land – is classified as ‘mineral lands’ where mining essentially trumps all other uses and

interests. The “free entry” mineral tenure system requires little to no prior consultation with any other

stakeholders including First Nations, landowners and local governments. So long as the proper steps are

followed, the government has no authority to deny a lease application, no matter the competing land uses, the

technical or financial capacity of the applicant or the applicant’s past environmental record (Stano and Lehrer,

2013).

The development and operation of a mine do have to accord with environmental and safety regulations

with fines potentially amounting to C$100,000. However, no penalties have been imposed on anyone by the

Ministry of Energy and Mines (MEM) since 1989. The Environment Ministry has issued about a dozen

citations in the past eight years. The current Liberal provincial government has sharply reduced its oversight:

the annual number of geotechnical mine inspections since 2001 has fallen to less than half the number of

inspections carried out during the 1990s. In 2001, MEM employed five geotechnical engineers. Between

2004 and 2011, that number fell to one, although it is now back up to three (Hoekstra, 2014).

The socio-economic context is also dramatically different from the California case. The Cariboo

Region, in which the Mount Polley mine is located, is sparsely populated, relatively poor, and highly

dependent on natural resource extraction industries. First Nations account for a relatively high share of the

region’s population.

First Nations in principle have a right to exercise informed consent about projects that may affect their

land. Under B.C. law, they have a 30-day period to review proposed mining projects. Given how long the

planning and development process is for mines, one might conclude that a 30-day response period is

unnecessarily restrictive. In any case, the right to block proposals is only relevant to the small share of First

Nations’ lands that are covered by formal treaties with the Crown (Stano and Lehrer, 2013). It is also the case

that First Nations have few good prospects for economic development and have looked to mining as a critical

source of revenue. In general, the guiding principle has been non-opposition to proposed developments,

provided that appropriate conditions are upheld (Stano and Lehrer, 2013).

Thus, although mining companies are encouraged to negotiate an “Impacts and Benefits” agreement

with affected First Nations groups, this is not mandatory and does not have to be achieved before the mine is

developed. Imperial Metals has been developing a second mine in the northwest part of B.C. – the Red Chris

mine. At the time of the Mount Polley disaster, Red Chris was reportedly “in the final stages of construction

and one of the last items Imperial needed to check off was a benefits agreement” with the First Nations

(Penner, 2014).

Why did the breach happen?

The government of British Columbia commissioned a report from a panel of experts to investigate why

the disaster occurred. The Report on the Mount Polley Tailings Storage Facilities Breach (referred to

hereinafter as The Report) was published on January 30, 2015 (IEEIRP, 2015). Here is a brief summary of its

findings.

1. Inadequate geotechnical analysis: The design engineering firm, Knight Piésold, failed to

detect critical characteristics of the soils underlying the proposed tailings dam. It appears the testing

did not probe sufficiently deeply and the instrumentation built into the dam to provide continuing

status information was inadequate.

2. Inadequate design:

a. The water balance model was based on average climatic conditions which could not

accommodate exceptionally wet years.

b. The design criteria for the tailings beach – the solid surface above the waterline and against

the embankent – were inadequate at 10 meters width and, in any case, were never achieved.

c. The design proceeded on an ad hoc basis, a year at a time. The tailings dam was contingent

on the weather, mine operations and the water balance. The TSF had already experienced a near-

overtopping episode in May of 2014.

3. The as-built dam differed in critical respects from the design criteria that had been

approved by the Ministry of Energy and Mines (MEM):

a. Stage 2 of the dam was constructed in an entirely ‘upstream’ configuration rather than the

planned ‘centerline’ configuration. An upstream dam is built towards the interior of the storage facility

so that the embankment crest moves steadily inwards. A downstream dam is built up on the outside

face with the embankment crest moving outwards. A centerline dam is built along the middle.

Upstream dams are cheaper to build and, of the three designs, considered the least reliable. They are

banned in countries such as Chile and Peru where there is a lot of seismic activity. Downstream dams

are most expensive and inherently the most reliable (see USEPA, 1994; State of Victoria, 2004).

b. The steepness of the embankment at the breach site was substantially greater than planned:

1.3H:1V rather than 2.0H:1V. Planned buttresses were not in place. The reason for this is that the

embankments were being built with mine waste which wasn’t being produced rapidly enough to

construct them to design.

c. The design called for a ‘tailings beach’ of at least 10 meters width. This was

never achieved. The result was twofold. The dam was retaining a lot of water as well as tailings. As a water-

retention facility, a different design for the dam would have been called for altogether. The second

consequence was that water was in direct contact with the embankments, weakening them.

d. It can be noted that the Engineer of Record (EOR) resigned in 2011 and responsibility was

transferred to a new EOR which undoubtedly added to the complexities of the situation. In its letter of

resignation, Knight Piésold noted that “The embankments and the overall tailings impoundment are

getting large and it is extremely important that they be monitored, constructed and operated properly to

prevent problems in the future.”vi It seems reasonable to suppose that the low-key language masks a

sense of considerable urgency and that this would have been apparent to the recipient and to the Chief

Inspector of Mines who was copied on the letter.

4. Inadequate regulation and regulatory supervision:

a. MEM was chronically short of staff during much of this period. The Manager of

Geotechnical Engineering position was vacant from 2009 to 2011, during which time there were no

inspections of the mine.

b. MEM by statute has limited influence over the design. The analysis and design are the work

of the EOR, not the Ministry; inspections by MEM personnel will not unearth problems the EOR has

not detected

c. MEM issued a “Departure from Approval” notice concerning the tailings beach, but the

problem was not rectified

d. MEM repeatedly urged raising the factor of safety (FOS) from 1.3 to 1.5, yet the mine never

exceeded an FOS of 1.3 and for some periods of time ran below even that figure.

The expert panel calculated that, based on historical experience and the number of active tailings dams

in British Columbia, there is roughly a 1-in-600 chance of a tailings dam failure in any given year. This

translates to an average of two failures every 10 years.

The Report provided some general observations about mining practice which are worth considering. It

recommends integrating tailings planning into mine planning: “This has not been common practice in the

industry to date…” (p.121). It notes that “Tailings management is often not a core skill in many mining

organizations” (p.125) and that tailings storage facility design studies submitted for regulatory approval “are

often lacking in detail regarding the factors that need to be considered in assuring safety of the facility.”

(p.126). As late as 2005, an account of the 1994 Merriespruit tailings dam collapse in South Africa was able

to conclude that “The appropriate construction and safe operations of tailings dams is now seen as an

important management responsibility by the mining industry” (Van Niekerk and Viljoen, 2005, emphasis

added; see also Gowan, 2006).

All of this implies that one of the most environmentally salient aspects of mining has long been

routinely handled in a worrisomely ad hoc manner. It will be recalled that the McLaughlin mine integrated

environmental management planning into the design and development process and that the design of the mine

was altered to accommodate unexpected environmental conditions.

Given all these factors, it is hard to avoid the conclusion that the Mount Polley tailings dam failure was

an accident waiting to happen. Further, without serious modifications to the design and construction process

and the regulatory and institutional structure, we can anticipate additional catastrophic failures in the future in

Canada and, plainly, elsewhere.

What to do with tailings

The Report suggests that best standards of practice for tailings dams now require independent technical

reviews by a panel of experienced engineers that meets at least annually. One would wish also to require an

annual report from the EOR on what had happened during the year in terms of design, construction,

instrumentation and the like, and that this report be backed up by a report from an independent engineering

firm on the dam’s status. The Mineral, Mining and Sustainable Development Project in fact recommends

independent peer review of TSF designs and regular independent audits of operations. Further, it recommends

a process of international certification of the designers of TSFs (MMSD, 2002a; see also State of Victoria,

2006).vii

The main geotechnical cause of TSF failures is water in the wrong place, whether causing overtopping

of the embankment or foundation failure (Gowan, 2012). Within the mine engineering community, a great

deal is known about how to manage tailings safely Figure 1, provides a consulting mining engineer’s

overview of the principal options available and likely to be more or less acceptable in the future. The riskiest

and most harmful forms of storage – upstream dam raises and riverine or lake deposition – are marked as

questions. In a more demanding and effective regulatory environment, we might conclude, these would no

longer be acceptable.

Figure 1 about here

I’d like to look more closely at just one approach that is growing in importance: filter-pressed dry stack

tailings. This technique involves vacuum or pressure filtered elimination of water to a level of roughly 70-

80% solids compared to 30-50% in conventional storage (Murphy and Caldwell, 2012; Gowan, 2006; AMEC

Earth and Environmental, Inc., 2006; MMSD, 2002a; MiningWatch Canada, 2009).

The benefits of this approach are considerable, especially where water conservation is important. Drier

tailings lead to less loss of water to the environment in general (e.g., through evaporation) and are not likely to

be mobilized even in the face of seismic activity. In short, physical failure is not an issue. The dry stack

footprint is typically much smaller than conventional storage. Removing the water also reduces the propensity

for chemical reactions, especially important in the case of sulfidic minerals, prone to acid production. Dry

stacks do not require impoundment dams and long term management of tailings ponds. This reduces potential

liability costs. Further, reclamation can begin rather early in the life of the mine. In sum, the risks to the

environment are substantially lowered and, as a side benefit, the costs of rehabilitation may also be lower.

The principal technical issues for dry stack storage include surface and groundwater management, dust

and erosion control. The principal drawback is the cost.

Conventional storage is still considerably cheaper.

Wet storage of tailings requires a dam that will last literally forever. During the life of a mine and for

some plausibly lengthy period after closure, one can imagine that regular inspection and maintenance would

maintain the dam’s integrity. If these safeguards cease, the dam will eventually fail. The threat to people,

property and the environment is not on a scale of radioactive waste storage, but the length of time proper

management is required is roughly the same.

Conclusion

The technical demands of safely sequestering and storing tailings are many and varied. It takes a high

degree of engineering training and insight to get it right. But it is possible to do.

Many in the mine engineering community are working hard to improve their knowledge and skill in

this arena. Nevertheless, whether as consultants or employees, engineers may find themselves under

irresistible pressure from companies to speed up their work, cut costs and cut corners. For those who are

unable to talk back or walk away for whatever reasons, it seems plausible that strong, well-conceived,

consistent regulatory environments would help them do what they know is right. They would be able to insist

on the practice not because it is good, but because it is necessary.

In at least some quarters within the mine engineering community, there is a clear sense that

environmental issues need to be addressed in the original feasibility and design studies of any mining project

rather than added on to a design that is solely concerned with economics. This is especially true for managing

wastes (Hart and Bolger, 2005; IEEIRP, 2015). Comments from a keynote address at a mine waste

management conference in 2005 are especially pertinent and worth quoting:

The technology is here now to make dry [tailings] disposal a reality. Yet the industry continues

to pursue unsustainable disposal practices such as riverine disposal and tailings dams. Tailings

dams fail on occasions but the argument is always made that it is too expensive to deal with a

dry disposal technology up front in most operations…. (Hart and Bolger, 2005, p. 6).

They add that the mining companies are persisting in unsustainable practices in part because the gap

between the technical people and the people who ultimately make the decisions is so great. For this reason,

best practice technologies are not being widely implemented even though they are well known within the

technical community (Hart and Bolger, 2005).

Will more stringent regulatory environments in some areas tend to push mining investment to laxer

regions? It would not appear so. The Fraser Institute is a libertarian-leaning think tank based in Vancouver

that conducts an annual survey of senior managers and executives in the mining industry (Jackson and Green,

2015). Their goal is to develop a picture of the pure mineral potential of 122 jurisdictions around the world (in

its latest survey) and the mining community’s perception of the policy environment in each of these

jurisdictions. This latter concerns the degree to which the policy environment encourages or discourages

investment in particular places. Survey questions place particular emphasis on the uncertainty and the

onerousnous of regulations concerning the environment, responsibility to local stakeholders, taxation and trade

barriers, all thought to be a disincentive to investment. It also assesses the legal environment, political

stability, infrastructure and labor supplies. A high ranking means that the regulatory environment does not

discourage investment.

The policy rankings do not tilt toward developing countries with lax regulatory regimes as one might

have expected. Finland is first. Botswana is the highest ranking developing country at #13 and it is widely

regarded as having its act together in terms of governance. British Columbia is ranked 42 and California is 48.

Papua New Guinea is ranked 100 and Honduras is last.viii

It is difficult to untangle the precise meaning of these rankings, especially since they are based on an

index that amalgamates such divergent ratings as tax burden and labor supply. In addition, states or provinces

have equal status with entire countries. But the results are of interest if only because the Institute is so

demonstrably in favor of the unfettered free market. Despite what one might imagine are its fondest hopes,

experienced mining people weight the quality of the mineral deposit at 60% and the policy environment at

40% in terms of influence on investment decisions. Here it appears evident that developed-country regulatory

environments – albeit not as effective as one might like – are not a systematic disincentive for investment. If

the resource is there, that is where the companies will go. In fact, it may be that institutional strength, good

infrastructure and political stability are much more important attractions for investment than many suppose.

If we set the question of TSFs in this context, several issues can be drawn out. One is that an exacting

regulatory environment is not necessarily a barrier to investment in the mining industry. Second, an exacting

regulatory environment can produce good environmental outcomes, as the case of McLaughlin illustrates. In

short, well-designed regulatory structures and effective enforcement plausibly will cause the mining industry

to adopt improved practices and so internalize its environmental externalities. This means that marginal ore

bodies will not be developed. It also means that mining will not take place in areas that are environmentally

fragile or stressed and where the cost of protecting the environment makes the venture insufficiently

profitable.

A further point is that mandated peer review of TSF design and operation could play an important role

in moving the industry in the direction of environmental sustainability. Peer review, it seems to me, is unlike

external audits of garment factories in such places as Bangladesh or Samoa which have well-known

weaknesses.ix It is done by experts who really understand the implications of technical decisions. If it is done

before the mine plan is permitted, it will help us avoid more environmental catastrophes. If it is continued

periodically while the mine is in development, in operation and during closure, it will also help us avoid more

environmental catastrophes. If the designers and developers know that they will be peer reviewed, it seems

plausible that they will strive to do their best work so as not to be embarrassed. If they do build a TSF that

fails catastrophically, it will presumably be easier to determine liability.

Further, peer review is something that can be documented. The campaigns to encourage consumers to

boycott resources mined in socially and environmentally unsustainable ways do not give the consumer that

much to go on. If entire countries adopt regulations requiring peer review, then we have a much better chance

of distinguishing sustainably produced from unsustainably produced minerals.

Getting to a point where adequate regulatory capacity and peer review are a normal feature of mining

is a political problem, not a technical one. That may be more promising than it sounds. It gives people

concerned about the social and environmental damages associated with modern mining something concrete to

promote and to monitor. It gives the companies something concrete to offer when they talk about the ‘social

license’ under which they operate. The main limiting factor might well be the number of potential peer

reviewers that exist at present.

Three case studies cannot provide a comprehensive picture of industry practices. Nevertheless, the

lessons that emerge from them are illuminating. The technology is advancing in ways that promise

considerable improvement in the management of mine wastes. But this will not happen in the absence of

significant political change.

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Figure 1

Tailings Storage Options and Possible Trends of Permitted Approaches

Storage facilities with impoundment dams

Upstream dam raises – likely to be phased out (?)

Greater reliance on centerline and downstream dam raises

Water storage dam design allowing water to pool at the dam face

Geomembrane-lined dams and impoundments

Thickened or paste tailings (smaller perimeter dam)

Disposal in lakes and streams – likely to be phased out (?)

Deep-sea disposal – if no impact to sea life can be demonstrated (?)

Waste pile co-disposal

Underground or open pit mine backfill

Dry filter-pressed stacks

Source: Adapted from Breitenbach, 2010

Map 1

The Ok Tedi Mine, Papua New Guinea

Cartography: Chris Kelley

Map 2

McLaughlin Mine, California

Cartography: Chris Kelley

Map 3

Mount Polley Mine, British Columbia

Source: Google Earth

Map 4

Mount Polley Mine area of damage

i On the home page of the IRMA website, where they state their basic principles, number 7 reads: “We recognize that in certain cases, whether or not there is governmental approval, due to potential impacts or other values or benefits, no mining could be the best option. We seek to advance methodologies that allow such decisions to be made within a sustainable development context. We also recognize that we must pursue solutions that avoid simply leaving the mining of such sites to less responsible operators.” www.responsiblemining.net accessed most recently on 1 May, 2015.ii I am relying in this section on the invaluable set of oral histories conducted by Eleanor Swent, transcripts of which are housed at the Regional Oral History Office of the Bancroft Library at the University of California at Berkeley. iii I was able to visit the mine site and vicinity courtesy of the Donald and Sylvia McLaughlin Natural Reserve and Homestake. My invaluable and very generous guide was Ray Krauss, the Environmental Manager of the mine and the person who devised the idea of converting the old mine site into a nature reserve. Scotty Moore provided a detailed and informative tour of the TSF.iv The mine’s history and operations data are taken from Imperial Metals’ website: http://www.imperialmetals.com/s/MountPolleyMine.asp?ReportID=584863. The figures are taken from Imperial Metals’ website: http://www.imperialmetals.com/s/Mt_Polley_Update.asp?ReportID=671041. Both were accessed most recently on 16 March, 2015. Further information can be found on the BC Ministry of the Environment website: http://www.env.gov.bc.ca/eemp/incidents/2014/mount-polley/ also most recently accessed on 16 March, 2015.v Toronto Stock Exchange, market capitalization figure on 17 March, 2015 from Bloomberg: http://www.bloomberg.com/research/stocks/snapshot/snapshot.asp?ticker=III:CN The stock price is C$11.39, down from a high of C$17.22 on July 9, 2014, just a month before the breach. This raises some questions about whether IMC will have the resources to adequately remediate the site. I don’t have any information on insurance, and I imagine there will be a lengthy legal tangle before the finances are resolved.vi Letter from Ken Brower, Managing Director of Knight Piésold to Brian Kynoch of the Mt. Polley Mine Corporation dated 10 February, 2011. The letter was countersigned by Jeremy Haile, President of Knight Piésold and copied to Al Hoffman, Chief Inspector of Mines.vii State of Victoria, Dept. of Primary Industries, 2006. “Management of Tailings Storage Facilities.” Melbourne: author; Mining, Minerals and Sustainable Development Project, 2002. “Mining, Minerals and the Environment, Chapter 10.” Breaking New Ground: Mining, Minerals and Sustainble Development, Final Report. London: International Institute for Environment and Development.viii Jackson, T. and Green, K.P., 2015. Fraser Institute Annual Survey of Mining Companies, 2014. Fraser Institute, Figure 2, p. 8 available at http://www.fraserinstitute.org/uploadedFiles/fraser-ca/Content/research-news/research/publications/survey-of-mining-companies-2014.pdf accessed most recently on 11 April, 2015. The survey is based on 425 responses.ix The IRMA standards, currently in draft form, must be met for formal certification by IRMA. They specify independent audits by IRMA-trained auditors on a number of counts. Whether this will mandate peer review on technical issues is not clear to me. Their website says: “Certificates will be issued by third-party certification bodies whose auditors are trained by IRMA. To determine whether or not a mine site has met the IRMA requirements, certification bodies will carry out audits of the mining operation. The audit will involve on-site visits, as well as consultations with the mining company employees, workers, union representatives, affected community members and other stakeholders. The certification body will publish a summary of its findings.”http://www.responsiblemining.net/the-irma-process/faqs/#HOWCERT accessed most recently on 1 May, 2015.