Mining, a risk too great for the Clarence River

Is it safe to mine in the Clarence Valley?

If anyone still has lingering doubts about whether mining should be allowed in the Clarence Valley, I suggest they consider the news emerging from western Tasmania. abc.net.au/news/2022-02-05/tasmanian-government-reapproves-mmg-rosebery-mine-lease/100807554

That story involves a copper, zinc and lead mine that has been operating for 80 years, producing toxic waste in the process which is currently stored in two very large tailings dams on the edge of the world renowned Tarkine forest.

Those existing dams will reach capacity within three years, and the owner, MMG, wants to construct a third dam inside the Tarkine, with a massive 285-hectare footprint. Naturally, this has drawn condemnation from concerned citizens and protests have already erupted leading to more than 40 arrests to date.

MMG argues that without the third dam, the mine would be forced to close, which highlights the fact that these toxic waste dumps are destined to remain there forever, and not cleaned up as many believe.

The reality is, the rehabilitation process is a matter of removing water, either by evaporation or reverse osmosis (desalination), leaving the millions of tonnes of accumulated dried sludge, and then covering it with dirt. There may well be some addition of chemicals like Gypsum to neutralise any acid mine drainage, but there is no neutralise he toxicity of heavy metals contained in those dams.

Those dam walls are still the feature that have to safely contain those toxins in perpetuity against seepage, and trust they withstand future extreme rain events, and even earth quakes, and not fail, releasing their deadly contents downstream. Mining companies are supposedly obligated to eventually rehabilitate the site when a mine is closed down. How will this occur in the Tasmanian case? If history is any indication, it probably won’t!

The well-respected Australia Institute, in its report “The dark side of the Boom” (2017) reported that over 60,000 mines had been abandoned across Australia, and found evidence of barely more than 20 that had been closed and relinquished. In fact, their researchers could only find evidence of a handful of successfully rehabilitated mines.

The report points out that “rehabilitating a single mine can cost millions or even billions of dollars”, which probably explains why, in more recent times, so many mines are “moth-balled”, rather than closed permanently, thus avoiding the required rehabilitation.

If mining for copper, gold, antimony, or any other heavy metals gets the go ahead in the Clarence, a similar toxic timebomb could be the legacy facing the valley’s residents in the future. The mountains surrounding the Clarence Valley are among some of the highest rainfall areas in Southern Australia, and this, combined with steep terrain and unstable soils, significantly increases the chances of tailings dam failure.

A case in point…

The valley already has legacy problems from old mines, a fact recently highlighted by the recent release of plans to reopen the Mt Carrington gold mine, just north of the township of Drake, shown on the map by the red asterisk.

Small-scale mining in the Drake area commenced around 1886, with the discovery of rich gold and other mineral deposits in the area, but large-scale commercial mining at Mt Carrington only began in 1976 and ran for just 2 years, only to recommence for 2 more years from 1988 to 1990.

The Mt Carrington mine is outside the Clarence Valley local government area, but well within the Clarence River catchment, the site draining into Sawpit Creek, thence via Timbarra River into the Clarence.

The mine was acquired by White Rock Minerals in about 2010, who have seemingly been waiting for the price of gold to reach a level when reopening the mine would prove financially viable.

The proposal

Details of White Rock Minerals’ plans are sketchy and contradictory, and as usual, the company’s structure appears designed to confuse. All signage at the site directs visitors to “White Rock Minerals” but, according to the project fact sheet provided to us by EMM, the consultancy company developing the project’s Environmental Impact Statement (EIS), White Rock is merely the owner of the exploration and mining licences: The company actually undertaking the exploration and mining is Thomson Resources, “a mining exploration and development company”.

EMM has distributed a fact sheet which explains the plan is to rework and expand three historical open cut pits, and construct a gold processing plant on the site. The fact sheet also details 2 other key components of the plan. They are to; “construct a larger tailings storage facility”, which would encompass the existing dam; and “establish a new waste rock emplacement, to encapsulate any potentially acidic waste rock extracted”.

Before going into details of these key components, we are also told of the benefits that would accrue from reopening the mine, the first of which is “The project would provide an opportunity to address legacy issues from historical mining activities, including acid mine drainage and improved site rehabilitation outcomes”, and the second being, of course, “Economic benefits and employment”!

The “legacy issues” relate to a long history of pollution problems that has plagued the site and you don’t need an engineering degree to see why. For a start, the tailings dam is just that, a dam wall placed across a creek, with multiple in-flow points (see topographical map). The natural creek line can be seen midway along the eastern perimeter.

Note also, the small dam immediately below the main wall. That is there to collect what is known as Acid Rock Drainage, otherwise known as Acid Mine Drainage, a process which is described below.

The reason why White Rock needs to triple the area of the already sizable tailings dam, currently about 400 metres across (see grey shading around the existing dam in the drawn image, top left) is so the dam wall can be raised and extended to completely surround the enlarged lake, which will then allow run-off from the sloping land to the west to be diverted around the dam, and back into the main channel downstream.

The following explains the “legacy issues from historical mining activities, including acid mine drainage”, mentioned in White Rock’s fact sheet.

Acid Mine, or Acid Rock, Drainage (ARD) at Drake

White Rock’s Fact Sheet explains that one key component of their plan is to “establish a new waste rock emplacement, to encapsulate any potentially acidic waste rock extracted”. However, there is not a “potential” for the presence of acid waste rock, it is already a problem on site, with Southern Cross University undertaking testing of a Bauxsol-based Permeable Reactive Barrier for the Treatment of ARD at the Mt Carrington tailings dam in about 2000 (Leon D. Munro, Malcolm W. Clark, and David McConchie).

That report explains: “ARD results from the oxidization of pyrite (FeS2) and other sulphide minerals in the presence of water to form ferric oxy-hydroxides and sulphuric acid (Appelo and Postma 1994; Evangelou 1995). ARD is common wherever waste rock, ore and/or mine tailings are stored and affects most Cu, Pb, Zn, Ni, Mo, As, Au, Ag, and coal beneficiation operations. ARD composition is directly linked to host rock geology and water chemistry, which combine to dictate toxicity. The combination of low pH and a potentially complex suite of metals can also promote synergistic toxic effects (Kelly 1999).

We also know that ARD is a serious problem wherever mining occurs all around the world, as is explained in the following report from the US:
“Construction Materials and Structures S.O. Ekolu et al. (Eds.) IOS Press, 2014 © 2014 The authors and IOS Press. All rights reserved. doi:10.3233/978-1-61499-466-4-1416

“The formation of ARD and the contaminants associated with it have been described as the largest environmental problem facing the mining industry. Contaminated water flowing from abandoned mines is one of the most significant contributors to water pollution. AMD can have severe impacts on aquatic resources, can stunt terrestrial plant growth and harm wetlands, contaminate groundwater, raise water treatment costs, and damage concrete and metal structures”.

The University team reported that: “Various sediment and water surveys of the site have indicated high levels of TCLP (Toxicity Characteristic Leaching Procedure) leachable Cd (up to 18.32 mg/kg), Cu (up to 263.9 mg/kg), Pb (up to 11.42 mg/kg) and Zn (up to 162.84 mg/kg) and similarly poor water throughout the site with high concentrations of dissolved metals, which concentrate during the dry season (Cd – up to 1.7 mg/L; Cu – up to >200 mg/L; Pb – up to 0.12 mg/L; Zn – up to 175 mg/L) (Clark et al 2001; Collins 1994; Maddocks 2000)”. Note: Cd = Cadmium; Cu = Copper; Pb = Lead; Zn – Zinc

The size of the current Mt Carrington tailings dam wall shown in perspective with a person standing atop the structure. The waste rock material used to construct the wall is the source of the current ARD problem

According to the Southern Cross University report, it was during the last mining period, 1988 to 1990, that extensions to the tailings dam wall were started, but not completed. “This resulted in a large quantity of waste and low-grade ore rock being dumped on the lower side of the dam wall as containment material. This exposed rock, rich in sulphide minerals (pyrite, chalcopyrite, chalcocite and sphalerite) is the main source of ARD at the mine (Lin et al. 2002)”.

The reported need to “establish a new waste rock emplacement, to encapsulate any potentially acidic waste rock extracted”, requiring the need to bulldoze about 20ha of forest containing core koala habitat to store this sulphuric acid producing rock, along with another 20ha or so to expand the tailings dam, is just more collateral damage that mining will inflict if allowed to proceed.


What could be impacted in the Clarence Valley if a catastrophic tailings dam failure were to occur?

Firstly, what are tailings?

Rock is mined and crushed to a fine powder to allow processing to remove the minerals. In most cases, 90% to 98% of ore is waste, known as tailings. Those tailings contain naturally occurring substances which are toxic, and also other toxins introduced during processing, commonly in the form of fluids. Therefore, the tailings usually come in the form of a slurry: a fairly even combination of solid waste and water, which is stored in open dams or ponds known as tailings dams.

Rain dilutes that sludge and will threaten to over-fill the ponds, so measures are taken to remove the excess water by evaporation, reverse osmosis (desalination), or other filtration processes which, over time, sees the toxic sludge become more and more concentrated.

Of course, those measures sometimes fail with catastrophic consequences!

What is a tailings dam?

Imagine huge ponds, dams, or holes in the ground, some of the largest man-made structures in the world. Now imagine those pits, each filled with up to 10 billion tons of toxic sludge, waste material from mining.

We need to understand that that toxic ‘time bomb’ will remain there in perpetuity unless, like the 4sq/km Mt Polley mine’s tailings dam, pictured below in Canada, something unforeseen happens and the structure collapses, spilling its billions of tonnes of toxic contents. The Mt Polley mine disaster happened in 2014, because the underlying earth contained a layer of glacial till, that had been missed by the company’s original engineering contractor. Human error invariably plays a part in tailings dam failures!

On average, three of the world’s 3,500 tailings dams fail every year, and the most frequent cause of failure are triggered by extreme rain events.

That rate of failure represents too great a risk for the fragile flood-prone Clarence River catchment, where land slippages are commonplace.

The Clarence River

The majestic Clarence River has the largest catchment of any river on the Australian east coast. It rises on the Queensland border some 260m above sea level, and cascades and meanders along its 394-kilometre journey to the Coral Sea. Along the way it is joined by twenty-four tributaries and countless minor streams, providing opportunities for active and passive recreation, and places for reflection.

It is the life-blood of the community, and has been for tens of thousands of years, providing food and water for the valley’s inhabitants. Today, many tens of thousands of residents, living between Iluka to Boambee depend on the Clarence River system for its drinking water, an essential resource that should never be placed at risk

The Clarence River’s Dreamtime and Cultural Heritage

The Clarence River has great cultural significance for the three nations that have called the Valley home for millennia, the Bundjalung, Gumbaynggirr and Yaegl people. Many islands and features along its banks are sacred or have spiritual significance to indigenous people, and most are familiar with the dreamtime story about the Giant Eel which travelled through the Clarence Valley, creating the Clarence River.
Another dreamtime story reflects the anger of Durrangan when her family tries to leave the land. She brings on stormy seas, which sink the family’s canoe. A rocky reef just off the breakwall where the Clarence enters the Coral Sea, is said to represent the old women.

There are traditional camp sites, middens, fish traps, and scores of other sites lining the ocean shores, and the banks of the various rivers that flow through the valley, all of which could potentially suffer directly or indirectly from the impacts of a toxic spill.

The Clarence Valley – a tourist destination

Tourism is a fast-growing industry in the Clarence valley which attracts visitors from around the world, and is the major contributor to the local economy. At its peak, pre Covid era 2015-16, the valley recorded 155,431 international tourist nights, 2,307,859 domestic tourist nights, and 446,639 day-trips.

Main attractions include, deep sea and river fishing, white-water rafting and kayaking, wilderness and nature walks, whale watching, surfing, sailing and boating, water skiing and wake-boarding, sightseeing etc. Visit the Clarence Valley Council’s on-line tourist information site My Clarence Valley, and it’s all about the river and beaches. Do we really want to risk all that?

Water-dependent industry in the Clarence Valley

The Clarence River is home to one of, if not the, largest commercial fisheries on the Australian east coast – The Clarence River Fisherman’s Co-op. This, along with deep-sea recreational fishing and whale watching tour operators; Boat building and maintenance; extensive irrigation of intensive greenhouse horticulture, orchards and sugar cane growing operations, dairy farming, and plant nurseries, are just some of the other industries that dependent on clean, non-polluted water.

The Clarence River’s Freshwater aquatic biodiversity

The Clarence Valley lies at the very centre of a world-renowned biodiversity hotspot, sometimes referred to as the MacPherson Macleay Overlap.

This is a region where flora from the subtropics is found intermingling with species from the temperate south. This amazing variety of plant life and ecosystems provide habitat for an equally diverse range of unique Australian fauna.

Warm tropical currents allow that wide diversity to be replicated offshore from the Clarence River mouth, where sea grasses are found growing alongside corals. Much of this ocean splendour is protected in marine parks and reserves. supporting an array of aquatic life that is difficult to equal.

A mining related disaster, such as a tailings dam failure, could place all of this at risk.

The Clarence Valley – Life on the Mudflats

The Clarence River is tidal for well over 150km from the coast, providing a range of mudflat ecosystems depending on salinity levels, and are some of the most ‘at-risk’ habitats along the river, not only from pollution in the river, but from rising sea-levels.
They are an essential feeding ground for shore birds including threatened species and migratory species protected under international treaties with countries like Japan and China.

Endangered Coastal Freshwater Wetlands

All of the many floodplain wetlands in the Clarence Valley are subject to periodic flooding, and as such, would be on the receiving end of any potential mine-tailings spillage. These wetlands provide critical habitat for dozens of rare and threatened species such as the endangered Black-necked Stork and protected Intermediate Egret, both pictured below.

Endangered mangrove communities

There are five mangrove species living along the NSW coastline, River Mangrove (Aegiceras corniculatum); Grey Mangrove (Avicennia marina): Black Mangrove (Bruguiera gymnorhiza); Milky Mangrove (Excoecaria agallocha), and Spider Mangrove (Rhizophora stylosa). All have been recorded near the mouth of the Clarence, except the latter, which has been recorded a short distance to the south near Red Rock
The mangrove communities, all of which are listed as threatened ecological communities, serve three key functions, providing habitat, food and, most importantly, they act as a buffer, reducing erosion and maintaining water quality.

As with coastal mudflats, mangrove communities would be the first ecosystems to suffer in the event of a toxic spill, putting at risk, not only the vegetation, but the dozens of fauna species that utilise the mangrove habitats, including the listed Mangrove Honeyeater.

Mangroves also provide crucial nursery habitat for fish, including recreationally important species such as mullet, bream, whiting, luderick, and flathead, along with prawns and crabs and other shellfish. In other words, mangroves are key to a number of industries and recreational activities.

The Clarence Valley’s wilderness areas

The Nymboida River is the largest of all the Clarence River tributaries, in terms of water delivery to the system, rising in the rugged mountainous regions surrounding the Dorrigo Plateau to the south of Grafton.
It provides drinking water to communities along the coast from Iluka to Bonville, including the regional centres of Grafton and Coffs Harbour. It also provides some of the country’s finest white-water rafting and canoeing in Australia.

For well over a decade, mining exploration has been occurring across the plateau, searching for a range of minerals that are either toxic themselves, or use toxic substances during the separation process.
To date those exploratory efforts have been in vain, but could mining be approved in such a remote wilderness area, which has one of the highest rainfalls levels in Australia? Until a viable resource is found, that question remains unanswered, but regulators will find it difficult to refuse a mining application after granting the operators a licence to look for them in the first place, and allow them to spend millions of investor dollars in the process. Mining exploration in such sensitive environments should be banned!

The Clarence Valley – World Heritage

The Clarence Valley is home to more than 125,000 hectares of World heritage wilderness, featuring the famous Gondwanan rainforests. These forests are so-named because the fossil record indicates that when Gondwana existed it was covered by rainforests containing the same kinds of species that are living today.

The Iluka World Heritage Park features unique littoral rainforest alongside the beach north from the mouth of the Clarence River.

While these World Heritage areas are unlikely to be directly impacted by any mining accident, they are an important component of the Clarence Valley tourist scene, which could well be impacted by such an event. It should also be noted that an unknown amount of littoral rainforest was cleared during sand-mining for heavy metals some 50-60 years ago, and the legacy of weed introduction still threatens that rainforest today.

The Clarence Valley’s Beach Culture

The Clarence valley beaches attract tourists from all across Australia and the globe; to enjoy the swimming, surfing, beach and rock fishing, kite surfing, and a host of other beach-side activities that are on offer, courtesy of our pristine beaches.

Immediately following the regular flooding that occurs in the valley, these beaches are often left littered with the flotsam and jetsam from the flood. Do we really want to risk adding toxic tailings dam sludge to that mix?

Recreation in the Clarence Valley

There is so much to do on and around the Clarence River and its tributaries, from the strenuous to the relaxing, white-water rafting, water skiing, and wake boarding, to bush walking, bird watching, dropping a line in the water in the hope of catching dinner, or even setting up an easel to do some painting.

None of this would be quite the same if the water was polluted!