Australian beaches and coastal dune systems have been mined for several reasons. The earliest sand miners extracted gold from the deposits of black sands that were found from the south coast of New South Wales to the beaches of central Queensland. Later mineral sand mining focussed on the heavy minerals, rutile, zircon, ilmenite, and monazite (Morley, 1981).
Rutile and ilmenite contain titanium, which is mainly used in the form of titanium dioxide (TiO2) as a white pigment in paints, plastics, paper, and other products that require a bright white pigment. Titanium metal is as strong as some steels, but only about half the weight, and is used in heart pacemakers, artificial joints, jewellery, and spacecraft, among other things.
Zircon contains zirconium, which is used in electronics, ceramics, engines, and spacecraft.
Monazite contains cerium, lanthanum, neodymium, and thorium, which are used in rechargeable batteries (Crow, 2011), x-ray screens, fibre optics, high performance magnets, ceramics, television tubes, and as a nuclear fuel (thorium) (Geoscience Australia, n.d.).
Australia has the world’s largest economic resources of rutile and zircon (49% and 46% respectively), and the second largest economic resource of ilmenite (16%, behind China, with 30%).
In 2009, Australia’s economic demonstrated resource of ilmenite was 200.4 million tonnes (Mt), of rutile 22.7Mt, and of zircon 40Mt. At 2009’s rate of production, those reserves would have been sufficient for 109 years in the case of ilmenite, 69 years for rutile and 71 years for zircon (Geoscience Australia, n.d.).
Mining of sand for extraction of heavy minerals only removes about 1% of the bulk of the sand, the rest being returned to the dunes in some form or other. Modern sand miners are required to reshape and revegetate the dune systems and leave them as close as possible to their original state (Unwin & Cook, 1986 cited in Burdett, 1994). However, that wasn’t the case in the past and the dune systems on very large stretches of the coastline have been seriously degraded by this industry.
As well as heavy mineral sand mining, sand is also mined for glass making and construction, and sometimes to replace sand lost from other beaches. These types of mining remove considerably more of the bulk of the sand and necessarily do more lasting damage to the dune systems.
This report focuses mainly on the effects of heavy mineral sand mining.
The birth of sand mining in Australia took place in Ballina, NSW, in 1870, when John Sinclair discovered gold in the black sand on Shaw’s beach. That discovery sparked a gold rush that lasted for nearly 30 years. At its peak there were about 300 people digging for gold on the beaches around Ballina (Morley, 1981).
It is, however, unlikely that the beaches were in pristine shape before the gold rush started. Cement production didn’t begin in Australia until about the same time as the beginning of gold mining on the beaches (NSW Heritage Office, 2003), so beach sand wouldn’t have been mined for construction work prior to that time. But cedar getters began working in the forests in the 1840s and they hauled logs to the beaches and out to schooners moored offshore (NPWS, 2007). This undoubtedly caused some significant damage to parts of the dune systems.
The beach gold miners depended on south-easterly gales to expose the black sand and bring the heavier, gold-containing particles to the beach surface (Morley, 1981) and mining was done entirely by hand (Nott, 1957 cited in Borland, 1999).
Within twenty years, most of the beach gold deposits were exhausted and the attention of the miners turned inland. By the end of the century, gold had been discovered on beaches from Bermagui, NSW to Fraser Island, Qld, but its peak had passed (Morley, 1981).
For the next couple of decades, mining for gold, platinum, and tin continued on the beaches around Byron Bay. But around 1920 there began to be an interest in other minerals that were found in the beach sands – rutile, zircon, and ilmenite, the “heavy minerals”.
The first large scale mining of heavy mineral sands was carried out in 1935 when Zircon-Rutile Ltd began production of zircon and rutile at Byron Bay. They only processed the ore, and engaged contractors to do the mining – which was done on the beach by hand, using shovels (Morley, 1981).
When mineral sand deposits were discovered in the back dunes and heathland country behind the beaches, mining techniques changed. Ponds were dug and small floating dredges were used to extract the minerals (Nott, 1957 cited in Borland, 1999).
In the 1950s, as a result of criticism of the environmental damage being done by sand mining, the NSW Mines department began to work towards improving the rehabilitation of mine sites. But it wasn’t until the late 1960s that any serious effort was put into this process (Unwin & Cook, 1986 cited in Burdett, 1994).
Around that time, reprofiling of sand dunes was improved by the introduction of a stacker boom to rebuild the dunes with the tailings sand returned from the separation plant (Burdett, 1994).
In the 1960s mining began in the aeolian high dunes of southern Queensland (Morley, 1981).
In the late 1960s, mining companies began to employ qualified rehabilitation workers for the first time. (Unwin & Cook, 1986 cited in Burdett, 1994).
A necessary first step in the sand mining process is the complete removal of vegetation from the area to be mined (Barry & Marshall, 2002). In the early days of heavy mineral sand mining, this vegetation was piled up and burnt. Early mining methods involved the use of soda ash and caustic soda to remove organic material which contaminated the concentrates (Borland, 1999).
As a result of these processes, after sand mining had ended, the soil was left with very little or no organic matter. Geotechnical investigations during the development of Casuarina, NSW, showed clean beach sand throughout the soil profile, to depths well below the water table (Barry & Marshall, 2002).
In the early days of sand mining (up until the 1940s) no thought was given to restoring the dune profile of the mined area and dunes were flattened and left in an unstable state. The lack of vegetation allowed wind to blow sand inshore and further reduce the height of the dunes.
Aunty Linda Vidler (2004), an Arakwal elder from the Byron Bay area, recalled 30 foot high sand dunes at Tallow Beach before sand mining took place. There were also dune swales and permanent lakes (Vidler 2003, cited in NPWS, 2007). Today the dune system there is more uniform, flat and simplified (NPWS, 2007).
It is likely that while sand mining continued, it caused increased erosion of the shoreline of Australian beaches, as seems to have been the case with sand mining in California (Thornton et. al., 2006). Landward displacement of frontal dunes has occurred (Dallas & Tuck, 2008). Lack of vegetation and dune instability in old, unrehabilitated mine sites continues to contribute to erosion of the dune systems.
Sand mining has destroyed archeological and heritage sites, such as Aboriginal camp sites, middens and possibly burial sites (Dallas & Tuck, 2008). Many sites of European and Aboriginal value were lost to sand mining around the Ballina area (Dept. of Land and Water Conservation, 2003).
When attention was first paid to stabilizing dune systems by revegetating them, there was no attempt made to regenerate the vegetation populations that had been there originally. Instead, fast growing and convenient plants were used to stabilize the mined dune systems.
From 1946 to 1968, South African bitou bush (Chrysanthemoides monolifera) was used in sand mine rehabilitation. Bitou has now infested about 80% of the NSW coastline, extending as far as 10km inshore in places. It is an invasive weed that smothers native plant systems and destroys natural habitat. The Australian federal government declared bitou a weed of national significance in 2000 (Office of Environment and Heritage, 2011).
Concentrated waste mineral sands were buried in places on old mine sites. These wastes may contain thorium, which is radioactive (Dallas & Tuck, 2008). Although naturally occurring along beaches, once concentrated, these radioactive materials are a potential health hazard and need to be managed.
Rehabilitation of sites that were mined before proper rehabilitation was a legal requirement remains a challenge. These sites are characterised by unstable dune systems, poor vegetation cover, serious weed problems, and lack of topsoil and organic matter.
Rehabilitation projects are continuing at a number of these sites around Australia, with varying degrees of success. The work is often carried out entirely by volunteers and in some cases has been going on for well over twenty years.
To successfully rehabilitate a sand mining site and return it to as close as possible to its pre-mining state, the rehabilitation process must be planned and commenced prior to the start of mining. The mining process itself should be designed with rehabilitation in mind.
Soil, vegetation, fauna, and heritage surveys must be carried out before any mining takes place. Seeds should be collected from the key species in the mine path and in the adjoining areas Any wetlands in the mine path should be drained to allow soil to be removed in a non-saturated state in order to give vegetative propagules the best chance of surviving intact (Brooks, 1996).
Depending on the type of vegetation on the mine site, it may be possible to harvest it for mulch before removing the topsoil from the mine path. The land mined by the Eneaba operation in Western Australia was dry heathland and mulch was collected by mechanically harvesting the vegetation in advance of mining and provided a valuable source of seed, as well as stabilising the rehabilitation zone (Petersen & Brooks, 1996). Proper management of such mulch is essential, and it should be returned to topographic sites consistent with the area where it was harvested (Petersen & Brooks, 1996).
Topsoil must be removed from the mine path progressively – only removing as much as is necessary at any one time. It is essential to manage topsoil carefully, as it is a natural store of seeds, nutrients, and micro-organisms. It also has a higher moisture content than the sand below it (Sibelco, n.d.).
At the Eneabba operation, topsoil was removed in two cuts. The first cut was about 50mm and contained most of the seeds, micro-organisms, and nutrients. The second cut was taken down to a significant colour change, usually about 150mm deep (Petersen & Brooks, 1996).
Topsoil storage time should be minimized to ensure the maximum survival of soil micro-organisms and seeds. Prior to commencement of the Bridge Hill Ridge operation in New South Wales, it was realised that, because the orebody was deep and large, the mine face would advance very slowly. Because of this, if topsoil was returned to the place it was removed from once the dredge pond had moved past, storage time would be excessive. To avoid this problem, they pioneered a technique of removing topsoil ahead of the operation and immediately spreading it on the newly reformed tailings behind the dredge pond (Lewis, 1991).
The original dune topography should be recreated as accurately as possible by the placement of tailings behind the dredge pond as it moves forward. Attention must be paid to drainage (Brooks, 1996). – particularly when reshaping high, steep dunes, as water in the tailings leads to a risk of slumping and of erosion at the toe of the reformed dune. At Bridge Hill Ridge, a series of bores was installed near the bottom of the dune to extract water and prevent erosion (Lewis, 1991). The lines carrying tailings to the higher levels of the dunes also had dewatering facilities to assist in dune stabilization (Stoupe, 1998).
After tailings have been replaced and shaped by bulldozers, the topsoil is spread over the newly formed dunes. At Sibelco’s mines on North Stradbroke Island, a mix of seeds from up to 30 native species are sown according to the results of pre-mining vegetation surveys. A sterile sorghum hybrid is also sown along with the native seeds, to help prevent erosion and give protection to the native seedlings during the early stages of growth (Sibelco, n.d.).
Sibelco apply biodegradable bitumen at this stage, for temporary dune stabilization. Brush matting and wind fencing may also be used to control erosion and protect the emerging seedlings (Unwin & Cook, 1986 cited in Burdett, 1994). Moderate doses of fertilizer may be applied at this time too (Brooks, 1996).
Later on, nursery stock of ecologically important species, particularly those which are difficult to propagate by direct sowing, can be planted (Brooks, 1996). Sibelco (n.d.) plant tubestock from their nursery approximately 18 months after the start of rehabilitation. They also transplant up to ten mature grasstrees (Xanthorrhoea johnsonii) per hectare each year. The transplanting of grasstrees and nursery stock helps reintroduce soil microfauna to the disturbed topsoil (Olive, D. Sibelco Australia Community Relations Coordinator, 2011, pers. comm.).
Log piles, bird perches and nesting boxes are used by Sibelco (n.d.) to provide habitat and encourage fauna to return to the rehabilitated areas.
Monitoring of ecosystem development must be carried out over the life of the rehabilitation process (Brooks, 1996). Data on landform stability, vegetation development, fauna, and soil should be collected (Sibelco, n.d.).
It is important to keep bushfires out of rehabilitation areas. Herath et. al. (2009) found that species diversity fell between 22% and 41% after fire in restored sites (compared to an increase of 4% to 29% in natural sites) and that vegetation in restored sites after fire diverged further from the targeted properties of natural communities. Weeds, such as bitou, should be controlled by hand pulling and spot applications of herbicide (Lewis, 1991).
One example of a mine site that has been successfully revegetated is Tallow Beach at Suffolk Park, NSW. The local dunecare group has been carrying out rehabilitation work on the dunes there for 25 years and the results are impressive. However, they are still struggling to keep bitou bush and other weeds under control and there are many environmental issues still needing to be addressed (Shorten, M. Bush regenerator, Suffolk Park Dunecare Group, 1994, pers. comm.; NPWS, 2007).
The outlook for sites where the rehabilitation process was planned in advance of mining is much more optimistic. On old mine sites diversity of fauna has improved, including vertebrates and invertebrates, and mycorrhizal fungi and other micro organisms have returned (CSIRO, 1984, cited in Burdett, 1994). At Bridge Hill Ridge, Brockhoff & Allaway (1989) found greater vegetation species richness in a site that had been mined nine years previously than in unmined sites in the same locality. They also found similar levels of vesicular-arbuscular mycorrhizae in both mined and unmined sites.
Studies by Fox and Fox (1984) and Twigg et al (1989) (both cited in Lewis, 1991) showed that recolonization by mammals of the rehabilitated mine site at Bridge Hill Ridge progressed in a similar pattern to that following a fire, but at a slower pace. Twigg and Fox (1991, cited in Lewis, 1991) found that reptile species were recolonizing the rehabilitated site, but also at a slower pace. It was suggested that it would take about 20 years for reptile numbers to increase to pre-mining levels.
However, Buckney and Morrison (1992, cited in Lloyd et. al., 2002) found that mined area vegetation in Myall Lakes National Park, NSW, was different to both unmined areas and to its pre-mining condition and that over time it was getting less similar to its pre-mining state. And McNair (1993, cited in Lloyd et. al., 2002), studying post-sand mining regeneration in the Port Stephens area, found little similarity between post-mining and pre-mining flora and an apparent decline in native plant species, with no change after more than 20 years.
On sites that were mined in the days before governments required serious environmental measures, rehabilitation continues to be a challenge many decades later. It seems it will be impossible to return most of those sites to anything like their original condition. Many such sites will remain problematic for the foreseeable future.
There has, however, been some considerable success in restoring plant populations and fauna in a limited number of these locations. This work has mainly been carried out by volunteers with limited resources and it seems likely that if governments were prepared to increase their spending on rehabilitation of old mine sites a lot more could be done.
The evidence seems to show that it is impossible to return a sand mining site exactly to its original condition. However, in the long term, such sites can be successfully returned to a reasonable approximation of native bushland, complete with a diversity of native flora and fauna. To achieve the best results, rehabilitaion must be planned from the very beginning, and mining must be carried out in a manner that maximizes the chances of succesful rehabilitation.
Barry, R and Marshall, R (2002) Integration of sustainable stormwater management into coastal developments. Brisbane: Cardno MBK. Retrieved from http://old.ipwea.org.au/papers/download/Barry_r.pdf on 29/7/11.
Brockhoff, J.O. and Allaway, W.G. (1989) Vesicular-arbuscular
mycorrhizal fungi in natural vegetation and sand-mined dunes at Bridge Hill, New South Wales. In Wetlands (Australia), 8(2). Retrieved from http://ojs.library.unsw.edu.au/index.php/wetlands/article/viewFile/80/96 on 5/8/11.
Dallas, M. and Tuck, D. (2008) Aboriginal & European cultural heritage assessment – Casuarina town centre, Kingscliff South, NSW. Report to Kings Beach No. 2 Pty Ltd. Retrieved from http://www.planning.nsw.gov.au/asp/pdf/06_0258_casuarinatowncentre_ea_att15.pdf on 29/7/11.
Dept of Land and Water Conservation (2003). Ballina Coastal Reserve Plan of Management – Volume 2 – Background Information – Resources and Values. Grafton, NSW. Retrieved from http://pandora.nla.gov.au/pan/112525/20091207-1522/vol2.pdf on 30/7/11.
Geoscience Australia (n.d.) Mineral sands down under, The Australian Atlas of Mineral Resources, Mines, and Processing Centres. Retrieved from http://www.australianminesatlas.gov.au/education/down_under/minerals_sands/index.html on 27/7/11.
Geoscience Australia (n.d.) Mineral Sands, The Australian Atlas of Mineral Resources, Mines, and Processing Centres. retrieved from http://www.australianminesatlas.gov.au/aimr/commodity/mineral_sands_10.jsp on 27/7/11.
Herath, D.N., Lamont, B.B., Enright, N.J., and Miller, B.P. (2009) Impact of fire on plant-species persistence in post-mine restored and natural shrubland communities in southwestern Australia. Biological Conservation, 142, pp2175–2180.
Lewis, J.W. (1991) Rehabilitation and post-mining monitoring in high dunes at Bridge Hill Ridge, central coast of New South Wales. In Mulligan D.R. (Ed.), Environmental management in the Australian minerals and energy industries, chapter 15 Heavy mineral sands. Sydney: University of NSW Press.
Lloyd, M.V., Barnett, G., Doherty, M.D., Jeffree, R.A., John, J., Majer, J.D., Osborne, J.M. and Nichols, O.G. (2002) Managing the impacts of the Australian minerals industry on biodiversity – Final Report. Brisbane: Australian Centre for Mining Environmental Research. Retrieved from http://pubs.iied.org/pdfs/G00569.pdf on 5/8/11.
National Parks and Wildlife Service (NPWS) (2007) Arakwal National Park plan of management. Byron Bay, NSW. Retrieved from http://www.environment.nsw.gov.au/resources/parks/arakwalpomfinal.pdf on 27/7/11.
NSW Heritage Office (2003) The Investigation and Repair of Historic Concrete. Paramatta NSW. Retrieved from http://www.heritage.nsw.gov.au/docs/Concrete_Part_1.pdf on 29/7/11.
Office of Environment and Heritage (2011) Bitou bush – fact sheet. NSW government. Retrieved from http://www.environment.nsw.gov.au/pestsweeds/BitouBushFactsheet.htm on 29/7/11.
Petersen, A.E. and Brooks, D.R. (1996) Environmental management practices at RCG’s Eneabba operation in the dry heath sandplains of Western Australia. In Mulligan, D.R. (Ed.), Environmental management in the Australian minerals and energy industries, chapter 15 Heavy mineral sands. Sydney: University of NSW Press.
Sibelco Australia (n.d.). Our Environment. Retrieved from http://www.sustainablestradbroke.com.au/environment-conservation.html on 30/7/11.
Sibelco Australia (n.d.). Our Rehabilitation. Retrieved from http://www.sustainablestradbroke.com.au/environment-rehabilitation.html on 30/7/11.
Stoupe, D.R. (1998) Bridge Hill Ridge — a review. In Environmental issues in decommissioning mine sites – workshop proceedings, Asher, C.J. and Bell, L.C. (Eds.), Brisbane: Australian Centre for Mining Environmental Research. Retrieved from http://www.acmer.uq.edu.au/publications/attachments/DecommissioningProceedings.pdf on 4/8/11.
Vidler, Linda, an Arakwal elder, talking to Jane Stapleton (2004) A walk in the park. ABC Radio National. Transcript retrieved from http://www.abc.net.au/rn/features/walkpark/prog6.htm on 27/7/11.