3.6 Links to research and investigations

Often, at some point during the operational life of a mine, the need emerges to develop more cost- effective methods, taking into account local conditions, for assessing and minimising impacts, restoring environmental values or rehabilitating degraded sites. A major reason for this is that all sites are different and change over time. While the approach and process used by other projects may have developed leading practice methods of addressing knowledge gaps, specific characteristics of the project site may require modifications to the procedures developed and optimised elsewhere, or the selection of new indicators.

This requires a leading practice approach—that is, a willingness to do research, trials or whatever other investigations are necessary to monitor, assess and manage impacts to an extent acceptable to all stakeholders.

Baseline and subsequent surveys can identify the need for research and investigations. For example, they may reveal:

  • endemic species whose sensitivities or ecological requirements are not known
  • floral species for which propagation methods are not known
  • faunal species whose habitat requirements are not well known
  • specific flora–fauna interactions that are not well understood but may be important for ecosystem sustainability
  • topsoil characteristics that need specific remediation or other treatment to ensure successful revegetation
  • characteristics of overburden material that need specific procedures to ensure the successful construction and long-term stability of waste dumps or tailings storage facilities
  • unusual water, soil or sediment characteristics that alter the bioavailability risks of minerals or contaminants suitable for post-mining land uses, decision tools and knowledge management frameworks
  • community subgroups with differing economic and land-use requirements and aspirations
  • gaps in local skills, education or other employment-related capacities
  • limited business diversity, which restricts opportunities for economic benefits to flow to the local community.

Ongoing monitoring through all phases of the mining project can also reveal problems that need addressing, such as:

  • problems relating to the establishment or growth of rehabilitation plantings
  • invasive species that alter the ecosystem’s form or function, altering its value or sensitivity
  • unexpected water-quality impacts arising from specific site characteristics and environmental values
  • difficulties associated with managing dispersive spoil material, together with characteristics, such as variable soil salinity, that indicate a need for different handling procedures
  • inappropriate distribution of financial benefits from the mine throughout the community
  • social structures that do not represent generally accepted social norms for human rights, women’s rights, vulnerable groups and the like.

In almost all cases, it is much better to discover issues that require further investigation earlier rather than later. This gives more time to develop solutions, which may reduce the duration or extent of impact and be more cost-effective. In the case of rehabilitation, the earlier problems are identified and rectified, the less the area of suboptimal rehabilitated land that, in the worst case, may need to be reworked. Well-designed and targeted research can result in more cost-effective rehabilitation, for example by discovering better ways of doing things and fixing rehabilitation problems while mining equipment is still on site.

Some issues might require detailed research programs, whereas others might be resolved using simple field trials, such as those used to finetune fertiliser and seeding rates in rehabilitation programs. Depending on the work involved and the skills and resources required, research and investigations may need to be done by external consultants or universities or other research institutions.

A commitment to leading practice monitoring, and, where necessary, to research investigations, can result in significant improvements in overall environmental performance. A good example of this is the mine rehabilitation program conducted by Alcoa in Western Australia (see case study). It has resulted in the attainment of a very high standard of rehabilitation as a result of a process of continuous improvement over a period of more than 30 years (Koch 2007a, 2007b; Grant et al. 2007; Majer et al. 2007; Nichols & Grant 2007).

Collapsed - Case study: Monitoring to improve the quality of rehabilitation

Alcoa operates two bauxite mines in the jarrah forest of south-west Western Australia. Around 600 hectares of forest are cleared, mined and rehabilitated each year. The published objective of the rehabilitation is ‘to restore a self-sustaining jarrah forest ecosystem planned to enhance or maintain conservation, timber, water, recreation, and other forest values’.

The success of the rehabilitation is assessed by using several different monitoring systems, each targeting a different aspect of rehabilitation quality. To fulfil the conservation component of Alcoa’s rehabilitation objective, it is considered essential to restore the floristic diversity of the forest in rehabilitated areas, so a botanical richness target has been developed: ‘The average number of indigenous plant species in 15-month-old restoration is 100% of the number found in representative jarrah forest sites, with at least 20% of these from the recalcitrant species priority list.’ Recalcitrant species are typically fire resprouters that are common in the unmined jarrah forest but are difficult to re-establish and are historically absent or under-represented in the restored mined areas. The resprouters give the jarrah forest a high resilience to natural disturbances, particularly fire and grazing, and hence are a crucial component of the ecosystem.

Progress towards this target is monitored when rehabilitated areas are 15 months old, using about 150 randomly located 80 square metre plots. At fixed intervals (6, 15, 30 and 50 years of age), a subset of the monitoring plots is repeat-monitored, which provides long-term data on plant succession and vegetation development. Identical plots are monitored in the unmined jarrah forest to provide reference site data.

The pattern of plant succession in rehabilitated bauxite mines tends to follow the ‘initial floristic composition’ model, in which the first plant species to establish on the sites dominate the vegetation for at least several decades. Long-term monitoring has shown that species richness shows little change over time and, in fact, can decrease as short-lived annual species and disturbance-opportunist species, such as the acacias, senesce over the first few decades.

Accordingly, Alcoa’s strategy is to restore the highest level of species richness possible in newly rehabilitated areas.

Rehabilitated bauxite pit monitoring

The photograph shows a 15-month old rehabilitated bauxite pit being monitored. Each year, approximately 150 plots, each of 80 square metres, are assessed.

In rehabilitated areas, plant species establish from three main sources: the natural seed in the returned topsoil, seeds that are collected and broadcast onto those areas, and planted greenstock (mostly the recalcitrant species described above). Natural recruitment by native species is slow; if areas are left bare, they are usually colonised by exotic weeds, which have strong dispersal and recruitment characteristics. Research has shown that correct soil-handling practices optimise the return of native species from the natural soil seed bank, which can contribute 70% of the species richness of a restored bauxite pit. Hence, the quality of the rehabilitation establishment procedures is closely reflected in the number of native plant species that establish in the first two winters; in other words, better rehabilitation procedures lead to higher native plant species numbers.

For example, carrying out the final ripping operation during dry soil conditions in summer (the dry season in the jarrah forest ecosystem) results in more plants and species establishing. By contrast, ripping the sites well after winter rains have begun significantly reduces the number of plant species by killing the newly germinating seedlings. In addition, the natural soil seed bank in summer is double the density of the winter seed bank, so summer is by far the best season to use this important resource.

Each year, the data collected during the 15-month monitoring program is compared with records of rehabilitation activities, which are stored in a GIS that includes the original source of the topsoil, the date of clearing of the source site, the date of removal of the topsoil, whether the topsoil was stockpiled or directly returned to the rehabilitated area, the location and duration of stockpiling, the date of respreading of the topsoil, the date of final contour ripping, and the date of seed application. This enables rehabilitation practices that lead to high returns of plant species, as well as those that result in poor rehabilitation, to be identified.

At a feedback session held each year, mine planners, environmental staff and rehabilitation operations staff review the monitoring results and discuss improvements to rehabilitation practices. Approved enhanced practices are then implemented. This intensive monitoring and plan–do–check–act cycle has enabled Alcoa to measure progress and make changes and improvements to its rehabilitation program over a 22-year period.

This graph shows the 15-month monitoring results for newly rehabilitated areas from 1990 to 2012. Identical plots are assessed in unmined forest controls, and the mean native species richness in the controls is nominally set as the 100% improvement target. The graph shows the effects of several different rehabilitation practices on the monitoring results obtained each year, including a decrease in plant species richness due to winter ripping in 2002–03. Source: Matthew Daws, Alcoa of Australia.

At a feedback session held each year, mine planners, environmental staff and rehabilitation operations staff review the monitoring results and discuss improvements to rehabilitation practices. Approved enhanced practices are then implemented. This intensive monitoring and plan–do–check–act cycle has enabled Alcoa to measure progress and make changes and improvements to its rehabilitation program over a 22-year period.

Graph showing the 15-month monitoring results for newly rehabilitated areas from 1990 to 2012. Identical plots are assessed in unmined forest controls, and the mean native species richness in the controls is nominally set as the 100% improvement target. The graph shows the effects of several different rehabilitation practices on the monitoring results obtained each year, including a decrease in plant species richness due to winter ripping in 2002-03.

This graph shows the 15-month monitoring results for newly rehabilitated areas from 1990 to 2012. Identical plots are assessed in unmined forest controls, and the mean native species richness in the controls is nominally set as the 100% improvement target. The graph shows the effects of several different rehabilitation practices on the monitoring results obtained each year, including a decrease in plant species richness due to winter ripping in 2002–03. Source: Matthew Daws, Alcoa of Australia.

While monitoring per se can identify the need for research or trials, in some cases there are no effective methods available to monitor a particular variable. In such cases, research will be needed to develop an appropriate method. A good example of this is the ACARP-funded study by Dunlop et al. (2011) that developed the first locally relevant ecosystem protection guideline for sulphate for the Fitzroy River system—the first such development of an ecosystem water quality guideline for sulphate in Australia. This research arose from reduced freshwater consumption by coalmines in the region, which resulted in increased salinity of water stored onsite, and sulphate was a key parameter in that water.

It is important for companies operating in Australia to develop research plans compatible with AusIndustry R&D requirements, by engaging registered research agencies, in order to gain the benefits of R&D tax incentive arrangements while developing solutions to site-based challenges

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