1.6 Monitoring and evaluating cumulative impacts

Primary and secondary impacts can be obvious or well known, such as the construction of roads or large infrastructure, while other activities can be smaller but when considered together or over a certain period they can become concerning to stakeholders. While advances are being made, many practitioners are still developing techniques and ways to adequately incorporate cumulative impacts and effects into their research and impact assessments (IFC 2013).

Cumulative effects and impacts arise from different sources, inputs and activities occurring in combination, and the resulting impact is potentially larger than the simple sum of the impacts predicted to arise from each of the sources alone. Cumulative effects can occur when impacts are:

  • additive (incremental)
  • interactive
  • sequential, or
  • synergistic.

In the mining context, cumulative impacts on society, the economy and the environment can arise from compounding activities of a single operation or multiple operations. Cumulative effects impact assessments are typically conducted at the scale of human communities, regional landscapes, catchments or airsheds and require monitoring data to quantify all of those aspects (DEAT 2004; Franks et al. 2013).

The IFC has produced extensive recent guidance for conducting cumulative impact assessments for emerging markets and economies (IFC 2013). This guidance notes that:

cumulative impact assessment is evolving and there is no single accepted state of global practice. What is important is that during the process of identifying environmental and social impacts and risks, developers or project sponsors (a) recognize that their development may contribute to cumulative impacts on valued environmental and social components (VECs) on which other existing or future developments may also have detrimental effects, and (b) avoid and/or minimize these impacts to the greatest extent possible. (IFC 2013)

Complementing the guidance produced by the IFC is the Sustainability reporting guidelines and Mining and metals sector supplement produced by the Global Reporting Initiative (GRI 2011).

A recent contribution from Australia to addressing the potential conflicts that arise between multiple land uses and associated impacts, including mining, is the COAG Energy Council’s Multiple Land Use Framework (MLUF) (SCER 2013). The framework has been developed to address challenges arising from competing land uses, land access and land-use change, with a focus on the mining industry. The aim of the MLUF is to enable government, community and industry to effectively and efficiently meet land access and use challenges, expectations and opportunities. The framework supports the ability of local and regional communities, industries and governments to maximise land use in a flexible, environmentally sustainable manner over time. The Strategic Framework for Managing Abandoned Mines in the Minerals Industry (MCMPR–MCA 2010) encourages managers to gather data to create jurisdiction-wide inventories as a basis for risk assessment and management.

Good practice requires that, as a minimum, the developers of a mining project assess whether their development may contribute to cumulative impacts on valued environmental and social components (VECs), may be at risk from cumulative effects on VECs they depend on for future viable operation of the project, or both.

Cumulative impact assessment can be applied over multiple scales—from a single operation to large parts of states or provinces. For example, the potential effect of an individual operation on the sustainability of a region may initially need to be addressed as part of the EIA process, with subsequent reporting against performance objectives required following approval and the start of mining. Equally as important is ongoing stakeholder communication and engagement to test and validate whether continuous improvement is occurring and company resources are adequate. Increasingly, however, the concept of cumulative impact assessment is being applied across regions in which there may be multiple existing, new or proposed mining developments. Such regional assessments are typically required when there are multiple mines affecting an economically and/or environmentally important river catchment, or where there are laterally extensive mineral deposits on which multiple mines exist or are being established.

A good recent international example of a regional cumulative impacts study addressing social, economic and environmental aspects is provided by the Ministry of Mines and Energy in Namibia. This strategic environmental assessment was conducted to address the possible consequences of a large expansion in the mining of uranium in that country (MME 2010). The assessment provided a big-picture overview and advice to the Namibian Government on how to avoid negative cumulative impacts, as well as how to enhance opportunities and benefits within the uranium sector and between mining and other industries. While the individual EIAs for the new mines and the EMSs in place at the existing mines deal with the impacts caused by the individual mines, the strategic environmental assessment considered the cumulative spatial and time-crowding effects of various possible uranium mining expansion scenarios. This provided the framework for being better able to develop synergies between operations in the context of integrated environmental, social and health management.

In Australia, the extensive iron ore deposits in the north of Western Australia and the major coal deposits in Queensland and New South Wales are the clearest examples of where the effect of multiple mines of the same type in relatively close proximity is requiring the effects of cumulative impacts to be addressed. In these cases, the impacts of multiple operations on the quantity and quality of groundwater and surface water and the ecological and human systems that depend on them have been the primary concern. The coalmining industry has been a particular focus in recent years after the inclusion of a ‘water trigger’ provision in the Australian Government’s EPBC Act. This change to the Act required all new coalmining and coal seam gas projects that are likely to have a significant impact2, including cumulative impacts, on water resources to be assessed under the provisions of the Act. In addition, proposed expansions of existing mines may be subject to assessment under the Act. Comprehensive guidance is available on approaches to address cumulative impacts from coalmining (DERM 2009; Franks et al. 2010a, 2010b, 2013); the most extensive report on this subject was produced with funding from the Australian Coal Association Research Program (Franks et al. 2010). The concepts discussed in these publications should be readily transferrable to the broader mining industry.

A world-leading practice example of the application of cumulative impacts monitoring and analysis to the management of river water quality is provided by the Hunter River Salinity Trading Scheme (NSWEPA 2015; Vink et al. 2013). This scheme is a collaboration between the coalmining and electricity generating industries and regulators in New South Wales. Its purpose is to minimise the impacts of discharges of saline water into a high-value river system that supports competing mining, agricultural and urban uses. A network of 21 flow-monitoring and electrical conductivity stations along the river transmits data at 10-minute intervals. A river model then calculates the allowable increment of discharge from each mine in response to changing rainfall and flow within the catchment area.

It is currently being proposed that a similar cumulative salinity trading scheme be established for the Fitzroy River in Queensland, which has the second largest catchment area of rivers in Australia (Vink et al. 2013). Like the Hunter River catchment, the Fitzroy River catchment contains many large coalmines that coexist with a diverse regional agricultural industry (and many more mines and an expanding coal seam gas industry are proposed over the next decade). Cumulative impacts from active and abandoned mines resulting from controlled and uncontrolled discharges of contaminated water were highlighted as being matters of concern in the report produced by the Queensland Floods Commission of Inquiry (Chapter 13, 2012; http://www.floodcommission.qld.gov.au/ data/assets/pdf ).

Collapsed - Case study: Strategic management of cumulative impacts of coalmine wastewater releases in the Fitzroy River Basin—a regulatory perspective

In order to develop an understanding of the cumulative impacts of economic development within a river catchment, a temporal and spatial perspective on all the current and potential future developments in the catchment is needed. Immediately, it would seem obvious that good strategic planning is required if sustainable water quality is to be achieved in a catchment where multiple activities are contributing contaminants to a river. Unfortunately, this has rarely occurred, and approvals are usually assessed on a case-by-case basis with limited information or assessment of other catchment inputs. The regulation of wastewater releases from coalmines in the Fitzroy River Basin is one example where regulation has significantly evolved to keep up with the rapidly changing water-quality issues downstream of multiple mining activities.

The Fitzroy River Basin includes six major rivers that constitute Australia’s largest east-draining river system. The Fitzroy catchment contains more than 40 currently operating coalmines that have the potential to contribute significant saline discharges to the basin’s waterways.

In 2008, unusually high rainfall caused flooding in a number of mines in the basin. The subsequent release of flooded mine pit water between February and September 2008, mainly from one coalmine, led to an increase in salinity in downstream drinking water supplies and many complaints about water quality. In response, the Queensland Government commissioned a review of the cumulative impacts of mining activities on the water quality in the Fitzroy Basin (DERM 2009).

The review provided a risk assessment for the most sensitive environmental values within the freshwater reaches of the Fitzroy, including aquatic ecosystems, crop irrigation and drinking water. On the basis of the volumes of water released from the mines and the salinity of downstream receiving water after releases, the review identified a potentially high risk from cumulative salinity, particularly in the Isaac River in the North Fitzroy, where there is a high concentration of mines. As a consequence of the 2009 cumulative impact study, standardised model conditions were developed and the environmental authorities for each of the Fitzroy mines were reviewed by the regulatory authority, which is currently known as the Department of Environment and Heritage Protection (DEHP).

The Queensland Government’s model water conditions for coalmines in the Fitzroy Basin (more recently revised as the ‘model mining conditions’ (DEHP 2013), provide a consistent strategy for releases of mine-affected water from coalmines such that saline waters are to be released only at times of high natural flow (that is, following heavy rain) to ensure adequate dilution, whereas water of comparatively low salinity can be released at times of base or medium natural flow. The intent was to protect environmental values downstream of the mines, including sensitive aquatic ecosystems and areas of high ecological value.1

Also developed was a release calculator that could allocate a proportion of the downstream assimilation capacity to several different mines, thereby reducing the potential for cumulative impacts. Substantial work has also been done in the catchment since 2008 to develop local water-quality guidelines and scheduling environmental values and water-quality objectives within the Queensland Environmental Protection (Water) Policy.2 Although water-quality objectives are not imposed end-of-pipe, this information has been essential for developing standardised conditions and approaches for assessing cumulative impacts in the region, and is used to assess outcomes in the environment.

Despite the adoption of the model mining conditions approach, many coalmines in the Fitzroy Basin have been unable to reduce volumes of retained flood waters, either because they have not been able to exploit high-flow opportunities when they arose or because subsequent high-rainfall events have exacerbated the problem. Therefore, in 2012, in a further response to continuing issues involving stored saline water, the Queensland Government initiated a pilot program in the Isaac River that would allow some mines to release saline water outside of the model conditions framework. This pilot program was subsequently expanded throughout the Fitzroy Basin in 2013 (DEHP 2013). Ongoing monitoring of water quality and biological integrity has been, and will continue to be, used to ascertain whether the rates and volumes of wastewater released under this policy successfully protect all downstream environmental values.

The experience in the Fitzroy Basin highlights the need for:

  • strategic future planning for all mining operations, particularly where multiple operations are likely to occur within a single catchment or subcatchment
  • basin-wide assessment of water quality and assimilative capacity modelling to allow an equitable distribution of river usage among all activities and stakeholders, including aquatic ecosystems, agriculture, mining and human consumption
  • greater emphasis on water management plans at the environmental impact statement stage of coalmine development applications to ensure that there is minimal build-up of saline waters over time, as a consequence of either onsite water management or extreme weather
  • ongoing monitoring and assessment of water quality and environmental values by approval holders and broader catchment managers.


1 An ecosystem of high ecological value is the highest ranked ecological condition defined in ANZECC–ARMCANZ (2000). It is effectively an unmodified or other highly valued ecosystem.

2 The Environmental Protection (Water) Policy (2009) is subordinate to the Environmental Protection Act. Details on the policy and its environmental value and water quality objectives are at http://www.ehp.qld.gov.au/water/policy/index.html.

Collapsed - Case study: Integrated water management by Anglo American’s Metallurgical Coal Business Unit

This case study describes stewardship actions adopted by Anglo American’s Metallurgical Coal Business Unit to better manage risks associated with water management at its open-cut coalmines in the Fitzroy River catchment in central Queensland and to improve monitoring to meet the requirements of new regulations, introduced after the 2010–11 floods, to manage water stored on site (DEHP 2013). The historical background to the development of the regulations is provided in the ‘Strategic management of cumulative impacts of coalmine wastewater releases in the Fitzroy River Basin’ companion case study in this handbook.

The highly variable climate of the Fitzroy River catchment creates dual challenges for mine operators: from lack of water in dry years and excess water in wet years. During and after the major 2010–11 floods, the ability of mines to rapidly release stored water into highly diluting catchment flows was often delayed as a result of issues with both available water management infrastructure and the nature of the approvals process in place at that time. By February 2011, 80% of the coalmines in the Bowen Basin had restricted operations due to excess water (QFCI 2012, Chapter 13). Excess water can close roads, inundate pits, damage infrastructure and compromise safety.

Following the 2010–11 wet season, the Queensland Government initiated a review of release conditions for mine water and proposed a framework that allows mine-water releases as long as there is sufficient flow in the surrounding environment to dilute the water and maintain environmental values. This framework recognises that, in times of large flows in creeks and rivers, the controlled release of mine-affected water at appropriate dilution ratios poses a greatly reduced risk to the environment. For the mines that adopted the framework, meeting those conditions for discharge required precise real-time measurements of both flow and water quality.

Anglo American’s Metallurgical Coal Business Unit consequently took action to adopt better forecasting of rainfall, real-time monitoring of stream flows and water quality, and better coordination between engineering and environmental teams. While mines already had monitoring systems in place, they were further refined to provide the data needed to meet the new requirements. Requirements for a high standard of monitoring and rapid-turnaround data analysis capability are becoming features of the modern mining sector.

Anglo’s operations have adopted a fully integrated approach to monitoring and managing onsite water. The expected benefits from the investment include:

  • reduced risk of mine pits being flooded
  • reduced safety risks to employees
  • reduced impacts on roads and machinery from flood damage
  • the ability to store as much water as is safely possible for future use onsite, while still providing contingency storage capacity for high-rainfall events.

The adopted strategies were:

  • exploring options to better anticipate rainfall and run-off through tracking and responding to medium-term (monthly) and longer term (1–5 years) forecasts
  • automated monitoring and real-time communication of upstream creek flows and levels of salinity and turbidity
  • daily data uploads into a state-of-the-art data management system for in-depth data analysis to address circumstances that can lead to more effective release conditions
  • monitoring mine-water levels and quality, and the establishment of visual dashboards in the environmental database for easy and effective communication of risks related to mine-water storage
  • detailed analysis of landforms and the design of levees and drains to divert excess water from mine infrastructure, where possible
  • upgrading roads and particularly creek crossings to maintain access during high-rainfall events
  • upgrading infrastructure to allow water to be rapidly moved around and managed (28 additional pumps and 135 km of new pipes at the Dawson and Capcoal mines)
  • improving the communication and coordination of site teams to better integrate engineering and environmental water management.

The business case for Anglo American’s $120 million investment in improved water monitoring and management was supported by substantially reducing the number of production days lost due to wet weather. The collateral environmental benefits included reducing the volume of floodwaters that enter pits and ensuring compliance with release conditions, monitored in real time, designed to ensure the protection of the receiving waterway.

During the 2010-11 floods, substantial volumes of legacy water accumulated in storage pits.

During the 2010–11 floods, substantial volumes of legacy water accumulated in storage pits.

Real-time monitoring of stream flows provides an effective tool with which to control and manage mine-water releases.

Real-time monitoring of stream flows provides an effective tool with which to control and manage mine-water releases.

The location of Anglo American’s operations in the Fitzroy River catchment - Moranbah North, Capcoal, Foxleigh and Dawson.

The location of Anglo American’s operations in the Fitzroy River catchment.

While metal mining in general is not subject to the water trigger provisions of the EPBC Act, there is an increasing expectation by state regulators that the cumulative effects of existing or proposed multiple mining operations in a region (such as the impact on water resources in a river catchment) be addressed as part of the approvals process. The simplest example of the need to consider cumulative impacts on water quality occurs when a proposed operation is located downstream of an existing operating or legacy site. In this case, there is a need to establish the upstream (that is, upstream of the new operation) baseline against which the performance of the new operation can be assessed and managed (for example, deriving a waste discharge licence and development of local water-quality criteria in collaboration with regulators).

It will not be practical to analyse the cumulative effects of a new or existing mine on every environmental receptor or social indicator. Hence, the focus of the assessment and reporting process needs to be on those indicators that must be protected and/or those for which meaningful monitoring or measurement results can be produced. A good starting point for identifying what needs to be monitored and assessed is the list of agreed environmental and social values for the area in which a mine is located. In a regulatory context, government will often assist in determining the requirements and the scope of the assessment. Overall, the scope of the assessment should be set (by agreement) so that the impact assessment is not attempting to measure effects on everything. Upon the completion of the impact assessment, an impact management plan can be implemented for ongoing monitoring and evaluation of management responses. Implementing an impact management plan will ensure a greater likelihood of obtaining high-quality monitoring data for the key identified attributes.


2 For the definition of ‘significant impact’, see Australian Government (2013).

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