Publications by Year
Closing pit lakes as aquatic ecosystems: Risk, reality, and future uses.
Mine pit lakes are formed when open-cut pits flood with water, and these lakes occur by the thousands on every inhabited continent. The remediation and closure of pit lakes is a pressing…
Mine pit lakes are formed when open-cut pits flood with water, and these lakes occur by the thousands on every inhabited continent. The remediation and closure of pit lakes is a pressing issue for sustainable development and provision of freshwater ecosystem services. While pit lakes can be spectacular examples of recreation and renewal, pit lakes may be better known for their poor water qualities and risks to communities and the environment. Often the public wants to simply “fill the pits in” to restore a terrestrial landscape, but this is not always possible. Therefore, planning for remediation and future uses is likely to provide the best outcome. Poor water quality is not necessarily a barrier to future use, although it may limit the number of uses. Short-term future uses tend to require commercial viability, active infrastructure investment, and maintenance, and should transition to complementary long-term uses that promote biodiversity. Long-term future uses require relatively less ongoing maintenance beyond the initial investment and adhere to the principles that pit lakes should be safe, sustainable, and non-polluting in perpetuity. Pit lakes will eventually develop “ecosystem values,” and the time to do so depends on the nature of the intervention and the values ascribed by the community. Where possible, closing pit lakes as sustainable ecosystems is the most realistic goal that permits a variety of future uses that is likely to see pit lakes valued by future generations.
Foreword to the Special Issue on Pit Lakes: The Current State of Pit Lake Science
IMWA Insights: Discussion of the public perception of a new open pit in As Pontes, Spain.
The Importance of Catchments to Mine-pit Lakes: Implications for Closure.
Saline Pit Lakes – What Biodiversity Values Can They Offer At Closure And Beyond?.
Macroinvertebrates and Microbes (Archaea, Bacteria) Offer Complementary Insights into Mine-Pit Lake Ecology.
Incorporating Microbes into Environmental Monitoring and Mine Closure Programs: River Diversions as Test Beds
Seasonal River Flow-through As A Pit Lake Closure Strategy: Is It A Sustainable Option In A Drying Climate?
Biophysical Closure Criteria Without Reference Sites: Evaluating River Diversions Around Mines.
Waste Not, Want Not – Using Waste Hay to Improve Pit Lake Water Quality
Pit lakes are a global legacy of mining: An integrated approach to achieving sustainable ecosystems and value for communities.
Pit falls of gold mine sites in care and maintenance.
Bio-physical closure criteria without reference sites: realistic targets in modified rivers.
Impacts of Artisanal Small-Scale Gold Mining on Water Quality of a Tropical River (Surow River, Ghana).
Setting goals and choosing appropriate reference sites for restoring mine pit lakes as aquatic ecosystems: a case study from south west Australia.
Regulation of artisanal small-scale gold mining (ASGM) in Ghana and Indonesia as currently implemented fails to adequately protect aquatic ecosystems.
Are We Approaching Pit Lake Closure from the Wrong Perspective?
Mine closure of pit lakes as terminal sinks: best available practice when options are limited?
Upper and lower concentration thresholds for bioremediation of Acid Mine Drainage using bulk organic substrates.
Importance of catchment vegetation and design to long-term rehabilitation of acidic pit lakes.
Breach and decant of an acid mine lake by a eutrophic river: river water quality and limitations of use .
Importance of topography and topsoil selection and storage in successfully rehabilitating post-closure sand mines featuring pit lakes.
Recreational use of acidic pit lakes – human health considerations for post closure planning.
Proceedings of the International Mine Water Association (IMWA) Conference. Bunbury, Australia.
Upper and lower concentration thresholds for bioremediation of Acid Mine Drainage using bulk organic substrates.
Closure Planning in a Developing country – a case study from the Phu Kham Mine, Laos, South-east Asia.
Riverine breach and subsequent decant of an acidic pit lake: evaluating the effects of riverine flow-through on lake stratification and chemistry.
Breach and subsequent decant of an acidic brackish pit lake in the Collie Coal region in south-western Australia occurred during flooding of a pre-mining diverted eutrophic river. Inflowing fresher river water with…
Breach and subsequent decant of an acidic brackish pit lake in the Collie Coal region in south-western Australia occurred during flooding of a pre-mining diverted eutrophic river. Inflowing fresher river water with high alkalinity and nutrient concentrations settled over more saline and acidic pit lake water. This created a halocline with better mixoliminion water quality and monimolimnion water quality typical of the pre-breach lake. Flow-through may represent the best long-term mine closure option for this and other pit lakes in the state and internationally where pit lake water quality degrades over time when excised from regional water systems.
Pit lakes as evaporative ‘terminal’ sinks: an approach to best available practice mine closure.
Pit lakes may form when open cut mining operations extend below groundwater level and then fill at cessation of mining and associated dewatering operations by ground and surface water influx. Pit lake…
Pit lakes may form when open cut mining operations extend below groundwater level and then fill at cessation of mining and associated dewatering operations by ground and surface water influx. Pit lake hydrogeology may function as an evaporative “sink” when pit lake water evaporation rates exceed influx rates.Although not ideal closure, management of local surface and groundwaters contaminated by Acid and Metalliferous Drainage (AMD) through entrainment toward an evaporative terminal pit lake may provide a best-case scenario for protection of regional water resources required by typical mine closure time scales of hundreds to thousands of years. We present two case studies from Western Australia; the first where closure of above ground landforms such as waste dumps by covers would arguably not be successful over long terms (1,000 years or more) and another where Potentially Acid Forming waste (PAF) management is limited by current waste rock dump location and suitable cover materials. Pit lake water balance modelling indicates both case study pit lakes will function as hydraulic sinks if they are not backfilled above their equilibrium water levels. A best closure outcome for these pit lakes may be to be backfilled with PAF encapsulated with alkaline/neutral waste and then filled as rapidly as possible to minimise PAF oxidation and ensure an evaporative sink pit lake is formed.
Sourcing organic materials for pit lake remediation in remote mining regions.
How does storage affect the quality and quantity of organic carbon in sewage for use in the bioremediation of acidic mine waters?
Ecological engineering of a novel lake district: new approaches for new landscapes.
Bioremediation of pit lake water by sulfate reduction.
How representative are pit lakes of regional natural water bodies? A case study from silica sand mining
In many regions, regulators view pit lakes akin to natural lakes and impose similar guidelines for water quality and biodiversity. At Kemerton (south Western Australia), extraction of silica sands is creating a…
In many regions, regulators view pit lakes akin to natural lakes and impose similar guidelines for water quality and biodiversity. At Kemerton (south Western Australia), extraction of silica sands is creating a large deep dredge pond. This is progressively split into smaller lakes, which are then rehabilitated. The water quality and macroinvertebrate communities of a rehabilitated pond, 3 other artificial wetlands, and 13 nearby natural wetlands were investigated. Catchment rehabilitation has successfully returned some terrestrial vegetation, however the pond edge lacked a developed riparian zone. Species diversity and abundance was substantially lower (≈ 50% and 10% respectively) than in natural wetlands. Overall the macroinvertebrate communities and water quality of artificial wetlands were significantly different to the natural wetlands.
Setting restoration goals for restoring pit lakes as aquatic ecosystems: a case study from south west Australia.
Pit lakes may form when open cut mining leaves a pit void that then fills with ground and surface waters. This often replaces terrestrial ecosystems that existed prior to mining with an…
Pit lakes may form when open cut mining leaves a pit void that then fills with ground and surface waters. This often replaces terrestrial ecosystems that existed prior to mining with an aquatic ecosystem, affording an opportunity to improve regional aquatic biodiversity values through targeted aquatic restoration (McCullough and van Etten, 2011). Restoration theory provides guidance when restoring disturbed systems towards landscapes that are of regional value and relevance. But how do we identify a restoration target for a novel aquatic habitat that only exists in the new post-mining landscape? This paper presents a process of first identifying and then surveying local representative aquatic systems, to provide a direction for pit lake restoration efforts and achievement criteria for pit lake relinquishment, using a case study from a sand mining operation amongst wetlands in southwestern Australia. The company mines silica sands following mechanical removal of topsoil and then extraction of the ore from below the watertable by dredging. Assessment of wetland and riparian vegetation was achieved through the establishment and measurement of temporary monitoring transects acrossfive natural wetlands in the Kemerton area. Several more regional wetlands were also visited and observations made to supplement and validate these data. Distinct vegetation zonation was found across each wetland, although typically wetland basins were unvegetated or filled with younger woody plants with patchy distributions. Fringing riparian vegetation consisted of few species (commonly the paperbark Melaleuca rhaphiophylla and the sedgeLepidosperma longitudinale), but community composition and structure were variable between wetlands. The pattern of vegetation seen across natural wetlands was best explained by topography and soil chemistry, with low lying wetland areas more likely to experience regular flooding and accumulate organic matter and nutrients. In conclusion, where they are available, regional natural waterbodies may constitute the best valid restoration goal. Nevertheless, the goal may need to consist of a range of closure design opportunities, rather than a single target.
Sand mining restoration on the Swan Coastal Plain using topsoil – learning from monitoring of previous rehabilitation attempts.
This paper reports on the results of several years of monitoring rehabilitation at a silica sand mine on the Swan Coastal Plain, south of Perth. Mining here occurs below the regional watertable…
This paper reports on the results of several years of monitoring rehabilitation at a silica sand mine on the Swan Coastal Plain, south of Perth. Mining here occurs below the regional watertable and leaves a post-mine landscape of dredge pond voids (pit lakes) with surrounding battered slopes. The restoration we recommended was to develop the pit lakes as wetlands of regional analogue and value. Several different restoration techniques have been applied to re-vegetate pit lake slopes over many years which have enabled an evaluation of reasons for success/failure of different restoration approaches. Learning acquired clearly showed the benefits of using fresh topsoil for restoration over topsoil that has been stockpiled for several years. Most topsoil used in restoration was from seasonal wetlands and consequently restoration was most successful in the riparian zone from the edge of pit lakes to about 2 m vertically above the water table. Topsoil restored areas above this level remained poor in plant species and cover. Conversely, remedial seeding/planting proved largely unsuccessful. Permanently and seasonally flooded pit lake margins recolonised relatively quickly and successfully with native sedges and rushes. Development of rehabilitated upper slope plant communities over time was evident with loss of typical wetland species and greater growth and survivorship of upland and dampland plant species on mid to upper rehabilitated slopes. Plant communities of lower slopes showed a converse pattern of development, with a shift towards a more typical wetland composition. We believe matching topsoil to site and development of topographic profiles similar to natural wetlands of the region are the keys to optimising restoration success of sand mines with shallow water tables.
Water resources in Australian mine pit lakes.
Bioassay toxicity assessment of mining pit lake water remediated with limestone and phosphorus.
Sustainable development of open pit mines: creating beneficial end uses for pit lakes.
More than water quality: environmental limitations to a fishery in acid pit lakes of Collie, south-west Australia.
Marron (Cherax cainii Austin) are a freshwater crayfish native to permanent waterbodies in the south-west of Western Australia. A popular aquaculture and sports species, marron are considered a potential end-use fishery species…
Marron (Cherax cainii Austin) are a freshwater crayfish native to permanent waterbodies in the south-west of Western Australia. A popular aquaculture and sports species, marron are considered a potential end-use fishery species for and have been deliberately released into several historic pit lakes of the Collie coal mining region. This study investigated what environmental factors in these acid mine drainage (AMD) contaminated pit lakes might be affecting the health and success of existing marron fisheries. Although pit lake water quality was often low (pH
Field scale demonstration of the potential for sewage to remediate acidic mine waters.
Field scale demonstration of the potential for sewage to remediate acidic mine waters.
Opportunities for sustainable mining pit lakes in Australia.
In-situ coal pit lake treatment of acidity when sulfate concentrations are low
Pit lakes (abandoned flooded mine pits) represent a potentially valuable resource to mining companies, the environment and community, if appropriate water quality can be achieved. However, the water is often of low…
Pit lakes (abandoned flooded mine pits) represent a potentially valuable resource to mining companies, the environment and community, if appropriate water quality can be achieved. However, the water is often of low pH with high dissolved metal concentrations. In Western Australia coal pit lakes are acidic (pH 3–5) but with low concentrations of sulfate and metals. Low sulfate concentrations prevent microbial sulfate reduction from reducing acidity in these lakes. However, stimulation of primary production and associated alkalinity generating processes may provide a cost effective and sustainable solution to the acidity problems. A field-scale experiment (with control) involving the treatment of in-situ macrocosms (~600 m3) in a small south-west, Western Australian coal mine lake with municipal mulch and phosphorus additions to enhance primary production was undertaken between June 2003 and June 2004. One macrocosm was treated with P additions, another with mulch, a third with mulch and P, and the untreated lake formed the control. Physico-chemical and algal (chlorophyll a) sampling of the macrocosms and lake occurred at monthly intervals. The decomposition of mulch reduced nitrogen concentrations in the macrocosms to very low levels and necessitated supplementation with urea fertilizer. Phosphorus concentrations dropped rapidly after addition as it became bound to iron, organic matter and sediment. Although there was virtually no difference between treatments and control for most physico-chemical parameters measured (including pH), a PCA of the data showed that the addition of mulch sent the macrocosms on a different trajectory to the control. This difference was reflected in observations of increased abundance and diversity of biofilms and macroinvertebrates within the treated macrocosms. In conclusion, the addition of mulch and phosphorus alone was not sufficient to increase the pH of Collie mine lakes, although it does provide a number of benefits for biota in the water. We therefore recommend that liming be used to increase pH, followed by organic matter and nutrient additions to stimulate primary production.
Pit lake sustainability; what is it, and how do I get it?
Due to operational and regulatory practicalities, pit lakes will continue to be legacies of many open-cut mining lease relinquishments. Unplanned or inappropriate management of these significant geographical features may lead to a…
Due to operational and regulatory practicalities, pit lakes will continue to be legacies of many open-cut mining lease relinquishments. Unplanned or inappropriate management of these significant geographical features may lead to a short-term liability to all stakeholders during mining operations, or to ongoing liability to the local community and environment following lease relinquishment. However, the potential for pit lakes to provide benefit to companies, communities and the environment is frequently unrecognised and yet may be a vital contribution to the sustainability of the open-cut mining industry. Improved remediation technologies are offering more avenues for pit lake end use than ever before, at the same time mining companies, local communities and regulatory authorities are also becoming more aware of the benefit these water resources have to offer. Sustainable pit lake management aims to better minimise short and long term pit lake liabilities, and yet also to maximise short and long term pit lake opportunities as well.
Microcosm testing of municipal sewage and green waste for full-scale remediation of an acid coal pit lake, in semi-arid tropical Australia.
Pit lakes (abandoned flooded mine pits) represent a potentially valuable water resource to mining companies, the environment and regional communities across arid inland Australia. However, the water is often of low pH…
Pit lakes (abandoned flooded mine pits) represent a potentially valuable water resource to mining companies, the environment and regional communities across arid inland Australia. However, the water is often of low pH with high dissolved metal concentrations. The addition of organic matter to the pit lakes to enhance microbial sulfate reduction is potentially a cost effective and sustainable remediation strategy for these acid waters. However, the cost and availability of sufficient quantities of suitable organic substrates is typically limiting in these remote regions. Nevertheless, small quantities of sewage and green waste (organic garden waste) are often available in these areas from the regional towns which support the mines. This paper reports on preliminary microcosm laboratory experiments in preparation for the treatment of an acid (pH 2.2) coal mine pit lake in semi-arid tropical, inland north Queensland, Australia with municipal treated sewage and green waste. A laboratory experiment using microcosms (acrylic tubes) containing acid pit lake water and sediment were treated as follows; controls (untreated), sewage, green waste and sewage and green waste. The pH increased to a maximum of 5.5 in 145 days in the green waste and sewage treatment, with notable decreases of iron, aluminium and toxic heavy metals. Our results indicated that the green waste was a key component in alkalinity production and heavy metal removal.
Bioremediation of acidic and metalliferous drainage (AMD) through organic carbon amendment by municipal sewage and green waste.
Restoring pit lakes: factoring in the biology.
Pit lakes: benefit or bane to companies, communities and the environment?
Due to operational and regulatory practicalities, pit lakes will continue to be common legacies of mining lease relinquishments. Unplanned or inappropriate management of these significant geographical features may lead to a short-term…
Due to operational and regulatory practicalities, pit lakes will continue to be common legacies of mining lease relinquishments. Unplanned or inappropriate management of these significant geographical features may lead to a short-term liability to all stakeholders during mining operations, or to ongoing liability to the local community and environment following lease relinquishment. Frequently unrecognised is the potential for pit lakes to provide benefit to companies, communities and the environment. Sustainable pit lake management aims to better minimise short and long term pit lake liabilities, and maximise short and long term pit lake opportunities as well. Improved remediation technologies are offering more avenues for pit lakes resource exploitation than ever before, at the same time that mining companies, local communities and regulatory authorities are also more aware than ever of the benefit of these water resources.