Publications by Year
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.
Regulator guidance and legislation relevant to pit lakes
Bioremediation of pit lake water by sulfate reduction.
Health and Safety working around pit lakes,
Water Quality of Mine Void Pit Lakes Used for Recreation.
Potential of sewage and green waste for acidic pit lake bioremediation.
Bacterial sulfate reduction-based bioremediation was trialled in an acidic pit lake, divided into two sections by an earth wall. Sewage and green waste was added to the smallest section, while the other…
Bacterial sulfate reduction-based bioremediation was trialled in an acidic pit lake, divided into two sections by an earth wall. Sewage and green waste was added to the smallest section, while the other was kept untreated as a control. Bioremediation initially increased the pH of the hypolimnion of the treatment lake but after 12 months the pH suddenly returned to pre-treatment levels. This proved to be only temporary and pH bounced quickly back to previous highs. The pH decreases appeared to be associated with heavy rainfall events. These rainfall events affected the bioremediation by mixing the lake and increasing acidity inputs from the catchment.
Evaluating the factors limiting algal biomass in acidic pit lakes of the Collie Lake District, Western Australia.
Acidic pit lakes often have elevated metal concentrations, very low nutrient concentrations and very low algal primary productivity. A microcosm experiment was performed to identify the main limiting factor(s) for algal biomass.…
Acidic pit lakes often have elevated metal concentrations, very low nutrient concentrations and very low algal primary productivity. A microcosm experiment was performed to identify the main limiting factor(s) for algal biomass. Nutrients (N, P and C) were added in all possible combinations to pit lake water in the presence or absence of pit lake sediment. Microcosms without sediment showed higher chlorophyll a concentrations compared to the treatments with sediment. Microcosms where nitrogen and phosphorus were added showed highest chlorophyll a concentrations. Results suggest that algal biomass in pit lakes may be primarily limited by low nitrogen and phosphorus concentrations.
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.
Limiting factors for crayfish and finfish in acidic coal pit lakes
World-wide, open-cut mining operations often leave pit lakes at closure. The Collie Lake District in south-west Australia has 13 pit lakes from open-cut coal extraction, with more expected. Many lakes may offer…
World-wide, open-cut mining operations often leave pit lakes at closure. The Collie Lake District in south-west Australia has 13 pit lakes from open-cut coal extraction, with more expected. Many lakes may offer beneficial end uses as fisheries habitat for biodiversity or for recreational species. However, pit lakes may have degraded water quality due to Acid and Metalliferous Drainage (AMD). A literature review and survey for marron (endemic crayfish of biodiversity and recreational value) and fin-fish (of only biodiversity value) found that crayfish were likely more limited by habitat and food availability, and fin-fish by water quality. Management of these mild acidic water bodies must address both issues if sustainable fisheries and aquatic biodiversity are desired beneficial end uses.
Modelling a pit lake district to plan for abstraction regime changes.
Mining pit lakes can form in open cut mining pits that extend below the groundwater table. Final lake surface levels generally represent the greatest risk of pit lake closure to stakeholders through…
Mining pit lakes can form in open cut mining pits that extend below the groundwater table. Final lake surface levels generally represent the greatest risk of pit lake closure to stakeholders through potential to overflow and discharge to regional surface water bodies and groundwater resources. An essential prerequisite for managing this risk is a good understanding of the lake’s water budget. Pit lakes in the Collie Coal Basin ,Western Australia form a lake district currently consisting of 13 lakes exceeding a total volume of 200 GL of acid and metalliferous (AMD) degraded water. Given long-term risks for off-site contamination, regulatory agencies often rely on geochemical predictions of future pit lake water quality to evaluate closure strategies that protect the surrounding environment. Using an existing regional groundwater model, we modelled representative pit lake types in the Collie Lake District, south-western Australia, to determine different regional groundwater abstraction regime effects on pit lake water levels. PITLAKQ was used to model three different lakes representing three distinct lake types identified by conceptual modelling: Historic (around 50 years old), New/Rehabilitated, and New/ Un-rehabilitated (both around 5–15 years old). An accurate representation of the water level-volume relationships was developed before all available data on major hydrological sinks and sources such as groundwater inflow/outflow, surface water inflow/outflow, as well as precipitation and evaporation were considered in lake water budget calculations. Although we found large deviations between measured and calculated water levels we could show reasonable limits for groundwater inflows and outflows by examining different scenarios. Reciprocally, this improved the groundwater model(s) suggesting coupling fine-scale pit lake models with groundwater models to identify the data quality for sinks and sources as an approach for other pit lake models. Our modelling scenarios showed that planned groundwater abstraction regime changes would lead to only limited changes in lake water depth compared to modelling uncertainties resulting from limited available data and the use of a regional groundwater model. This example illustrates pit lake modelling with low data availability still allows useful scenario testing under different operational scenarios.
Model-based investigations of acidity sinks and sources of a pit lake in Western Australia.
Lake Kepwari is a rehabilitated lake in the Collie Basin lignite mining area in Western Australia. The water quality of Lake Kepwari was modeled with the pit lake hydrodynamic and water quality…
Lake Kepwari is a rehabilitated lake in the Collie Basin lignite mining area in Western Australia. The water quality of Lake Kepwari was modeled with the pit lake hydrodynamic and water quality model PITLAKQ. Based on a hydrodynamically validated model, water quality scenarios were used to quantify the sensitivity of different acidity sources including groundwater exchange, surface runoff and erosion, providing new insights into the system. The technique of monthly aggregation of all sources and sinks of acidity, based on detailed model output, provided the basis for useful conclusions. Model results suggest a new focus of field investigations to improve modeling certainty and a follow-up, improved phase of modeling.
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.