Mine Closure of Pit Lakes as Terminal Sinks: Best Available Practice When Options are Limited?

McCullough, Cherie D.; Marchand, Geneviève; Unseld, Jörg

doi:10.1007/s10230-013-0235-7

Cited by 31 publications

(17 citation statements)

References 16 publications

(5 reference statements)

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“…Higher ORP was likely due to inputs of acid groundwater when the lake became an evaporative sink during this dry season (McCullough et al, 2013b). Low ORP following the winter rains was likely due to lower acidity surface runoff water accumulating and even slightly surcharging Lake Kepwari during the wet season (Müller et al, 2011).…”

Section: Lake Water Quality and Limnologymentioning

confidence: 98%

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Consequences and opportunities from river breach and decant of an acidic mine pit lake

McCullough

2015

Ecological Engineering

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Section: Lake Water Quality and Limnologymentioning

confidence: 98%

“…Salinity may also increase through time due to evapo-concentration processes (Niccoli, 2009;McCullough et al, 2013b). This impaired water quality may leave a significant liability at mine closure and may also reduce end use values and opportunities (McCullough and Lund, 2006).…”

Section: Introductionmentioning

confidence: 98%

Consequences and opportunities from river breach and decant of an acidic mine pit lake

McCullough

2015

Ecological Engineering

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“…Dynamic probabilistic models are effective at predicting lake data temporally when system inputs and outputs are known in significant detail (Balistrieri et al 2006), but they are limited in their accuracy when the groundwater component is not well understood or well quantified. In regions where groundwater is thought to be the main source of pit lake recharge or discharge, estimating a reasonable groundwater inflow value is critical for a representative water balance (Hanna et al 1994;Niccoli 2009;McCullough et al 2013).…”

Section: Pit Lake Modellingmentioning

confidence: 99%

Modelling the long-term water balance of a pit lake with recreational end uses

Carlino¹,

McCullough²

2019

Proceedings of the International Conference on Mine Closure

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Pit lakes can be used for recreation when water quality is suitable. However, when lake levels are too low, pit lakes may pose access and slope instability risks to recreational users. An essential tool to assist in managing these risks is a good understanding of the lake water balance. A groundwater model was developed to investigate whether impending cessation of mine water discharge into historic Lake Stockton (Collie, Western Australia) would result in reduced recreational values, e.g. for water skiing. Currently, the lake water level is kept reasonably constantly elevated with the addition of mine water from nearby dewatering at Ewington mine (Lanco, Griffin Coal) operations. Lake Stockton has a maximum depth of 30 m and groundwater flows through historic underground mine workings contribute largely to the overall pit inflow. A steady state groundwater model was used to emulate the regional groundwater flow in the Collie Coal Basin. The model gave estimates of groundwater fluxes and predictions of the future lake water level if mine discharges were to stop. Transient simulations forecast a 3.6-3.9 m decline in the long-term lake water level without mine water input, with non-mine groundwater inflow rates increasing from commensurately steeper hydraulic gradient from a declining lake level in steady state. As a result, although the water level of Lake Stockton would still be suitable for public recreation, the decline in the water level would expose steep pit walls and reduce the regulation recreational area by 17%. Consequently, rehabilitation planning for this lake should account for safe access if recreation is to be permitted when the predicted decline in water levels takes place. The study highlights the critical importance of understanding the hydrogeological setting and the controls over lake levels in-pit voids for maintenance of recreational end use values.

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“…Where pit voids extend below local groundwater levels then waste can be stored in saturated conditions (Schultze et al 2011). However, prior to such storage being considered, consideration of groundwater flow paths such as by hydrogeological modelling should always be undertaken either specifically required by regulators such as contaminates lands legislation or as leading practice (McCullough et al 2013b).…”

Section: Contaminated Mine Watersmentioning

confidence: 99%

Key mine closure lessons still to be learned

McCullough¹

2016

Proceedings of the International Conference on Mine Closure

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The focus of mining project feasibility studies and operations is still on short-term profitability with little view to a post-closure landscape and liability. The faults of both the original and the operation's mine planners are therefore vested upon the closure teams who must deal with these planning decisions. Following completion of operations, most mining companies that have not adequately prepared for mine closure will face an inability to relinquish their project leases as a result of closure planning process shortfalls. Following from our own closure project experiences and of recent international mine closure conferences, we propose seven key lessons still to be learned if successful mine closure is to be achieved. Firstly, a paucity of baseline environmental monitoring data often incapacitates good closure planning from the outset with a failure to understand key closure risks and risk drivers for the site. Well-characterised environmental information prior to mining disturbance and monitored progressive rehabilitation is a great strategy to address this fault. An insufficient understanding of the physical and chemical characteristics and volumes of waste materials is a second critical fault of closure processes. A third significant issue is contaminated mine waters such as acid and metalliferous drainage (AMD). AMD is arguably one of the single biggest liabilities and management issue post-closure. Failure to engage stakeholders in a documented process is a fourth prime failing often seen with the fifth of mine closure procrastination. Like all of these causes, this problem often arises from thinking mine closure is an activity at end of life-of-mine rather than as a process that begins with the initial mine plan and then regularly continues throughout mine life. Diligent attention to regular planning assessment and stakeholder consultation from an early operational phase may fend off later criticisms, lead to closure outcomes better directed by years of underpinning work and also reduce end of mine costs.

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Mine Closure of Pit Lakes as Terminal Sinks: Best Available Practice When Options are Limited?

Cited by 31 publications

References 16 publications

Consequences and opportunities from river breach and decant of an acidic mine pit lake

Consequences and opportunities from river breach and decant of an acidic mine pit lake

Modelling the long-term water balance of a pit lake with recreational end uses

Key mine closure lessons still to be learned

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