GoldSim allows you to create realistic models of mine systems in order to carry out risk analyses, evaluate potential environmental impacts, support strategic planning, and optimize operations.
GoldSim combines the flexibility of a general-purpose and highly-graphical probabilistic simulation framework with specialized modules to support water quality modeling and reliability analysis (e.g., of pumps and other equipment). This allows you to predict future behavior, identify which factors have the greatest influence, answer "What if?" questions, and evaluate alternatives. GoldSim is not only powerful and flexible (so that it can accurately represent mine systems), but GoldSim also facilitates construction of graphical and highly transparent models that can be easily explained to decision-makers and stakeholders.
GoldSim has been used extensively in the mining industry worldwide to address a broad range of issues, including:
- Mine water management;
- Contaminant transport and environmental compliance;
- Evaluation of mine closure options;
- Mine material management and logistics
- Reliability and throughput analysis of processing facilities.
GoldSim has been used at hundreds of mine sites worldwide by the world's largest mining companies, as well as by leading consulting firms that support the mining industry.
- GoldSim: Using Simulation to Move Beyond the Limitations of Spreadsheet Models
- Mining Applications Using GoldSim
Proving a New Refinery Design Using Reliability Proving a New Refinery Design Using Reliability Throughput Modelling
2011 International Applied Reliability Symposium, North America: San Diego, California – June 7 - 9, 2011
The design, construction and operation of large-scale resource projects are now subject to extreme levels of competition and cost, with many projects running into billions of dollars. For this reason, resource companies, bankers and every participant in the design train are now compelled to understand every aspect of risk to be undertaken, usually well before the project becomes a reality. A key element of the design process is knowing if the plant can actually produce the required output – along with a clear understanding where the areas of potential risk might be. Rather than ignoring the reality of failure effects or, more commonly, de-rating the entire design by some “accepted” operating availability number and trying to justify it, companies are now turning to plant reliability modeling up-front to prove more efficient designs, even with the uncertainties of failures well before plant startup. The concept of calculating “throughput” provides an absolute plant (design) model output for given inputs, by directly linking plant flows and consequences to the equipment availability. This presentation describes a project recently undertaken, including the project background, modeling stages and processes, and the successful outcomes provided for one client who is currently undertaking a very large-scale resource investment.
This presentation describes how GoldSim and the Reliability Module were used to simulate the throughput of an alumina refinery, accounting for failures and preventive maintenance schemes, to support facility design.
Black Butte Project Water Balance
Appendix L of the Black Butte Copper Project Mine Operating Permit Application – December 2015
Mediha Hodzic, Knight Piesold Consulting
The Black Butte Copper Project is a proposed underground copper mine located approximately 32 km north of White Sulphur Springs, Montana. An update to the life-of-mine site wide water balance model has been completed by Knight Piésold (KP) to incorporate the transfer of surface water from the Process Water Pond and the Cemented Tailings Facility to the Water Treatment Plant, with subsequent treatment and release to the environment. Surface water includes direct precipitation on mine facilities, as well as runoff contributing to mine facilities. This letter details the model objectives, parameters, assumptions, and results.
The model was developed using the GoldSim© modeling platform. Deterministic and stochastic approaches were used, and 15 years were modeled including two pre-production years and 13 years of operations.
Yeelirrie Water Balance Study
Report prepared for Cameco Australia Pty Ltd – June 2015
Nazuha Rosli, URS
This report presents the results of the Water Balance modelling for the proposed Yeelirrie Project, which supports the Public Environmental Approval (PER) submission process, aimed to validate the performance of the Project water management strategy. The water balance developed for this project was first developed using GoldSiom by URS in 2011 and has since been updated to reflect changes to the proposed mine plan.
Mine Water Balance Modelling for Goedehoop Colliery
Report No.: JW191/14/D952- Rev 0 for Anglo-American Thermal Coal – October 2014
Simphiwe Ngcobo, Jones and Wagener Engineering and Environmental Consultants
Anglo-American Thermal Coal invited Jones & Wagener Engineering and Environmental Consultants to develop a Life of Mine water balance for the Goedehoop South Colliery in Vandyksdrift in the Mpumalanga Province. The water balance was based on relevant hydrological data and mine water management information received from the client. The data and information were compared against known estimates and logical assumptions made. The water balance modelling was performed in the GoldSim modelling environment and the results were analysed.
A Probabilistic Water Balance
Thesis Paper, UMI Dissertations Publishing – 2014
Wade, Lisa, Montana Tech of the University of Montana
This is a Thesis, describing the research and development of a probabilistic water budget model for a mining and milling operation using GoldSim. The model incorporates climate data, well water supply, dewatering and water entrainment within a tailings storage facility. The issues revealed by the GoldSim model results were of critical importance and their identification will result in financial savings, as well as the avoidance of any emergency or crisis situations with respect to environmental management of water and tailings at the project.
Snap Lake Mine Site Water Quality
Mine Water Quality Report Update – December 2013
De Beers Canada Inc.
A mass and flow balance model built in GoldSim was used to integrate the flow and mass loading from the components of a Mine site to develop overall estimates of water quality and mass load for the Mine site water quality. The Contaminant Transport module is used to track mass movement and develop estimates of mass load and concentrations at various points in the system.
Red Hill Mining Lease - EIS Water Balance Modeling
EIS Water Balance Modeling Report, Final - Revision 0 – November 2013
S. Buckley, Sinclair Knight Merz
Sinclair Knight Merz (SKM) was commissioned by BHP Billiton Mitsubishi Alliance to prepare water balance modelling to support the Environmental Impact Statement (EIS) in association with the proposed Red Hill Mining Lease. The study was undertaken using a water balance model developed for the Goonyella Riverside and Broadmeadow mine complex operation using GoldSim. This study builds on the operational model to provide input to the EIS.
Minyango Project Environmental Impact Statement
Water Balance Report for the Minyango Project – April 2013
WRM Water and Environment Pty Ltd.
WRM Water and Environment Pty Ltd was commissioned to complete a water balance assessment as part of an EIS for the Minyango Project. The water balance, which includes water supplies, demands, and storages over the life of the mine, was developed using GoldSim. The model dynamically simulates the mine operations and accounts for site water volumes and quality on a daily time step.
Water Balance Model for the Mt. Todd Mine Production and Closure
Appendix 1, Surface Water Assessment prepared by GHD Australia Pty Ltd. for Vista Gold Australia Pty Ltd – May 2013
A GoldSim model was developed to simulate the performance of a water containment system during pre-production, production, closure and post-closure of the mine's life cycle. The water balance includes climate and runoff, site seepage and other losses, tailings reclaim water, water demands, water balance logic, water supplies and discharge to the environment. This was all simulated under varying conditions and rules as the mine facilities change during its life cycle.
Water Management Plan for Mangatangi Mine
Appendix B Water Management Plan (WMP) Golder Associates (NZ) Limited – October 2012
A GoldSim water balance and water quality model was developed by Golder Associates for the Mangatangi Mine in behalf of Glencoal Energy Limited. Stream flow depletions and potential boron concentrations were calculated on the basis of the water flow and contaminant mass balances performed in the model.
Mine Water Management from Pre-feasibility to Closure
Mine Water Management and Treatment, Kuopio, Finland – September 2013
Seth Mueller, Boliden Mineral AB
A mine water management plan was developed to assist with regulatory permitting and planning for a mine in Finland. GoldSim was used to simulate the water management from pre-feasibility through closure. The model accounts for pre and post mining conditions, various water demands and recycling, extreme climate events, and impacts on water quality. The model takes advantage of GoldSim's powerful dynamic and probabilistic functionality to optimize mine operations under uncertain conditions.
Use of an Integrated Source-to-Receptor Model to Faciliate Rapid Assessment of Water Quality Impacts During Mine Planning
Reliable Mine Water Technology, IMWA; Golden CO USA – 2013
Tina Pint, Peter Hinck, Barr Engineering Company
An integrated source-to-receptor model for assessing potential project-wide water impacts can save time and money by facilitating rapid evaluation of multiple design options. GoldSim was used to develop an integrated source-to-receptor model for a mine site in northern Minnesota and used to evaluate various mine closure options during the mine planning process.
Mine Water Quality Predictions Model
Project Report, Casino Mining Corporation – December 2013
Source Environmental Associates, Inc.
A site-wide water quality model was developed for a proposed Mining Project. The model simulates water quality in the mine discharge and receiving environment. The water quality model is also used as a planning tool to help select water quality mitigations. The water quality model was built within the GoldSim modelling platform, and was run for a simulation timeline of 200 years and includes 29 water quality parameters.
Mine Water Quality Model
Quality Assurance Technical Memorandum, Environmental Resources Management – February 2013
Barr Engineering Company
A technical memorandum (link below) summarizes a series of Quality Assurance (QA) evaluations that were performed on two water quality models used to estimate environmental impacts associated with a proposed mining project. The two models, one for a mine site and one for a plant site, were programmed using GoldSim. The models were developed by Barr Engineering Company (Barr) to estimate potential effects from the proposed mine on the quality and quantity of water resources.
Waste Discharge Charge System: The Practical Implication from a Gold Mining Perspecitve
Mini-dissertation, North-West University – October 2012
K.C. de Waard, J.H. Stander, Potchefstroom Campus of North-West University
A case study was used to determine what information and instruments will be required at a gold mine to implement the Waste Discharge Charge System (WDCS). The determining of the point and diffuse discharges require multidisciplinary studies with the integration of different spheres of the environment. To assist with this a GoldSim model was developed. The main function of the model was to determine the seepage rates per day from pollution sources using available information. The seepage rates and water quality data were used to determine waste loads discharged to the environment.
Geochemical Pit Lake Predictive Model
Report for Rosemont Copper Project, Revision 1 – November 2010
A dynamic systems computer model (DSM) was developed in GoldSim to simulate the hydrologic water balance and the mixing of the chemical loads from the various hydrologic processes (e.g., groundwater inflow, pit wall runoff, precipitation) for the anticipated Rosemont pit lake. Outputs from the DSM predictive simulations were used as inputs to a final simulation model step using PHREEQC.
Water Balance for a TSF Using GoldSim
Tailings and Heap Leach Pad Workshop – April 2010
This presentation summarizes the benefits of using GoldSim for a waste and tailings water balance for the Mount Carlton mine. Some benefits of using GoldSim over a Spreadsheet are noted: GoldSim better facilitates handling of complex climatic data, saves significant model runtime to view multiple scenarios, better estimates water volumes in dry seasons, easier to run optimizations.
Linking Fundamental Geochemistry and Empirical Observations for Water Quality Predictions Using GoldSim
Mine Water and Innovative Thinking, IMWA, Wolkersdorfer. Ch. and Freund, A., p 313-316, Sydney, Nova Scotia, Canada – 2010
Brent Usher, Roald Strand, Chris Strachotta and Jim Jackson
Prediction of water quality across different components of a mine site is often a challenging proposition, due to both the technical challenges of water quality modelling and the variability of available data. A methodology of integrating site-specific mine waste characterization results and minewater balances through the use of fundamental considerations and empirically-derived constraints to predict water quality from mine waste sources has been developed. The adoption of GoldSim as visual interface software with capacity for matrix calculations has facilitated the development of linked water quality sub-models for different mine facilities. Fundamental and observed geochemical responses from on-site monitoring, field kinetic tests and laboratory data have been incorporated with Phreeqc and geochemists Workbench modelling to identify the most important geochemical processes across the mine site. Based on the static geochemical data to populate the models, the determined geochemical generation rates, the site specific geochemical properties and the mine-site water balance, the GoldSim platform has been used to realise the conceptual understanding of each aspect and construct a framework to provide mine scale water quality projections. In this way, models have been built to assist in a range of situations from a large operating poly-metallic open cut mine to assess mine waste and mine water management alternatives to determination of likely water quality at a proposed large mine in a tropical environment.
Modelling of Contaminant Release from a Uranium Mine Tailings Site
Proceedings of the 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM) – September 2007
R. Kahnt and T. Metschies
Uranium mining and milling continuing from the early 1960s until 1990 close to the town of Seelingstädt in Eastern Germany resulted in 4 large tailings impoundments. Leakage from these tailings impoundments enters the underlying aquifers and is discharged into surface water streams. High concentration of salts, uranium and several heavy metals are released from the tailings. A compartment model representing the tailings impoundments and the surrounding aquifers for the calculation of contaminant release and transport was set up using GoldSim. This compartment model describes the time dependent hydraulic conditions within the tailings and the surrounding aquifers taking into account hydraulic and geotechnical processes influencing the hydraulic properties of the tailings material. A simple geochemical approach taking into account sorption processes as well as retardation by applying a kd-approach was also implemented. The model was used to predict the effect of various remediation scenarios in a fast and traceable way.
Mine Water Management – Dynamic, Probabilistic Modelling Approach
10th International Mine Water Association Congress – June 2008
Przemek Nalecki and Mike Gowan, Golder Associates
This paper presents a holistic approach to mine water management. The proposed approach provides a framework and methodology for integrating different components of mine water infrastructure by explicitly representing the relationships, feedback mechanisms and uncertainties about the conditions and processes involved, using a dynamic, probabilistic simulation method.
Development and Operation of a Water Balance at Rio Paracatu Mineracao, Brazil
Proceedings of the 7th International Conference on Acid Rock Drainage (ICARD), St. Louis, MO – March 2006
Tobias Puhlmann, Juliana Esper, and Rodrigo Dutra Amaral, Kinross Gold Corporation; Charles Voss, Golder Associates
This paper describes a site wide water model of the Rio Paracatu Mineração that was developed to a) evaluate ways to optimize the operation of the existing water management system and b) evaluate alternative water infrastructure and water supply options that would meet the requirements of future mine expansions.
Peruvian Mine Operation Using Dynamic System Modeling
Southwest Hydrology – July/August 2006
Charlie Voss, Golder Associates; Henri Letient, Compania Minera Antamina S.A.
This article describes the GoldSim model of the Antamina mine that was created to allow different water management strategies to be evaluated to ensure that they would meet regulatory constraints
Applying Numerical Hydrochemical Models as Decision Support Tools for Mine Closure Planning
Presentation at Tailings and Mine Waste '08, Vail, CO – October 2008
Ted Eary, Jody Eshleman, Ryan Jakubowski and Andrew Watson, MWH
This presentation describes the use of decision-support models for evaluating closure alternatives for pit lakes.
Site-Wide Water Balance of the Pierina Gold Mine, Peru
Presentation – 2008
Liane George, William Ludwick and John Chahbandour, Schlumberger Water Services
This presentation describes a site-wide water balance model for the Pierina Gold Mine in Peru that was designed to ensure compliance with environmental regulations.
Rehabilitation of Meirama Pit Lake
Proceedings of the 9th International Mine Water Conference, Oviedo, Spain – February 2012
Juan Luis Delgado, Lignitos de Meirama, SA
This paper describes a model built to evaluate closure options for a coal mine, taking into account possible water quality issues.
Simulating the Effectiveness of Remedial Measures at a Coal Mine (New Zealand)
Proceedings of the 2006 Water in Mining Conference – November 2006
Jan Vermaak and Paul Lindsay, Golder Associates
This paper describes a GoldSim model that was developed to simulate the effectiveness and costs of a number of conceptual remedial measures aimed at reducing acidity and metal concentrations in the Ngakawau River and its tributaries near the Stockton Coal Mine, situated on the West Coast of New Zealand.
Probabilistic Modeling for Tailings Remediation and Restoration
Mine Water – Managing the Challenges, IMWA; Aachen, Germany – 2011
Gareth Digges La Touche, Helen Culshaw, Richard Lansley, Golder Associates (UK) Ltd
Tailings Management Facilities represent a hazard to the down gradient surface water and groundwater environment. The assessment of the risks such facilities pose to the water environment is an important issue for mine closure, particularly when the potential for an impact on the water environment has been identified. This paper will describe the application of probabilistic simulation in quantitative analytical models to assess the risks where confidence in modelled outcomes may otherwise be inhibited due to limited environmental data. The application of probabilistic modelling will be illustrated through case studies illustrating the use of probabilistic risk assessment to appraise differing closure and remediation strategies for a tailings management facility and the use of such tools to quantify the level of uncertainty in the assessment of risk.
Water Balance Modelling of a Uranium Mill Effluent Management System
Journal of Hydrology – June 2017
Valérie Plagnes, Areva Resources Canada and Sorbonne Universités; Brad Schmid, University of Saskatchewan; Brett Mitchell and Ian Judd-Henrey, Areva Resources Canada
A water balance model was developed to forecast the management strategy of a uranium mill effluent system, located in northern Saskatchewan, Canada. Mining and milling operations, such as pit dewatering or treated effluent release, can potentially influence the hydrology and the water quality downstream of the operations. This study presents the methodology used to predict water volumes and water quality discharging downstream in surface water bodies. A compartment model representing the three subsequent lakes included in the management system was set up using the software GoldSim. The water balance allows predicting lake volumes at the daily time step. A mass balance model developed for conservative elements was also developed and allows validating the proportions of inputs and outputs issued from the water balance model. This model was then used as predictive tool to evaluate the impact of different scenarios of effluents management on volumes and chemistry of surface water for short and longer time periods. An additional significant benefit of this model is that it can be used as an input for geochemical modelling to predict the concentrations of all constituents of concern in the receiving surface water.
Development of a Tailings Management Simulation and Technology Evaluation Tool
PhD Dissertation, University of Alberta – 2015
Nicholas A Beier
This research aims to assist in the assessment of tailings management technologies through the development of a dynamic simulation model. The developed model (TMSim) incorporates the mine plan, various stages of dewatering including classification, pre- and post-deposition dewatering, and an impoundment material balance including tailings, process water, construction material and capping materials. GoldSim was used as the "simulation engine" for the model. It chosen as the simulation package for TMSim because of its ability to simulate dynamic systems such as a tailings system, balance of computational power with ease of use, and other features such as ability to link with external software. The modeling approach adopted, using GoldSim, will assist the planner to understand the TMS and its boundaries, identify key variables and clarify complex interrelationships.
3D Deposition and Water Balance Modelling with Muk3D and GoldSim
Proceedings of Mine Water Solutions 2018 – June 12–15, 2018
Carlo Cooper, MineBridge Software; Jaco Grobler, Consultant; Miguel Palape Reyes, MineBridge Software
This paper discusses how GoldSim and Muk3D have been integrated allowing for 3D tailings deposition to be incorporated into an existing water balance model. The difference in results between the 2D models for a TSF used in GoldSim and the same models run using a 3D deposition model are explored, and advantages and limitations of this approach are discussed.
Predicted Post-Closure Contaminant Loads and Water Quality Conditions in Myra Creek, Nyrstar Myra Falls, Canada
Proceedings of Mine Water Solutions 2018 – June 12–15, 2018
Paul Ferguson, Christoph Wels, and Alexander Trapp, Robertson GeoConsultants; Nicole Pesonen, Nyrstar Myra Falls
This paper will describe Robertson GeoConsultants' conceptual load balance model and a numerical load balance model that was developed with the software GoldSim. The numerical model was calibrated to daily zinc (Zn) loads in Myra Creek from 2012 to mid-2016, and water quality data was collected from within the mine site. Once calibrated, the model was used to simulate the improvement in water quality conditions in Myra Creek during the future operation of the Lynx Seepage Interception System (SIS) and after the Old TDF has been closed and the Lynx TDF berm has been raised to its final height and covered.
Innovative Application of Water Quality and Flow Modeling to Design a Softening, UF/RO and Brine Handling System for Copper and Gold Mining Wastewater Treatment in the Peruvian Andes
Proceedings of the Water Environment Federation – 2014
Burbano, Arturo; Sansom, Stephanie; Kinser, Karla; Rozas, Jose; Corser, Pat
A systematic approach was utilized to design a water treatment plant to treat tailings water at a copper mine in northern Perú. Water to support the mine operation was stored in a tailings pond, which needed to maintain a maximum level to ensure dam stability and avoid overflows of untreated water. The latter are likely to occur during times of excessive precipitation and need to be avoided at all cost, as they may threaten a nearby river used by the surrounding communities for drinking water supply. A GoldSim water balance model provided an estimate of the required design flow to build a plant that would avoid these issues, and process modeling facilitated definition of the treatment requirements to meet the stringent discharge regulations, especially for sulfate, calcium and nitrite. A robust and reliable treatment system including RO membranes was subsequently designed around the model results and incorporated sufficient flexibility to meet compliance of the upcoming regulations even under extreme water quality conditions.
Modelling approach to predict peak inflows at the Argyle block cave mine, Western Australia
Proceedings IMWA 2016, Freiberg/Germany – 2016
Geoff Beale, Schlumberger; Toddy Syaifullah and Dadang Saepulloh, Rio Tinto; Stuart Daley, Schlumberger
Argyle Diamond Mine is situated in the East Kimberley region of Western Australia. Block-cave mining is ongoing below the mined-out South Bowl pit. In 2014, two major rainfall events occurred: 175 mm falling in 48hrs on 15th-16th January; and 213 mm falling in 72hrs on 6th-8th February. The January 2014 rainfall event caused a short term peak mine inflow of 500 L/s, whilst the February 2014 event caused a peak inflow of 1200 L/s. A rainfall-runoff-frequency model was created to assess runoff volumes reaching the base of the pit. This was coupled with a numerical flow model developed to assess the passage of water from the pit floor to the mine extraction level. The model incorporated rock mass hydro-geomechanical changes based upon the predicted future Life of Mine cave zone propagation. The coupled model was calibrated to the two major 2014 runoff events. The model was then used to simulate a series of potential future rainfall-runoff events and future underground inflows. The analysis was used to develop a Trigger Action and Reponse Plan (TARP) for the future flood management.
Te Kuha Mine Project GoldSim Drainage Model and Predicted Chemistry
Report prepared by CRL Energy Ltd – March 2016
James Pope, Aaron Dutton, CRL Energy Ltd
GoldSim was used to model the discharge from the Te Kuha mine site into surrounding environment after water treatment for total suspended sediment. The model utilises climate data collected at the mine site, long term climate data from Westport, surface and groundwater data collected at the mine site as well as geochemical data collected through column leach tests. A relationship between measured data from the site and long term climate data has been established that enables the long term data to be used as input for the GoldSim model. This means that the surface water conditions on site can be adequately simulated to enable sizing of infrastructure and predict downstream impacts. The GoldSim model is calibrated against rainfall runoff data collected in Camp Creek with good agreement between modelled and measured data. Therefore the model will generate surface water flows that represent the intensity and variability likely on the Te Kuha mine site.
Coupling PHREEQC with GoldSim for a More Dynamic Water Modeling Experience
11th ICARD | IMWA | WISA MWD 2018 Conference – Risk to Opportunity, Pretoria, South Africa – 2018
Brent C. Johnson, Pamela Rohal, and Ted Eary
Mining operators strive to improve their tools for decision-making about water management to minimize risks and costs related to water quantity and quality issues. These issues are typically interrelated and complex such that interpretation and prediction of system dynamics requires implementation of innovative approaches that make use of observed data and fundamental hydrochemical concepts. We have developed an approach that couples the dynamic systems modelling framework of GoldSim with the geochemical reaction simulation capabilities of PHREEQC as described by Eary (2007). The approach utilizes a dynamic link library (DLL) code to handshake and transfer data between the two programs at every model timestep.
The coupled GoldSim-PHREEQC approach simulates mixing and reactions taking place at key mixing points along flow paths and at key water storage locations (e.g., ponds, tanks, pit lakes). Empirical factors affecting chemical loads can be calibrated to observed flows and chemistry at multiple locations and then used for predicting future water quality as operating and environmental conditions change.
Including geochemical reactions at each model time-step provides an efficient approach for applying a thermodynamic framework for understanding important geochemical processes that affect water chemistry. The approach also identifies the subset of reaction processes that may not be well explained by thermodynamic-based calculations and require empirical adjustment and time periods in response to events such as facility shut downs, climate events, and closure and remediation. The resulting calibrated model can be used to challenge our understanding of the reactions that are attenuating or not attenuating solutes at various site locations and to help understand, predict, and manage water quality going forward.
This modelling approach was applied to a proposed mine site in the northern Michigan (U.S.A.) to simulate various stages of operational and closure conditions to predict the quality of water that will require treatment. The model provided an efficient approach for making robust predictions of treatment requirements in terms of both water quality and quantity as a function of mine operations and closure.
Modelling Complex Mine Water Closure Challenges using a Coupled FEFLOW-GoldSim Model
11th ICARD | IMWA | WISA MWD 2018 Conference – Risk to Opportunity, Pretoria, South Africa – 2018
Nick Martin and Michael Gabora
A current limitation in modelling pit lake evolution from active mining through closure to optimise management strategies is the separation between physical process and operational modelling tools. To overcome this limitation, a GoldSim water balance model of pit operations is dynamically coupled with a FEFLOW, physically-based, model of groundwater inflow to the pit. This approach can be used as part of mine project planning to provide robust estimates of conditions at closure, including an improved representation of the pit lake system physical response, closure cost analysis, and risk assessment through uncertainty analysis.