Authors: Herrell, MK; Prestia, AL; Bowell, R; Bosley, G

Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2215_29

Cite As:
Herrell, MK, Prestia, AL, Bowell, R & Bosley, G 2022, 'Pit lake geochemical modelling methods for closure', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 429-438, https://doi.org/10.36487/ACG_repo/2215_29

Download citation as:   ris   bibtex   endnote   text   Zotero


Abstract:
Open pit mining can result in the formation of pit lakes at closure for projects that extend below the water table and have a positive water balance. The water quality of the pit lake has important implications for closure, rehabilitation and long-term management of mining projects, both financial and environmental. A prediction of future pit lake water quality is therefore necessary so appropriate mitigation strategies can be developed and implemented if required. In addition, in many environments the lake can represent a potential long-term benefit dependent on water quality. An understanding of pit lake water quality is evaluated through the application of predictive geochemical and hydrogeological models that rely on real world inputs to define the overall system. The water quality of the pit lake is dependent on several factors, including: the quality of the groundwater and surface water entering the pit; the contribution of chemical load from the exposed talus on benches and surfaces in the highwall above the pit lake; the prevailing climate conditions and hydrodynamics of the pit lake; and pit lake water management activities. In the absence of a present day analogue, accurate prediction of future pit lake water quality can be challenging, even when industry best practices are followed. This paper presents a case study of a pit lake geochemical model focusing on the approach and lessons learned. Generalised guidance for updating pit lake modelling best practices is also provided.

Keywords: pit lakes, geochemical modelling

References:
Bird, DA & Mahoney, JJ 1994, ‘Estimating post mining pit lake geochemistry utilizing geochemical and numerical modelling’, SME Preprint 94–241, Littleton Colorado.
Bowell, RJ 2002, ‘Hydrogeochemical dynamics of pit lakes’, in PL Younger & N Robins (eds), Mine Water Hydrogeology and Geochemistry, Geological Society of London Special Publication, pp. 159–187.
Bowell, RJ & Parshley, JV 2005, ‘Controls of pit lake chemistry by secondary minerals, Summer Camp Pit, Nevada’, Chemical Geology, vol. 215, pp. 373–385.
Brown & Caldwell 2021, Draft Stibnite gold project stibnite hydrologic site model refined modified proposed action (ModPRO2) report.
Castendyk, DN & Eary, LE (eds) 2009, ‘Mine pit lakes: characteristics, predictive modeling and sustainability’, SME, Littleton, Colorado, 304 p.
Dzombak, DA & Morel, FMM 1990, Surface complexation modeling: hydrous ferric oxide, John Wiley and Sons, Inc.
Eary, LE 1998 ‘Predicting the effects of evapoconcentration on water quality in mine pit lakes’, Journal of Geochemical Exploration, vol. 64, pp. 223–236.
Kelsall, PC, Case, JB & Chabannes, CR 1984, ‘Evolution of excavation-induced changes in rock permeability’, International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, vol. 21, no. 3, pp. 123–135.
Nordstrom DK & Nicholson, A (eds) 2017, ‘Geochemical modelling for mine site characterization and remediation’, SME, Littleton.
Parkhurst, DL & Appelo, CAJ 1999, ‘User's guide to PHREEQC (version 2) – A computer program for speciation, batch-reaction, onedimensional transport, and inverse geochemical calculations’, US Geological Survey Water-Resources Investigations Report 99-4259, 312 p.
Siskind, DE & Fumanti, RR 1974, ‘Blast-produced fractures in Lithonia granite’, US Bureau of Mines, Report of Investigations 7901, US Department of the Interior Library.
SRK 2021a, ‘Stibnite gold project ModPRO2 site-wide water chemistry (SWWC) modeling report’, SRK Consulting (USA) Inc., prepared for Perpetua Resources Idaho, Inc.
SRK 2021b, ‘Stibnite gold project ModPRO2 site-wide water chemistry (SWWC) sensitivity analysis report’, SRK Consulting (USA) Inc., prepared for Perpetua Resources Idaho, Inc.




© Copyright 2024, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
View copyright/legal information
Please direct any queries or error reports to repository-acg@uwa.edu.au