Isua

New Report: Applied Glaciology Primer

Posted by William Colgan on November 13, 2015
Applied Glaciology, Glaciers and Society / No Comments

The Geological Survey of Denmark and Greenland (GEUS) has been involved in several applied glaciology projects since the early 1980s, such as assessments for the hydropower plants now operating at Ilulissat and Nuuk, and glacial lake outburst flood assessments for Isortuarsuup and Qorlortossup in South Greenland. In a report entitled “Unique applied glaciology challenges of proglacial mining” in this year’s Report on Geological Survey Activities, we provide a brief overview of four unique glacier-related geotechnical challenges confronting industrial operations adjacent to a glacier. We discuss these four especially unique applied glaciology challenges in the context of a new generation of mining projects that seek to excavate through glaciers to reach sub-glacial ore, such as the active Kumtor Mine in Kyrgyzstan and the approved Isua Mine in Greenland. The four uniquely glacier-related geotechnical challenges we discuss are supraglacial runoff, subglacial water flow, ice movement and supraglacial access roads. We also highlight how climate change is poised to further exacerbate these geotechnical challenges, as increased meltwater production generally enhances both water flow and ice flow into proglacial sites. We hope this report can serve as a quick survey of recent applied glaciology activities for non-specialists.

ROSA_sites

Site overviews of the recently approved Isua project in Greenland (left) and the recently approved Kerr-Sulphurets-Mitchell and Brucejack projects in Canada (right).

*W. Colgan, H. Thomsen and M. Citterio. 2015. Unique applied glaciology challenges of proglacial mining. Geological Survey of Denmark and Greenland Bulletin. 33: 61–64.

*This report serves as the citation for the proglacial mining projects open-file located here.

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New Estimate of Ice Sheet Runoff at Isua Site

Posted by William Colgan on April 14, 2015
Applied Glaciology, New Research / No Comments

My colleague Lukas Arenson and I have a paper in the Proceedings of Mine Water Solutions in Extreme Environments this month, which uses the Isua site in Southwest Greenland as a case study for extreme runoff in proglacial environments (Arenson and Colgan, 2015). The recently approved Isua mine will be an open pit mine intersecting the ice sheet, with ice pit walls around about half the pit, to access what is presently a subglacial iron deposit (site overview here). Using a Monte Carlo approach, we estimate a 95 % (or two sigma) upper confidence limit of 2.8·109 L/day of ice sheet runoff potentially reaching the Isua site in July and August. While this potential inflow rate, equivalent to 44 t/s, is relatively large in the context of conventional mine water management, it is relatively small in the context of contemporary Greenland ice loss due to climate change, which is approximately 8,300 t/s when averaged over a year (Andersen et al., 2015).

Isua_meltwater_runoff_estimate

Minimum and maximum plausible supraglacial ice sheet catchments associated with the Isua site. Shading denotes mean annual meltwater runoff over the 2004 to 2013. Background image source is Landsat 8 (source: Arenson and Colgan, 2015).

To place our estimate in context, London Mining Plc, the initial developer of the Isua site, presented a pre-feasibility study water balance in which ice sheet runoff into the pit was estimated as 7.8·106 m3/year (London Mining, 2011). Assuming a 60-day melt season, this is equivalent to an average site inflow of 1.3·108 L/day. Our estimate is therefore 22 times greater than the design estimate. There are many potential sources of uncertainty when assessing ice sheet runoff, including model uncertainty and climatic variability, but by far the biggest source of uncertainty is delineating the ice sheet catchment draining to a specific portion of the ice sheet margin. Regardless of whether 108 or 109 L/day of meltwater is flowing into the Isua site, it will certainly be a challenging operating environment, and will require some very adaptive engineering to minimize site contact water!

Isua_SNC_Budget

Proponent water budget for the Isua Mine (source: London Mining, 2011).

Isua_2011 173

Oblique aerial photograph looking west from the Greenland ice sheet across the Isua site in 2011. Deeply incised supraglacial meltwater channels are visible draining towards the margin. (source: Lukas Arenson)

References

Andersen et al., 2015. Basin-scale partitioning of Greenland ice sheet mass balance components (2007–2011). Earth and Planetary Science Letters 409: 89-95.

Arenson and Colgan. 2015. Water management challenges associated with mining projects in Greenland. Proceedings of Mine Water Solutions in Extreme Environments. 533-543.

London Mining PLC. 2011. Isua iron ore project: Isua 15 Mtpa scoping study report.

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Proglacial Mining Projects (Open File)

Posted by William Colgan on January 08, 2015
Applied Glaciology, Glaciers and Society / No Comments

Proglacial mines, meaning mining operations adjacent to, or very close to, glaciers, face a variety of unique glaciological challenges not present in conventional mining operations: (1) Removing ice overburden to access a subglacial ore introduces both ice excavation and ice flow management challenges. (2) In addition to potential crevasse hazards, supraglacial vehicle access roads must use adaptive engineering to counteract ice movement (both horizontal and vertical) as well as differential surface ablation. (3) Tremendous glacier meltwater runoff, concentrated during the summer melt season, can be difficult to route across highly transient glacier surfaces in order to minimize site inflow/contact water. (4) The dust created by open pit operations or access roads can darken the surface of nearby glaciers, enhancing their solar absorption and surface melt rates, and ultimately expand the impact footprint of a mine. (5) The catastrophic drainage of supraglacial and/or ice-dammed lakes represent outburst flood hazards which can rapidly increase site inflow rates. (6) Subglacial hydrology can interact with the groundwater seepage in underground mining operations beneath glaciers. We touch on some of these glaciological hazards in the new textbook: “Snow and Ice-Related Hazards, Risks, and Disasters”. These geotechnical challenges make proglacial mining projects very unique. I started this “open file” inventory of proglacial mining projects (past, present and future) and their associated glaciological challenges as I pull together information for an applied glaciology review paper. Please alert me to any errors or oversights!

ProjectPrime
Minerals
LocationGlaciological ChallengesApparent
Status
Isua
[Fig. 1]
Fe 65.195 °N, 49.790 °W
(Greenland)
- ice removal / flow management
- glacier access roads
- meltwater runoff
- supraglacial lake outbursts
- darkening of nearby glaciers
Approved in 2013.
Kumtor
[Fig. 2]
Au41.862 °N, 78.196 °E
(Kyrgyzstan)
- ice removal / flow management
- glacier access roads
- meltwater runoff
- darkening of nearby glaciers
Active since 1997.
Kerr-Sulphurets-
Mitchell
[Fig. 3]
Au, Ag, Cu, Mo56.491 °N, 130.335 °W
(Canada)
- glacier access roads
- meltwater runoff
- darkening of nearby glaciers
Approved in 2014.
TutoN/A76.417 °N, 68.269°W
(Greenland)
- ice removal / flow management
- glacier access roads
- meltwater runoff
Historic project (1955 to 1959).
GranducCu56.247 °N, 130.089 °W
(Canada)
- ice removal / flow management
- meltwater runoff
- darkening of nearby glaciers
Historic project (1964 to 1983).
MalmbjergMo 71.964 °N, 24.289 °W
(Greenland)
- glacier access roads
- meltwater runoff
- darkening of nearby glaciers
Prospect.
Brucejack
[Fig. 3]
Au, Ag56.468 °N, 130.164 °W
(Canada)
- glacier access roads
- meltwater runoff
Approved in 2015.
Maarmorilik
(Phase Two expansion)
Zn, Pb71.094 °N, 51.027°W
(Greenland)
- meltwater runoff
- darkening of nearby glaciers
Prospect.
Svea Nord | Gruve
[Fig. 6]
C77.893 °N, 16.689 °E
(Norway)
- subglacial miningActive since 2001.
El Morro
(La Fortuna expansion)
[Fig. 4]
Cu, Au33.167 °S, 70.274 °W
(Chile)
- darkening of nearby glaciersActive since c. 2008.
Permit suspended in 2014.
Pascua Lama
[Fig. 5]
Au, Ag29.327 °S, 70.035°W
(Chile / Argentina)
- darkening of nearby glaciersActive since 2010.
Permit suspended in 2013.
KvanefjeldU60.963 °N, 45.957 °W
(Greenland)
- darkening of nearby glaciersProspect.
Red MountainAu, Ag55.970 °N, 129.721 °W
(Canada)
- proglacial and/or subglacial depositsProspect.
Grasberg [Fig. 7]Au, Cu4.060 °S, 137.146 °E
(Indonesia)
- darkening of nearby glaciers
- glacier removal to access subglacial deposit
Active since c. 1995.

Below are some site overview figures, they are available for distribution without attribution tags as well. I hope to make one for each project by the end of 2015. Content on this page can be cited as:

Colgan, W., H. Thomsen and M. Citterio. in press. Unique Applied Glaciology Challenges of Proglacial Mining. Geological Survey of Denmark and Greenland Bulletin.

Isua_Mine

Figure 1 – The Isua Mine in Greenland: Contemporary ice margins, proposed approximate pit area, and winter 2005/06 ice surface velocity vectors overlaid on a 2014 Landsat image.

Kumtor_Mine

Figure 2 – The Kumtor mine in Kyrgyzstan: Historic ice margins and contemporary mine area overlaid on a 2014 Landsat image.

Kerr-Sulphurets-Mitchell_Mine_Brucejack_Prospect

Figure 3 – The Kerr-Sulphurets-Mitchell Mine and Bruckjack Prospect in Canada: Contemporary ice margins, approximate mine surface areas, and proposed supraglacial access roads overlaid on a 2014 Landsat image.

El_Morro_Mine

Figure 4 – The El Morro mine in Chile: Contemporary ice margins and mine area overlaid on a 2014 Landsat image.

Pascua_Lama_Mine

Figure 5 – The Pascua Lama mine on the Chile/Argentina border: Contemporary ice margins and mine area overlaid on a 2014 Landsat image. The Valadero mine is also visible immediately south of the Pascua Lama mine.

Svea_Nord_and_Gruve_Mines

Figure 6 – The Svea Nord / Gruve Mines in Svalbard (Norway): Contemporary ice margins and underground mine area overlaid on a 2014 Landsat image.

Grasberg_w_label2

Figure 7 – Grasberg Mine in Indonesia: Contemporary mine area and ice margins in a 2003 Landsat image.

 

 

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Ice Excavation in an Open Ice Pit

Posted by William Colgan on September 24, 2014
Applied Glaciology, New Research / No Comments

I have a paper in this month’s issue of the Journal of Cold Regions Engineering that examines the ice excavation required to establish and maintain an open ice pit. Excavating an open ice pit is a very non-linear applied glaciology problem, as the excavation of ice from an open ice pit enhances subsequent ice flow into the open ice pit. This is because ice velocity is very sensitive to changes in ice geometry, with third and fourth order dependencies on ice slope and thickness respectively! The paper examines scenarios based on excavating an open ice pit on the Greenland ice sheet margin that extends 1000 m into the ice sheet, with a 200 m high ice wall. That is the approximate dimension of the Isua Prospect, Greenland, which is projected to excavate about 36,000,000 tonnes of glacier ice per year.

Working with such unnatural combinations of ice slope and ice thickness compels you to reconsider fundamental principles of glacier mechanics, such as the appropriate relation between stress and strain at tremendous basal shear stresses, which are inconceivable in virtually all natural glacier settings. Despite an increasingly pressing need for a comprehensive understanding of how glaciers respond to highly transient forcings, however, most private sector glacier management projects cannot contribute meaningful observational data to advance such fundamental science due to proprietary considerations. Perhaps that can change in the future!

W. Colgan. 2014. Considering the ice excavation required to establish and maintain an open ice pit. Journal of Cold Regions Engineering. 28: 04014003. doi:10.1061/(ASCE)CR.1943-5495.0000067. Available here.

Supplementary online material (including animations): http://www.williamcolgan.net/som/CRENG113

cross_sectional_ice_velocity_open_ice_pit

Cross sectional ice velocities flowing into an open ice pit at excavation years 2.5 (left) and 10.0 (right) sampled from 30-year animations. Dashed black line denotes original ice surface, dash red line denotes ice pit wall. (from Colgan, 2014)

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