A Rookie in the Oilsands – Part 2

Date: June 2, 2025 Author: Ken Kuchling Comments: Leave a reply

The article is Part 2 of discussion on my experiences working in the oilsands at the Syncrude Mine in northern Alberta. Part 1 can be read at this link https://kuchling.com/a-rookie-in-the-oilsands-part-1/

In Part 1, I described the great Engineer-in-Training rotational program that Syncrude had in place for new engineering graduates. Initially I had rotated through the Overburden Geotechnical and Industrial Engineering departments. I was then fortunate enough to go though the Mine Geotechnical department and Short Range Planning. Here are some experiences from those assignments.

Will the Draglines Be Safe

Syncrude had four large walking draglines, each with a 80 cubic metre bucket and 110 metre operating radius. These were very big machines; you could sit one in the end zone of a football field and the bucket would be digging (or dumping) in the other end zone. Two draglines were on the East side of the mine and two were on the West, mining the oilsand in 25 m wide strips.

Mining oilsand while from the top of a 50 metre high and 45 degree highwall had never been done before. The geotechnical conditions were new. They were also dramatically different on the East and West sides of the mine, even though mining in the same orebody.

The East side was far more a greater geotechnical concern than the West side. I happened to be the West side mine geotechnical engineer (lucky for me I guess).

The oil sands are sedimentary deposits, and consist of inter-layered sands, silts and clays. At the Syncrude mine, the clay layers were regionally dipping towards the west at 5 to 10 degrees (as shown in the sketch below). Hence they were dipping into the wall on the West side and dipping out of the wall on the East side. The orebody also contained ancient creek scour channels, now infilled with clays and sands.

On the flanks of these scour zones, the thin clay layers could dip up to 25 degrees out of the wall. This was a problem. In university we learned rock slope failures generally require 30-35 deg dipping joint structures for sliding to occur; but here in the clays, sliding (block slides) could occur along 15 to 25 deg dips.

There were numerous instances of East mine block slides, where large portions of the upper slope would fail as large blocks, 50 metres long and up to 30 metres back from the crest. The fear was that if a dragline happened to be sitting on one of these failing blocks, the entire machine would slide along into the pit. Many block slides did occur over the years, but only a few came close to jeopardizing a machine. The geotechnical monitoring programs in place were successful (described later).

The insitu clay structures were identified using oil and gas borehole logging technology, with tadpole dipmeter plots (see image) used to analyse the bedding (the tail on the tadpole shows the dip direction). The vertical axis is depth from surface or elevation. The geotech engineers would use this information, combined with structural mapping of previously mined faces, to forecast potentially unstable areas.

In these problem areas, the geotech teams would install slope indicators that were monitored while the dragline was mining through the area. Dedicated 24 hour field engineers were assigned to each of the East side draglines and mining operations were closely monitored at all times.

It was not uncommon for the Syncrude geotechnical engineer to get a 2 am phone call at home saying movement has been detected and they walked the dragline back from the face and then get asked “What should we do now?”.

In the places that the engineers knew were going to be very risk, they could implement mitigation measures. How would you deal with the steeper scour zones? They had three main options.

mine through the area with intense geotechnical monitoring in place, using slope indicators, survey prisms, and visual ground inspections.
sub-excavate the zone; using the dragline to dig out the area and then backfill with the same material to destroy the clay bedding. Then they could safely mine through the area, although the days used to sub-excavate would remove the dragline from oilsand production.
another option was to blast the area ahead of time, to destroy the clay bedding and allow pore pressure dissipation.

All three options were available at the discretion of the geotechnical engineering team. However they all cost money and/or loss in mining production, but safety was always the priority.

The four draglines are now mothballed and thankfully none were ever harmed. All oilsand mining operations are now based on truck-shovel systems.

Basal Slope Failures

On the West side of the mine, the bedding was mainly into the highwall, so block slides were not a major concern. In my brief time there, we never had a block slide on the West side although we did continually review dipmeter plots and face mapping results. One still couldn’t be too careful or get lazy.

The main geotechnical issue on the West side were basal slope failures, termed this due to sliding along weak clays and muds at the base of the highwall. This photo shows a typical basal failure. Basal failures also occured on the East side.

Generally, these slope failures did not jeopardize the dragline since they occurred on freshly cut highwalls away from the machine. Eventually the dragline would be required to operate next to existing basal failures when mining the next panel (as shown in the photo).

The dragline would sit 15-25 metres from the wall, the closer is better to maximize reach into the pit.

The main concern with basal failures was that the toe of the failed slope would move beyond the reach of the dragline and could not be mined. As well, sometimes the dragline would need to cast waste layers back into the mined out pit while avoiding the burial of the oilsand toe. If the waste couldn’t be cast back inpit due to toe failure, it would be placed on the operating bench and trucked away later (at a cost).

The Alberta government focused on maximizing oilsand resource recovery. If the dragline could not reach the ore due to a failure, we would need to send mobile equipment down to get it. If we couldn’t do this due to access issues, we needed to prepare an Ore Loss Report that was tracked and submitted to the government agency (ERCB). We hated to submit those reports, taking it as a personal disappointment that we couldn’t get to that ore.

In the basal failure photo, one can see a vertical scarp next to the dragline. The oilsands were a “locked sand” in that the sand grains were tightly compacted or interlocked from the compressive weight of over a kilometre of glacial ice thickness in the past. The vertical scarps would stand indefinitely, sometime spalling off in slabs. The oilsand itself was a very strong geotechnical unit (friction angles in excess of 50 degrees).

Conclusion

Hopefully the above narrative is informative about on mining in the oilsands in the 1980’s. There are plenty more examples of technical issues that our engineering teams had to deal with, whether in the mining operation or tailings disposal area. As a new graduate engineer, it was a great learning experience.

Once our engineer-in-training rotation program was complete, we were to be assigned to a more permanent position. For me, that was going to be as an East side geotechnical engineer – ugh!. It’s at that time I decided to look for greener pastures. Three years was long enough from 1980 to 1983; given the amount of learning and responsibility I had undertaken. Other colleagues left the same time, while many other friends stayed in Ft McMurray for their entire careers.

I enjoyed the mine planning and scheduling work more than geotechnical engineering. The stress of the East side geotechnical role was not really for me. These days, I commend the tailings engineers that willingly accept the Engineer of Record role for tailings dams, knowing the risk, consequences, and potential legal ramifications of their work.

My next career move (after getting an M.Eng from UBC) was going to the Saskatchewan potash industry. One thing common between open pit oil sand mining and the underground potash mining was the heavy reliance on conveyor usage at both. I was getting very comfortable around conveyors. If you found this oilsand narrative mildly interesting, you can read about potash experiences at the blog post “Potash Stories from 3000 Feet Down – Part 1”. .

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Here is short cheesey video of what the oilsands were about in the 1980’s and 1990’s.

A Rookie in the Oilsands – Part 1

Date: May 22, 2025 Author: Ken Kuchling Comments: 2 Replies

Whenever I walk past a road repair crew laying down asphalt, I am taken back to my days working at Syncrude in the oilsands. The smell of the road tar is the same as the smell in the open pit mine. For three years that was my everyday experience. It’s the same as when I get a whiff of diesel fumes, it often reminds me of my days working underground. It seems that smell really can bring back memories, for me at least.

In Part 1 of this two part blog post I would like to share some stories from the early days of my career working in Fort McMurray.

Hopefully they will be interesting and help shed some light on what it can be like working in the mining industry. Syncrude provided my first job out of engineering university and hence will always be special to me.

In the early 1980’s Syncrude was producing about 90,000 barrels of oil a day by processing oilsand at a rate of 180,000 t/day, so it was a big mining operation.

The Engineer in Training Program

I started at Syncrude in the winter of 1980. At that time, the two main places hiring mining engineers were the oilsands in northern Alberta and the iron ore mines in northern Quebec / Labrador. A few mining graduates also went to work in Calgary in the conventional oil & gas industry, since they were looking for engineers and petroleum engineers were in scarcity.

At the time Syncrude had an excellent engineer-in-training program for new graduates. Every six months they would rotate engineers into different technical areas.

These areas could consist of: overburden stripping planning; overburden geotechnical; short range mine planning, mine geotechnical, industrial engineering, tailings planning, and tailings geotechnical. Long range planning tended to be left to the more senior people.

Probably about 15 mining / geological engineers were hired at the same time as me. We came from McGill, Queens, UBC, Laurentian, Univ of Alberta, and Nova Scotia. All of us were in the same boat, rotating through various departments for the first few years.

I ended up in four of the areas listed above; I don’t think anyone actually went through all of them. My first role was in Overburden Geotechnical department, where we had responsibility for waste dump stability, haulroad construction QA/QC, and dragline pad preparation. Each of these tasks required a lot of on the job learning for me.

A Fish Out of Water

At McGill, in the mining engineering program, we took some courses on rock mechanics, focusing on “rock”. The mines in eastern Canada were mainly hardrock mines so that was the learning priority. We leaned about joint mapping, stereonets, compressive and tensile strength testing and kinematic analysis.

Well, at Syncrude there was no rock. All geotechnical work here was based on soil mechanics, something we learned little of at university. Perhaps the civil engineers did more of this. Working in the oilsands, one had to learn about sands, silts, and clays, Atterberg limits, grain size curves, compaction methods, and limit equilibrium stability analysis.

I quickly realized that even after finishing university, the learning does not end. In fact, the real learning starts. Everything you do is now applied on the job site, not just submitted in a term paper for marks, so you better learn fast.

The following is one such learning experience.

A Powerline in Trouble

As mentioned above, my first role was in Overburden Geotechnical, where waste dump design, stability, and monitoring were part of my job responsibility. We already had about three out of pit dumps underway and a few inpit backfill dumps. The waste dumps were comprised of inter-mixed clay & sand built upon mainly clay foundations. That’s not the same as building rock dumps on rock foundations.

A few months on the job while on my daily site inspection route I noticed that, next to one of our waste dumps, the main 240 kV powerline coming to site was starting to lean over (see sketch). My first thought was “Fiddle sticks this isn’t good”. Gradual creep of the waste dump slope was starting to push on the power line. The guy wire anchors were holding tight but the base of the power poles were being moved.

I hurried back to the office to explain the situation to my supervisor and the issue quickly went up the chain of command. We jumped into action, first by relocating waste dumping activity to another area. Next, we started to investigate the cause to see if we could stop the creep. The dump did not actually fail catastrophically; it was just moving slowly. Generally, when slope creep starts, it is difficult to stop.

We drilled several hollow stem auger holes from the dump surface down into the foundation to see what was there. We installed a few slope indicators to see at what depth the sliding was occurring. These pinched off within a day or two, but at least we knew at what depth (about 20m down the hole).

Next we sampled that depth carefully, revealing that frozen muskeg layers were present. When we installed standpipe piezometers in these holes, we saw water flowing out of the top of the pipes. This means the foundation pore pressure is high, way too high.

We concluded that a few years prior the waste dump was built in winter when the muskeg was frozen. The dump insulated the muskeg from thawing and the frozen layer would not allow upward pore pressure dissipation from the dump surcharge. The clay foundation didn’t allow downward dissipation. The muskeg layer was acting like a water bed, floating the waste dump on top of it.

Every day one could see the power poles leaning a little bit more, so time was of the essence. We tried to implement foundation depressurization measures, but drilling angle holes in soft clay was problematic, and targeting the over-pressured zones was difficult. Management quickly made the decision to relocate a section of the powerline. Helicopters were brought in to help install a new powerline around this area. The entire exercise probably cost several million of dollars, but a major plant outage was avoided.

Welcome to the real world.

Not All Jobs Were Exciting

The one rotation that the engineers generally tried to avoid was Industrial Engineering. This is an area that looks at operational and cost efficiencies in the mine. It tends to focus on smaller details rather than the big picture mining operation. I had a 4 month stint in this department, which taught that me, that in life you don’t always get what you want. The IE projects would vary depending on the mine’s needs.

For example, one project I had was to monitor the performance of different brands and styles of conveyor idlers. We would track about 2,000 individual idlers; when they were installed on the conveyors; when they were removed, why they were removed (bearing failure, cover failure, something else).

The idea was to figure out which idler manufacturers were the best – important but not exciting work. If you liked statistics, this was a good job, although around 1981 we didn’t have Excel (or even Lotus 123) at that time (1982), so it was a manual process.

Another project was to try to improve the time efficiency of mine conveyor belt splicing operations. With steel cord belts, there are numerous steel cords in the interior of the belt that carry the tensile load. When it comes time to do a splice (to add in a new section of belt) each splice took about 2-3 days, which meant that mining area would be out of commission.

To splice, one must clean each steel cord individually then overlay the cords from the two belt section side by side, then cover the cords with rubber and vulcanize under heat and pressure. It all took lots of time. Naturally this time study project required spending long days out with the splice crews, watching them do this work while making notes on the actions and activities and durations. Important .. but less than exciting.

One good thing about this job was that the Industrial Engineering supervisor loved to use the expression “That’s politically explosive” for stuff that really wasn’t. That phrase made such an impression on me that I still try to use it today.

End of Part 1

This concludes Part 1. In the next article I will discuss a few other engineering aspects unique to the oilsands and how the engineering teams dealt with them.

Dragline mining of oilsand was never done before, so engineers were learning on the fly. Given the size of the operation, we could not afford to be wrong on the decisions made. It was an interesting, and also stressful, time for many.

In the 1980’s both Syncrude and Suncor had mainly electrified oilsand mining systems, consisting of bucketwheel excavators & conveyors at Suncor and draglines, bucketwheel reclaimers, conveyors at Syncrude. Years later both operations switched to diesel focused truck and shovel operations and mothballed the electric mega-excavators. I’d be curious to know if in 2025 they would still make the same decision based on carbon emission issues and the push for electrification in mining.

Part 2 of this blog post series can be read at this link “A Rookie in the Oilsands – Part 2“

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Mine Reconciliation – Standardization Please

Date: May 7, 2025 Author: Ken Kuchling Comments: Leave a reply

Mine through mill reconciliation, in my view, is an under appreciated topic that could benefit from more conversation amongst industry members. Unfortunately, reconciliation is sometimes viewed as a time consuming frustrating activity, with what some consider less than verifiable results. However given the ongoing innovation that we are seeing in mining, reconciliation may need to play a bigger role than ever.

The mining industry is implementing more and more technology in the mining cycle.

For example, this can range from AI assisted resource modelling, down hole logging, blast movement tracking, GPS controlled dig limits, MineSense bucket grade tracking, load scanning, truck dispatch control, smart mining and edge computing, online grade analyzers, belt weightometers, drone surveying of stockpiles, and real time process controls.

Lots of different innovations are continually being adopted by the mining industry, contrary to what some may say.

The question is does all this innovation improve the overall performance of a mining operation, and if so, by how much? It can cost a lot of money to implement the new technology, is there a payoff?

One cannot answer those questions if one doesn’t undertake proper mine reconciliation. A concern might be that mining is innovating faster than the ability to assess the results of that innovation. To monitor it, you need to measure it.

What is Mine Reconciliation

Mine reconciliation is the process of comparing and aligning the estimated production with the actual production from mining and processing. It requires assessing the accuracy of pre-mining predictions against actual results to identify inconsistencies in the system and hopefully improve it, be it resource estimation, mine planning, or process efficiency. Comparisons can be made between multiple stages in the mining system, as shown in the image below.

Mine reconciliation requires information such as initial predictions from exploration data and geological models, actual measurement: data from mining sources, such as blast holes, stockpile samples, or mill feed. As well it will need data on the final product being shipped off site. Do the metal quantities balance out throughout the mining operation?
Mine reconciliation tends to aggregate over longer time periods (monthly, quarterly or annually) due to short term impacts of material handling in stockpiles and plant circuits and the labour time needed to collect the input data.
Mine reconciliation ultimately attempts to assess how well the delivery of the final metal product relates to the initial resource model (i.e. what the project decision was originally based on)? It is also tool to evaluate the impact of any innovation implementation on the operation.
Reconciliation will help mine operators highlight issues and optimize extraction, manage costs, and ensure compliance with regulatory or investor expectations. Factors such as poor resource estimation, excessive dilution and ore loss, inaccurate sampling, etc. can cause discrepancies, making reconciliation an important part of any operation.
The reconciliation process is also used to derive Mine Call Factors. These factors are used to modify the forecasts from long range models, short range models, and grade control models to better represent the actual performance the operation will likely see. Large call factors suggest something is amiss in the “forecast to actual” progression. The first problem is to identify the causes. The list of the common sources of error can be lengthy. Then, once identified, the second problem is how to fix them.

Harry Parker initially suggested various reconciliation parametrics and labelled them F1, F2, F3. In a 2009 paper by Fouet titled “Standardising the Reconciliation Factors Required in Governance Reporting”, indicates that Rio Tinto had decided upon fifteen (15) different possible reconciliation correlations (see image below). Each one provides an insight on the efficiency of the operation in one way or another. I have seen modified versions of the reconciliation relationships, so it appears there may be no industry standard at this time. Fouet was asking about industry standardization in 2009 (an excellent paper to read by the way).

Mining Codes Getting Involved

It appears that the JORC Code may be recognizing the importance of reconciliation. In an August 2024 Exposure Draft JORC is suggesting the following text: “Where an Ore Reserve has been publicly reported for an operating mine, the results of both production reconciliation and any prior estimate comparison must also be included in the annual Mineral Resources and Ore Reserves statement. Refer to Clause 2.36. The relationships and variables being reconciled must be described in plain language or depicted graphically and must include reconciliations of both the Mineral Resources and Ore Reserves.”

Interestingly, it appears that NI43-101 has not yet jumped on the bandwagon about the importance of disclosing reconciliation results. However, it may just be a matter of time before it becomes one of their disclosure requirements.

If more regulatory focus will be put on mine reconciliation disclosure, then perhaps more industry standardization is warranted. This would help better define some of the terminology and “F factors” shown in the diagrams above to ensure consistency and help avoid each mine doing reconciliation in their own way.

Excel versus Cloud Based Reconciliation

Each mine site may be unique with respect to; ore sources; terminology; ore types; mining methods; stockpiling philosophy; processing methods; technology availability; and personnel capability. So often the easiest approach for mine reconciliation is based on the Excel spreadsheet. (Reconciliation is generally not an easy undertaking).

Spreadsheets can be built site specific, based on an operation’s unique characteristics.

Spreadsheets are often built by a user for that user. They are tailored for the tailor. In my experience, typically the modeler is the only one comfortable with an Excel model’s logic, since all of us may think differently. Unfortunately, with the spreadsheet approach, it becomes more difficult to standardize an industry wide reconciliation process.

An alternate solution to spreadsheets is to use a cloud based standardized software package. Toronto based Minebright has one option, called Pit Info (see link for more info). There are a few other reconciliation software applications available. They tend to be cloud based, hence multiple people can have access to the input modules or output modules. (I would like to thank the Minebright people for steering me towards some of the technical papers on this subject).

The cloud based approach may help make reconciliation a group effort instead of a tightly controlled internal function. It may also help standardize reporting from a company’s multiple operations, reporting from the mining industry globally, or simply for consistent JORC reporting.

The downside to the cloud approach is the mine site teams must learn the software and tailor it to their operation. However, once that hurdle is passed, personnel changes become less onerous due to the model consistency. I have seen cases where a person doing the Excel reconciliation task has left their job, and hence forward the reconciliation effort came to a halt. The people remaining may be too busy or simply don’t want to have to figure out the Excel logic of someone else.

The other nice thing about a cloud software approach is that when improvements are rolled out, every user gets the same update. The “wisdom of crowds” will result in learnings and suggestions that will tend to improve the application functionality over time. There are a lot of smart people out there, and it would be nice to see them working together rather than individually, as the open source software community has demonstrated.

With AI, we also may get to the point where cloud based mine reconciliation platforms can use learnings from other projects, and help identify where the likely technical shortfalls are at a mine site and why production is not reconciling. Let’s ask AI do some of the thinking for us to get to the bottom of a problem.

Conclusion

Mine reconciliation is becoming more and more important, but it can be a forgotten aspect. Sometimes this is because it is difficult to do properly. However, that doesn’t mean it shouldn’t be attempted. The more one can learn about one’s operation, the more likely it can stay efficient, relevant, and in business. The more one knows whether technology improvements are making a difference, the more one may be willing to take on even more new technology.

Shifting some people (like me) away from Excel based solutions can be a challenge, but this is an area where it makes sense. Years ago, many engineers did mine production scheduling using Excel, but we have gradually moved away from that, thankfully. Reconciliation should maybe follow that path.

Disclaimer: Mining is a global business, and perhaps more progress is being made on reconciliation standardization than I am aware of sitting here in my Toronto office. Mine operations around the world are at the forefront of developing new systems. Perhaps we are seeing great things being done in the area of mine reconciliation, or maybe we are not. Please share your experiences if you’re comfortable doing that.

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Spying on Tailings Using Satellites

Date: June 28, 2024 Author: Ken Kuchling Comments: Leave a reply

There have been recent heap leach pad failures in the Yukon and Turkey and tailings dam failures in Chile and the Philippines. As a result I have been seeing more posts on LinkedIn about the application of satellite based InSAR deformation monitoring. Prior to that I had never heard of InSAR, so thought a little bit of background study might be worthwhile.

The following are my observations on what InSAR is and where it may be going. I am by no means an expert in this technology. I am merely viewing it from the perspective of a mine design engineer.

What is InSAR

InSAR is satellite-based “Interferometric Synthetic Aperture Radar”. It can measure the distance from a satellite to a ground feature. With repeated imaging it is used to detect changes in distance and measure displacements to within 5-10 millimetre accuracy. Hence it can be used as a potentially cost-effective slope monitoring tool, albeit it cannot be the only tool, as discussed later.

The relevant satellite images have been available for years. Currently the availability of analytical software to interpret the satellite data is improving. It can detect millimeter-scale displacements, however only in the line-of-sight (LOS) direction of the satellite. Using two or more satellites in different orbits, displacements in horizontal and vertical directions can be defined.

An example of a satellite being used is the Sentinel-1, launched in mid-2015 by the European Space Agency. This satellite information is open-source data. It will have a 6 to 12 day revisit cycle in many locations.

The results of an InSAR displacement survey are typically shown as a series of colored data points, typically coloured green for the stable points, trending to yellow and red for points that are moving.

This blog has some example images.

Some Limitations With InSAR

There are some limitations with InSAR, so it can only be part of a monitoring program. These limitations are:

The displacement direction is only measured in the direction of the satellite. Hence one may not know in which direction the movement is occurring. The magnitude of displacement could be underestimated depending on the apparent angle of measurement.
The movement being measured could consist of vertical settlement due to material consolidation and may not be horizontal and related to impending failure.
The displacement magnitude measured on opposite sides of a facility may have different accuracy, depending on the slope orientation versus the line-of-sight.
Areas with heavy vegetation may be difficult to monitor
Areas with heavy or persistent cloud cover can be difficult to monitor.
Areas with snow cover will be difficult to monitor.
The satellite return period may be weekly or every two weeks, so one is not able to analyze daily movements if a situation is critical. If the return visit day has cloud cover, there will be no new satellite data collected.
Areas with on-going construction or tailings deposition will lead to erroneous results.
Due to the line of sight, not all slope failure modes may be detectible (for example piping failure).

Regardless of these limitations, InSAR can still play a role in any monitoring program since it is able to monitor large areas quickly. Consider it as a pre-screening tool, being aware that not all failure modes may be detectible with it.

Discussion

On LinkedIn, one can see numerous posts where independent experts are examining historical InSAR data for recent failures to see whether early movement should have been detected. The results seem to be quite positive in that areas that have failed might have been red-flagged prior to failure.

There are also zones that showed critical displacements but have not failed.

Typically, there are four ways to monitor displacement in pit slopes, tailings dams, heap leach pads, and waste dumps. They are:

Insitu monitoring using embedded instruments, for example slope indicators, extensometers, and settlement gauges. These instruments provide information on what is happening internally within a slope, where actual movement is occurring, and they can be used in warning alert systems.
Surface monitoring using radar (ground based InSAR) systems and survey prisms. These tools measure only surface movements in selected areas, can be monitored as frequently as needed on an automated basis, and integrated into warning alert systems.
Drone or aerial surveys can be used to measure topography and monitor movements over large areas. This method requires a data processing delay (not real time) to derive the movement information, but such surveys can be done as frequently as needed.
InSAR from satellite can be used over very large regions to highlight areas with movement. That should trigger the implementation of one or more of the other monitoring approaches (if not already in place).

Conclusion

A mining site consists of numerous constructed embankments and slopes of all types and heights. Many of these slopes may be creeping and moving all the time – it’s a living beast.

The operator’s awareness about their site will be better the more monitoring tools they use. This awareness is important given the critical role that slope stability plays. We will see if InSAR technology achieves much wider adoption in the mining industry as a first phase of a stability monitoring programs.

Since InSAR monitoring is done from space, it does not require access to a property. Hence it can be used by third parties or NGO’s to “spy” on facilities of concern anywhere.

Possibly over the next few years we will see independent donor-funded organizations monitoring tailings facilities around the globe. They will be able to notify the public and mine operators “Hey, there is some movement on this mine site that needs to be addressed”. An organization called World Mine Tailings Failures has started some discussions on this concept. Check it out.

Finally, it is great for a mine site to collect a lot of displacement data, hopefully to forewarn of movement, displacement acceleration, and imminent failure. However, this assumes that someone experienced is interpreting the data and its not just generating graphs for the file cabinet. Perhaps AI can play a role here in the future, if the technical personnel to do this are lacking.

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Mining Under Lakes – Part 1: Examples

Date: May 28, 2023 Author: Ken Kuchling Comments: 2 Replies

Springpole Project

I recently saw an investor presentation from First Mining Gold about their Springpole Project. The situation is that their open pit is located within a lake and will require the construction of a couple of small cofferdams to isolate the pit area from the lake. The concept is shown in this image.

Over the last couple of years I have been involved in a few early-stage studies for mining projects in which nearby bodies of water play a role in the design. In Canada’s north there are thousands of lakes and rivers, so its not surprising to find mines next to them.

That got me thinking about how many other mines are in the same situation, i.e. projects that may be located very close to, or within, a lake, river, or ocean. Hence I have compiled a short list of a few such mines.

I have been directly involved with some of those in the list, while others are only known to me with limited detail. Some mines I had never heard of before, but their names were provided to me by some Twitter colleagues.

My observation is that building a mine within, or adjacent to, a body of water is nothing new and this has been done multiple times successfully.

Some of these projects may refer to the dams as “dikes”, “cofferdams”, “sea walls” but I assume they are all providing roughly the same function of holding back water for the life of the project. They are not viewed as permanent dams.

This is Part 1 of a two-part blog post. Part 1 provides some examples of projects where water bodies were involved in the design. Part 2 provides a discussion on specific geotechnical and hydrogeological issues that would normally have to be examined with such projects.

Some Lake Mining Examples

The following are some examples of operating mines involving lakes. I have captured a few Google Earth images, unfortunately some have only low resolution vintage satellite imagery.

This is a project I was working on with in 1997 to 2000 while it was still at the design and permitting stage. My role focused on pit hydrogeology and geotechnical as well as mine planning.

The project would require the construction of three dikes in sequence to mine four lakebed kimberlite pipes.

The three dikes were named after the associated kimberlite pipe being mined inside it; A154, A418, and A21.

The first dikes were built in 2002 and the last dike (A21) was completed in 2018.

The total dike length for the three dikes is about 6.2 km.

For those interested in learning a bit more about Diavik, I have posted an earlier article about the open pit hydrogeology there, linked to at " Hydrogeology At Diavik – Its Complicated".

This is a project I was involved with several years ago. The bauxite deposit extends beneath the Suriname River and the goal was to mine as much ore as possible.

Given the flow rates in the river, especially during the wet season, it would be difficult to maintain a cofferdam out into the river.

The shoreline overburden consisted of sands and soft clays, so the decision as made to construct a sheet piling wall along the river bank to protect the pit from river erosion. This was mined out successfully and eventually reclaimed.

Conclusion

As one can see, the idea of mining into a body of water is nothing new. Its not a preferred situation, but it can be done economically and safely. The technical challenges are straightforward, and engineers have dealt with them before. However there also are instances where the design could not economically address the water issue, and thus played a role in the mine not getting built.

If you know of other mines not listed above that have successfully dealt with a water body, please let me know and I can update this blog post.

This concludes Part 1. Part 2 can be read at this link " Mining Under Lakes – Part 2: Design Issues" discusses some of the concerns that engineers need to consider when building a mine in these situations.

Finally, the worst-case scenario is shown in this grainy video of a tin mine (Pantai Remis Mine) pit slope failure. It seems they mined too close to the ocean. Watch to the end, its hard to believe. Its looks like something out of a Hollywood disaster movie.

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The article is Part 2 of discussion on my experiences working in the oilsands at the Syncrude Mine in northern Alberta. Part 1 can be read at this link https://kuchling.com/a-rookie-in-the-oilsands-part-1/

Will the Draglines Be Safe

Mining oilsand while from the top of a 50 metre high and 45 degree highwall had never been done before. The geotechnical conditions were new. They were also dramatically different on the East and West sides of the mine, even though mining in the same orebody.

The East side was far more a greater geotechnical concern than the West side. I happened to be the West side mine geotechnical engineer (lucky for me I guess).

In these problem areas, the geotech teams would install slope indicators that were monitored while the dragline was mining through the area. Dedicated 24 hour field engineers were assigned to each of the East side draglines and mining operations were closely monitored at all times.

It was not uncommon for the Syncrude geotechnical engineer to get a 2 am phone call at home saying movement has been detected and they walked the dragline back from the face and then get asked “What should we do now?”.

In the places that the engineers knew were going to be very risk, they could implement mitigation measures. How would you deal with the steeper scour zones? They had three main options.

mine through the area with intense geotechnical monitoring in place, using slope indicators, survey prisms, and visual ground inspections.

sub-excavate the zone; using the dragline to dig out the area and then backfill with the same material to destroy the clay bedding. Then they could safely mine through the area, although the days used to sub-excavate would remove the dragline from oilsand production.

another option was to blast the area ahead of time, to destroy the clay bedding and allow pore pressure dissipation.

All three options were available at the discretion of the geotechnical engineering team. However they all cost money and/or loss in mining production, but safety was always the priority.

The four draglines are now mothballed and thankfully none were ever harmed. All oilsand mining operations are now based on truck-shovel systems.

Basal Slope Failures

The main geotechnical issue on the West side were basal slope failures, termed this due to sliding along weak clays and muds at the base of the highwall. This photo shows a typical basal failure. Basal failures also occured on the East side.

Generally, these slope failures did not jeopardize the dragline since they occurred on freshly cut highwalls away from the machine. Eventually the dragline would be required to operate next to existing basal failures when mining the next panel (as shown in the photo).

The dragline would sit 15-25 metres from the wall, the closer is better to maximize reach into the pit.

Conclusion

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Here is short cheesey video of what the oilsands were about in the 1980’s and 1990’s.

Mining at Syncrude

In Part 1 of this two part blog post I would like to share some stories from the early days of my career working in Fort McMurray.

Hopefully they will be interesting and help shed some light on what it can be like working in the mining industry. Syncrude provided my first job out of engineering university and hence will always be special to me.

In the early 1980’s Syncrude was producing about 90,000 barrels of oil a day by processing oilsand at a rate of 180,000 t/day, so it was a big mining operation.

The Engineer in Training Program

At the time Syncrude had an excellent engineer-in-training program for new graduates. Every six months they would rotate engineers into different technical areas.

These areas could consist of: overburden stripping planning; overburden geotechnical; short range mine planning, mine geotechnical, industrial engineering, tailings planning, and tailings geotechnical. Long range planning tended to be left to the more senior people.

Probably about 15 mining / geological engineers were hired at the same time as me. We came from McGill, Queens, UBC, Laurentian, Univ of Alberta, and Nova Scotia. All of us were in the same boat, rotating through various departments for the first few years.

A Fish Out of Water

I quickly realized that even after finishing university, the learning does not end. In fact, the real learning starts. Everything you do is now applied on the job site, not just submitted in a term paper for marks, so you better learn fast.

The following is one such learning experience.

A Powerline in Trouble

We drilled several hollow stem auger holes from the dump surface down into the foundation to see what was there. We installed a few slope indicators to see at what depth the sliding was occurring. These pinched off within a day or two, but at least we knew at what depth (about 20m down the hole).

Next we sampled that depth carefully, revealing that frozen muskeg layers were present. When we installed standpipe piezometers in these holes, we saw water flowing out of the top of the pipes. This means the foundation pore pressure is high, way too high.

Welcome to the real world.

Not All Jobs Were Exciting

For example, one project I had was to monitor the performance of different brands and styles of conveyor idlers. We would track about 2,000 individual idlers; when they were installed on the conveyors; when they were removed, why they were removed (bearing failure, cover failure, something else).

The idea was to figure out which idler manufacturers were the best – important but not exciting work. If you liked statistics, this was a good job, although around 1981 we didn’t have Excel (or even Lotus 123) at that time (1982), so it was a manual process.

One good thing about this job was that the Industrial Engineering supervisor loved to use the expression “That’s politically explosive” for stuff that really wasn’t. That phrase made such an impression on me that I still try to use it today.

End of Part 1

This concludes Part 1. In the next article I will discuss a few other engineering aspects unique to the oilsands and how the engineering teams dealt with them.

Dragline mining of oilsand was never done before, so engineers were learning on the fly. Given the size of the operation, we could not afford to be wrong on the decisions made. It was an interesting, and also stressful, time for many.

Part 2 of this blog post series can be read at this link “A Rookie in the Oilsands – Part 2“

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The mining industry is implementing more and more technology in the mining cycle.

Lots of different innovations are continually being adopted by the mining industry, contrary to what some may say.

The question is does all this innovation improve the overall performance of a mining operation, and if so, by how much? It can cost a lot of money to implement the new technology, is there a payoff?

One cannot answer those questions if one doesn’t undertake proper mine reconciliation. A concern might be that mining is innovating faster than the ability to assess the results of that innovation. To monitor it, you need to measure it.

What is Mine Reconciliation

Mine reconciliation tends to aggregate over longer time periods (monthly, quarterly or annually) due to short term impacts of material handling in stockpiles and plant circuits and the labour time needed to collect the input data.

Mine reconciliation ultimately attempts to assess how well the delivery of the final metal product relates to the initial resource model (i.e. what the project decision was originally based on)? It is also tool to evaluate the impact of any innovation implementation on the operation.

Mining Codes Getting Involved

Interestingly, it appears that NI43-101 has not yet jumped on the bandwagon about the importance of disclosing reconciliation results. However, it may just be a matter of time before it becomes one of their disclosure requirements.

Excel versus Cloud Based Reconciliation

Spreadsheets can be built site specific, based on an operation’s unique characteristics.

The cloud based approach may help make reconciliation a group effort instead of a tightly controlled internal function. It may also help standardize reporting from a company’s multiple operations, reporting from the mining industry globally, or simply for consistent JORC reporting.

Conclusion

Shifting some people (like me) away from Excel based solutions can be a challenge, but this is an area where it makes sense. Years ago, many engineers did mine production scheduling using Excel, but we have gradually moved away from that, thankfully. Reconciliation should maybe follow that path.

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The following are my observations on what InSAR is and where it may be going. I am by no means an expert in this technology. I am merely viewing it from the perspective of a mine design engineer.

What is InSAR

An example of a satellite being used is the Sentinel-1, launched in mid-2015 by the European Space Agency. This satellite information is open-source data. It will have a 6 to 12 day revisit cycle in many locations.

The results of an InSAR displacement survey are typically shown as a series of colored data points, typically coloured green for the stable points, trending to yellow and red for points that are moving.

This blog has some example images.

Some Limitations With InSAR

There are some limitations with InSAR, so it can only be part of a monitoring program. These limitations are:

The displacement direction is only measured in the direction of the satellite. Hence one may not know in which direction the movement is occurring. The magnitude of displacement could be underestimated depending on the apparent angle of measurement.

The movement being measured could consist of vertical settlement due to material consolidation and may not be horizontal and related to impending failure.

The displacement magnitude measured on opposite sides of a facility may have different accuracy, depending on the slope orientation versus the line-of-sight.

Areas with heavy vegetation may be difficult to monitor

Areas with heavy or persistent cloud cover can be difficult to monitor.

Areas with snow cover will be difficult to monitor.

The satellite return period may be weekly or every two weeks, so one is not able to analyze daily movements if a situation is critical. If the return visit day has cloud cover, there will be no new satellite data collected.

Areas with on-going construction or tailings deposition will lead to erroneous results.

Due to the line of sight, not all slope failure modes may be detectible (for example piping failure).

Regardless of these limitations, InSAR can still play a role in any monitoring program since it is able to monitor large areas quickly. Consider it as a pre-screening tool, being aware that not all failure modes may be detectible with it.

Discussion

On LinkedIn, one can see numerous posts where independent experts are examining historical InSAR data for recent failures to see whether early movement should have been detected. The results seem to be quite positive in that areas that have failed might have been red-flagged prior to failure.

There are also zones that showed critical displacements but have not failed.

Typically, there are four ways to monitor displacement in pit slopes, tailings dams, heap leach pads, and waste dumps. They are:

Insitu monitoring using embedded instruments, for example slope indicators, extensometers, and settlement gauges. These instruments provide information on what is happening internally within a slope, where actual movement is occurring, and they can be used in warning alert systems.