Remove the Overburden in Mine Permitting

CEC mining experts Rob Livermore and Brad Renwick discuss investigations that can be performed to evaluate the feasibility of opening a new mine or expanding an existing one.

Podcast Transcript

Announcer: Welcome to CEC Explains your deep dive into fascinating subjects from the worlds of engineering in the environment, brought to you by Civil & Environmental Consultants, Inc. And now from our CEC studios around the nation, this is CEC Explains.

Rob: Hi, I’m Rob Livermore. I’m a Principal with Civil & Environmental Consultants in the Phoenix, Arizona office. I serve as a corporate leader of the mining market group. I have over 35 years’ experience throughout the mine life cycle, focusing on environmental compliance and risk reduction strategies in the U.S. and Canada, as well as some regional experience in Europe, Africa, Indonesia, and Latin America. I’d like to introduce you to Brad Renwick out of our Chicago, Illinois office, who has over 15 years of experience in the mining and environmental Industries. He’s been the lead geologist on several large investigations for new mines or expansions to existing facilities. He has considerable experience with identification of new mineral sources for aggregate clients and has run drilling programs to delineate the source and provide an estimation of reserves available for mining. And he will be talking about things to consider when developing or expanding a new mine.

Brad: Thanks Rob. As Rob mentioned. I’m Brad Renwick. I’m a geologist and senior project manager here at the Chicago office. And I’ve been in the industry for the better part of 15 years. I have worked at the majority of those years in the mining and/or solid waste industry either consulting as a hydrogeologist, for some feasibility studies, groundwater modeling, reserve investigations. I also had a brief stint for about three and a half years where I worked as a field geologist for an exploration drilling company here around the Chicago market, which, when I was able to come back to CEC, it helped improve that base. I’ve had considerable experience, as Rob mentioned, with finding new lands, investigating new lands, and helping clients figure out things. And that’s what we’re going to talk about today, is that some of the things I’ve come across in my career and starting mines, things to look for, from start to finish. I’ve done a lot of expansion and also greenfield work. Some of the things that I’ve seen early on are what are the minerals are going after? Is it construction aggregate? Is it a sole source for a pharmaceutical grade high-cal limestone or cement limestone? I’ve also done quite a bit of investigation work for silica sands when the oil and gas markets were really up and everybody was looking for silica sands, identifying properties and things to look for there.

Rob: So Brad, how do you go about developing or expanding a new mine?

Brad: Well, number one: What are we looking for? Is it just purely construction aggregate or like I said, you know, are we looking for a particular chem-quality stone? And what are the the clients’ limitations? Where is the reserve? Do they have certain logistical constraints that they’re working with as far as railroads or barges? Things we’ve talked about in the past are logistics are the biggest constraint. Really can’t develop a mine unless you can get the product to the market. You could have a very vast reserve out in the middle of nowhere, but it does nobody any good unless it makes sense from a financial standpoint to get that product to the market it needs to serve.

Rob: With the new infrastructure bill, I’m sure a lot of people are looking to expand. So, what are some of the obstacles that people should look out for when they’re trying to develop or expand a new mine? 

Brad: Well, you brought up one of the biggest ones to what is the political environment? A new infrastructure bill. There’s still some question as to, you know, if it will pass, what size it will be and who it’s going to serve. And also locally, what is the political or socioeconomic climate in the area you want to expand, or build this mine. Some of those can be pretty big. If and when the new infrastructure bill passes, it will create that that need for aggregate to get to the market based on the the needs of the construction. What it’s going to serve and what infrastructure is already there to get those products to the market. What’s the expected life of the mine? Things like that.

Rob: So with the new Biden administration being tougher on environmental justice and getting more tribal input, do you see those as requiring more upfront or due diligence when you’re looking at a new mine, or a location, or especially with the WOTUS rules might be being rolled back as far as wetlands, and it’s a location and public input is probably going to be a bigger issue moving forward?

Brad: That from what I’ve seen here will be a big driver. Many times, at least for the markets I’ve served, a lot of the mines are out in more rural areas, but there are a lot of producers out there with, not mines, but also ancillary support services, whether it be a railyard, that are in what might be considered more environmental justice areas, and that just goes to working with the client to … they always want to be a good neighbor, and what sort of products or improvements can you provide for the communities in which you’re going to operate, whether that’s new parks, more monitoring. I know air monitoring is going to be a big one around the perimeter to, like I said, make sure they are going to be a good neighbor. I know there’s going to be probably more enforcement of PM10 monitoring around a lot of mine perimeters, depending on the community they’re in. And you bring up a good point about the engagement of that community in which you want to operate early on in the process. Going back a little bit, more of a 10,000-foot view or a 30,000-foot view, I should say, where does a reserve sit? What’s the geologic structure? Does it make sense? And once they’ve honed in on a certain area or even a particular parcel of land, really engaging the community at the forefront to work with them so that you know, they want you there. The clients can provide jobs and hopefully some infrastructure on that end. That’s a good thing to bring up, staying active in the communities in which you operate. 

Rob: Well, I’ve always heard the rule of thumb, especially in aggregates, is you want to have a source within a 50-mile radius because I think transportation is one of the highest costs when you’re opening up a new mine. I can see that getting some peoples’ buy-in, especially going to be local to a community is pretty important. And now with the environmental justice you want to make sure you are going to be in an area of disadvantaged groups to, you know, talk to them early on and possibly offer training or job experience in order to help those types of communities out. So, what other type of permits, after you’ve found your source, your location, what kind of permits would a typical sort of mine be looking at? 

Brad: Well, depending on their operation, if they’re going to be watching a lot of aggregate and/or sand and gravel, silica sand even, are they going to be a high-end user of a lot of water? They may need a high-water-usage permit? What are they going to do with this water afterward? They probably likely need an NPDES water permit to discharge some water to the state. If they’re going to have a substantial crushing, what sort of air permits would they need to get their plants up and running? Some states are relatively simple depending on the operation. Others can go all the way up to a Title 5 air permit. It all depends on what the client’s needs are from the get-go. How much they want to produce annually, or even weekly, to see what kind of air permits they would need. And it differs from state to state. But typically, any sort of mine permit would would go through the Department of Natural Resources. I’m not sure how it works out west, but here in Illinois, we always go through the Department of Natural Resources for both their mine operating permit, depending on how much land they’re going to affect each year and also goes to their bonding requirements, which are also tied to their reclamation plan. How are they going to return the land back to some sort of former use after the mine is depleted or as areas of the mine are depleted, how are they going to return that land back to a use that can be used by the public. Whether that’s industrial development, recreational parks, things like that, state parks. 

Rob: Yeah, it’s interesting. I know out here in Arizona, we have more public lands than usually other states and sometimes they’ll want access agreements. And the interesting thing out here is once you define your resource, you have to negotiate a royalty with the state of Arizona. If it’s on State of Arizona land, they’ll take a royalty for the materials that you remove, which is kind of an interesting thought. So part of that, when you’re doing your sort of your initial feasibility, what are some of the sort of the fatal flaws that you’ve seen in your experience, when you’re going through sort of this initial feasibility study?

Brad: Existing infrastructure, whether it be something that can be seen quite easily as a highway or even a road. Other times, natural gas pipelines, any fiber optics that may be crossing the land, you may have to engage those operators early on in the process, even before you go out there and start drilling. Some of those can be identified from aerial photographs, differences in drainage patterns, things like that. Any anecdotal evidence of threatened and endangered species. I know of a couple of projects here in Illinois that were stalled. One was a highway project, the other was actually a mine project that were stalled for the better part of 15 to 20 years until they figured out what they were going to do with either a small, I think it was a dragonfly, and the other side was a small frog. So those are things that, albeit small, you want to take note of because if you don’t identify them early on, they could really become a real sticky wicket later in the in the process. 

Rob: Yeah, I’ve heard that. I know are Indianapolis office did a study where they knew there was four or five cultural sites, but they actually ended up identifying about 12. And so those sites had to be set aside. They couldn’t utilize that in their plans. So I thought that was kind of interesting that you think you’re going in with a certain idea, and then you start funding wetlands, or threatened endangered species, or cultural historic sites, that impede the development that you originally thought of.

Brad: And you bring up a good point. Early on it’s very good to educate or at least work with the client work, work with any operator, to educate them in what we know. Because I have seen producers in the past or even other industrial clients that may not even think to worry about something as small as a dragonfly. But the front-end work, just identifying those and engaging the agency early on whether it be the DNR or U.S. Fish and Wildlife Service early on the process is, from my experience, a lot less costly than having to deal with it on the back end. 

Rob: How about, I’m sure when you’re doing some of your studies, if you have a large overburden that probably affects the economics because you’re having to remove a lot more topsoil than maybe you anticipated.

Brad: Absolutely. Going into the the actual geology, the reserve may be there in its form, but how to get to it? What are your stripping ratios going to be? Does the is the producer or whoever you’re working with, do they have a top end? And even before you go out drilling, may be able to do some relatively simple geophysics to identify how thick that overburden is or any anomalies that you met in cover in those geophysics, whether it’s some karst terrain, paleokarst that has been filled in with clay. You’re definitely have to go out and groundtruth that with an extensive drilling program. But once again, it’s those those steps you need to take to identify what the reserve is and how it’s structured. I actually had experience with a project a while back where the infrastructure and the need were there. There was some infrastructure that was supposed to go in and they had done a lot of ground research and acquired the land and the geologic structure was identified and there were some things that were identified in the geophysics and the drilling program that would have made mining this very difficult but still feasible because the need for that was very close to the source. Things changed on the political climate and that infrastructure ended up not being constructed and it really changed the financials of how they were going to mine that. And, to this day, I believe that land is still sitting idle. So, just going back to your point, other than just getting the reserve and extracting it, what are the obstacles to get to it to uncover that overburden and where you going to put it? What are your constraints? It kinds of goes also back into the operating plan of the mine. Where is your overburden going to go? Where’s your material handling process plant going to be? Things like that.

Rob: What’s the general rule of thumb when you’re developing a drilling program, let’s say for a 50-acre site? In our business, I know the more information the better, but of course that costs a client more. So what’s the minimum boring per acre that you’ve seen that gives you enough information in order to make a mine an economic resource?

Brad: Well, speaking as a geologist and not an engineer, not being able to give you a hard-and-fast answer, my rule of thumb when I’m working with the client to develop a drilling program obviously depends on the mineral you’re going for. If it’s construction aggregate, limestone, dolomite, bedrock, I typically go with about one hole per 40 acres. If it’s a sand or gravel reserve that has more potential to be a lot more heterogeneous and different throughout, then that number shrinks down to about one hole per 10 acres.

Rob: Does geophysics help, you determine your drilling program? Do you try to use those in concert or do you sometimes not use geophysics? 

Brad: Sometimes I haven’t used geophysics. Many times, If it’s a new terrain or region, or if there’s reason to suspect there might be some problems such as a fault that people know of locally but they haven’t really identified it, geophysics is a good tool because you can go out there and collect a lot of information across a vast amount in a relatively short period of time and then ground truth that. Using that geophysics will help you develop that drilling program moving forward. And also staying in tune with the fact that you have a plan but that plan could change as you get out there in the field and start collecting that information. 

Rob: So geophysics might help in an area that you don’t know as well or the client doesn’t know as well, or maybe a whole new greenfield site that they have no experience to give them an idea of what the material is that they might be mining?

Brad: Correct. And it will also give you some insight into the hydrogeology of the area, as well. And the hydrogeologic study also goes into part of the drilling program. You want to collect as much data out there as you can, and that’s one thing we haven’t touched on is some sort of basic hydrogeologic investigation as to how, when you open up this pit either through time or at its life’s, how are you going to affect not only the local aquifer system, but also how much water you going to draw into the mine? What are your water handling expectations, as well as how are you going to treat that water and and eventually discharge it? 

Rob: So how does the size and shape of the reserve that you define fit into the overall mine plan?

Brad: Differences in the geology. You may have to incorporate that into what equipment you’re using for the operation. And once you have developed, you’ve got your drilling program, and once you’ve developed a basic geologic model, what are the operational, expectations of the client? How are they going to … what’s their process? And really getting them in and also the equipment suppliers and manufacturers and their contractors, working with them to develop a mine plan that compliments the operational plan.

Rob: Once you’ve looked at the economics and the reserves and you’ve divined the permitting and the infrastructure and how you’re going to transport the material, how do you come up with a general reclamation plan for the life of the mine and how you’re going to close it at the end?

Brad: Typically, it goes back to what we talked about in the beginning. How does that fit into the local landscape or the geographic area? If it’s a large rural area with a population that may want a hunting, or an efficient reserve, things like that. If it is a an industrial area, early ideas about post-end use. If it’s an underground mine, can you use it for underground storage? Can you use it for any sort of truck storage and incorporating those ideas early on in even just the planning process, having an end use in mind. Not only just for reclamation plan, but also can that be a an additional source of revenue for the client, for the mine operator even after they’ve exhausted the reserve?

Rob: Yeah, I’ve seen that pretty well out here in the West. They’ve converted some of these old mine pits with the help of Ducks Unlimited, creating duck preserves or other people have done redevelopment on top of them. Solar is getting to be big where they’re redeveloping these areas because the infrastructure is already there. So there’s a lot of options for a mine operator at the end of mine life, like you were saying, that there might be additional income streams outside of the mine. 

Brad: Yeah, and to your point that has become a bigger picture idea here in the Chicago metro area. The logistics ports are are huge. And I know of at least one or two projects, where they had ideas for a logistics port. They just needed a good engineering plan to get the material out, so they could create this infrastructure underground. The other project that comes to mind here around Chicago is the tarp system. It’s essentially using Old Mines to create reservoirs to redirect stormwater and treat stormwater. 

Rob: That’s an amazing project. I’m glad I’m glad you invited me out there to look at it. It’s pretty amazing. If people don’t know, they used an old limestone pit to collect stormwater for the city of Chicago during flood events. A lot of other people, especially with the climate change issue, are possibly using old aggregate pits as a method to handle stormwater for various cities. So, you’re actually being a benefit for the communities you’re in. You have a area where stormwater can go in and not impact houses or buildings or towns. That’s getting to be a new thing. 

Brad: That was a neat project to be part of, knowing the initial thoughts and engineering for that started back in the, I want to say the ’80s just initial feasibility, and now we’ve got three online that are connected by, I want to say 108 miles of 30 foot diameter tunnels that are running all over the the Chicago Metro area. I’ve seen some relief. When they get the the last one fully online and engaged, it’ll be neat to see how it actually works.

Rob: It was great talking to you today on issues relating to developing a new mine resource. Remember, working safely may get old, but so do those who practice it.

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