Acid Mine Drainage

Acid Mine Drainage

Hello these is a Brad Striebig and in this section we’re going to talk about what happens to acids in the environment, how they can degrade the environment but also how engineers and scientist can look at that process, understand the acidification process and remediate or restore the area that is impacted by that acid conditions. In this case we’re going to look particularly at acid mine drainage and in chapter five we’ll talk about acid rain which can be remediated in much the same way. One of the most common processes for acid to get into the environment is through the acid emissions of sulfur dioxide and some nitrogen oxide into the atmosphere, both nitrogen oxides and sulfur dioxide can create localized acid rain conditions where we have high concentrations of the sulfur and nitrogen gases in the atmosphere. That dissolves into the raindrops but in this case because the sulfur concentrations and nitrogen concentrations, if high enough can actually decrease the pH in the rainfall fall. The rainfalls onto the ground and forms a precipitation this acid rain then can kill plant life, pollute rivers and streams and erode stone work masonry and other architectural details such as monuments. Acid deposition is formed most significantly from sulfuric acid, from sulfur dioxides emitted from combustion processes. The process of conversion is that we have two sulfur oxide molecules react with oxygen and some particulate matter in the atmosphere to form 2SO3 in the air. The SO3 dissolves in solution or reacts with water to form the sulfuric acid H2SO4 in solution.

The nitric acid formation is a little bit more complicated where we have NO2 reaction with the hydroxyl radical in solution. Plus some metal catalyst to form nitric acid HNO3 in solution and the evening the nitrogen oxide can react with ozone to form the nitrate. This can form N2O5 which also can dissolve in water to form two nitric acid molecules. The acid rain then containing extra H+ and numerous anions such as sulfates, ammonia, nitrates, carbon dioxide, carbonates and chlorine in the air can come in contact with the soil. This can result in human decay decaying the soil itself and decreasing or leaching some of the minerals in the soil. Such as lowering the availability of calcium by reacting with lime stones in the solution, changing the pH of aluminum that dissociates the aluminum and other compounds that may inhibit plant growth and removing other positive metal ions from the environment. About 47% of sulfur dioxide emissions are due generally to power emissions in the Midwest. This weather pattern transport the sulfur oxide into the Northeastern states and has led to acidification of lakes and streams that were not buffered by naturally occurring minerals especially lime stones. This has led to a decline in plant and aquatic diversity in many of the Northeast US lakes and rivers and can substantially increase the concentration of dissolved heavy and potentially toxic metals in these waterways as well.

Here we see a topographic map of pH in the US where we have the highest regions occurring in the Mid-Atlantic States Pennsylvania, New York and parts of Maryland and West Virginia where the pH has been logged as less than 4.3 for acidic rainfall. In the Western parts of the country, there are some regions where we have some acidic rainfall but largely limited to the Midwest and as the wind carries those currents from the coal fire power plants towards the Northeast. In addition acid rain can interfere with plant stem cells, eroding cuticular wax , cause an increase evaporation or transpiration in drying out or in injuring portions of the trees and leaves themselves. It can increase the acidity of the soil and change the natural plants that would be there. It may deplete minerals such as magnesium, potassium, requiring that additional fertilizers be placed which will have other downstream effects that’s are negative on waterways that will be discussed in the next chapter in chapter 4. It can also increase the concentration of mercury and cadmium in lake waters. The good news is that sulfur emissions since the passage of the Clean Air act and further amendments in 1991 had decreased substantially over the last 20 or 30 years.

We see in the early 1990’s the tonnes per generating unit of sulfur dioxide concentrations actually going down even though and this is very important as we discuss sustainability; this graph noticed the number of generation units is going up but the concentration and emissions of sulfur dioxides and nitrogen oxides from generating units between 1995 and 2008 was steadily decreasing, leading to less acid gas production. Once rainfall hits we said that this could mobilize other compounds in the soil, this is especially true where we have surface mining. Surface mining as we see can expose various strati. Differential strati here showed as Lexington B, Lexington A, Pikes Gully, so different geological formations in their earth. These different geological formations are made up of different minerals that can react differently to changing pH in precipitation. Here we see a surface mine and we see a (6:14 unclear) downhill from that surface mine so that those mine tailings can contaminate agricultural practices and other areas downhill from the places where the mining is occurring due to exposure of naturally occurring minerals and sediments. Once such place is in Oak County, Pennsylvania, this is actually a state gain lands called the Dense Run ecosystem. Here we see a map of Pennsylvania lower right-hand quadrant of that slide and the outlines of the watershed for Dense Run. In that watershed there is an open pit mine and that open pit mine led to acidification of Dense Run and other streams in this area which degraded the natural ecosystem.

This is an area in Elk county, which Elk had been released and are trying to be reintroduced to the area to increase what was many hundreds of years ago a naturally occurring (7:19 unclear). But now it’s limited mostly to a few Northern States in Pennsylvania. Recently though, Elk has also been reintroduced to parts of West Virginia and Virginia as well to farther diversify the environments and create more bio diversity in these regions. Prior to mining as rain fell it would filter through the soil perhaps raining some sulfides but going into the groundwater and being largely diluted with most of the rainfall going off as surface runoff. However after surface mining we see that we can expose those underlying sulfides to the environmental rainfall. These sulfides can then be transported along the surface runoff or reach the groundwater much more quickly than they would have otherwise reached the groundwater by having to filter through the soil. This can result in sulfuric acid formation just like acid gas formation which increases heavy metals in the stream and those heavy metals can result in fish kills. We see here prior to 2010 the concentration of hydrogen ions in several streams in the Dense Run watershed, several of the pH’s, Porcupine Run headwaters for instance are as low as a pH of 2.9 and incredibly acidic condition for naturally incurring environment.

This is due to the acid mine drainage from open mines that existed in this region upstream. So we can see very far upstream in the northern reaches of the watershed uphill from the mine, the pH was close to a natural level of 6.6 or 6.3. Which in this area of the country was fairly good, as we moved downstream however due to acid acidification the pH was reduced drastically down to as low as 3.3 and 2.9 in different areas of Porcupine Run in this water shed. This acid was neutralized, so the pH was measured, the amount of acid was determined and then calcium carbonate. And other acid neutralizing compounds were put into the watershed upstream of Porcupine Run where the water would infiltrate into the mines but have to go through an acid neutralizing section or pond We see prior to 2010 there is no neutralizing capacity present so we had very low pH, after the neutralizing capacity was added to Dense Run and Porcupine Run area we had an increase of pH from 2.9 to 6.55, At several areas along the way this region of 6.6 is tolerable for most fish species and decreases the amount of hazardous metals also that leach into the stream.

Here we see a picture of this Porcupine Run, the red color of the water, this is truly a red color of the water is red from the dissolved minerals and dissolved metals in the solution that can reach such a high concentration because of acidic conditions those metals become very soluble. At less acidic conditions they remain in the soil and do not go into the water of the (10:52 spelling) phase. The combination of the low pH and the high metal concentration is toxic to a large number of species and will decrease the bio diversity of this area. In this picture we see a before and after picture of the vegetation in the area as well. So prior to re-vegetation and neutralization this area was relatively un-vegetated allowing the surface vegetation not to occur and runoff through occur very quickly, On the right-hand side we see after the neutralization process has occurred vegetation was replanted and allowed to reform to farther decrease the amount of surface runoff from these sulfated and potentially acid mine drainage producing soils. In the very bottom graph we actually see in this area some of the native elk herd actually bathing in this neutralized pond near Porcupine Run where the pH is conducive to freshwater and greater biodiversity in the area.

Both cleaning up the area to make it more aesthetically pleasing but also increase the bio diversity actually enhancing the bio diversity bringing back elk and other species that have not been present since the beginning of perhaps the industrial revolution and other fish species that may have been degraded through the acid rain emissions from the 1950’s 60’s and 70′ Unfortunately the United States is not the only area that uses large amounts of coal and produces large amounts of sulfur emissions, China as well as other countries that use large amounts of coal also can have similar problems for acid gas emissions. And we see similar problems in the coal burning regions of China where we have high emissions of sulfur oxides producing very low pH levels in waterways that can lead to very many of the same environmental impacts that were discussed in the Northeast United States. In summary if we understand the chemistry of resource use, waste and environmental impacts, this understanding can allow us to lead to transformations of degradation processes to neutralize acid conditions and reverse the environmental impacts so that not only do we have preservation but increasing bio diversity of previously endangered ecosystems.

First Speaker: While the Sun is setting on the decades of gold mining, nature is rebelling by pushing toxic acid mine drainage (AMD) to the surface. This problem is the drainage of acidic waters from the mines in the Witwatersrand. A potential disaster threatens because there’s a gigantic underground Lake under did witwaterstrand. Divided in an Eastern , Western and Central Basin.

Anthony: Under JHB there’s a mine void five times the volume of Lake Kariba.

First Speaker: To prevent mines from being flooded, this water needs to be pumped to the surface because as it rises in the mine, chemical reactions cause the water to become acidic and in turn the acid dissolves heavy metals in the rock making the water radioctive and harmful to health, amongst other things. That’s why it’s necessary to treat mine water but many mines have closed down meaning that Water treatment and pump operations were halted and this allow a toxic cocktail of chemicals to rise up unhindered threatening our rivers and drinking water. Already some of this AMD seeping through to the surface in visible on the West Rand.

Anthony: That alone is putting plus minus 100tons of salt every day just that on decant, 100 tons of salt every day into that river. If we were clever as a country, we would’ve already learnt from the Western Basin. We haven’t learnt any of those lessons because we seem to live in a culture of denialism.

Second Speaker: since the report, which has been both applauded and criticized, Government had appointed the TCTA (Trans-Caledon Tunnel Authority) to action the first stages of remedying this massive AMD crisis. In the studio tonight Simon has five experts to bring us up to speed with the latest findings and government plan.

Simon: On the panel tonight we have from the Trans-Caledon Tunnel Authority, Johann Claasens. We have professor Anthony Turton, who is the vice president of the international water Resources Association. We have Mr Marius Keet from the department of water Affairs. We have Dr Henk Coetzee From the council for Geoscience and we have Mariette Liefferink who is the CEO of the Federation for a Sustainable Environment. Mariette, let’s start with you. You’ve been heavily involved with this problem probably from the first moment that the public became aware of it. What is the state of play at the moment?

Mariette: it was very heartening and commendable that acknowledgement was given at parliamentary and cabinet level to the AMD situation. There’s no longer denial or suppression of facts and that is heartening. An inter-ministerial committee was established and the Trans-Caledon Tunnel Authority and a task team were appointed that presented an expert report. However, we are aggrieved that the public, the end users of water, are not participating in this decision making process. We are a participatory democracy and that’s why we feel that the public that have to carry the costs aren’t being consulted and keep involved. It also upsets us that the short-term solution is neutralisation. It leave behind a large volumes of radioactive and toxic sludge, as well as high volumes of salts that’s sulphates that are deposited in ecosystems and river systems.

Simon: we will chat about the issue of neutralisation in a moment. Marius, let’s just bring you in. Mariette has said that things do seem to be moving at the moment but cost is going go be a huge issue, isn’t it?

Marius: If I can just take you back to the middle of last year when this whole ADM issue was elevated to Cabinet level and from the department’s side we first made our presentation to cabinet, to the IMC (inter-ministerial committe) on 1 September, so from government’s side, the problems on the ground were recognized as well as the commitment made by government.

Simon: From a technical point of view, am I correct that it’s the Trans-Caledon Tunnel Authority (TCTA) that’s been brought into now run this process?

Marius: that’s right.

Simon: I know of you guys, as I’m sure many laymen do, as an organization that’s good at drilling holes in the ground and transporting clean water around the country. Are you well geared to deal with this sort of problem which I think is very different?

Johann: Simon, just explain, we don’t claim to be the world experts on AMD (Acid Mine Drainage) but the approach . Will follow and / project implementation methodology, allows us the appointment of experts in the field so that’s the way we’re managing this project.

Simon: Henk, the Council for geosciences highlighted the urgency with which action needs to be undertaken. Now it does seem to be that we’re a fair way down the road with at least putting structures in place but is enough actually being done?

Henk: I don’t think at the moment enough is being done. What we emphasized in the report that we submitted to cabinet is that there is a crisis in the Western Basin. AMD has been seeping out since 2002 and there has been enough done to control it. So that’s one of the priorities, to have something in place as soon as possible. In central and Eastern Basins where there’s rising water, it gives us a time frame in which we have to do things and if I look at the project management being done, we’re reaching some of those targets and hopefully we’ll reach all of them.

Simon: Are we, from a technical point of view, well-placed to now make some progress?

Anthony: My personal view and I’ve made a public stance on this in the past, is that we can treat this. The technologies are available, there are a range of technologies. However, if you are going to treat water to portable standards then I believe it is incumbent upon engineers, scientists, professional people not to allow the cheapest possible technology to be selected because ultimately you must never forget that we are dealing with hazardous waste here. Firstly, you must engage with the 11 million consumers who currently get water from Rand Water. They should be engaged and be made aware of the fact that A portion of the drinking water will now be this acid mine drainage.

Mariette: The argument is used by government departments that the reason that there’s no public participation is due to the critical situation of AMD. However that Doesn’t wash as justification because the AMD has been decanting since 2002 so it’s not a new situation and we demand that the public has to be consulted.

Simon: Marius, on what basis does the department me their decision as far as which technology is being used?

Marius: Simon, I’m very glad that we’re talking about this point and Mariette keeps on mentioning that there was no public participation and she’s totally right. The Department of Government realize that we can do much better but you have to remember that Some years back when the water started seeping out of the Western Basin we as government didn’t know which mines were in control of the area. So a legal process had to be followed to find out who the responsible person was for the water. You basically had two processes. We had a legal process on the one side and on the other side we tried to find technical solutions to the problem. So it was difficult to focus on seeing to it that Everybody got involved while the acid mine drainage was spilling out that Would’ve been missing the point.

The most important to us is to look at who is responsible, to sort that out and then to sort out the problem like removing the AMD from the system.

Simon: Johann, you have a point?

Johann: simon from a project Implementation point of view, we fully appreciate the importance of public participation. Over the year, we’re learnt that if you leave the public behind then all the trouble starts with the implementation side.

So the first thing they did for us was to compile a report looking at the critical dates, we have a very limited period of about a year and if you’re going to follow that process in its standard form, it will take about 2 years. We are going to follow a strategy that Will perhaps give us a certain exemptions that will allow us to do some things that are critically essential but at the same time, in parallel, follow the full process to ensure that all the participation is there.

Simon: Henk from your perspective as a geoscientist; are you confident that the technical solutions on the table at the moment are things that we can move forward with?

Henk: Yes because it’s known technology it is possible to do in these time frames. Where the problem comes in with some of the desalination technologies is that there are those that we know work but they are very expensive. Then there are cheaper options and other options, other ways to approach the matter and it could turn into a very expensive mistake we make if we go in too fast to choose one and start applying it.

Simon: You bring up the issue of price and Johann, you and Henk together went to parliament to present to some of the sub committees and at that meeting you made the point that R225 million is being set aside so far but you would like to see nearly three times that being earmarked for this project How long before you run out of money?

Johann: The money for us at this stage is limited to the R225 million but we will have to go back to government to say “that those figures were based on very preliminary estimates, we’ve now done some more work and it is in fact closer to R750 million that I mentioned”.

Simon: Let’s just quickly address the issue of who should be responsible. How difficult is it to keep the current operation mines responsible for this problem?

Marius: You see Simon that’s the challenge very recently – like the January 31st, we had the stopping of pumping from the Eastern Basin where Grootvel mine just stopped there pumps and Aurora has now disappeared from the scene, you can’t find them. This is actually now where the government will have to intervene.

Simon: Surely there must be legal avenues that the department can explore to force companies like Aurora to do something about the problem?

Marius: That’s correct but you are flogging a dead horse. Aurora does not exist, they are not there and they are bankrupt.

Mariette: The directions are still there.

Marius: That mining company has been taken over by the liquidators.

Mariette: The directors in their individual capacity as well as in their joint capacity can be held responsible not only for pollution on their mining sites but also outside the mining sites that occurred knowingly or unknowingly. I have to mention that the retrospective application that the polluter pays principle can also be enforced. For instance, in the Aurora case we know how the environmental responsibility and liabilities were transferred. It began with Gengold, then Petman, then Harmony gold, then Pamodzi gold and then the Aurora mining group. In other words, that whole range can be held responsible. It’s distasteful that those costs have to be carried by the public as well as being unethical and immoral and the law has made provision for it.

Anthony: There is a very important thing that is happening here, the current AMD debate as it is now being pitched is about the nationalization of liabilities. So it’s about writing off that liability and allowing us to move forward which may or may not be a good idea but that’s what it’s about.

Mariette: That’s why we have to make a very good compromise between what is economically, ecologically and socially viable.

Simon: Johann, the TCTA is taking over the management of this problem on behalf of the department but we’ve seen from the conversation today that there is a more to this than just trying to pump water of old mines. At what point does your scope end?

Johann: Simon that is so, if we look at our mandate we have a very limited mandate at this stage and that is to complete the first phase of the AMD project. We will spend quite a bit of money, so it’s not really sensible to construct the short term solution in such a way that it doesn’t link in with a long term solution. Although we don’t at this stage have the mandate to look at the long term solution, we have to plan now in such a way that whatever we do will link in later.

Simon: Is that enough to get us out of the woods and into the situation where we’ve now turned this into a water opportunity or are there significant areas that need to be looked at again?

Anthony: What we have here us a slow onset disaster. Now the problem with the slow onset disaster is; at what point in time do you say it’s a disaster? It’s a slow onset thing that is happening, I think what it’s driving to do ultimately, is we are rethinking our national macro-economic model. Business as usual is no longer an option; if we continue to do business as usual we are going to crash and burn. We’ve reached the limit of where we can go at the macro-economical level with doing what we do at the moment. In a way it’s kind of driven by crisis but many of your technical solutions are driven by crisis and what I’m particularly comfortable about is the fact that there is now acknowledgment about it. We’ve now got serious players, TCTA for example, they are serious players, they are now in the arena if anyone can solve the problem from project management perspective these are the people that can do it. So in general I think we can sleep well tonight.

Marius: I think it’s very important to realize that government intervened last year and the message was clear that government wants to take control of the AMD situation and that was the quickest that I have ever seen minister’s get together. Within two months everything was arranged. The inter-ministerial committee was arranged, a report was requested etc. and so government began exercising control over the matter and Johann is 100% right. The long term process we all realize now can’t take too long.

Simon: In the short term, the next 3 to 12 months, what would you like to see happening or what do you think people should be aware of? Mariette.

Mariette: As the public we need to co-operate with the solutions, I just want to say on record that we’re in a crisis situation because there weren’t any proactive management plans applied or enforced for years. It’s a pity; it’s lamentable that the reaction only can come when it was already a crisis situation.

Henk: What we have to look at now, we have a decant in the Western Basin and that has to be stopped and any water coming out must be of a much better quality. In the Central and Eastern Basins we’re looking at the rising water levels that also have to be stopped before it creates a new environmental problem. So we are bringing something that was out of control, under control and that is what we have to watch in the immediate future and keep on doing.

Anthony: We are starting to see the emergence of a new way of thinking and I think the current thinking is that we have a problem caused by the mines therefore the tax payer must put money on the table to solve the mines problem. I don’t think that is the correct way to go forward, I think there is a new business model would be – we have a problem, we have an alternative source of water, can we not take that water mine the water for the minerals inside it, put the water back in the river in a reasonable quality and not sell it off for potable purposes. As soon as you are going to sell water for potable purposes which is being driven by the business model at the moment to cover the cost of remediation. As soon as you do that, that’s when you start opening the can of worms. Because I’d never forget it’s about hazardous waste that was toxic yesterday but tomorrows it’s going to be drinking – trust us, we can get it right for you. It’s in that trust us process you have to have credible people at the table that sign that off.

Johann: Simon, I’m just happy from TCTA’s side that we are involved. I think we can make a contribution and we should like to be part of the solution. I also believe that if we look at TCTA’s business model and basically apply it as we have done at some of our other projects we can convert the problem into a long term solution.

Simon: Marius, in a recent Sunday Times article we’ve seen the Western Utilities Company are highlighted as a company that’s going to provide a technical solution to the department in sorting this problem out. There seems to be some concern around focusing fairly narrowly on only one technology. Is that a concern for the department?

Marius: That was the problem and that’s the reason why government realized that we had to almost start a new, with a process in which there is public participation and also to look at the different technologies. That’s why the inter-ministerial committee stated very clearly that it’s good that people come in with ideas but government must take control of them and that is what is happening now. As far as the technology is concerned we have nothing against the technology to the contrary, I think it’s a very good technology but there are so many technologies worldwide government is bombarded almost on a daily basis with different people and technologies and we have to look at everything.

Anthony: Can I get on the record whether a deal has been done with the Western Utilities or not? I think it would be a very useful thing to get on the record.

Marius: Easy, there was no deal with the Western Utilities Corporation, because at the time when we asked the mines to come up with a solution the mines appointed the Western Utilities Corporation. So we never said this is it and we’re going to follow it strictly, we said from the beginning here’s a possibility, let’s investigate it. So in short, no we did not accept it.

Anthony: Then I can place on the record my full support for that because if it is a private deal like that, it simply becomes an incestuous relationship.

Simon: A final word from Government, Marius.

Marius: I think form the government’s side it’s very important that we show everybody that we have a proactive model on the table. You know, I’m also very tired of just defending all the time, just defending all the attacks. So it’s very nice to be able to say now there is a plan on the table although it still has to be finished but we have a proactive approach. It’s important that people realize that what is past is past. You can’t retrospectively go to mines that existed 50 years ago, we have to deal with what is on the table and it would be great for me too if I pass the Western Basin and there is no water seeping through.

Simon: There’s clearly a huge problem but there seems to be some very fine minds working on it and I’m sure with people like Mariette watching them closely hopefully we will see some solutions start to come through. Thank you.