 Myself, I am DN Singh, Professor in Department of Student Engineering. I started my career in 1994 and I am continuing doing research and academic work quite profusely. You can write down my email address which is dns at civil.iitb.ac.in, try to sort out most of the queries in the classroom or you are most welcome to communicate to me through email. Let us start with the overview of the course. This course normally I define it as a philosophy and that to the engineering philosophy. Basically deals with the, in calculating the influence of environmental effects. In bracket you must be noticing that I write either manmade or natural on conventional geo technical engineering practices. The basic idea is I try to draw a simulation between what is happening in the nature and how this simulation can be done in laboratory by using different methodologies and techniques which are known to human beings or technocrats. Now again I would like to emphasize on the word philosophy, you will find this course slightly unconventional. It is not a very stereotype of a course where you expect me to give you lot of equations and solving the problems by inputting the parameters. I am sorry that is not the whole idea of this course and slowly and slowly you will discover that this course has been developed over the years particularly by assimilating the information which has been given to me by my own students. So it is a very interesting way in which this course has evolved and the journey continues. Every day, every thesis, every dissertation is a learning experience for me particularly and I thank my students for guiding me properly. So this course is gaining significant attention of engineers, researchers and planners due to rapid and uncontrolled industrialization which yields a huge amount of hazardous space or the contaminants which normally we use as a connotation rather than talking about the hazardous space. How do you define a contaminant? That is very good. Can you dissect the word contaminants and define it further or what is the literal meaning of the word contaminants? The substance which make the something not useful. Okay next. The substance which has a tendency to contaminate other things like contaminant. We are trying to find out the definition of contaminant itself. Yeah. Yeah. Which has a hazardous effects on both nature and also human life. Pollutants we can see. Okay. Yes please. Sariqa. Sir contaminants are the substance. Which disturb the characteristics of the substance can say and results in some hazardous waste. Good. Next. I think contaminant is something which when comes in contact with normal standard qualities will be changed when this contaminants will be mixed. So that will be creating harmful effects both for the environment and to the human beings. That's right. Okay. Next please. It's like substance which not only affects the man can but also it gives its hazardous effect on environment also. Good. Next one. Contaminants are those materials which can be man made substances or by naturally harmful and it causes harmful effect to the environment. Good. Contaminants are basically toxic and they affect the quality of environmental. Yeah. So most of you understand what is the meaning of contaminants of my life and my job becomes very simple. Whatever you have defined these are the traits of the contaminants you are right. In simplest possible words a contaminant would be a foreign material or a foreign body which tries to what spoils the basic characteristics of a system. Alright. Well, so what we will do is we will try to study this statement again. It is gaining significant attention of engineers, researchers and planners due to rapid and uncontrolled industrialization. I hope you will agree. This is what is going on presently in the country and all over the world and this phenomena leads to a huge amount of generation of waste because waste are not needed, unwanted. We term them as contaminants. Alright. Now as far as the subject is concerned it's a blend of geotechnical engineering and environmental engineering and basically it deals with studies related to safe disposal and handling of the waste, estimation of its spread and fate in the subsurface, method to contain its spread in the subsurface and some schemes which you can derive for remediation of the contaminated land. So what you will notice is the scope of the study or the subject is too much. What I will try to do here is I may not go into the details of each and every step which I have talked about here. I will just try to give you the basic idea about what is the genesis of the subject which we are trying to study and what are its applications or implementations. But truly speaking all these things should be borne in mind when we talk about the subject and that is how I say that the overview of the subject deals with so many facets. This subject also encompasses safe transportation and disposal and development of suitable strategy for proper utilization of the waste. Now this is where the concepts of recycling, reuse, re-application of the waste is coming in focus these days. Apart from a discussion on these issues, this course highlights the importance and relevance of revising the basic concepts of geotechnical engineering so as to deal with the concerns raised by these issues in the most befitting manner. This is something very tricky and this is where actually I spend most of my time in explaining that how the two concepts one is which is slightly I would say old concept is going to get modified by the new concepts or the new concepts which we put into the practice to solve most of the problems which we are dealing with in day to day life. So the basic aim of the study which we are going to do is to get some solutions to the problems which exist in nature and which are of severe importance to the mankind or the society or the nation or the world as such. In addition to this, the course focuses on pointing out the role and importance of the parameters and mechanisms that govern interaction of contaminants with geomaterials. Now this would be a slightly new word or terminology for you. Most of the time we talk about interaction. How two things are going to you know communicate with each other. Now this is what is the meaning of interaction is literally. So most of the time I would like to bring you back or your attention to the fact that how we are going to simulate the interaction of two systems. One could be a contaminant another one could be a porous system or a geomaterial. So truly speaking enough emphasis is given here to understand how a porous system is going to interact with contaminants. Now when you talk about this type of interaction, if the interaction happens to be prolonged, the tendency of the system is to get degraded. So this is where the second step comes into the picture. After interaction the interaction or prolonged interaction leads to degradation. So the degradation due to the presence of chemicals or radio nucleates in undesirable concentrations and at elevated temperatures in the long run. So when we will discuss about the attributes of the contaminants, what we will notice is that apart from the chemical activity, a contaminant can have radioactivity associated with it or concentration of chemicals and that too at elevated temperatures. So you think of a situation where you have three components of or three attributes of the contaminants like temperature, too much of radioactivity, too much of chemical concentration and how these three parameters are going to influence the interaction of this contaminant with a porous system which happens to be geomaterial. Now interestingly, this interaction can be defined or can be quantified with the help of concepts of mechanics. So the studies which you have done till now related to soil mechanics and geotechnical engineering, using them as the base, I will add on the top bit of concepts related to how to model a certain mechanism. So this becomes environmental geomechanics. That means we are going to study how the influences of environmental factors can be encompassed or studied or can be imbibed in the system in the most unique way or in the most appropriate manner. So here few words are very important. As I said the first one is interaction. The second one is prolonged interaction may result in degradation and the attributes of the chemicals or the contaminants where we talked about three things, concentration, temperature, radioactivity and so on. And of course we talk about this phenomena to take place in a prolonged manner, that is the long run. However as contaminant geomaterial interaction is an extremely slow process and a complex process and this primarily depends on the physical, chemical and mineralogical properties of the system. It is quite difficult to study this interaction under laboratory or in situ conditions. These are some new words which I am coining over here. I hope the contaminant geomaterial interaction part is clear to you. Now when we talk about this interaction, it is a very slow process even if you talk about the migration of water which is nothing but the seepage or hydraulic conductivity. The hydraulic conductivity of geomaterials are very very small 10 power minus 7, 10 power minus 8, 10 power minus 12, 10 to minus 14 meter per second and so on. And then slowly and slowly we will see that there are few mechanisms which are going to be much slower than this mechanism or the mechanism of seepage of water or a fluid to the system. Diffusion is one of them. So there could be a situation where diffusion takes over the seepage process or advection process. I hope right now you might not be able to envisage that what type of situation this would be but just to give you an example for the sake of completeness if you think of salt water migration or salt water intrusion where the contaminant transport mechanism is mostly going to be a diffusion process not the advection process. So this is where actually we talk about extremely slow processes which are very complex in nature and which primarily depend on the physical properties of the system chemical properties of the system and mineralogical properties of the system. Now this is a very holistic approach which we are talking about that means till now people have been talking about only physical characteristics forgetting what is the chemical characteristic and the mineralogical characteristic of the contaminant geomaterial system though it is a very difficult task but then this type of interaction has to be simulated first in the laboratory so that the generalized models can be developed and hence we can prove what is going on in the laboratory whether it is commensurating with the facts or the phenomena which govern in the nature. So this is where actually we require different modeling techniques. So certain part of the course I will be devoting on studying or telling you how to model these mechanism by adopting the latest techniques such as accelerated physical modeling I am sure you must be doing a course on centrifuge modeling also which is nothing but accelerated physical modeling using a geotechnical centrifuge finite element difference based numerical modeling techniques and another new concept is if you want to study how a geomaterial gets degraded over a period of time because of its interaction with the contaminants we can talk about the physical, chemical, mineralogical modeling. So this would be something very interesting and unique which I would like to cover in this course. Any questions? How it is going? Sir, that is one question. Now here you said that basically degradation of the geomaterial but in conventional geotechnical engineering we study soil stabilization so where we add something to so can we say that this concepts of this environmental geomechanics also they have the genesis from the soil stabilization that is the positive effect. So you are studying basically the negative effect of this material. It is a very good question. Again a very thought-provoking question. Any answer from the audience here? Seema. It is a philosophical question so it requires a philosophical answer. One capsule of medicine is a medicine but more than a certain dose becomes a poison. I do not know whether it is correct to this analogy or not. When you talk about stabilization the concentration of chemicals which you are inputting in the system are controlled but when we talk about interaction of contaminants with porous system the concentration and the hazardicity of the waste is beyond control. So I hope you can now correlate the things. If the doses are controlled it is a stabilization process. This well monitored process is going to lead to a good stabilization process. However if the concentrations and attributes are quite extreme or very high then what happens in that case? This becomes a case of environmental or geomaterial degradation. This is what is to my knowledge. Any addition to this? Yes please. I would like to add something. Please feel free to interact. Your interaction is very important than the contaminant geomaterial interaction. I also want to one more question. I want to ask you. I mean you have used the one physical, chemical, mineralogical modeling techniques. I understand physical means it refers to the characterization of soil that tests we do but what type of tests we generally do for chemical and mineralogical modeling? Just a brief. So Seema's question is that what is essentially meant by physical, chemical, mineralogical modeling techniques? Everybody understands what is meant by physical characterization of the material that is you first work out the particle size distribution, the specific gravity, surface area, shape of the particles, angularity of the particles and so on. So this is very well understood phenomena in geomechanics. All of you must have done experiments to classify your soil. Your classification schemes are based on physical classification only. You come out of it a bit. When you talk about Etterberg limits, it is add on to the physical process. How? You add water to soil. All right. And then you try to understand what is the activity of the minerals which are present in it. So this is where the importance of minerals come into the picture. I will be talking about the mineralogical characterization of materials also in this course a bit. Normally we conduct XA fluorescence techniques which is known as XRF and XRD to find out the chemical composition of the soil mass or the geomaterial or mineralogical composition by conducting XRD that is XA diffraction technique. I will be discussing about these things. Some of the other chemical attributes of the material can be determined by conducting test like pH measurement in the pore solution or cation exchange capacity that is CEC or zeta potential of the soil mass and so on. Anything which I missed out? So normally we talk about pH, cation exchange capacity, zeta potential of the soil. Of course sulphate, chloride which are present in the system and so on. So basically what we are trying to do is we are trying to work on a model which talks about the totality of the material properties that is the physical properties, chemical properties and mineralogical properties. Another part of your question should have been that why these properties are so important to be studied. Now if you remove the chemical and mineralogical aspects of the geomaterial it becomes a passive soil. So what is the difference between a clay with kaolin and a clay which is having more of montmorillonite or bentonite in itself. That means chemically they are different and mineralogically they are different. So this is why actually it is important to study the overall properties of the geomaterials and then try to see how these properties are going to attribute their impact on the answers which you are trying to get. Is this okay? Yes please. Sorry. What are the agents which can accelerate the interaction of geomaterial and contaminants? Yes this again very good question he is asking your name please. Shiv Prakash. Shiv Prakash is asking a question that what are the parameters which may accelerate this interaction. How do you behave when the temperatures are very high outside? So you just understand that we are the living entity. Soil is also a living entity. Rocks are also living entity in a geological time frame and all of us behave in a similar manner whether it is exposed to the temperature, humidity or the pressure. So any phenomena, any interaction which takes place in this world which happens to be a physical phenomena has to be guided by temperature, pressure and what else humidity. Now if you keep these parameters in your mind you will and go back to the rock cycle how soils are formed. So this gives you a easy answer to understand that because of humidity because of weathering the soils were formed. Is it not? So all these interactions will get influenced by the parameters, temperature, pressure, humidity, activity of different types which are available in nature. Like as a civil engineer we never bothered about the bioactivity which is present in the soil mass. We always believed in taking out a sample bringing it to the lab remoulding it and then doing the modeling and getting some parameters which fail miserably when you do a modeling in the nature or in the field. Why? Because we have ignored there the effect of bioactivity, the microbial activity, the climatic conditions which are going to exist and so on. It is a big list. So I will try to answer these questions slowly and slowly but please excuse me because as I said the course happens to be so big and so large it is very difficult to cover in one course, one semester. So you keep on asking the question the best way is I think most of the doubts for both of us can be cleared. Is this okay with you or you have another doubt? Yes please. Sir actually you have mentioned that physical, chemical and mineralogical modeling techniques. Sir like in the chemical like it means the water content present in the soil and all like they will be altered when they have an interaction with like some hazardous materials and all. But how will these physical characteristics of the soil be affected by those? Like actually they will be generally affected by like the shape, size and angle they will be affected due to that pressure conditions and weathering and all but how will they be affected by? Very good question. One part of the question you have already answered. Second part is in the simplest form how shape is going to attribute to the activity of the material? What is the difference between sands and clays? When you say surface area of sands is very less and surface area of clay minerals is very high okay. I hope this answers your question. That means there is a very distinct relationship between the physical attribute which happens to be a surface area or specific surface area of each mineral and each material in fact each fraction of the soil also clear? This is one of the answer. The second answer would be what guys the specific gravity of the material? Shape okay. So if shape is or if the particle size is very small the specific gravity is going to be more. Similarly we talk about porosity and so on which will fall in line slowly. I hope this answers your part of the question okay. What was the second part of the question? Will they be getting affected by this? Chemical action also. Well the chemistry is the mother of all sciences people say. So when you talk about the chemical attributes you must have noticed in your food plate you like to have different types of variety why? Something is sweet, something is sour, something is salty, something is less salty, something is spicy what is this? This is nothing but the chemical compositions are different clear? And if you take them together it affects your digestion system. If you do not take something in proper proportion something is going to get affected. Similarly you think of the soils which are made up of pure silica. Now silica is a passive material it is not going to react with anything. So you keep on pouring any amount of contaminants on silica the net result would be not much it will not get affected much. However if you take clays which may have a different composition different oxides different mineralogy and if they come in contact with chemicals you will notice slowly and slowly when we discuss these issues which come under the sorption desorption techniques that they have a great affinity towards chemical species. A good example of this type of a question or good answer to this type of question would be why do you use some typical clays as a cleansing agent for your body? Good example is multanimity it is nothing but bentonite. Why do not you use sands for cleansing your skin? So sands will give you more scrubbing effect while the clay has more cation exchange effect. So what it does is it takes out the cations from your body in the form of sweat and what is sweat? So it is nothing but all the chemicals which are oozing out of the skin. So this is a good example of how physical, chemical, mineralogical interactions are going to govern the overall process of waste coming in contact with geomaterials. Yes please any other question? If you do not agree please let me know and you answer someone can take the charge of answering the question. Okay.