 So, in nutshell, what is the basic philosophy of lysimeters, truly speaking that two strata, one is the lower compartment which is the leachate collection system and the upper compartment which is filled with the material sensors and moisture extraction systems like cups. And what I can do is I can find out the how the system is going to behave when I talk about let us say encapsulated nuclear waste because disposal of the nuclear waste has been a big issue and the country bonds to become a muscular country in terms of you know today's socio-political situation. So, radioactivity and dealing with it has become very important. This is where the attenuation properties of soils become very very important. So, what I can do is I can take the atomic waste or highly toxic waste in case it in a unit, this is what is known as encapsulation. So, I can freeze the entire material contamination into the matrix of cement or sometimes glass, those of you who are interested read more about how this is done. So, glass is the best source of encapsulation of toxic waste, why? Because glasses are more first, you remember XRD patterns. So, there you are looking for the glassy phase which is more reactive. So, glass will not let anything come out of it. Now, when I am talking about this, you should also Google about the salt domes, salt domes which nature provides salt domes, D-O-M-E-S domes. So, which nature provides and these are the best places to dump the atomic waste coming out of your reactors, why? Again the same thing, salt is the most reactive phase which will not let any species of contaminants go out of it and hence it acts as a best possible barrier system naturally provided, clear? So, coming back to this story, I can take toxic waste, atomic waste, bio waste, encapsulate it in a matrix of concrete, cement paste, different type of raisins and I can solidify it. Now, the question is before I dump it somewhere, I have to prove that nothing from this unit is going to leach out. So, this was the project which I dealt with for India and was very educating work and this type of modelling we did, real life situation and what I did is after embedding it somewhere here in the upper layer, I induced artificial grains and leave this system for certain duration and whatever leaches come you can analyze and you can show that the encapsulation which has been done is perfectly alright, nothing will go out, everybody is happy. Are you realizing the importance of this simple experiment which was done? Are you getting a feel of this? Minus this everybody would have been asking what will be the effect of this material on JOL run and then they will not let you install atomic establishments and if nothing of this sort happens then what will happen? You will always remain in 17th century deprived of electricity and power and weapons and what not, radiotherapy and medicines, so many applications. So, are you realizing the whole cycle where the science and technology gives answers to the questions which would safeguard the society against? The concepts are clear, so I can design here how much is being retained by the soil attenuation property, what is the desorption studies and everything. I can do a beautiful modelling to even see what is the effect of temperatures, ambient temperatures, after disposal what are the temperatures in the ground, whether thermal cracking of the soil is taking place or not because these are the thermal stresses, thermal stresses, radiation stresses all put together, beautiful example of coupled phenomena and we use these concepts to find out the validity of the models which are being used. So, until now we have been talking about the saturated systems of the soils, zero tension lysometers and now I would like to show you how the tension lysometers look like, primarily they are used for unsaturated soils where you do not allow ingress of water happening in the soil mass, clear? So, this is how these systems look like, these are the glass tubes or PVC tubes which are specially designed, so these are typically PVC tubes or the glass tubes of different lengths, at the end there is a specialized ceramic cup which is attached and this is also known as thimble, T-H-I-M-B-L-E thimble, so these are the systems which have a specific air entry values, in medical sciences they use this type of things quite a lot. Also the research in environmental geomechanics is being replicated after seeing the human body and how it functions, clear? So, these systems which are normally used in medical sciences are now being used in geomechanics. So, in this tube there are tube pipes which are inserted, the philosophy is like this that once I insert it into the soil mass which is unsaturated, leave it for some time, apply suction, so when you apply suction the water from the unsaturated soil gets sucked and the suction should be so modulated that the pore solution comes and sits inside the tube and once this happens you can have another pipe which is connected to the sample bottle while and you can keep some sample which you have collected by applying some vacuum suction. So, this is how the tension lysimeter works, I will show you how it looks like and how it is calibrated and the things. What is the importance of the lysometric studies? This was the project which I did for Atomic Energy Regulatory Board of India and BRC, so as I said the lysimeters are basically the devices which create a control volume of soil for studying various contaminant transport mechanisms under in situ conditions. There are two types of this field and laboratory studies, in field studies unfortunately there is not much control on the boundary conditions, alright and they are very expensive and very very time consuming though we did some of the field studies and laboratory studies also cannot simulate the in situ stresses because once you have retrieved the sample you know the in situ stresses cannot be simulated. Another problem is you cannot simulate the real matrix of the soil or the soil structure which was lying in the which was in the real life situation. Another issue is the special variability cannot be taken into account because the sample sizes are very very small in the laboratory studies. So, under these circumstances the lysometric studies can be utilized as a intermittent approach and I can simulate in situ conditions also by controlling the boundary conditions. So, you may say that this is a sort of a one type of a solution which I get by doing lysometric studies. So, this is the case which I was talking about what type of instrumentation has been done at a place where the atomic waste is dumped in India. So, what you are seeing over here is a stainless steel ring of 1.2 meter diameter and this was about 2 meter long. This ring was not 2 meter long this was also 1.25 meter length you can see it from here. So, this was inserted into the ground by pressing it from the top the way the piling is done. So, inside the soil mass becomes a control volume and it does not get influenced by the outside surroundings alright. Now, as far as the instrumentation is concerned what you are observing is that there are 2 tubes T1 and T2. So, these are the PVC tubes which were installed after the sample was created. These are known as TDR tubes, Time Domain Reflectometry tubes and what you are observing here is a TDR probe. This is what is known as Time Domain Reflectometry probe and this is used for profiling the moisture content from top to bottom of the zone of interest and the type of volumetric moisture which you obtain from here. Remember this is the volumetric moisture which you get from the TDR probes can be utilized to profile the variation of groundwater regime in this sample. This is the groundwater. So, fluctuation of water table can also be captured when you use a TDR probe alright. So, if you probe from top to bottom and you try to create a moisture profile these type of probes are very useful. Why 2? Because we wanted to see the spatial variation within a small control and they were installed at different radial distances and different depths. So, this is a typical tension lysimeter alright and what I have shown here is a thimble which is made up of a specialized ceramic cup which has a peculiar air entry value. So, this is the setup which has been created. Now what is normally done is we remove the top 100 mm of the soil and replace it with sand alright and this sand is utilized as the source of contamination which is going to migrate through the soil mass. So, by using these type of setups we could study the cesium, hobalt and tritium. These are the radio nucleates which we use to study their interaction with the soils alright. Why these radioisotopes were used because these radioisotopes are present in the sludge which comes out of the atomic reactors. So, this is what actually we wanted to study. The choice is yours you can use different combination of the radio nucleates. This is how the suction samples look like. We train them in a CBR mold to see whether they are working alright or not and then when you apply suction you know pore solution gets collected. Just to show you how the activities are done in the field. This is how the whole system has been created. The two excess tubes are fitted, four suction samplers are fitted. These are the you know tubes which are connected to the suction samplers. Now you can see that we are giving you know this is the strontium crimson red color is typical color of the strontium radio nucleate and then we leave this whole thing for rainfalls to come. This experiment which was very expensive was done during the flash floods of. You can see here the experiment was going completely alright from 15th June and to July and then came the flash floods of 26th July 2005. These glass tubes were broken and they got flooded you may say but we got good data based on which we did the analysis. As I said TDR studies are normally done to establish the variation of soil moisture in the entire domain and particularly this is the groundwater variation which causes this type of profile. This could be because of the percolation due to the rains also and this takes care of the evapotranspiration because on this axis if you remember the soil sample is exposed to the environment. So evapotranspiration, percolation, fluctuation of groundwater table everything is taken care of. So this is a very comprehensive setup which has been done. If you want to read this outcome of the study you should refer to this work which we published in Geotechnical and Geological Engineering application of in situ like symmetric studies for determining soil hydraulic conductivity under field conditions. This is how we establish the movement of cesium and cobalt in its active form. And we did the modeling for 500 days and the whole purpose was to design the repositories where the waste is being dumped and how the whole system behaves you know how much is getting sobbed onto the soil mass at a given depth. So these type of studies become very useful when you design the repositories where the waste is being dumped. Now this is the another instrument which was fabricated by one of my master's student Dr. Vikas Thakur. Now he is a professor at NTNU in Norway. So this is the system which was created. Now what you are seeing observing here is that this is a control volume where I can keep the sample and this is connected to a pressure retention unit and pressure retention unit is connected to a compressor. So with the help of the compressor the pressure is built up in the retention unit and this pressure of air can be used to pressurize the sample in the pressure membrane extractor. So rather than using the water in the cell the sample which is kept here is being pressurized with the compressed air and why it is being done answering your question. Now you are seeing a situation where the fluid is compressed and it is percolating through the sample. So it displaces the pore solution which gets connected into the boil which is kept over here. So if you look at the closer view of the pressure membrane extractor this is how it looks like it is a chamber where the bottom portion is connected to a drain and on the drain we keep a percolating material mostly a geotextile. On the top of this we keep a cellulose acetate membrane. Cellulose acetate membranes are used for lot of treatments of the human body particularly the filtration of different type of fluids. Membrane technology is a big subject in chemical engineering. So to create a membrane which will function add a certain pressure for certain types of contaminants or ions. A good example of membrane technology is the ROs which you are using or the water filters which you are using alright. So when the air is inlet what happens this air pressure acts on the samples of the soils which are kept in small small these are the rings. So they are open from both top and bottom and what we do is we keep the filter paper on the top of the filter paper we keep the ring and we pour the soils in the rings and we place them over here. So when you apply air pressure the pore solution comes out and that is collected in the bottles. So this is a pressure membrane extractor this was done by ourselves but now in the market you will find that commercially available pressure membrane extractors are available. These are primarily used by the guys who are working in unsaturated soil mechanics or the guys who are working in biomedical engineering or agricultural scientist those who are very much interested in uptake capacity of the soils and the plants and those who are working in the field of nutrition ingress and loss from the soils. So these type of equipments can be utilized quite easily.