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Shree Swami Atmanand Saraswati Institute of
Technology
Prepared By:-
Korat Harshad 120763106022
Mehta Moxesh 120763106024
...
Content
• Introduction
• Pumping Test
• Percolation Test
• Single Ring Falling Head Infiltrometer Test
• Double Ring Infil...
Introduction
• What is Permeability….?
• Permeability is a property of soil which allows a water or any fluid to pass
thro...
Pumping test
• The purpose of pumping test is to get the information of permeability;
• Pumping test is the active way to ...
• The well will consist of an open-ended pipe, perforated or fitted with a screen in the
aquifer to allow water to enter t...
6
7
• After the pump reaches a steady state ( the water table drawdown does not
change with respect to time), for a given amou...
Percolation Test
• Percolation test is a passive and cheap way to estimate soil permeability.
• Need more than 6 holes, af...
in situ hydraulic conductivity tests for compacted clay soils adapt similar
approach as showed in the above percolation te...
11
Slug tests
• The aquifer tests that we have discussed so far involve pumping and have
some practical problems. They are ex...
• Procedure
In this slug test, water level is raised in a well, and the level of
the water in the well is measured over ti...
• The ratio of H/H0 is equal to a defined function:
H / H0 = F(η,µ)
Where...
• Values of F have been tabulated for differe...
• We can solve the following equations and find permeability
(K):
15
Single Ring Falling Head Infiltrometer Test
• Principles:
Known boundary and pressure
conditions are used to determine the...
Methods:
A single steel ring with dimensions (20cm
diameter and 17cm tall) is inserted 2cm into
the soil surface.
It is wi...
Analysis
output for analysis of C1, linear equation sited
(note the exclusion of points not in a steady
state of infiltrat...
Double Ring Infiltrometer Test
Principle of how it works:
The double ring Infiltrometer is a way of measuring saturated hy...
The outer ring virtually turns a 3D single ringed
system of looking at infiltration into a one
dimensional model by allowi...
Description of apparatus/method:
• Before the double rings can be placed in position the ground cover must be removed
with...
22
Analysis of Data:
Data is gained by a drop in water height, giving an infiltration of water over
time. These data points a...
Problems with method:
Some draw-backs of the double ring are that
1- It is very time consuming,
2- Requiring frequent atte...
Estimated Methods- Based on Grain Size
Hazen Method:-
Applicability: sandy sediments
• K = C*d10
2
• d10 is the grain diam...
Guelph and Amoozegar
Borehole Permeameter
Field Testing 26
• The Guelph Permeameter is an easy to use
instrument for quickly and accurately measuring
in-situ hydraulic conductivity....
28
• The Guelph Permeameter (GP) is a constant-head device,
which operates on the Mariotte siphon principle and provides a
qu...
• Auger Cutting Diameter - 6.0 cm (2-3/8”)
• Well Height Range - 2.5 cm to 25 cm
• Hydraulic Conductivity Range – 0.0001 t...
• Simply center the Tripod over the well
hole and slowly lower the Permeameter
so that the Support Tube enters the well
ho...
Where…
a - Well radius, in cm.
C - Shape factor dependent primarily on the H/a ratio
C1, C2 - C factors corresponding to H...
References
• http://www.soilmoisture.com
• http://www.water-research.net
• www.specializedengineering.com
• www.gmeconsult...
Thank You
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Methods of in site Permeability Test

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Methods of in site Permeability Test

  1. 1. Shree Swami Atmanand Saraswati Institute of Technology Prepared By:- Korat Harshad 120763106022 Mehta Moxesh 120763106024 Dhameliya Dhaval 120763106025 Vaghani Shaunak 120763106026 Seminar on Methods of in site Permeability Test Guided By:- __________________1
  2. 2. Content • Introduction • Pumping Test • Percolation Test • Single Ring Falling Head Infiltrometer Test • Double Ring Infiltrometer Test • Slug tests • Hazen Method • Guelph Permeameter 2
  3. 3. Introduction • What is Permeability….? • Permeability is a property of soil which allows a water or any fluid to pass through it… • Methods of determination of permeability in field is shown in fig. 3
  4. 4. Pumping test • The purpose of pumping test is to get the information of permeability; • Pumping test is the active way to get k, the permeability. The passive way is to do the percolation test. • The principle of a pumping test is that if we pump water from a well and measure the discharge of the well and the drawdown in the well and in piezometers at known distances from the well, we can substitute these measurements into an appropriate well-flow equation and can calculate the hydraulic characteristics of the aquifer 4
  5. 5. • The well will consist of an open-ended pipe, perforated or fitted with a screen in the aquifer to allow water to enter the pipe, and equipped with a pump to lift the water to the surface • A pumping test does not require expensive large-diameter wells. If a suction pump placed on the ground surface is used, as in shallow watertable areas, the diameter of the well can be small. A submersible pump requires a well diameter large enough to accommodate the pump. • The well should be drilled to the bottom of the aquifer, if possible, because this has various advantages, one of which is that it allows a longer well screen to be placed, which will result in a higher well yield. • The well should be developed by being pumped at a low discharge rate. When the initially cloudy water becomes clear, the discharge rate should be increased and pumping continued until the water clears again. This procedure should be repeated until the desired discharge rate for the test is reached 5
  6. 6. 6
  7. 7. 7
  8. 8. • After the pump reaches a steady state ( the water table drawdown does not change with respect to time), for a given amount of time T, the amount of water has been pumped out is Q, in the unit of volume, like cubic meter. where k is permeability H is the head q is the flow rate, and h1 & h2 is head 8
  9. 9. Percolation Test • Percolation test is a passive and cheap way to estimate soil permeability. • Need more than 6 holes, after test do the average; • Each hole to certain depth, usually 3’-5’ • Put 2” thick of coarse sand or gravel into the hole; • Fill 12” water above the sand/gravel • Stay overnight • In the next day before testing filling water by 6”above the sand/gravel • Measure the water level drop at 30 minutes interval for 4 hours. Every time, if needed, add 6” of water again • The drop occurred at the final 30 min. is used to determine the percolation rate • If the soil is highly permeable, use 10 min. for the duration of 1 hour 9
  10. 10. in situ hydraulic conductivity tests for compacted clay soils adapt similar approach as showed in the above percolation test. It is dry and straight forward, you can easily read through it. 10
  11. 11. 11
  12. 12. Slug tests • The aquifer tests that we have discussed so far involve pumping and have some practical problems. They are expensive, requiring monitoring wells and many person-hours of labor to conduct • An alternative to a pump test is a slug test (also called a baildown test). In this test the water level in a small diameter well is quickly raised or lowered. The rate at which the water in the well falls (as it drains back into the aquifer) or rises (as it drains from the aquifer into the well) is measured and these data are analyzed. • Water can be poured into the well or bailed out of the well to raise or lower the water level. However, perhaps the easiest way to raise the water level in the well is to displace some of the water in the well by lowering into it a solid piece of pipe called a slug, So that’s where the name comes Slug Test 12
  13. 13. • Procedure In this slug test, water level is raised in a well, and the level of the water in the well is measured over time as the water drains back into the aquifer and the level falls. A plot is made on semi-log graph paper, with the ratio of the measured head to the head after injection (H / H0) plotted on the Y (linear ) axis and time plotted on the X (logarithmic) axis. 13
  14. 14. • The ratio of H/H0 is equal to a defined function: H / H0 = F(η,µ) Where... • Values of F have been tabulated for different µ (mu) and η (eta). To analyze the slug test data we need to match the data curve to one of a series of type curves. • Each type curve consists of H/H0 values plotted against a range of η values for a particular value of µ. • In this case, we need to keep the Y axis of the two graphs the same, while sliding the overlay along until the data points are matched by one of the curves. • The matched curve gives us an approximate value for mu, while reading the time value from the data graph that is equivalent to eta = 1, gives us a t1 value. 14
  15. 15. • We can solve the following equations and find permeability (K): 15
  16. 16. Single Ring Falling Head Infiltrometer Test • Principles: Known boundary and pressure conditions are used to determine the unrestricted 3-dimensional infiltration capacity, of a soil confined below the single, steel ring. The ability for the soil to transmit water (be permeable) is hence determined through steady state calculations and, this Saturated Hydraulic Conductivity (Ksat), which is universally used as an empirical constant to quantify specific, soil-water flow and infiltration capacity problems. Ksat “is one of the most important factors playing a role in many agronomic, engineering and environmental activities” (Herman et al, 2003) and hence, is a useful term to quantify. Single ring Infiltrometer ; in action Single ring Infiltrometer; finished 16
  17. 17. Methods: A single steel ring with dimensions (20cm diameter and 17cm tall) is inserted 2cm into the soil surface. It is with 2L of fresh water by sealing with a plastic sheet, pouring the water over the plastic and pulling the plastic slowly. The initial height is measured once all the water is released and time initiated. Further water level (height) measurements are taken at 15-second intervals for the first few minutes and, after 2 minutes another 15 seconds is added to the interval period (subject to intensity of infiltration; figure 2). This process is continued until all the water has infiltrated or a steady state rate is recognisable. The single ring infiltrometer was used at all 10 sites within the study area and at the soil pit. Filling ring with water and taking initial measurement Method for taking continuous height measurements17
  18. 18. Analysis output for analysis of C1, linear equation sited (note the exclusion of points not in a steady state of infiltration, the red line represent the steady state function) For each individual site, the x,y distribution of time against cumulative infiltration is displayed, so that the point steady state infiltration can be visually determined. A line is then fitted along the steady state portion of the graph. Within the resulting linear equation, the gradient is equated as the soil- water flux (q). Using q = Ksat.{(C/G.pi.r)+1} Ksat (mm/h) of the soil can be determined as all other components are known or estimated. q = statistically determined (cm/min) C = wetting front potetenial (estimated for clays at 150 cm) G = shape factor for infiltration (0.8456) pi = 3.1415... r = radius of ring (10cm) 18
  19. 19. Double Ring Infiltrometer Test Principle of how it works: The double ring Infiltrometer is a way of measuring saturated hydraulic conductivity of the surface layer. It consists of an inner and outer ring inserted into the ground. Each ring is supplied with a constant head of water either manually or from mariotte bottles. Hydraulic conductivity can be estimated for the soil when the water flow rate in the inner ring is at a steady state. It works by directing water onto a known surface area due to the parameters of the inner ring. The rate of infiltration is determined by the amount of water that infiltrates into the soils per surface area, per unit of time. Infiltration can be measured by either a single or double ring infiltrometer, with preference usually lying with the double ring because the outer ring helps in reducing the error that may result from lateral flow in the soil.
  20. 20. The outer ring virtually turns a 3D single ringed system of looking at infiltration into a one dimensional model by allowing water in the center ring to flow nearly exclusively straight down. This allows much easier calculation by taking out the need to account for lateral flow. This schematic diagram shows the vertical flow that is generated form the inner ring which is allowed by the outer ring accounting for all the lateral flow. 20
  21. 21. Description of apparatus/method: • Before the double rings can be placed in position the ground cover must be removed without disturbing the soil surface. • The rings can be set in position and knocked into the ground about 10cm, or until the rings are set firmly in the ground. • When filling up the rings the outer ring is filled first so that the soil profile around the inner ring would be wet and only vertical flow would occur when the inner ring is filled later. • Apply the water to the centre ring, then finally measuring infiltration at certain time intervals. • When filling the inner ring water is poured in on a plastic sheet, then once the desired amount of water is in the ring on the sheet, the sheet is removed quickly. The level of the water is recorded at this point as the start of infiltration. • Water can be supplied inside the rings either by a marriotte bottle assembly, to keep a constant head or manually.
  22. 22. 22
  23. 23. Analysis of Data: Data is gained by a drop in water height, giving an infiltration of water over time. These data points are plotted in a graph of infiltration versus time. Theoretically, once the soil becomes saturated, a steady state infiltration rate will be reached, which is seen on a graph as a section of data points infiltrating showing linearity. Once this linear section is identified other outlying data points can be excluded from the analysis and a line of best fit can be fitted to the applicable data. The gradient of this fitted line gives the steady state infiltration rate for that particular soil. The steady state infiltration rate can then be multiplied 1.45, to obtain the hydraulic conductivity (Ksat), of that soil. This is a measure of how conductive a soil is at saturation, which is a measure of permeability.
  24. 24. Problems with method: Some draw-backs of the double ring are that 1- It is very time consuming, 2- Requiring frequent attention, either by recording measurements or by maintaining equilibrium in the height between the rings. 3- The practicality of the instrument is reduced by the fact the rings are extremely heavy to move. 4- It also requires a flat undisturbed surface which sometimes is not available. 5- The infiltration rate varies with different soil types, which can effect the accuracy of the results. 6- The soil type that the above results were obtained from is a Vertosol. These soils are known for their shrink/swell properties, which result in cracks when dried and can lead to misleading results. The double ring method is not reliable on soils with vitric properties. (McKenzie et al., 2002).
  25. 25. Estimated Methods- Based on Grain Size Hazen Method:- Applicability: sandy sediments • K = C*d10 2 • d10 is the grain diameter for which 10% of distribution is finer, "effective grain size" - where D10 is between 0.1 and 0.3 cm • C is a factor that depends on grain size and sorting Very Fine Sand, poorly Sorted 40 - 80 Fine Sand with fines 40 - 80 Medium Sand, Well Sorted 80 - 120 Coarse Sand, Poorly Sorted 80 - 120 Coarse sand, well Sorted, clean 120 - 150 C- Factor 25
  26. 26. Guelph and Amoozegar Borehole Permeameter Field Testing 26
  27. 27. • The Guelph Permeameter is an easy to use instrument for quickly and accurately measuring in-situ hydraulic conductivity. Accurate evaluation of soil hydraulic conductivity, soil sorptivity, and matrix flux potential can be made in all types of soil. The equipment can be transported, assembled, and operated easily by one person. Measurements can be made in 1/2 to 2 hours, depending on soil type, and require only about 2.5 liters of water. • Measurements can be made in the range of 15 to 75 cm below the soil surface. The Guelph Permeameter is a complete kit consisting of the Permeameter, field tripod, well auger, well preparation and cleanup tools, collapsible water container, and vacuum test hand pump, all packaged in a durable carrying case. 27
  28. 28. 28
  29. 29. • The Guelph Permeameter (GP) is a constant-head device, which operates on the Mariotte siphon principle and provides a quick and simple method for simultaneously determining field saturated hydraulic conductivity, matric flux potential, the α* parameter and soil sorptivity in the field. • Using the Guelph Permeameter, measurements in high and moderately permeable soils can usually be made and results calculated in less than an hour • The implements needed for excavating and preparing a well borehole are included in the Guelph Permeameter Kit. 29
  30. 30. • Auger Cutting Diameter - 6.0 cm (2-3/8”) • Well Height Range - 2.5 cm to 25 cm • Hydraulic Conductivity Range – 0.0001 to 0.0000001 m/sec 0.01 to 0.00001 cm/sec • Collapsible Water container Capacity - 11.36 liters (3.0 gallons) • Maximum Permeameter Capacity - 3.18 liters (.84 gallons) • Overall Carrying Case Size - 132.08 cm (50”) long x 44.45 cm (17.5”) wide x 15.24 cm (6”) deep • Overall Carrying Case Weight - 11 kg (25 lbs) • Depth Range, “Standard Unit” - 15 - 75 cm (Note: with Extension Tubes, measuring depths can be increased). • Cell Constant Values with Standard Deviation - X = 35.22 ( + 0.18 (1%) - Y = 2.16 ( + 0.04 (2%) 30
  31. 31. • Simply center the Tripod over the well hole and slowly lower the Permeameter so that the Support Tube enters the well hole, being careful not to knock debris off the sides of the well into the hole bottom. Flexibility in the Tripod Base allows the angle of the Tripod Legs to be adjusted to accommodate variation in slope of the land. The Tripod is used to support the Permeameter in wells down to approximately 38 cm (15 inches) in depth. The tripod chain can be loosened as necessary to allow the Tripod Legs to flex. 31
  32. 32. Where… a - Well radius, in cm. C - Shape factor dependent primarily on the H/a ratio C1, C2 - C factors corresponding to H/a H2/a, respectively H1, H2 = Well height for first and second measurements respectively, in cm. K - Hydraulic conductivity, in cm/sec. Kfs - Field-saturated hydraulic conductivity (entrapped air present), in cm/sec. α - Alpha Parameter, slope of the line relating the natural log of K, hydraulic conductivity, to Q, the soil water pressure head, in cm-1 α* is obtained from the site analysis Analysis 32
  33. 33. References • http://www.soilmoisture.com • http://www.water-research.net • www.specializedengineering.com • www.gmeconsultants.com • http://www.usyd.edu.au/agric/web04/Single %20ring%20final.htm 33
  34. 34. Thank You 34

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