Shree Swami Atmanand Saraswati Institute of Technology
Prepared By:-Sandip vekariya 120763106001Gaurang kakadiya 120763106002Jigar balar 120763106003
Seminar onMethods of in site Permeability Test
Guided By:-__________________1
Content
• Introduction
• Pumping Test
• Percolation Test
• Single Ring Falling Head Infiltrometer Test
• Double Ring Infiltrometer Test
• Slug tests
• Hazen Method
• Guelph Permeameter
2
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
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
• 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 water
table 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.5
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
7
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.8
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 Test9
• 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.
10
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; finished11
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
recognizable.
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 measurements12
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.
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.
14
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 center 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 Marriott bottle assembly, to
keep a constant head or manually.
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).
• 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.
19
• The Guelph Permeameter (GP) is a constant-head device, which
operates on the Mariette 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.
21
• 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%)22
• 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.23
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
24