Fundamentals of Geotechnical Engineering (MindTap Course List)
5th Edition
ISBN: 9781305635180
Author: Braja M. Das, Nagaratnam Sivakugan
Publisher: Cengage Learning
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Chapter 6, Problem 6.15P
To determine
Find the hydraulic conductivity of the clayey sand layer (k).
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A site consists of a homogeneous dense silty sand layer of 11 m thickness, which is underlain by an impervious stiff clay stratum. The initial water table was at 2 m depth below the ground level. A
pumping test was carried out by pumping out water at the rate of 0.7 m° /min. Observation wells were dug into the ground at 20 m and 40 m distances from the center line of the well. At steady
state (i.e., when there was no change in water levels in the observation wells), the water levels in the two wells dropped by 500 mm and 200 mm, respectively.
Determine the hydraulic conductivity of the clayey sand layer.
(Enter your answer to three significant figures.)
k
cm/s
A field pumping test was conducted from an aquifer of sand soil of 4 m thickness confined between two impervious strata. When equilibrium was established, 90 liters of water was pumped out per hour. The water elevation in an observation well 3.0 m away from the test well was 2.1 m and another 6.0 m away was 2.7 m from the roof level of the impervious stratum of the aquifer. Find the value of k of the soil in m/sec.
A site consists of a homogeneous dense silty sand layer of 9 m
thickness, which is underlain by an impervious stiff clay stratum. The
initial water table was at 4 m depth below the ground level. A
pumping test was carried out by pumping out water at the rate of 0.7
m°/min. Observation wells were dug into the ground at 15 m and 50
m distances from the center line of the well. At steady state (i.e., when
there was no change in water levels in the observation wells), the
water levels in the two wells dropped by 600 mm and 100 mm,
respectively.
Determine the hydraulic conductivity of the clayey sand layer.
(Enter your answer to three significant figures.)
k =
cm/s
Chapter 6 Solutions
Fundamentals of Geotechnical Engineering (MindTap Course List)
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- A field pumping test was conducted from an aquifer of sandy soil of 4 m thickness confined between two impervious strata. When equilibrium was established, 105 liters of water was pumped out per hour. The water elevation in an observation well 3.50 m away from the test well was 2.1 m and another 6.0 m away was 2.7 m from the roof level of the impervious stratum of the aquifer. Find the value of k of the soil in m/sec.arrow_forwardA sand deposit of 12 m thick overlies a clay layer. The water table is 3 m below the ground surface. In a field permeability pump-out test, the water is pumped out at a rate of 540 liters per minute when steady state conditions are reached. Two observation wells are located at 18 m and 36 m from the Centre of the test well. The depths of the drawdown curve are 1.8 m and 1.5 m respectively for these two wells. Determine the coefficient of permeability. Answer must be: 4.5 × 10–1 mm/sarrow_forwardA site consists of a homogenous dense silty sand layerof 8m thickness which is underlain by an imprevious stiff clau stratum. The initial water table was at 3m depth below the ground level. A pumping test was carrier out by pumping water at the rate of 0.7 m^3/min. Onservation wells were dug into the ground at 25m and 50m distances from the center line of the well. At steady state (i.e., when there was no change in water levels in the observation wells), the water levels in the two wells dropped by 500mm and 150mm, respectively. Determine the hydraulic conductivity of the clay sand layer.arrow_forward
- 2. A well with a diam. of 0.6 m. is constructed in a confined aquifer as shown. The sand aquifer has a uniform thickness of 15 m. overlain by an impermeable layer with a depth of 35 m. A pumping test was conducted to determine the coefficient of permeability of the aquifer. The initial piezometric surface was 15 m. below the ground surface datum of the test well and observation wells. After water was pumped at a rate of 13 liters/sec. for several days, water levels in the wells stabilized with the following drawdowns, 6.4 m. in the test well, 3.7 m. in the observation well 10 m. from the test well and 2.4 m. in the second observation well at a distance 30 m. From these data, o Find the depth of water in the test well. • Calculate the permeability of the aquifer. O Compute the transmissibility of the impermeable layer. 71-30 Ground surface 20 15m Water Leve intern 72=10 Static water level observation wall -impermeable confined aquifer hi hrarrow_forwardA saturated aquifer sample core of diameter 2.54 cm and length of 6 cm weighs 63 grams. After drying the sample weighs 53 grams. The core sample was placed into an permeameter and exposed to a unit hydraulic gradient. The measured flowrate was 25.4 milliliters/second. The water levels in three wells in the same aquifer were measured in meters above MSL. The levels were: Well MW-1: 83.1 m; Well MW-2: 84.6 m; Well MW-3: 83.9 m. Well MW-2 is located 1km due north of Well MW-1, and Well MW-3 is located 700 meters Northeast of Well MW-1. Determine: 1. Estimate the porosity of the aquifer. 2. Estimate the hydraulic conductivity of the aquifer. 3. Sketch the relative positions of the three wells. Use MW-1 as the origin of the local (your sketch) coordinate system, and North is to the top of your sketch. 4. Determine the magniture and direction of the hydraulic gradient in the aquifer monitored by the three wells. Indicate the hydraulic gradient on your sketch (direction and magnitude) 5.…arrow_forwardA field sample of an aquifer is packed in a test cylinder. The cylinder has a length of 120 cm and a diameter of 12 cm. The field sample with a porosity of 0.24 is tested under a constant head difference with water at 10°C. If the estimated hydraulic conductivity of the sample is 40 m/day and the hydraulic gradient is 1.5, calculate the average flow velocity (pore velocity). Ply Sand column Datum plane O a. u = 166.63 m/d O b. u = 250.00 m/d O c.u = 200.00 m/d O d. u = 48.00 m/darrow_forward
- A well was constructed to pump water from a confined aquifer. Two observation wells were constructed at distances of 350 m and 800m respectively. At a steady pumping rate of 0.39 m^3/min, the drawdown in the observation wells were respectively equal to 1.6 m and 7.8 m. Diameter of the test well is 0.95 m and thickness of confined aquifer is 16 m. a. Determine the hydraulic conductivity of the soil in m/min. (IN EXPONENTIAL FORM AND IN 2 DECIMAL PLACES) b. Determine the drawdown at the test well in m. (IN 2 DECIMAL PLACES) c. What is the value of the transmissivity of the confined aquifer in m^2/day? (IN 2 DECIMAL PLACES)arrow_forwardA pumping test was carried out in confined aquifer thickness 2 m and the following measurement was recorded. Rate of pumping was 10 m^3/s; drawdown in pumping well was 2.0 m while on the observation well located at 15 m and 20 m from the centre of the pumping well were 1.6 m and 1.4 m, respectively. Determine the hydraulic conductivity of soil.arrow_forwardQuestion 2 * A well with a diameter of 0.6 m is constructed in a confined aquifer. The sand aquifer has a uniform thickness of 15 m, overlain by an impermeable layer with a depth of 35 m. A pumping test was conducted to determine the coefficient of permeability of the aquifer. The initial piezometric surface was 15 m. below the ground surface datum of the test well and observation wells. After water was pumped at a rated of 13 liters/sec for several days, water levels in the wells stabilized with the following drawdowns, 6.4 m in the test well, 3.7 m in the observation well 10 m from the test well, and 2.4 m in the second observation well at a distance of 30 m. From these data: o Find the depth of the water in the test well Calculate the permeability of the aquífer.arrow_forward
- i) A pipe of 1.2 m diameter was provided in a reservoir to act as an outlet. Due to disuse, it was buried and completely clogged up for some length by sediment. Measurements indicated the presence of fine sand (coefficient of permeability, K, = 10 m/day) deposit for a length of 100 m, at the upstream end and of coarse sand (coefficient of permeability, K₂ = 50 m/day) at the downstream end for a length of 50 m. In between these two layers the presence of silty sand (coefficient of permeability, K3 0.10 m/day) for some length is identified. For a head difference of 20 m on either side of the clogged length, the seepage discharge is found to be 0.8 m³/day. Estimate the length of the pipe filled up by silty sand. =arrow_forwardA permeability pumping test was carried out in a confined aquifer with the piezometric level before pumping of 2.18m below the ground surface. The aquiclude has a thickness of 5.7m measured from the ground surface and confined aquifer is 7.6m deep until it reaches the aquiclude at the bottom. At a steady state pumping rate of 15.6 ?7??6?3/?2h?7??1? the drawdown in the observation wells were respectively equal to 1.62m and 0.47m. The distances of the observation wells from the center of the test well were 15m and 32m respectively. The radius of the test well is 1m. Determine the coefficient of permeability (m/hr) Select the correct response: 2.15x10-5 0.215 0.597 5.97x10-5arrow_forwardProblem (4) The following results have been reported for field pumping test from a well, where the top permeable layer is unconfined and underlain by an impermeable layer, for a steady state condition: m3 q = 0.68 min h, = 5.6m at r, = 60m h, = 5m at r, = 30m Calculate the hydraulic conductivity (cm/s) of the permeable layer.arrow_forward
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