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 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.
A permeability pumping test was carried out in a confined aquifer with the piezometric level before pumping is 2.18 m. below the ground surface. The aquiclude (impermeable layer) has a thickness of 5.7m. measured from the ground surface and the confined aquifer is 7.6 m. deep until it reaches the aquiclude (impermeable layer) at the bottom. At a steady pumping rate of 15.6 m3/hour the drawdown in the observation wells were respectively equal to 1.62 m. and 0.47 m. The distances of the observation wells from the center of the test well were 15 m. and 32 m. respectively.
1.Compute the depth of water at the farthest observation well.
2. Compute the coefficient of permeability.
3. Compute the transmissibility of the impermeable layer.
A pump well is dug through a confined aquifer having a thickness of 32 meters. The piezometric surface of the aquifer is 18 meters measured from the top impermeable layer. The first observation well is 75 feet directly west of the pump well and the second observation well is 75 feet directly north of the first observation well. Determine the hydraulic conductivity of the aquifer if it supplies a discharge of 10 liters per second and the drawdown of the observation wells are 13 feet and 23 feet.
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Fundamentals of Geotechnical Engineering (MindTap Course List)
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- A confined aquifer has a thickness of 30m (m) and is fully penetrated by well where the aquifer is pumped at the rate of 500 litres per second. The groundwater thickness (H₁) is 50 m. The drawdown measured in two observation wells located at distance of 10 m and 100 m from the well are 7.5 m and 0.5m respectively. Determine the average hydraulic conductivity of the aquifer. At what distance from the well the drawdown is insignificant i.e. is zero (R).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. Include FBD.arrow_forwardA tube well is constructed in a confined aquifer. The discharge of the tube well is 10 L/s, where the thickness of the aquifer is 11 meters, and the draw down is 20 meters at the tube well. The hydraulic conductivity of the permeable soil is 12 meters per day. An observation well at a radius of 500 meters has a piezometric surface of 47 meters. Calculate the diameter of the well.arrow_forward
- ) A pumping test carried out in a 50 m thick confined aquifer resulted in a flow rate of 600l/min. The thickness of the impermeable layer above the aquifer is 20 m and the originalwater level in the well was 2 mm below the ground surface (which is also the top of theimpermeable layer). Drawdowns in two observation wells located 50 m and 100 m fromthe well are 3 and 1 m respectively. Calculate:i) The coefficient of permeability of the aquifer, ii) The drawdown in the well, iii) The radius of influence. The diameter of the well is 0.6 m.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_forwardA pumping test was carried out in a confined aquifer 15m thick overlain by an impermeable layer 30m thick. Rate of pumping was 0.12 m3/s, drawdowns in observation wells located 15m and 30m from the center of the pumping well were 1.60 m and 1.40 m respectively, from the initial groundwater level. The diameter of the pumping well is 0.40m. Determine the coefficient of permeabilityarrow_forward
- A fully penetrating well with diameter of 0.25 m is bored into an unconfined aquifer with hydraulic conductivity of 22 m/d and porosity of 0.3. The water table is initially at a height of 55 m above the bottom of the aquifer. After continuous pumping, a steady state drawdown of 12 m is reached. (a) If the pumping rate has no effect on the water table at a distance of 1.2 km from the pumping well, determine the pumping rate. Determine the drawdown in an observation well 600 m away from the pumping well. Determine the travel time from the observation well to the pumping well.arrow_forwardA 30 cm well completely penetrates an unconfined aquifer of saturated depth 40 m. After a long period of pumping at a steady rate of 1500 lpm, the drawdown in two observation wells 25 and 75 m from the pumping well were found to be 3.5 m and 2.0 m respectively. a.) Determine the transmissivity (m^2/s) of the aquifer. b.) What is the drawdown (m) at the pumping well?arrow_forwardA well penetrates an unconfined aquifer. Prior to pumping the water level(head) is ho = 25m after a long period of pumping at a constant rate of 0.05 m^3/s the drawdowns at distances of 50m and 150 m from the well were observed to be 3 m and 1.2 m respectively. Compute the hydraulic conductivity of the aquifer and the radius of influence of the pumping well. What type of deposit is the aquifer material?arrow_forward
- 1. Calculate the equivalent hydraulic conductivity for the soil profile shown in figure 2. An excavation is proposed for a square area near the bend of a river, as shown in figure. It is expected that the flow of water into the excavation will come through the silt layer. Pumping test reveal an average horizontal hydraulic conductivity of 2 x 10 -5 cm/s in the silt layer. The excavation has to be kept dry. Determine the flow (qs) into the excavation.arrow_forwardA permeability pumping test was carried out in unconfined aquifer with the piezometric level before pumping is 2.18m below the ground surface. The first permeable layer has a thickness of 5.7m measured from the ground surface and the unconfined aquifer is 7.0m deep until reaches the aquiclude at the bottom. At a steady pumping rate of 15.6m^3/hr the drawdown in the observation wells were respectively equal to 1.62m and 0.47m. The distance of the observation wells from the center of the test well were 15m and 32m respectively. Compute the Transmissibility?arrow_forwarda 30 cm well penetrates an unconfined aquifer of saturated depth 25m. When a discharged of 2100 lpm was being pumped for a long time, observation wells at radial distances of 30 and 90 m indicated drawdown of 5 and 4 m respectively. estimate the coefficient of permeability of the aquifer and the drawdown at drawdown at pumping well.arrow_forward
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