The static level of water table in an unconfined aquifer was 30 m above the underlying impermeable stratum. A 150 mm diameter well, penetrating the aquifer to its full depth, was pumped at the rate of 20 liters per second. After several weeks of pumping, the drawdown in observation wells 20 m and 50 m from the well were 3.5 m and 2 m respectively, and the observed drawdowns were increasing very slowly (B.Sc., DU, 2012). a) Assuming equilibrium conditions, estimate the hydraulic conductivity and transmissivity of the aquifer. b) Estimate the drawdown just outside the pumped well. c) What will be the yield of a 300 mm diameter well which will produce the same drawdowns just outside the well and at the 50 m distance observation well in (2)? What would be the drawdown at a nearer observation well?

The static level of water table in an unconfined aquifer was 30 m above the underlying impermeable stratum. A 150 mm diameter well, penetrating the aquifer to its full depth, was pumped at the rate of 20 liters per second. After several weeks of pumping, the drawdown in observation wells 20 m and 50 m from the well were 3.5 m and 2 m respectively, and the observed drawdowns were increasing very slowly (B.Sc., DU, 2012). a) Assuming equilibrium conditions, estimate the hydraulic conductivity and transmissivity of the aquifer. b) Estimate the drawdown just outside the pumped well. c) What will be the yield of a 300 mm diameter well which will produce the same drawdowns just outside the well and at the 50 m distance observation well in (2)? What would be the drawdown at a nearer observation well?

Fundamentals of Geotechnical Engineering (MindTap Course List)

5th Edition

ISBN:9781305635180

Author:Braja M. Das, Nagaratnam Sivakugan

Publisher:Braja M. Das, Nagaratnam Sivakugan

Chapter6: Hydraulic Conductivity

Section: Chapter Questions

Problem 6.15P

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Given A pump test was conducted on a test well drilled into a confined aquifer that is 4.80 m thick. Two observation wells were drilled at 11 m and 44 m from the observation well, respectively. Once equilibrium was reached, the height of the piezometric surface was 7.3 m at the first observation well and 9.2 m at the second observation well. Required If 425 L/min were pumped at steady flow, determine the coefficient of permeability of the permeable soil in the aquifer, in cm/s (include 3 digits after the leading zeros). Your Answer:
2. (a) A well in an aquifer is pumped over a long period at a rate of 0.05 m3 /s under approximate steady-state conditions. The steady-state drawdowns, from the water table level, at two observation wells at 25 m and 50 m from the abstraction well were observed to be 15.3m and 9.5m, respectively. If the saturated thickness of the aquifer prior to pumping is 80 m, determine the hydraulic conductivity of the aquifer material. (b) Will the actual drawdown in the pumping well be more than the theoretical drawdown? If yes, why and what measures can you recommend for reducing the drawdown in the pumping well?
31 Yuri wants to determine the permeability of an aquifer. The aquifer has a test well 300-mm in diameter with two observation wells. A pumping test was conducted for 24 hours with the discharge being held constant at 5,721.4 m^3/day. The first one, 81.07 meters from the test well, has a draw-down of 0.6 meters. The second one, 40 meters from the test well, has a draw-down of 1.43 meters.The static water table penetrates the well to a depth of 25 meters. Determine the radius of influence of the aquifer in meters. Round off to three decimal places.
QUESTION 12 1. A 40 cm well completely penetrates an unconfined aquifer of saturated depth 40 m. After a long period of pumping at a steady rate of 0.025 m³/s, the drawdown in two observation wells 20 m and 80 m from the pumping well were found to be 4.0 m and 2.0 m respectively. Determine the hydraulic conductivity of the aquifer. Round off to two (2) decimal places, Fill in the blank_ x 105 m/s
The static level of water table in an unconfined aquifer was 35m above the underlying impermeable stratum. A 75mm radius well, penetrating the aquifer to its full depth, was pumped at the rate of 28 liters per second. After several weeks of pumping, the drawdown in observation wells 20m and 50m from the well were 3m and 2.5m respectively, and the observed drawdowns were increasing very slowly. (B.Sc., UAE, 1989).a) Assuming equilibrium conditions, estimate the hydraulic conductivity and transmissivity of the aquifer.b) Estimate the drawdown just outside the pumped well.
a 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.
b) A 30-cm well fully penetrates an unconfined aquifer of saturated depth 25 m. When a discharge of 2100 Ipm was being pumped for a long time, observation wells at radial distances of 30 m and 90 m indicated drawdown of 5 and 4 m respectively. i. Estimate the coefficient of permeability and transmissibility of the aquifer. ii. What is the drawdown at the pumping well? *Ipm = liters per minute *h = H-s, where H = saturated depth
A well in an aquifer is pumped over a long period at a rate of 0.05 m3 /s under approximate steady-state conditions. The steady-state drawdowns, from the water table level, at two observation wells at 25 m and 50 m from the abstraction well were observed to be 15.3m and 9.5m, respectively. If the saturated thickness of the aquifer prior to pumping is 80 m, determine the hydraulic conductivity of the aquifer material.
b) A 30-cm well fully penetrates an unconfined aquifer of saturated depth 25 m. When a discharge of 2100 lpm was being pumped for a long time, observation wells at radial distances of 30 m and 90 m indicated drawdown of 5 and 4 m respectively. Estimate the coefficient of permeability and transmissibility of the aquifer. What is the drawdown at the pumping well?
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A 2‐ft diameter well penetrates vertically through a confined aquifer 50 ft thick. When the well is pumped at 500 gpm, the drawdown in a well 50 ft away is 10 ft and in another well 100 ft away is 3 ft.(a) What is the approximate head in the pumped well for steady‐state conditions, and what is the approximate drawdown in the well?(b) Compute the transmissivity. Take the initial piezometric level as 100 ft above the datum.