Question

Question 5: (25 marks) A fully penetrating pumping well is located in a confined aquifer that can be considered to have an infinite extent in all directions. There is no recharge to the aquifer and no other pumping wells in the area. There are two observation wells located at 100 and 500 m, respectively, from the pumping wells. The aquifer and the pumping well have the following properties: Depth to top of aquifer: 50 m Aquifer thickness: 5 m Aquifer hydraulic conductivity: 0.001 m/s Porosity: 0.3 Storage coefficient: 0.0001 Well diameter: 20 cm Pumping rate: 100,000 L/day After pumping for a long time, the aquifer reaches a steady state. The depth to water in the well is 20 m Draw a schematic cross-section of the confined aquifer, indicating the ground surface, wells, water level surface between wells, etc. (6 marks) a) b) Determine the drawdown in two observation wells (6 marks). c) Determine Darcy velocity and seepage velocity in the aquifer at the location of the observation well at 100 m (6 marks). d) In the context of this question, explain the practical meaning of the following terms: confined aquifer, steady state condition, and well screen (7 marks).

Answer 1

o T aapifer5 0.5 42 - Tt e. t-timl laped from the Sta사吋pumping client onlivi in peinecable material i tuated hot above and belaw the aquifes, causi bo be in pretkne 'cot.wh ute/) 氵t.s Penha well, the uoaterv Lll e above H the topaquifo Seady state: The condition n ohich disdage doemt change hime g device idh pimi, Waken to enter the well from the adu deda9μ. and prevenk Sedimnt from entoxi the well. Cs Scanned with CamScanner