ES 402 Assignment #3 26 Feb 97 by FyY11D7p


									ES 402                                 Assignment #3                    Due 17 & 18th Mar 2008
         (Part 1(a) due on the 17th at the beginning of class; the rest on the 18th, in lab)

1. (3 pt) Darcy’s Law and hydraulic conductivity: Hand in completed copies of Tables 1-4 from
   lab #6. Use the measurements made in Lab. Exercises #6 and 7 to answer the following

   (a) Calculate the average hydraulic conductivity for the sample or samples you analyzed in
   labs #6 and 7. Refer to Fig. 11.4 and 11.6 in your textbook to answer these questions: Are
   the results reasonable? Would an aquifer 50 m thick (i.e., its vertical dimension) made of
   either the sand or the gravel from Lab #6 provide a useful source for a well? What about the
   gravel-sand mixtures you tested?

   (b) Prepare an ORAL PRESENTATION on Darcy’s Law for lab on March 18th. Your
   team’s presentation should take about 10 minutes. Use of visual aids is preferred – I can
   make transparencies for you but need 2 days advanced notice. Give a general introduction to
   Darcy’s Law and cover the results of BOTH Labs #6 and 7. Discuss the material from (a),
   including the hydraulic conductivities and Reynolds numbers estimated for each material
   used. How did your team measure the hydraulic conductivities for the materials in the
   groundwater model (Lab #7) and what were the results? How did they compare to the
   measurements from Lab #6? What experiment did your team perform on the aquifer model
   and what were the results?

2. (1 pt) You have been asked to investigate a confined aquifer that has been used for several
   years for a municipal well. The well is pumped at a constant rate of 695 L/minute. You
   supervise the installation of 2 piezometer tubes, one 10 m and the other 50 m from the well.
   The potentiometric heads in the piezometers are measured as 30 and 30.8 m, respectively,
   and are unchanged 2 and 4 days later. Use these data to determine the transmissivity of the
   aquifer. What assumptions do you need to make? If the aquifer is 100 m thick, what is its
   average hydraulic conductivity? How would you rate this well’s potential for municipal
   water supply?

3. (1 pt) A test well is drilled through the full thickness of a confined aquifer, 20 feet. The
   aquifer is horizontal, homogenous and isotropic, with K = 25 ft/day and S (coefficient of
   storage or storativity) of 0.0004. The test well is pumped at a constant rate of 30,000 ft3/day
   for 2 days. What would be the drawdown of the potentiometric surface in a piezometer 100
   ft from the test well after one hour? At the end of the 2 days of pumping?

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