Question

6TH question

5. A 6-in.-diameter well that fully penetrates a 40-ft-thick open aquifer is pumped at a rate of 100 gpm. The drawdown in the well is 22 ft when a steady water level is established. The drawdown in a well 152 ft distant is 12 ft. Estimate the coefficient of permeability of the soil deposit. CHAPTER 5 STRESS ANALYSIS AND ENGINEERING PROPERTIES 6. Discuss the validity of the answer obtained in Problem 5. Suggest how you would improve the test data obtained to produce a better value of k. Why?

Answer 1

Calculation...

- Asper given data : n=0.5 feet Ground level y Water table 14 draw down curve. 3= 22 ft H= 40 feet h4042 - 28 feet Th=40-22 = 18 feet R=182 ft How rate = Q = 100 gpm = 13.368 /min. then by using theirs theory (modification of dupits theory) - a= tek ( 62 - h?) R = 152 feet 2.303 1030 [ Blow) Yw= radius of wells bespreek a 13.368 = (3.14) (K ) (162& 183) 20308 109.. (20153) K = 0.0593o7 feet per minute required resulta K = 0.71168 inch per minute

volution of che Validity of above result... - medium should be homogenous means property's of soil - in any direction of every partical is game. o medium should be isotropic, means property of mealium partical at a particular place in all direction should be same. ② medium should be infinit means there in no limitation of boundry. (here we consider in horisontal direction as 1. infinite ) 4 flow must be radial , houzontal and laminar in - the vicinity of well. ③ draw-down slope is small go we consider sind u tano for derivation of formula (ased above), way to improve above result is ♡ as in the above question, discharge is constant after an or certain draw-down which is rare case so we can use another test named as Reccuperation test, in this test no need to calculate the constant discharge. In this Jest water is recuperated in water well in specific time period, is noted and we find the yield and then -permeability of goil medium.