Ans) Given,
Pumping rate (Q) = 200 gpm
Thickness of aquifer (D)= 12 m
Distance between observation well and pumping well (r) = 250 ft
Step 1) Find to from the plot
From the above pot we can see that at time = 0.30 min , drawdown = 0
therefore, to = 0.30 min
Step 2) Find Z for values t1 = 10 min and t2 = 100 min
Z(drawdown) at t = 10 min , S = 0.70 m
At t = 100 min , S = 1.10 m
Z=1.10 - 0.70
Z = 0.40 m
or 1.31 ft
Step 3) Compute Transmissivity (T),
T = 264 Q / Z
T = 264 x 200 / 1.31
T = 40305.34 gpd / ft
or 500.5 m2/day
Step 4) Compute storativity (S)
S = Tt0 / 4790r2
S = 40305.34 x 0.30 /(4790 x 2502)
S = 4.04 x 10-5
Step 5) Compute Hydraulic conductivity (K)
T = K x D
500.5 = K x 12
K = 41.708 m/day
or K = 4.83 x 10-4 m/s
Step 6) Compute Specific storage (Ss)
S = Ss x D
4.04 x 10-5 = Ss x 12
Ss = 3.36 x 10-6 m-1
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