Use data from the table below to fill in the last row, and to define the hydraul
ID: 112255 • Letter: U
Question
Use data from the table below to fill in the last row, and to define the hydraulic gradient (3 point problem). Based on your results in Table 1 and the geotechnical engineering properties given in Table 2, estimate how far the advective front (upsilon*t) of a conservative solute would travel, assuming the contaminant source is at the location of well A and that the contamination began 25 years ago. You'll need the geotechnical data to give you the properties controlling flow (K, eta_c). Constant head test (Darcy tube) data: Core length: 8.0 cm Core diameter: 2.5 cm Geotechnical test results: Dry bulk density: 2.10 g/cm^3 Density of solids: 2.65 g/cm^3Explanation / Answer
From the given values, the condition the th wells are given.
Water table elevation = land surface elevation - depth to water below land su
Advective front of a conservative solute = v * t
v= velocity, t= time
again v= k/n * (dh/dl)
where, k= hydraulic conductivity
dh/dl= hydraulic gradient
From the Darcy's law, Q= k A (dh/dl)
Q= Specific discharge
A= Area
So from the Darcy's law,
Q= 0.0280 + 0.049 + 0.093 = 0.170
A= 2 pi rh + 2 pi r^2 = 34.95 ( r= core radius= core diameter/2
h= core length )
dh/dl = (4.9-1.5)/ 70 = 0.48
So k = Q/A * dl/dh
=(0.170/ 34.95) * (1/0.48)
= 0.0048 * 2.08
=0.01
Therefore, v = k/n * dh/dl
= 0.01 * 0.048
= 0.000485
So advective front = v*t
= 0.000485 * 25
= 0.0121
Wells Water table elevation Well A 810-18= 792 Well B 816-27= 789 Well C 802- 21= 781
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