{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

CEE 350 - Korshin - Winter 2012 - Homework 7(1)

# CEE 350 - Korshin - Winter 2012 - Homework 7(1) - CEE 350...

This preview shows pages 1–4. Sign up to view the full content.

1 CEE 350 Week 7 Homework Solutions Problem 1 (Textbook 5.47) A confined aquifer 30.0 m thick has been pumped from a fully penetrating well at a steady rate of 5000 m 3 /day for a long time. Drawdown at the observation well 15 m from the pumped well is 3.0 m, and the drawdown at a second observation well 150 m away is 0.30 m. find the hydraulic conductivity of the aquifer. The formula to calculate drawdown in a confined aquifer is ¸ ¸ ¹ · ¨ ¨ © § ± 1 2 1 2 ln 2 r r KB Q h h S Accordingly, from the data given in the problem ² ³ ² ³ ² ³ ² ³ ² ³ d m h h r r h h B Q K / 6 . 22 15 150 ln 3 . 0 0 . 3 30 14 . 3 2 5000 ln 2 1 2 1 2 ¸ ¹ · ¨ © § ± ± ± u u u ¸ ¸ ¹ · ¨ ¨ © § ± S Problem 2 (Textbook 5.50) A stagnation point in a capture zone type curve is a spot where groundwater would have no movement. For the case of a single extraction well, the stagnation point is located where the capture zone curve crosses the x axis. Us the fact that for small angles tan T|T to show that the x-axis intercept of the capture zone curve for a single well vB Q x S 2 ± The general formula for the capture zone curve in polar coordinates is ¸ ¹ · ¨ © § ± S I 1 2 Bv Q y where ¸ ¹ · ¨ © § x y arctan I For the stagnation point in front of the well, ² ³ ¸ ¹ · ¨ © § ± ± S G S 1 2 Bv Q y and G is zero for the stagnation point itself. Accordingly, it follows that

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 vB Q y S G 2 where in general x y ± | G G tan and x y vB Q y S 2 ± Where x is the distance from the well to the stagnation point. From the above formula it follows that vB Q x S 2 ± Problem 3 (Textbook 5.51) Suppose a spill of 0.10 m 3 of trichloroethylene (TCE) distributes evenly throughout an aquifer 10.0 m thick forming a rectangular plume 2000 m long and 250 m wide. The aquifer has porosity 0.40, hydraulic gradient 0.001 and hydraulic conductivity 0.001 m/s. a. Given the solubility of TCE, could this much TCE be totally dissolved in the aquifer? What would be the concentration of TCE (mg/L) in this idealized groundwater plume? b. Using capture zone type curves, design an extraction well field to pump out the plume under the assumption that the wells are all lined up along the leading edge of the plume, with each well to be pumped at the same rate not to exceed 0.003 m 3 /s per well. What is the smallest number of that could be used to capture the whole plume? What minimum pumping rate would be required for each well? c. What would be the optimal spacing between the wells (at that minimum pumping rate)? a. The specific gravity of TCE is 1.47 g/cm 3 (Table 5.14) and its maximum solubility is 1100 mg/L. Therefore the total mass of TCE in the aquifer is 147 kg. The overall volume of contaminated groundwater in the aquifer is ² ³ 3 000 , 000 , 2 250 2000 10 40 . 0 m w Bl V plume plume plume u u u K If all TCE is mixed with this water, its concentration will be
3 ² ³ ² ³ ² ³ L mg m g m g V M C plume TCE / 0735 . 0 / 0735 . 0

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}