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Unformatted text preview: Introduction to Hydrogeology Homework 4 Name:
Due Feb. 17, 2012 1. Dryﬂquartz sand completely ﬁlls a cylinder of radius 2 cm and a length of 10 cm.
35 cm’ of water is then added to the cylinder just to the top of the sand.
A. Calculate the porosity of the sand. You then let the water drain from the sand overnight and collect 28 cm3 of water
the next morning. B. Calculate the speciﬁc yield of the sand. C. Calculate the speciﬁc retention of the sand. 2. Determine the bulk density of the sand in problem 1 as mass over volume if you
used 233g of dry quartz sand to ﬁll the cylinder. Estimate the porosity of the sand
again assuming a particle density of quartz as 2.65 gm/cm3. 3. What type of porosity did you measure in problem 1?
What type of porosity did you measure in problem 2? 4. A permeameter as the one depicted below is used to measure the hydraulic
conductivity of a porous medium. The permeameter is perfectly round in cross
section, with a diameter of 50.0 mm. The following parameters are measured: 21—12200 mm 22:1500 mm pllpg = 320.0 mm pzlpg = 280 mm L33 00 mm Q discharge at lower end = 500.00 mm3 min" A. Which way is water ﬂowing in the column? Is water ﬂowing from high to low
hydraulic head? From high to low pressure? B. Calculate the speciﬁc discharge, q (mm mind)
C. Calculate the hydraulic conductivity, K, of the material (m s") D. Calculate the intrinsic permeability, k (m2) 5. In a constant‘head test, the discharge out of the apparatus is S cm3/s for a
column 5 cm in diameter and 50 cm in length. The constant head is 60 cm.
A. Calculate the hydraulic conductivity (cm/s). B. Calculate the speciﬁc discharge, q (cm/s).
C. Assuming a porosity of 0.25, calculate the seepage velocity (cm/s). ...
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 Spring '08
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 Hydrogeology

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