Page 92 - Materials Chemistry, Second Edition

Plume Migration in Aquifer and Soil 75

kgρ (9.87 10 cm )(0.997048 g/cm )(980 cm/s )× − 9 2 3 2
K = = = 1.08 10 cm/s× − 3
µ 0.00890 g/scm⋅
2
= (1.08 10 )(2.12 10 )× − 3 × 4 = 23.0 gpd/ft = 23.0 meinzer

Discussion:

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1. The value of 2.12 × 10 used in parts (a) and (b) is a conversion
factor (1 cm/s = 2.12 × 10 gpd/ft ) from Table 3.1.
2
4
2. As mentioned, hydraulic conductivity depends on the proper-
ties of the fluid flowing through it. This example illustrates that
a porous medium with an intrinsic permeability of 1 darcy has
2
2
a hydraulic conductivity of 18 gpd/ft at 15°C and 23 gpd/ft at
25°C. The hydraulic conductivity of this formation at a higher
temperature (25°C) is larger than that at a lower temperature
(15°C).
3. The intrinsic permeability is independent of temperature.
4. The unit of gpd/ft is commonly used by hydrogeologists in the
2
United States. The unit is also named the meinzer after O. E.
Meinzer, a pioneering groundwater hydrogeologist with the US
Geological Services [1]. The unit of cm/s is more commonly used
in soil mechanics. (For example, the hydraulic conductivity of
clay liners in landfills is commonly expressed in cm/s.)
From Example 3.4, one can tell that a geologic formation with an intrinsic
permeability of one darcy has a hydraulic conductivity of approximately 10
−3
cm/s or 20 gpd/ft for transmitting pure water at 20°C. Typical values of
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intrinsic permeability and hydraulic conductivity for different types of for-
mation are given in Table 3.3.

TABLE 3.3
Typical Values of Intrinsic Permeability and Hydraulic
Conductivity
Intrinsic Permeability Hydraulic Conductivity
(darcy) (cm/s) (gpd/ft )
2
Clay 10 –10 −3 10 –10 −6 10 –10 −2
−9
−5
−6
−3
Silt 10 –10 −1 10 –10 −4 10 –1
−2
−6
−1
−5
Silty sand 10 –1 10 –10 −3 10 –10
−2
Sand 1–10 2 10 –10 −1 10–10 3
−3
Gravel 10–10 3 10 –1 10 –10 4
−2
2