Environmental Engineering Reference
In-Depth Information
Recent flowmeter logging in the Biscayne aquifer (
Cunningham and Sukop,
2011
) indicates that these stratiform, touching-vug, macroporous, bioturbated
zones can stack to form an extremely transmissive aquifer over a wide-ranging
area, with macroporous
Ophiomorpha
-dominated zones extending over a lateral
distance of at least 8.4 km (
Fig. 2
). Macroporous zones with maximum
Ophiomorpha
ichnofabrics are even more widely distributed at the hundred-
kilometer scale in the “bryozoan facies” of the Miami Limestone assigned to
MIS 5e by
Multer et al. (2002)
and mapped by
Hoffmeister et al. (1967)
in south-
ern Florida. But even these distances are conservative in comparison to the broad
extent of modern, shallow-subtidal, carbonate-sand environments intensively
burrowed by endobenthic callianassids (
Curran and Martin, 2003; Shinn, 1968
).
The range in intrinsic permeability values calculated from LBM for five
Biscayne aquifer subsamples with macropore networks dominated by an
Ophio-
morpha
ichnofabric is between 15
10
6
darcies (
Cunningham and
Sukop, 2011; Cunningham et al., 2009
;
Fig. 5
and
Table 1
). Intrinsic permeabil-
ity is a fluid-free conductance parameter that depends only on the properties of a
solid matrix, not on the properties of a fluid passing through it. The conductance
parameter, hydraulic conductivity, which is commonly used by hydrologists, is
related to both the properties of the matrix and the fluids moving through
it (
Freeze and Cherry, 1979
). The important point is that the five intrinsic per-
meability values derived from LBM-calculated values (
Cunningham and
Sukop, 2011, Cunningham et al., 2009
) are very high (
Fig. 5
and
Table 1
).
10
3
and 27
FIGURE 5
Lattice Boltzmann-calculated intrinsic permeability and laboratory air-permeability
values derived from carbonate samples with networks of ichnofabric-related macroporosity
(modi-
fied from
Cunningham and Sukop, 2011
).
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