1988-04-11_PERMIT FILE - C1981008A ‎(9)‎

• Permit No: C1981008A
• IBM Index Class Name: PERMIT FILE
• Doc Date: 4/11/1988
• Doc Name: Hydrologic Description ‎(Part 1 of 2)‎
• Section_Exhibit Name: Tab 7
• Media Type: D
• Archive: Yes

where:
0 = flow (ft3 day-1)
K = Hydraulic conductivity (ft day-1
)
A = Cross sectional area of the aquifer perpendicular to the flow direction (ft2)
I = Average hydraulic gradient of the aquifer (ft/ft)
The hydraulic conductivities (K) were calculated based on the saturated thicknesses
determined from the potentiometric maps (Exhibits 7-2 through 7-4). The following
assumptions were considered when determining K values for the overburden. Inflow (ground
water discharge) equals outflow (baseflow stream discharge). The ground water discharge
to streamflow occurs primarily in the upper portions of the overburden aquifer. Based on
lithology the upper portions of the overburden aquifer have a higher transmissivity than
the deeper portions of the aquifer. Consequently, transmissivity values have been
adjusted to account for the difference.
Cross sectional areas for the three aquifers were calculated by multiplying the width of
each unit normal to the flow direction by the mean saturated thickness of each respective
unit (see Exhibits 7-2 through 7-4). The average hydraulic gradients were determined at
the vicinity of each cross section.
K = 3.7 ft/day (Overburden at Cross Section A)
K = 5.4 ft/day (Overburden at Cross Section B)
K = 5.4 ft/day (Overburden at Cross Section C)
K = 0.16 ft/day (Dakota Coal at Cross Section A and B)
K = 0.46 ft/day (Underburden)
I = .031 ft/ft (Overburden at Cross Section A)
I = .0342 ft/ft (Overburden at Cross Section B)
I = .043 ft/ft (Overburden at Cross Section C)
I = .0297 ft/ft (Dakota Coal at Cross Section A)
I = .043 ft/ft (Dakota Coal at Cross Section B)
I = .0301 ft/ft (Underburden)
A = 133,000 ft2 (Overburden at Cross Section A)
A = 253,500 ft2 (Overburden at Cross Section B)
A = 40,000 ft2 (Overburden at Cross Section C)
7-15 Revised 04/11/88