PERMFILE58702

• Permit No: M1997054
• IBM Index Class Name: Permit File
• Section_Exhibit Name: EXHIBIT G WATER INFORMATION
• Media Type: D
• Archive: No

Exhibit G CMLRB 112 Permit Application
Agile Stont Systems. Inc.
• 5.0 Ground Water Hydrology
The hydrogeology of the Pazkdale Project azea is best understood and discussed by first
defining 2 principal hydrostatigraphic units, those being the glacial outwash aquifer of
Quatemary age and the bedrock aquifers of Mesozoic age. These aquifers are cut
through and hydraulically bounded by the Arkansas River; faulting adds structural
boundaries within the bedrock aquifer system. Potentiometric heads and water elevations
within the project aquifers are driven by rechazge in topographically higher outcrop areas,
with discharge at lower elevations through subcrops and springs.
5.1 Outwash Aquifer
The glacial outwash aquifer beneath the project azea is a sand and gravel deposit of
Quaternary age, as mapped by the USGS and shown in the previous Geology section.
This aquifer is bounded on the north and east by the Tallahassee Creek, on the west by
Precambrian and Mesozoic rocks and on the south by the Arkansas River. The total
thickness of the deposit ranges to at least 67', depending on location.
Bedrock units of Jurassic and Cretaceous age subcrop beneath the outwash aquifer. In
stratigraphically ascending order these units include the Morrison Formation, the Dakota
Group (Purgatoire Formation and Dakota Sandstone), the Colorado Group (Graneros
Shale, the Greenhorn Limestone, and the Carlisle Formation) and the Niobrara
Formation. Structurally, the bedrock units were deformed during the Laramide Orogeny
into a syncline whose axis trends generally NW-SE and passes beneath the project area.
During the Larmide, the region and project azea were also cut by several faults as shown
on the USGS geologic map.
High to very high hydraulic conductivitie (400 to 2,000'/day characterize the outwash
aquifer, based on an interpretation of sieve a sands and gravels, percolation
tests and water production rates measured during the drilling of monitoring wells at the
project site. Saturated thickness of the outwash aquifer ranges from a feather edge along
the western, northern and eastern margins to more than 25' along paleochannels cut into
the Carlisle, Graneros and Morrison Formations.
Along the Arkansas River and lower Tallahassee Creek, springs mark a series of seepage
areas where the outwash aquifer discharges to surface streams. Ground water discharged
from the springs and seeps evidently has as its major source, surface water from
Tallahassee Creek as evidenced by total dissolved solids (TDS) measurements, water
chemistry and water table elevations.
Water chemistry analyses for major ions indicate that surface water is a calcium
bicarbonate-type having TDS ranging from about 160 mg/1 for the Arkansas River to 280
milligrams per liter (mg/I) for Tallahassee Creek and 380 mg/1 for Currant Creek.
Ground water in the outwash aquifer has TDS ranging from about 350 to 400 mg/1 and is
also calcium bicazbonate type. On a Piper diagram enclosed, the outwash water has
• noticeably more sodium (shifted rightwazd in the central plotting diamond) relative to
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