2008-07-10_PERMIT FILE - M2008006 ‎(4)‎

• Permit No: M2008006
• IBM Index Class Name: Permit File
• Doc Date: 7/10/2008
• Doc Name: Groundwater Motoring Plan
• From: Connell Resources
• To: DRMS
• Section_Exhibit Name: Ex. G-10
• Media Type: D
• Archive: No

SITE CONDITIONS
Information on the subsurface conditions for the project site was derived from site samples
and other pits in the area. The SerFer Pit site is underlain by Cretaceous age bedrock composed
of Pierre Shale. It is likely that the upper part of the Pierre Shale is transitional with Fox Hills
Sandstone, and grades from predominately shale to shale interbedded with siltstone and sandstone
(Robson, 2000). The bedrock is overlain by unconsolidated Quarternary age sediments composed
of alluviun, colluvium and colian deposits associated with the Platte River basin and Cache la
Poudre Valley.
ALLUVIAL AQUIFER CHARACTERIZATION
Aquifer information was obtained from United Sates Geological Survey (USGS) maps (Robson,
2000) that encompass the site, and local published pump test data (Wilson, 1965). In addition,
water levels were observed during drilling of the exploration holes on the property north of
Highway 392 (Kyger property), (EEC 1999), and (Empire 1985).
Using available groundwater contour maps (Robson, 2000), the groundwater gradient is estimated
to be on the order of 0.006(0.6 feet decline per 100 feet of horizontal distance).
The saturated thickness of the alluvial aquifer varies across the site from about 8 to 12 feet,
averaging approximately 10 feet. In addition, although specific measurements are not available,
published estimates of porosity for the alluvial material (sand and gravel) below the zone of
saturation range from 20 to 30 percent.
The hydraulic conductivity for the aquifer was estimated from local pump test data (Wilson, 1965).
Using the available data, the estimated bulk hydraulic conductivity for the alluvium is 334 feet/day.
This value is within the range of reported hydraulic conductivity values for unconsolidated clean to
silty sands and gravels presented in Freeze and Cherry (1979)
Groundwater velocities across the site will likely vary with localized change in hydraulic
conductivity, hydraulic gradient and porosity. However, the average linear-velocity of groundwater
flow across the site is estimated to be 2 feet/day. This estimate was based on the previously
discussed hydraulic conductivity value, water table gradient, and an average porosity of 25 percent.
PIT DEWATERING AFFECTS
The alluvial aquifer parameters discussed in the previous section were used to estimate the
influence of pit dewatering operations at the SerFer Pit. Dewatering operation include the
construction of perimeter trenches that fully penetrate the alluvium. The bottom of each trench
will be sloped to direct water to one or more pumps where the water will be collected and pumped
from the site.
The perimeter of the entire completed pit is estimated to be approximately 4,600 feet. Although
the average saturated thickness of alluvial groundwater is somewhat less, the alluvial thickness of
10 feet was used to estimate dewatering affects. Therefore the surface area of the alluvial aquifer
exposed by the pit and dewatering trench is 55,200 ftz. Darcy's Law approximates flow into the
trench based on the exposed surface area and the hydraulic properties of the aquifer. Using Darcy's
Connell Resources, Inc. I Serfer Pit Groundwater Monitoring Plan