2009-06-08_REVISION - M1997032 ‎(21)‎

• Permit No: M1997032
• IBM Index Class Name: REVISION
• Doc Date: 6/8/2009
• Doc Name: EPP ‎(AM-01)‎ Attachment 1,2,&3 of Attachment A ‎(part 2)‎
• From: Denison Mines
• To: DRMS
• Type & Sequence: AM1
• Email Name: RCO
• Media Type: D
• Archive: No

Secfion 4
Pofenfia/forRock fo be Toxic Forming
• approach including description of model nodes and boundary conditions, description
of climate data sources, and definition of soil characteristics.
0

Exhibit 4-3 summarizes the results of the modeling effort for the West Sunday and
Topaz Mines on an annual basis. Additional detail, including daily percolation
estimates are included in Attachment 6. The estimate was completed for the West
Sunday and Topaz Mines and for average annual precipitation and the wettest year
on record.
Exhibit 4-3. Summa of UNSAT-H modelin results
Model Run Annual Annual Annual Annual Annual Annual
Potential Precipitation Actual Runoff (in.) Infiltration Percolation
ET (in.) (in.) Evap. (in.) (in.) (in.)
West 67.0 12.8 12.7 0.0527 12.7 0.0103
Sunday-
Average
Precipitation
West 67.0 19.9 18.07 0.190 19.7 0.0106
Sunday-
Wettest year
on Record
Topaz- 67.0 12.8 12.7 0.0185 12.7 0.00822
Average
Precipitation
Topaz- 67.0 19.9 18.1 0.0619 19.8 0.00849
Wettest year
on Record
Based on the UNSAT-H simulations, the estimated percolation through the rock piles
is estimated to range from 0.008 to 0.011 inches per year. The simulations show the
importance of evaluating upward movement of water from the rock piles caused by
evaporation because the majority of water that infiltrates the surface of the
development rock piles evaporates in the semi-arid environment.
The UNSAT-H simulations suggest that significant percolation from the base of the
development rock piles is unlikely. However, a small amount of percolation is
estimated for all simulations. The simulations further suggest that infiltration of
precipitation followed by upward evaporative flux of water stored within the
development rock areas are dominant mechanisms controlling the volume of
percolation through the development rock areas. Minor differences in the physical
characteristics of the development rock from West Sunday and Topaz mines as well
as the magnitude of annual precipitation are less important controls on the expected
volume of percolation. Additional sensitivity analyses were also conducted and
indicate that the model is not particularly sensitive to modifications in convergence
4-13