2009-06-08_REVISION - M1997032

• Permit No: M1997032
• IBM Index Class Name: REVISION
• Doc Date: 6/8/2009
• Doc Name: EPP ‎(AM-01)‎ Amendment Application and Sections 1-19 ‎(part 1)‎
• From: Denison Mines
• To: DRMS
• Type & Sequence: AM1
• Email Name: RCO
• Media Type: D
• Archive: No

Section 13
Geochemical Data and Analysis
•
Exhibit 13-1. Estimated Percolation Through Development Rock Areas for Average Precipitation
Month Potential
ET (in.) Precipitation
(in.) Actual
ET (in.) Runoff
(in.) Infiltration
(in.) Percolation
(in.)
October 3.36 1.51 1.36 0.15 1.36 0.00
November 2.19 1.05 0.95 0.11 0.95 0.00
December 0.48 0.85 0.48 0.09 0.77 0.00
January 0.47 0.88 0.47 0.09 0.79 0.00
February 1.94 0.76 1.30 0.08 0.69 0.00
March 2.93 1.04 0.94 0.10 0.94 0.00
April 3.70 1.01 0.91 0.10 0.91 0.00
May 4.93 0.94 0.84 0.09 0.84 0.00
June 5.72 0.47 0.43 0.05 0.43 0.00
Jul 6.34 1.18 1.06 0.12 1.06 0.00
August 5.74 1.35 1.22 0.14 1.22 0.00
September 4.43 1.50 1.35 0.15 1.35 0.00
Annual Total 42.33 12.55 11.29 1.25 11.29 0.00
The estimate summarized in Exhibit 13-1 indicates that potential ET exceeds average
precipitation by a ratio of approximately 3.4 to 1. Under average conditions, available
ET is adequate to evaporate water infiltrating the surface of the rock piles. A
temporary increase in stored soil moisture would occur during the months of January
and February, but this water would be removed from the pile by ET in later months.
Monthly estimated ET exceeds monthly precipitation during all months of the year.
Exhibit 13-2 presents a similar estimate using precipitation conditions the occurred
. during the wettest year on record, 1997.
Exhibit 13-2. Estimated Percolation Through Development Rock Areas for Wettest Year on Record
Month Potential
ET (in.) Precipitation
in. Actual
ET (in.) Runoff
in.) Infiltration
(in. Percolation
(in.
October 3.36 2.36 2.12 0.24 2.12 0.00
November 2.19 2.16 1.94 0.22 1.94 0.00
December 0.48 1.80 0.48 0.18 1.62 0.00
January 0.47 1.09 0.47 0.11 0.98 0.00
February 1.94 0.48 1.94 0.05 0.43 0.00
March 2.93 0.17 0.30 0.02 0.15 0.00
April 3.70 2.41 2.17 0.24 2.17 0.00
May 4.93 1.78 1.60 0.18 1.60 0.00
June 5.72 0.62 0.56 0.06 0.56 0.00
Jul 6.34 1.20 1.08 0.12 1.08 0.00
August 5.74 1.10 0.99 0.11 0.99 0.00
September 4.43 4.70 4.23 0.47 4.23 0.00
Annual Total 42.23 19.87 17.88 1.99 17.88 0.00
The estimate summarized in Exhibit 13-2 for the wettest year on record indicates that
potential ET exceeds precipitation by a ratio of approximately 2.1:1, and suggests that
water infiltrating the pile also evaporates during the year. During the months of
December and January, the monthly precipitation exceeds the estimated monthly ET.
Therefore, stored moisture within the rock pile would be expected to increase during
December and January. However, excess ET occurring in latter months is estimated to
be adequate to remove this moisture through ET, preventing percolation through the
13-6
T:\64986-Denison Mines\Task Order 4 - EPP Sunday Mines Group-Van4\Van4\FINAL Repod\FINAL - Environmental Protection Plan Van4.doc