2009-05-19_REVISION - M1981021 ‎(32)‎

• Permit No: M1981021
• IBM Index Class Name: REVISION
• Doc Date: 5/19/2009
• Doc Name: EPP ‎(AM-01)‎ Attachment A: Transport; Att.B,1,2 Geochem. ‎(part 2)‎
• From: Denison Mines
• To: DRMS
• Type & Sequence: AM1
• Email Name: RCO
• Media Type: D
• Archive: No

Section 4
Potential for Rock to be Toxic-Forming
•

Exhibit 4-1. 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 4-1 indicates that potential ET at the Sunday Mines Group
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 exceed monthly precipitation during all months of the year.
Exhibit 4-2 presents a similar estimate using precipitation conditions the occurred during the
wettest year on record, 1997.
Exhibit 4-2. 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
Janus 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 4-2 for the wettest year on record indicates that potential
ET exceeds precipitation by a ratio of approximately 2.1, 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
CDM 4-11
7:184986-Denison MineslTask Order 3 - DMO Sampling and Analysis Plan%Task 3.12 - Soil, Ore, Rock Data Assessment Reporll6unday Rock Reportlfinal reportlReporBFinal Sunday Mines Group Soil Ore Rock
Data Assesamera Report_951509.doc