2009-05-19_REVISION - M1977416 ‎(29)‎

• Permit No: M1977416
• IBM Index Class Name: REVISION
• Doc Date: 5/19/2009
• Doc Name: EPP‎(AM-01)‎ Att 4: Bioavailability; Att 5: Water Bal; Att 6: Percolation; Att 7: Lab Rpts. ‎(part 4)‎
• From: Denison Mines
• To: DRMS
• Type & Sequence: AM1
• Email Name: RCO
• Media Type: D
• Archive: No

Job #: 68838.64986.03.3.14 Calc By: N. Anton; M. Nelson
Client: Denison Mines CHK By: G. Hazen Date: 1/27/2009
Project: Hydrogeology Report Date: 2/3/2009 Calc #: 1
Detail: Water Balance Estimation of Percolation
MA5 lo5 + SmAC4 = 1.291 MA5 is now than less than PETS, so AET5 = MA5, and
there is no additional water left for soil moisture
AET5 := MA5 = 1.291 storage.
SmMONTH5 lo5 - AET5 = -0.607 Monthly Sm calculation.
SmAC5 SmMONTH5 + SmAC4 = 0 Total accumulated Sm equals current monthly Sm plus the
previous month's total accumulated Sm.
After February, all of the stored moisture has been evaporated from the soil. For all of the
remaining months of the year, there is no more excess soil moisture storage. No percolation was
estimated to occur based on the water balance model approach for this case.
The same calculations can be completed for the second modeling case, for the wettest water year
on record. The water balance calculations are shown below in Table C:
Table C - Water Balance Ca lculati on for Wettest Water Year (1997)
Moisture Holding Capacity (Sa) = 2.07

onth Total
Monthly Pi
Water Year
1997* (in)

PET
(in)

Ro
(in)

Io
(in)

MA
(in)

AET
(in)

Monthly S,,,
(in)
Total
Accumulated
S,,, (in)

P.
(in)
October 2.36 3.36 0.24 2.12 2.12 2.12 0.00 0.00 0.00
November 2.16 2.19 0.22 1.94 1.94 1.94 0.00 0.00 0.00
December 1.80 0.48 0.18 1.62 1.62 0.48 1.14 1.14 0.00
January 1.09 0.47 0.11 0.98 2.12 0.47 0.51 1.65 0.00
February 0.48 1.94 0.05 0.43 2.08 1.94 -1.51 0.14 0.00
March 0.17 2.93 0.02 0.15 0.30 0.30 -0.14 0.00 0.00
April 2.41 3.70 0.24 2.17 2.17 2.17 0.00 0.00 0.00
May 1.78 4.93 0.18 1.60 1.60 1.60 0.00 0.00 0.00
June 0.62 5.72 0.06 0.56 0.56 0.56 0.00 0.00 0.00
July 1.20 6.34 0.12 1.08 1.08 1.08 0.00 0.00 0.00
August 1.10 5.74 0.11 0.99 0.99 0.99 0.00 0.00 0.00
September 4.70
1 4.43 0.47 4.23 4.23 4.23 0.00 0.00 0.00
Annual Total 19.87 42.231 1.99 17.88 20.82 17.88 0.00 2.94 0.00
11997 is the we ttest water year on record at the Uravan, CO N OAA weather station.
For this modeling case, the same results are observed as for the first case. A buildup of soil
moisture occurs during the winter months, followed by a decrease in soil moisture until all
moisture is evaporated during each month.
6.0 Conclusions/Results
Estimation of percolation through Sunday Mine Group development rock piles were completed
using a water balance approach. Climate data from the Uravan, CO NOAA weather station and
laboratory geotechnical data from the Topaz Mine development rock pile sample was used to
run the model calculations. The model was completed on a monthly basis for average
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