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Subject Piñon Ridge Made by GG Job No 073-81694

Water Balance Calculation Checked by KFM Date 5/7/2010

Tailings Cell Approved by KFM Sheet No 1 of 7

INTRODUCTION

Golder Associates Inc. (Golder) has prepared this revision of the Tailings Cell Water Balance for Energy 

Fuels Resources Corporation (EFRC) for the Piñon Ridge Project located in Montrose County, Colorado. 

Calculations in this document were based on the water balance originally submitted as a part of the tailings 

cell design by Golder (2008a) for Tailings Cell A (see Figure B-1). For completeness, input parameters and

assumptions used by Golder (2008a) as well as more recent modifications to the design parameters are 

summarized below. 

ASSUMPTIONS AND WATER BALANCE COMPONENTS

Since three tailings cells (A, B, C) of approximately equal tailings storage volume and dimensions have been 

designed for the Piñon Ridge Project to meet a total capacity of approximately 7.3 million tons, the 

probabilistic water balance has been performed for Tailings Cell A only (see Figure B-1). The water balance 

for Tailings Cells B and C will be similar to that of Tailings Cell A. Each of the tailings cells is designed for 

approximately 14 years based on a milling capacity of 500 tons per day (tpd). 

The following water balance components were considered: (1) the amount of water entering Tailings Cell A 

from the mill [revised quantities were developed by CH2M Hill (2009) and are summarized in Figure B2]; (2) water entering the system through meteoric precipitation; (3) the amount of water released to the 

atmosphere through evaporation; (4) the amount of water returning to the mill from Tailings Cell A (as 

provided by CH2M Hill and summarized in Figure B-2); and (5) the excess water available to be pumped 

from the tailings cell. As shown in Figure B-2, the volume of raw water entering the process plant 

averages 130 gpm. This flow rate is less than the total of 141 gpm required for operations, which 

also include non-processing uses such as dust suppression and truck washing. 

Precipitation values are likely to exhibit the largest variations, and were therefore treated as stochastic inputs 

(i.e., probabilistic), while the other parameters were treated as deterministic variables. Water balance 

calculations were performed using the computer program GoldsimTM. The water balance model was run for 

a time of operation of 14 years assuming a milling rate of 500 tpd. 

The water balance model was based on the following equation: 

∆S = (Q + P) – (E + RW + EW)

where:

∆S = change in stored solution volume 

Q = inflow from the mill

P = precipitation collected within the lined footprint of the tailings cell

E = evaporation from the tailings cell surface

RW = reclaimed water from the tailings cell pumped back to the mill

EW = excess water not required by the mill but available to be pumped from the tailings 

cell

INPUT PARAMETERS

Water balance assumptions and sources of input data are summarized in Table 1. 
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Subject Piñon Ridge Made by GG Job No 073-81694

Water Balance Calculation Checked by KFM Date 5/7/2010

Tailings Cell Approved by KFM Sheet No 2 of 7

Table 1. Water Balance Model Assumptions

Property Value Source Comment/Assumptions

Dimensions for 

Tailings Cell A 

725 feet (ft) x 

1,847 ft 

(maximum 

dimensions)

See Figure B-1 Designed as two cells within Tailings Cell A 

with a divider berm constructed at elevation 

5,500 ft and with two independent leak 

collection and recovery systems (LCRS) and 

tailings underdrain systems. Internal side 

slopes of 3H:1V with minimum base grade of 

one percent (%) and 3 ft of dry freeboard.

Watershed Area for 

Tailings Cell A

32.5 acres Golder (2008a) Golder design assumptions. The watershed 

area includes the lined area and the area for 

the access road (due to slope inward toward 

cell). 

Tailings Disposal 

Rate

500 tpd CH2M Hill

(2009)

(see Note 2 and 

Figure B-2) 

Use disposal rate of approximately 500 tpd 

(41,500 lb/hr) to achieve design flow of 252 

gpm (tailings + raffinate). 

Specific Gravity of 

Solids

2.69 CH2M Hill

(2009)

(Note 1)

Solids Content 27.3% CH2M Hill

(2009)

(Note 1)

Average In-Place 

Tailings Dry Density

95 pounds per 

cubic foot (pcf)

Golder (2008a)

Beach Slope 2 and 0.5 % Golder (2008a) Compound slope with 2% for approximately 

500 ft in the perimeter sand zone and 0.5% in 

the slimes zone.

Pumping Rate (from 

Tailings Cell A to 

mill)

187 gpm CH2M Hill 

(2009)

(see Note 2 and 

Figure B-2)

Design return volume flow from Tailings

Cell A to the mill

Percentage of 

Tailings Beach that is 

wet

100% CH2M Hill 

(2009) & Two 

Lines (2009)

(Note 2)

Water sprays used in summer months to 

maintain saturation.

Percentage of 

Tailings Area 

Covered With BirdBalls

50% CH2M Hill 

(2009) & Two 

Lines (2009)

(Note 2)

Climate Data Varies Attachment 1 Use climate date for Uravan 

(NCDC No. 058560)

Annual Pan 

Evaporation

55 to 60 inches See Attachment 1

– Figure 10

Use pan factor of 0.7 to estimate Tailings 

Cell A evaporation

Notes:

1. Based on CH2M Hill (2009). 

2. Based on CH2M Hill (2009) and Two Lines (2009).
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Subject Piñon Ridge Made by GG Job No 073-81694

Water Balance Calculation Checked by KFM Date 5/7/2010

Tailings Cell Approved by KFM Sheet No 3 of 7

The evaluation of climate data conducted by Golder for nearby weather stations indicates that the Uravan 

weather station is likely to provide reasonable precipitation estimates (see Attachment 1). The average 

monthly precipitation values for the Uravan weather station are summarized in Table 2. 

The Hargreaves (1985) method, as discussed in Allen et al. (1998), was used to estimate monthly evaporation 

values at the Piñon Ridge site, based on the available climate data from the Uravan weather station (i.e., 

precipitation, air temperature, etc.). The calculated pan evaporation values were scaled by a factor of 0.7 to 

represent tailings cell evaporation. Monthly evaporation values used for the water balance calculations are 

summarized in Table 2. 

Table 2. Monthly Precipitation and Evaporation Values 

Month

Average* 

Precipitation

(inches)

Minimum*

Precipitation

(inches)

Maximum*

Precipitation

(inches)

Tailings Cell A 

Evaporation 

(inches)

January 0.88 0 3.19 0.8

February 0.76 0 2.05 1.2

March 1.03 0 3.43 2.2

April 1.01 0.03 2.68 3.3

May 0.94 0 2.85 4.8

June 0.48 0 1.65 5.8

July 1.19 0.09 3.54 6.3

August 1.36 0.18 3.32 5.4

September 1.5 0.06 4.78 3.8

October 1.51 0 5.89 2.5

November 1.05 0 2.39 1.2

December 0.88 0.03 3.55 0.7

* Precipitation values obtained for Uravan weather station from 1961 to 2007. 

Based on design-level process water balance information provided by CH2M Hill (2009) and summarized in 

Table 1 and Figure B-2 (with average flow values corresponding to a milling rate of 500 tpd), the design 

mass of solids discharging from the mill to the tailings cell is approximately 41,500 lb/hr. 

As described in Table 1, Tailing Cell A has been designed as essentially two ponds (Cells A1 and A2) within 

a pond (Figure B-1). For simplicity in modeling, the tailings cell water balance was developed assuming that 

Cell A2 will be filled first to its maximum storage capacity prior to initiating tailings slurry discharge flow to 

Cell A1. Once both sub-cells are filled to the mid-height bench level, tailings slurry will then be discharged 

into the entire tailings cell. Tailings slurry will be discharged from several positions around the perimeter of 

the tailings cells. 

Per the design criteria, it was assumed that 3 ft of dry freeboard will be maintained at all times to avoid 

overflow of the tailings cell solution. Solution will only be reclaimed from the tailings cell pool and returned 

to the mill when water pool depth is 5 ft or greater (the lowest assumed water depth for barge pumping 

operation). 
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Subject Piñon Ridge Made by GG Job No 073-81694

Water Balance Calculation Checked by KFM Date 5/7/2010

Tailings Cell Approved by KFM Sheet No 4 of 7

DEVELOPMENT OF STOCHASTIC PRECIPITATION PARAMETERS

In order to develop the stochastic precipitation input for the Goldsim model, continuous probability 

distributions were calibrated against the available monthly precipitation data from the Uravan weather 

station. The Weibull distribution was selected due to its flexibility to represent a wide range of values. The 

distribution is truncated at its lower end and has a long tail to the upper end, making it well-suited to 

modeling extreme positive values, such as precipitation events with longer return periods. Separate Weibull 

distributions were fitted to non-zero precipitation records collected for each month. A moment estimation 

method was used to determine distribution parameters resulting in fitting coefficients summarized in Table 3. 

Table 3. Weibull Distribution Parameters

Month Slope Parameter

(-) 

Mean Minus Minimum*

(inch/month)

January 1.49 0.78 

February 1.35 0.71 

March 1.27 0.97 

April 1.32 0.93 

May 1.13 0.89 

June 0.98 0.44

July 1.57 1.09 

August 1.51 1.28

September 1.28 1.39 

October 1.25 1.46

November 1.75 0.98 

December 1.48 0.76 

*Minimum monthly precipitation was set to 0.1 inches per month for all Goldsim simulations.

To verify the adopted probability distributions, a precipitation model was constructed in GoldsimTM and 

allowed to run for a 1-year period using Monte-Carlo sampling with 1,000 realizations. Goldsim results are 

compared against recorded values for the Uravan weather station in Figures B-3 to B-14 for the months of 

January through December, respectively, with annual totals in Figure B-15. Goldsim results show favorable 

agreement between the measured and calculated extreme values on both a monthly and an annual basis. 

WATER BALANCE RESULTS

The adequate pool volume and additional volume of water available for reclaim were evaluated at different 

stages of Tailings Cell A development assuming a maximum time of operation of 14 years corresponding to 

a milling rate of 500-tpd. Goldsim calculations were based on the stochastic monthly precipitation records 

generated using Weibull’s distribution parameters presented in Table 3, and illustrated in Figures B-3 

through B-14. 
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Subject Piñon Ridge Made by GG Job No 073-81694

Water Balance Calculation Checked by KFM Date 5/7/2010

Tailings Cell Approved by KFM Sheet No 5 of 7

The 1 in 1,000 year reoccurrence storm event was modeled to estimate the pool volume and additional 

volume of water available for reclaim as follows:

( )n Cumulative 11 −−= pyprobabilit , 

where

p = annual probability of occurrence 

n = number of years to evaluate 

Thus, the probability that the 1,000-year storm event will occur during the 14-year tailings disposal period 

for a 500-tpd milling rate is approximately 1.4%. Based on this probability of occurrence, the estimated pool 

volume capacity for Tailings Cell A was estimated for the 98.6th percentile probability. A Monte-Carlo 

simulation with 5,000 realizations (due to relatively high target probabilities in Monte Carlo simulations) was 

used to evaluate the 98.6th percentile quantities after 1, 2, 5, 7 and 14 years of operation. 

Table 4 summarizes the probabilistic tailings cell pool volume during operations for the median and 98.6th

percentile results at various points in time. As shown, the difference between the median value and the 98.6th

percentile result is small, with the pool volume generally increasing during production. The reason for the 

increase in tailings pool volume is directly related to the increase in tailings area during operations, with the

tailings beach maintaining saturation and the minimum depth of water over tailings to enable pumping (set to 

a constant value of 5 feet). These results are illustrated graphically in Figure B-16. 

Table 4. Probabilistic Tailings Cell Pool Volumes

Probability Unit Tailings Cell Pool Volume at Different Times of Operation

Year 1 Year 2 Year 5 Year 7 Year 14

98.6th

percentile

ft3 1,140,490 1,767,720 3,636,150 5,200,970 7,990,870 

Acre-ft 26.2 40.6 83.5 119.4 183.4 

Median ft3 1,140,490 1,767,720 2,811,930 4,584,920 7,697,730 

Acre-ft 26.2 40.6 64.6 105.2 176.7 

* The model was run for a time of operation of 14 years and a milling rate of 500 tpd.

Table 5 presents data for the probabilistic cumulative excess water volume available during operations for 

the median and 98.6th percentile results at various points in time. These results are shown graphically in 

Figure B-19. Based on the median results, a nominal increase in excess water occurs until the beginning of 

Year 5 (approximately 50 months), from which point the excess volume of water is relatively constant. 
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Subject Piñon Ridge Made by GG Job No 073-81694

Water Balance Calculation Checked by KFM Date 5/7/2010

Tailings Cell Approved by KFM Sheet No 6 of 7

Table 5. Probabilistic Cumulative Excess Water Volumes Available from the Tailings Cell

* The model was run for a time of operation of 14 years and a milling rate of 500 tpd.

Table 6 summarizes the probabilistic average excess pumping rate from the tailings cell (above the design 

rate of 187 gpm) during operations for the median and 98.6th percentile results at various points in time. This 

information is presented graphically in Figure B-18. The volume of water available as excess decreases to

nearly negligible amounts by Year 3 based on the median and 98.6th percentile results. Due to the smaller 

footprint of tailings placed early on during operations, the volume of water available for pumping is likely

greater as it takes less water to achieve increased water depth (above 5 feet). 

Table 6. Probabilistic Average Excess Pumping Rates

Probability Unit

Probabilistic Average Excess Pumping Rates at Different Time 

Intervals of Operation

Years 0-1 Years 0-2 Years 3-5 Years 6-7 Years 8-14 

98.6th

percentile

gpm 16.4 16.4 1.7 1.8 1.2 

Acre-ft/yr 26.5 26.5 2.7 2.9 1.9

Median gpm 2.1 2.1 0.6 0.0 0.0 

Acre-ft/yr 3.4 3.4 1.0 0.0 0.0 

SUMMARY

The stochastic water balance model for the 500-tpd milling rate indicates that a maximum tailings cell pool 

volume of approximately 7.99 million ft3 (Mft3

) (i.e., 183.4 acre-ft) is obtained for the 98.6th percentile (i.e., 

1,000-year storm occurs during deposition), with a median pool volume of 7.70 Mft3 (176.7 acre-ft) (Figure 

B-16). At all times during operations, a minimum excess volume capacity of 3.94 Mft3 (90.4 acre-ft) of 

freeboard volume (corresponding to 3 ft of dry freeboard) will be available to prevent overtopping during 

tailings deposition. 

As demonstrated on Figures B-18 and B-19, the volume of excess water available as make-up (in excess of 

the design return volume flow to the mill) is essentially negligible after approximately 4 years (50 months). 

The average excess pumping rates available to pump excess water from the tailings cell at different time 

intervals of the operation are summarized in Table 5. Results were estimated assuming that the mill will 

have a pumping rate of 187 gpm available to pump back reclaimed water from the tailings cell to the mill 

(per CH2M Hill [2009] as illustrated in Figure B-23), and that the available excess water can be: (1) pumped 

back to the mill where the water could be used as make-up water; or (2) discharged into the evaporation pond 

system. It should be noted that the design raffinate flow rate to the evaporation ponds, provided by CH2M 

Probability Unit

Probabilistic Cumulative Excess Water Volumes Available from the 

Tailings Cell at Different Times of Operation 

Year 1 Year 2 Year 5 Year 7 Year 14

98.6th

percentile

ft3 740,432 1,561,560 6,291,930 8,015,720 14,640,000

Acre-ft 17.0 35.8 144.4 184.0 336.1 

Median ft3 305,920 761,941 4,064,210 4,064,210 4,535,010

Acre-ft 7.0 17.5 93.3 93.3 104.1
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Subject Piñon Ridge Made by GG Job No 073-81694

Water Balance Calculation Checked by KFM Date 5/7/2010

Tailings Cell Approved by KFM Sheet No 7 of 7

Hill, is an average value which already accounts for this potential excess flow from the tailings cells during 

discrete time intervals. 

As shown on Figure B-17, a design return volume flow of 187 gpm might not be achievable at some time 

intervals over the design life of the tailings cell. The excess water available from the tailings cell during wet 

times, therefore, can be used to accommodate this need during the dry times. As demonstrated by the water 

balance, the mill is designed to maximize reclaim and re-use of water to the mill for processing. 

A separate water balance has been developed to size the evaporation pond system (i.e., aerial extent) for the 

Piñon Ridge Project, as presented in Golder (2008b). The evaporation pond water balance was performed 

based on a design process water inflow (raffinate from the mill) to the evaporations ponds of 63 gpm for 500 

tpd milling operations. As shown in Figure B-2, the design flow rate to the evaporation ponds has reduced 

nominally to 53 gpm. In effect, the volume of raffinate flowing from the mill to the evaporation ponds will 

be disposed of via evaporation. 

REFERENCES

Allen, R.G., Pereira, L.S., Raes, D. and Smith, M., 1998, “FAO Irrigation and Drainage Paper No. 56 – 

Crop Evapotranspiration” (latest revision 2002). 

CH2M Hill Engineers, Inc. (CH2M Hill), 2009, “Basic Engineering Report and Cost Estimates, 

Piñon Ridge Project, Naturita, Colorado.” 4 February 2009. 

Hargreaves, G.L., Hargreaves, G.H., and Riley, J.P., 1985, "Agricultural benefits for Senegal River Basin", 

Journal of Irrigation and Drainage Engrg, ASCE 111:113-124. 

Golder Associates Inc. (Golder), 2008a, “Tailings Cell Design Report, Piñon Ridge Project, Montrose 

County, Colorado,” October.

Golder Associates Inc. (Golder), 2008b, “Evaporation Pond Design Report, Piñon Ridge Project, Montrose 

County, Colorado,” October.

Two Lines, Inc., 2009, “Estimation of Radiation Doses to Members of the Public from the Piñon 

Ridge Mill,” Report prepared for Energy Fuels Resources Corporation, November. 
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FIGURES

Process Plant

12 gpm

VENTS

130 gpm

RAW WATER

53 gpm

VANADIUM SX RAFFINATE

EVAPORATIONPONDS

TAILINGS CELLS

252 gpm

TAILINGS PLUS VANADIUM SX RAFFINATE

187 gpm

RETURN WATER

65 gpm53 gpm

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

BALANCE FLOW RATES FOR 500-TPD PRO

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

Process Plant

12 gpm

VENTS

130 gpm

RAW WATER

53 gpm

VANADIUM SX RAFFINATE

EVAPORATIONPONDS

TAILINGS CELLS

252 gpm

TAILINGS PLUS VANADIUM SX RAFFINATE

187 gpm

RETURN WATER

65 gpm53 gpm

BALANCE

LEGEND:

NOTES:

1. Balance flows provided are for 500 tpd operations and are aver

2. Refer to figure B‐2 for effects of precipitation on the water bala

3. Flow valuesfrom CH2M Hill (2009).
0 05

0.1

0.15

0.2

0.25

0.3

Probability Density

January Data Histograms with Weibull Distribution Fit to Uravan Historical Precipitatio

Data

Weibull DistGoldisim VaData Values

GG May-10 

KFM AS SHOWN KFM 

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL D

JANUARY

0

0.05

0.1

0.15

0.2

0.25

0.3

-0.13

0.13

0.38

0.63

0.88

1.13

1.38

1.63

1.88

2.13

2.38

2.63

2.88

3.13

3.38

3.63

3.88

4.13

4.38

4.63

4.88

5.13

5.38

5.63

5.88

6.13

6.38

6.63

6.88

7.13

7.38

7.63

Probability Density

Data Value

January Data Histograms with Weibull Distribution Fit to Uravan Historical Precipitatio

Data

Weibull DistGoldisim VaData Values
0.05

0.1

0.15

0.2

0.25

0.3

Probability Density

February Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution Goldisim ValuesData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIS

FEBRUARY

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.05

0.1

0.15

0.2

0.25

0.3

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

8.00

Probability Density

Data Value

February Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution Goldisim ValuesData Values
0.05

0.1

0.15

0.2

0.25

Probability Density

March Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIS

MARCH

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.05

0.1

0.15

0.2

0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

800

Probability Density

Data Value

March Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values
0.04

0.060.08

0.1

0.120.140.160.18

0.2

Probability Density

April Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution GoldData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIS

APRIL

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.020.040.060.08

0.1

0.120.140.160.18

0.2

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

800

Probability Density

Data Value

April Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution GoldData Values
0.05

0.1

0.15

0.2

0.25

Probability Density

May Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution GoldiData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIS

MAY

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.05

0.1

0.15

0.2

0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

800

Probability Density

Data Value

May Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution GoldiData Values
0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Probability Density

June Data Histograms with Weibull Distribution Fit to Uravan Historical Precipitatio

Data

Weibull Distribution GoData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIST

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

Probability Density

Data Value

June Data Histograms with Weibull Distribution Fit to Uravan Historical Precipitatio

Data

Weibull Distribution GoData Values
0.05

0.1

0.15

0.2

0.25

Probability Density

July Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DI

JULY

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.05

0.1

0.15

0.2

0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

8.00

Probability Density

Data Value

July Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values
0.04

0.060.08

0.1

0.120.140.16

Probability Density

August Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributionGoldisim ValuesData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIS

AUGUST

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.020.040.060.08

0.1

0.120.140.16

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

8.00

Probability Density

Data Value

August Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributionGoldisim ValuesData Values
0.04

0.060.08

0.1

0.120.140.16

Probability Density

September Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIS

SEPTEMBER

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.020.040.060.08

0.1

0.120.140.16

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

8.00

Probability Density

Data Value

September Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values
0.04

0.060.08

0.1

0.120.140.160.18

Probability Density

October Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DI

OCTOBER

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.020.040.060.08

0.1

0.120.140.160.18

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

800

Probability Density

Data Value

October Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull DistributioGoldisim ValuesData Values
0 05

0.1

0.15

0.2

0.25

0.3

Probability Density

November Data Histograms with Weibull Distribution Fit to Uravan Historica

Precipitation Data

Weibull DistributGoldisim ValuesData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL DIS

NOVEMBER

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.05

0.1

0.15

0.2

0.25

0.3

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

800

Probability Density

Data Value

November Data Histograms with Weibull Distribution Fit to Uravan Historica

Precipitation Data

Weibull DistributGoldisim ValuesData Values
0.1

0.15

0.2

0.25

0.3

0.35

Probability Density

December Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution GoData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL D

DECEMBER

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

3.00

3.25

3.50

3.75

4.00

4.25

4.50

4.75

5.00

5.25

5.50

5.75

6.00

6.25

6.50

6.75

7.00

7.25

7.50

7.75

Probability Density

Data Value

December Data Histograms with Weibull Distribution Fit to Uravan Historical 

Precipitation Data

Weibull Distribution GoData Values
0.04

0.060.08

0.1

0.120.140.160.18

Probability Density

Annual Data Histograms with Weibull Distribution Fit to Uravan Historical Precip

Data

Weibull DistribGoldisim ValueData Values

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

URAVAN DATA, GOLDSIM RESULTS AND WEIBULL D

ANNUAL PRECIPITATION

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0

0.020.040.060.08

0.1

0.120.140.160.18

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

16.00

17.00

18.00

19.00

20.00

21.00

22.00

23.00

24.00

25.00

26.00

27.00

28.00

29.00

30.00

31.00

Probability Density

Data Value

Annual Data Histograms with Weibull Distribution Fit to Uravan Historical Precip

Data

Weibull DistribGoldisim ValueData Values
1.0E+06

2.0E+063.0E+064.0E+065.0E+066.0E+067.0E+068.0E+069.0E+06

Pool Volume (ft

3

)

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

TAILINGS CELL POOL VOLUME FOR 500-TPD M

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0.0E+001.0E+062.0E+063.0E+064.0E+065.0E+066.0E+067.0E+068.0E+069.0E+06

0 20 40 60 80 100 120 140 

Pool Volume (ft

3

)

Time (month)

Mean Least Result 5% 25% Median 75% 95% Gr
110

120130140150160170180190200

Pumping Rate (gpm)

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

PUMPING RATE AVAILABLE TO RETURN RECLA

TO MILL FOR 500-TPD MILLING RAT

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

100110120130140150160170180190200

0 20 40 60 80 100 120 140 

Pumping Rate (gpm)

Time (month)

Mean Median 95% Greatest Result
2

468

1012141618

Pumping Rate (gpm)

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

EXCESS PUMPING RATE FOR 500-TPD MILL

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

02468

1012141618

0 20 40 60 80 100 120 140 160 

Pumping Rate (gpm)

Time (month)

Mean Median 95% Greatest Result
5.0E+06

1.0E+071.5E+072.0E+072.5E+07

Excess Volume (ft

3

)

GG May-10 

KFM AS SHOWN KFM FiguresB-rev6May2010.xlsm 

AVAILABLE EXCESS MAKE-UP WATER V

FOR 500-TPD MILLING RATE

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

0.0E+005.0E+061.0E+071.5E+072.0E+072.5E+07

0 20 40 60 80 100 120 140 16

Excess Volume (ft

3

)

Time (month)

Mean Least Result 5% 25% Median 75% 95% Greate
May 2010 073-81694 C:\Users\kglaspey\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Outlook\S56HZGBQ\Attachment B Text-WBCalc-07May2010 (2).docx

ATTACHMENT 1 TO APPENDIX B

WEATHER DATA ANALYSIS





S ÑO G

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

SITE VIEW PIÑON RIDGE

EF 1/16/2008

N.T.S

FIGURE.PPT

KFM GG
Uravan

S O OC 

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

WEATHER STATION LOCAT

EF 1/16/2008

N.T.S

FIGURE.PPT

GGKFM
16

18

Nucla

1214

in]

Grand Junction AirportMontroseUravan

8

1012

Precipitation [

46

Total 

02

1999 2000 2001 2002 2003 2004 2005 2006 

O C O 

Year

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

TOTAL ANNUAL PRECIPITATION 

1999 TO 2007

EF 1/16/2008

N.T.S

FIGURE.PPT

GGKFM
5800

6000

Nucla

54005600

t)

Montrose

Piñon Ridge Project Elevation EL. 5,480 ft

480050005200

Elevation (ft

Grand Junction 

Uravan

420044004600

E

Grand Junction 6ESE

40004200

8 9 10 11 12 

Mean Annual Precipitation (in)

VARIATION IN ANNUAL PRECIPITATION 

Annual Precipitation (in)

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

EF 1/16/2008

N.T.S

FIGURE.PPT

VARIATION IN ANNUAL PRECIPITATION 

REGIONAL METEOROLOGICAL 

GGKFM
3

URAVAN 1965

2

2.5

[in]

URAVAN 1989

1

1.5

Precipitation 

0

0.5

Month

MONTHLY PRECIPITATION FOR DRIES

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

MONTHLY PRECIPITATION FOR DRIES

YEAR FOR URAVAN SIT

EF 1/16/2008

N.T.S

FIGURE.PPT

GGKFM
3

URAVAN 1965

2

2.5

in]

URAVAN 1965Grand Junction Airport 1965

1

1.5

Precipitation [

0.5

0

O C O CO 

Month

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

EF 1/16/2008

N.T.S

FIGURE.PPT

MONTHLY PRECIPITATION COMPAR

URAVAN AND GRAND JUNCTION FO

GGKFM
2.5

URAVAN 1989

1 5

2

[in]

Grand Junction Airport 1989

1

1.5

Precipitation 

0

0.5

Month

O C

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

EF 1/16/2008

N.T.S

FIGURE.PPT

MONTHLY MAXIMUM TEMPERATURE C

FOR URAVAN AND GRAND JUNC

GGKFM
74

76

Nucla

7072

]

Grand Junction AirportUravanMontrose

666870

m Temperature [°F]

62

Maximu 64m

5860

1999 2000 2001 2002 2003 2004 2005 2006 

CO 

1999 2000 2001 2002 2003 2004 2005 2006 

Year

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

EF 1/16/2008

N.T.S

FIGURE.PPT

ANNUAL MAXIMUM TEMPERATURE CO

1999 TO 2007

GGKFM
6000

Nucla

540056005800

Montrose

Piñon Ridge Project Elevation EL. 5,480 ft

480050005200

evation (ft) Grand Junction Uravan

440046004800

Ele

Grand Junction 6ESE

40004200

40 50 60 70 80 

Mean Annual Maximum Temperature (oF)

VARIATION IN ANNUAL MAX TEMPERATURE 

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

EF 1/16/2008

N.T.S

FIGURE.PPT

VARIATION IN ANNUAL MAX. TEMPERATURE 

REGIONAL METEOROLOGICAL S

GGKFM
COLORADO

Piñon Ridge site

G O O ( C S

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

EF 1/16/2008

N.T.S

FIGURE.PPT

AVERAGE ANNUAL EVAPORATION (INCHES

LAKES

GGKFM
O O S O 

ENERGY FUELS RESOURCES CORPORATION

PIÑON RIDGE PROJECT

EF 1/16/2008

N.T.S

FIGURE.PPT

M

ONTHLY EVAP

OTRAN

SPIRATI

ON AND P

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