2007-11-01_PERMIT FILE - C1982056A ‎(4)‎

• Permit No: C1982056A
• IBM Index Class Name: Permit File
• Doc Date: 11/1/2007
• Section_Exhibit Name: 2.06 Special Categories of Mining
• Media Type: D
• Archive: Yes

Middle Creek is not considered in this evaluation because the CMLRD has previously concluded that
Middle Creek "would no[ be affected and need not be considered further" by the proposed Foidel Creek
• mining operations (page 14 of Foidel Creek Mine, C-056-82, Findings Document). Since no hydrologic
connection exists between [he Foidel Creek Mine and Middle Creek and since the proposed mining is
moving further away from the Middle Creek drainage, no additional evaluation of the impacts of irrigation
along Middle Creek is necessary.
In evaluating the potential crop salt tolerance interactions, the information calculated for the salt loading
analysis in the Probable Hydrologic Consequences section was used. As recommended by the CMLRD,
the data utilized in this analysis are based upon historical low Flow conditions encountered in the August,
September and October period. Projected mine water discharges were factored into the historic Flow rates
to arrive at a projected water quality value. In order to assure that "worst case" conditions were satisfied
and since irrigation waters are applied over an extended period of time, an average electrical conductivity
value for the August through October time period was used.
In order to evaluate whether or not a potential problem of salinization exists, the following equation in
Handbook GO (page 36) was used.
Diw/Ds = (ds/dw) (SP/ 100) (DEC/ECiw)
•
where:
Diw = the depth of irrigation water;
Ds = depth of soil;
ds = soil density;
dw = density of water;
SP = saturation percentage;
DEC = allowable change in soil salinity threshold is crossed; and
ECiw = conductivity of irrigation water.
Inputs into this equation were obtained from site specific soils and water data collected by TCC and its
affiliated companies and by prior research efforts in the immediate mine plan area. The density of the soil
(ds) was obtained from hydrologic studies conducted by the USDA Agricultural Research Service in prior
hydrologic investigations and from their current hydrologic investigations of grazing of reclaimed mine
areas at Energy Mines No. 2 and 3. A total of 22 undisturbed soil bulk density values at these sites yielded
an average bulk density of 1.25 gms/cm3. The density of water (dw) was assumed to be equal to 1.0
gms/cm3. The saturation percentage of the soil (SP) was obtained from 238 undisturbed soil samples
collected by Energy Fuels, the U.S. Forest Service and TCC and submitted in CYCC Permit Application
79-177 and in this permit revision application. The average saturation percentage value was found to
equal 46.4 percent. The allowable change in soil salinity was calculated from an average of 238 electrical
conductivity values collected in the same studies referenced for SP, plus 22 soil conductivity values
obtained from soils data collected and analyzed by the Colorado State University on irrigated agricultural
lands along Trout Creek and the Yatnpa River. The average of the 22 alluvial samples was found to equal
0.509 mmhos/cm while the average of all of the soil conductivity values was found [o equal 0.606
nunhos/cm. In order to be conservative, the higher EC value was used. Using the threshold value for
altalfa of 2.0 mmhoslcm, as previously described in Table I of Maas and Hoffman, an allowable change in
electrical conductivity of the soil is 1.394 mmhos/cm ~EC equals 2.0 - 0.606). The parameter ECiw was
calculated along Fish Creek to equal 1.22 mmhos/cm and 0.82 mmhos/cm along Trout Creek at the points
where affected waters of the Foidel Creek drainage may first be utilized for irrigation. The combined
value of waters below the conFluence of Fish Creek and Trout Creek was calculated to be 0.91 mmhos/cm.

MR 97-I54
2.06- 17
Revised 12/09!97