PERMFILE67692

• Permit No: C1982056
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 49 PHC Modification Support Tables
• Media Type: D
• Archive: No

•
Table E49-17
Impacts to Receiving Streams -Minimum Required Stream Flow at Maximum Site 115 Discharge, 2014
Minimum Flow Rate in Trout below Fish Creek to prevent exceeding 250 mglL Sulfate in Dry Year
Mine discharges (max. loading)
(see Case 1) Flow I
cfs Flow
gpm j TDS . Conduct. ~
mg/L ;umhos/cm; Sulfate Year
mg/L 1
109 1.361 612; 23001 31001 13001 2014
115 2.67; 1200; 2900; 3900; 1800; 2014
Baseline Mean Flow Calculated; Baseline Dry Year Flow
Estimated Baseline Flow ~ TDS ~ Conduct. ~ Sulfate Flow TDS ~ Conduct. ~ Sulfate
cfs ; mg/L ; umhos/cm ~ mglL cfs mg/L ; umhos/cm1 mglL
Trout Creek, above Fish Creek 46.41 383; 511; 158 53.21 412t 549 174
Fish Creek above confl. W/ Trout 26.01 4411 5881 172 22.3. 456. 6081 181
Trout Creek below Fish Creek 1999 72.4;
; 404;
; 538;
; 163 75.41 425; 6 176
Predicted Values ;
;
;
;
;
;
;
2014 ; ; ;
;
;
;
Trout Creek, above Fish Creek 47.81 _ 4381 5851 191 54.51 4591 6131 202
Fish Creek above confl. W/ Trout Creek 28.7j 670; 897; 324 24.91 718; 961; 355
Trout Creek below Fish Creek 76.4; 5 5 702 241 79.51 5401 722 250
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Trout Creek below Fish Creek flow rate iteratively changed until sulfate concentration equaled 250 mg/L. Fish Creek above confl.
w/ Trout flow rate estimated to be 29.5% of Trout Creek below Fish Creek (see Table 12). Trout Creek above Fish Creek
is difference between two other flows
Mine Discharge Data Flow 8 conductivity from estimated future water balance. TDS calculated from conductivity:
TDS = 0.75' cond. Except for conductivities greater than 5000 umhoslcm: TDS = 0.84 • cond.
Sulfate far 109 from 3/30/99 analysis of 6 Right inflow, lower values prorated from TDS value
Sulfate for 115 from 2/8/99 analysis, lower values prorated from TDS value
Baseline Water quality data taken Low Flow Data from Exhibit 32
Trout Creek below Fish Creek is value being calculated
Other segment flows set to be same ration of flows in Low Flow baseline conditions in Exhibit 32
Predicted values calculated using mass balance equation shown in text (2.05.6(3)(b)(iii) Probable Hydrologic Consequences, Surtace
Water Systems, Impacts of Mine Water Discharge)
TR 9837 Table E49-17
11/15/99