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 E49-18
Impacts to Receiving Streams -Minimum Required Stream Flow at Minimum Site 115 Discharge, 1999
Minimum Flow Rate in Trout below Fish Creek to prevent exceeding 250 mg/L Sulfate in Dry Year
Minimum Mine Discharge Rates Required to Discharge All Net Mine Inflow
Mine discharges (max. loading) Flow Flow TDS ;Conduct. ; Sulfate Year
1
(see Case 1) cfs gpm mg/L ~ umhos/cm; mg/L
109 0.76 3421 3000; 4000; 16001 1999
115 0.12; 55: 6100; 7300; 3300; 1999
Baseline Mean Flow Calculated Baseline Dry Year Flow
Estimated Baseline Flow TDS Conduct. 1 Sulfate Flaw 1 TDS 1 Conduct. 1 Sulfate
cfs mg/L ; umhos/cm ; mg/L cfs mg/L ;umhos/cm; mg/L
Trout Creek, above Fish Creek 46.41 3831 5111 158 13.41 4121 5491 174
Fish Creek above confl. W! Trout 26.0; 441; 588; 172 5.6; 456; 608; 181
Trout Creek below Fish Creek 1999 72.41
1 4041 5381
1 163 19.01
1 4251 567{ 176
Predicted Values ~ 1
1999
Trout Creek, above Fish Creek 47.21 4251 5671 181 14.11 5521 735; 251
Fish Creek above confl. W/ Trout Creek 26.1; 468; 619; 187 5.7; 577; 751;
~ 248
-
Trout Creek below Fish Creek 73.3; 4401 586; 183 19.9; 559; 74
0; 250
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
a is difference between two other flows
'G
'O Mine Discharge Data Flow & conductivity from estimated future water balance. TDS calculated from conductivity:
~ TDS = 0.75 • cond. Except for conductivities greater than 5000 umhos/cm: TDS = 0.84 'cond.
~ Sulfate for 109 from 3/30/99 analysis of 6 Right inflow, lower values prorated from TDS value
C
F=9 Sulfate for 115 from 2/8/99 analysis, lower values prorated from TDS value
t~
~ Baseline Water quality data taken Low Flow Data from Exhibit 32
~ Trout Creek below Fish Creek is value being calculated
o 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, Surface
o Water Systems, Impacts of Mine Water Discharge)
`~ Example: Fish Creek above confl. W/Trout Creek, 1999 Predicted TDS =
[[0.12(Flow~)•6100(TDS)]+[26.0(FlowZ)•441(TDSZ)]]/26.1(FIOwT~) = 468
TR 9372 Table E49-18
11/15/99